Going End to End to Deliver High-Speed Data

NASA Technical Reports Server (NTRS)

2005-01-01

By the end of the 1990s, the optical fiber "backbone" of the telecommunication and data-communication networks had evolved from megabits-per-second transmission rates to gigabits-per-second transmission rates. Despite this boom in bandwidth, however, users at the end nodes were still not being reached on a consistent basis. (An end node is any device that does not behave like a router or a managed hub or switch. Examples of end node objects are computers, printers, serial interface processor phones, and unmanaged hubs and switches.) The primary reason that prevents bandwidth from reaching the end nodes is the complex local network topology that exists between the optical backbone and the end nodes. This complex network topology consists of several layers of routing and switch equipment which introduce potential congestion points and network latency. By breaking down the complex network topology, a true optical connection can be achieved. Access Optical Networks, Inc., is making this connection a reality with guidance from NASA s nondestructive evaluation experts.

Nonlinear optical and G-Quadruplex DNA stabilization properties of novel mixed ligand copper(II) complexes and coordination polymers: Synthesis, structural characterization and computational studies

NASA Astrophysics Data System (ADS)

Rajasekhar, Bathula; Bodavarapu, Navya; Sridevi, M.; Thamizhselvi, G.; RizhaNazar, K.; Padmanaban, R.; Swu, Toka

2018-03-01

The present study reports the synthesis and evaluation of nonlinear optical property and G-Quadruplex DNA Stabilization of five novel copper(II) mixed ligand complexes. They were synthesized from copper(II) salt, 2,5- and 2,3- pyridinedicarboxylic acid, diethylenetriamine and amide based ligand (AL). The crystal structure of these complexes were determined through X-ray diffraction and supported by ESI-MAS, NMR, UV-Vis and FT-IR spectroscopic methods. Their nonlinear optical property was studied using Gaussian09 computer program. For structural optimization and nonlinear optical property, density functional theory (DFT) based B3LYP method was used with LANL2DZ basis set for metal ion and 6-31G∗ for C,H,N,O and Cl atoms. The present work reveals that pre-polarized Complex-2 showed higher β value (29.59 × 10-30e.s.u) as compared to that of neutral complex-1 (β = 0.276 × 10-30e.s.u.) which may be due to greater advantage of polarizability. Complex-2 is expected to be a potential material for optoelectronic and photonic technologies. Docking studies using AutodockVina revealed that complex-2 has higher binding energy for both G-Quadruplex DNA (-8.7 kcal/mol) and duplex DNA (-10.1 kcal/mol). It was also observed that structure plays an important role in binding efficiency.

Definition, analysis and development of an optical data distribution network for integrated avionics and control systems

NASA Technical Reports Server (NTRS)

Burns, R. R.

1981-01-01

The potential and functional requirements of fiber optic bus designs for next generation aircraft are assessed. State-of-the-art component evaluations and projections were used in the system study. Complex networks were decomposed into dedicated structures, star buses, and serial buses for detailed analysis. Comparisons of dedicated links, star buses, and serial buses with and without full duplex operation and with considerations for terminal to terminal communication requirements were obtained. This baseline was then used to consider potential extensions of busing methods to include wavelength multiplexing and optical switches. Example buses were illustrated for various areas of the aircraft as potential starting points for more detail analysis as the platform becomes definitized.

Processing and analysis of cardiac optical mapping data obtained with potentiometric dyes

PubMed Central

Laughner, Jacob I.; Ng, Fu Siong; Sulkin, Matthew S.; Arthur, R. Martin

2012-01-01

Optical mapping has become an increasingly important tool to study cardiac electrophysiology in the past 20 years. Multiple methods are used to process and analyze cardiac optical mapping data, and no consensus currently exists regarding the optimum methods. The specific methods chosen to process optical mapping data are important because inappropriate data processing can affect the content of the data and thus alter the conclusions of the studies. Details of the different steps in processing optical imaging data, including image segmentation, spatial filtering, temporal filtering, and baseline drift removal, are provided in this review. We also provide descriptions of the common analyses performed on data obtained from cardiac optical imaging, including activation mapping, action potential duration mapping, repolarization mapping, conduction velocity measurements, and optical action potential upstroke analysis. Optical mapping is often used to study complex arrhythmias, and we also discuss dominant frequency analysis and phase mapping techniques used for the analysis of cardiac fibrillation. PMID:22821993

Towards Cost-Effective Operational Monitoring Systems for Complex Waters: Analyzing Small-Scale Coastal Processes with Optical Transmissometry

PubMed Central

Gonçalves-Araujo, Rafael; Wiegmann, Sonja; Torrecilla, Elena; Bardaji, Raul; Röttgers, Rüdiger; Bracher, Astrid; Piera, Jaume

2017-01-01

The detection and prediction of changes in coastal ecosystems require a better understanding of the complex physical, chemical and biological interactions, which involves that observations should be performed continuously. For this reason, there is an increasing demand for small, simple and cost-effective in situ sensors to analyze complex coastal waters at a broad range of scales. In this context, this study seeks to explore the potential of beam attenuation spectra, c(λ), measured in situ with an advanced-technology optical transmissometer, for assessing temporal and spatial patterns in the complex estuarine waters of Alfacs Bay (NW Mediterranean) as a test site. In particular, the information contained in the spectral beam attenuation coefficient was assessed and linked with different biogeochemical variables. The attenuation at λ = 710 nm was used as a proxy for particle concentration, TSM, whereas a novel parameter was adopted as an optical indicator for chlorophyll a (Chl-a) concentration, based on the local maximum of c(λ) observed at the long-wavelength side of the red band Chl-a absorption peak. In addition, since coloured dissolved organic matter (CDOM) has an important influence on the beam attenuation spectral shape and complementary measurements of particle size distribution were available, the beam attenuation spectral slope was used to analyze the CDOM content. Results were successfully compared with optical and biogeochemical variables from laboratory analysis of collocated water samples, and statistically significant correlations were found between the attenuation proxies and the biogeochemical variables TSM, Chl-a and CDOM. This outcome depicted the potential of high-frequency beam attenuation measurements as a simple, continuous and cost-effective approach for rapid detection of changes and patterns in biogeochemical properties in complex coastal environments. PMID:28107539

Optical potential approach to the electron-atom impact ionization threshold problem

NASA Technical Reports Server (NTRS)

Temkin, A.; Hahn, Y.

1973-01-01

The problem of the threshold law for electron-atom impact ionization is reconsidered as an extrapolation of inelastic cross sections through the ionization threshold. The cross sections are evaluated from a distorted wave matrix element, the final state of which describes the scattering from the Nth excited state of the target atom. The actual calculation is carried for the e-H system, and a model is introduced which is shown to preserve the essential properties of the problem while at the same time reducing the dimensionability of the Schrodinger equation. Nevertheless, the scattering equation is still very complex. It is dominated by the optical potential which is expanded in terms of eigen-spectrum of QHQ. It is shown by actual calculation that the lower eigenvalues of this spectrum descend below the relevant inelastic thresholds; it follows rigorously that the optical potential contains repulsive terms. Analytical solutions of the final state wave function are obtained with several approximations of the optical potential.

Optically active red-emitting Cu nanoclusters originating from complexation and redox reaction between copper(ii) and d/l-penicillamine

NASA Astrophysics Data System (ADS)

Long, Tengfei; Guo, Yanjia; Lin, Min; Yuan, Mengke; Liu, Zhongde; Huang, Chengzhi

2016-05-01

Despite a significant surge in the number of investigations into both optically active Au and Ag nanostructures, there is currently only limited knowledge about optically active Cu nanoclusters (CuNCs) and their potential applications. Here, we have succeeded in preparing a pair of optically active red-emitting CuNCs on the basis of complexation and redox reaction between copper(ii) and penicillamine (Pen) enantiomers, in which Pen serves as both a reducing agent and a stabilizing ligand. Significantly, the CuNCs feature unique aggregation induced emission (AIE) characteristics and therefore can serve as pH stimuli-responsive functional materials. Impressively, the ligand chirality plays a dramatic role for the creation of brightly emissive CuNCs, attributed to the conformation of racemic Pen being unfavorable for the electrostatic interaction, and thus suppressing the formation of cluster aggregates. In addition, the clusters display potential toward cytoplasmic staining and labelling due to the high photoluminescence (PL) quantum yields (QYs) and remarkable cellular uptake, in spite that no chirality-dependent effects in autophagy and subcellular localization are observed in the application of chiral cluster enantiomer-based cell imaging.Despite a significant surge in the number of investigations into both optically active Au and Ag nanostructures, there is currently only limited knowledge about optically active Cu nanoclusters (CuNCs) and their potential applications. Here, we have succeeded in preparing a pair of optically active red-emitting CuNCs on the basis of complexation and redox reaction between copper(ii) and penicillamine (Pen) enantiomers, in which Pen serves as both a reducing agent and a stabilizing ligand. Significantly, the CuNCs feature unique aggregation induced emission (AIE) characteristics and therefore can serve as pH stimuli-responsive functional materials. Impressively, the ligand chirality plays a dramatic role for the creation of brightly emissive CuNCs, attributed to the conformation of racemic Pen being unfavorable for the electrostatic interaction, and thus suppressing the formation of cluster aggregates. In addition, the clusters display potential toward cytoplasmic staining and labelling due to the high photoluminescence (PL) quantum yields (QYs) and remarkable cellular uptake, in spite that no chirality-dependent effects in autophagy and subcellular localization are observed in the application of chiral cluster enantiomer-based cell imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01492e

An optical model description of momentum transfer in heavy ion collisions

NASA Technical Reports Server (NTRS)

Khan, F.; Khandelwal, G. S.; Townsend, Lawrence W.; Wilson, J. W.; Norbury, John W.

1989-01-01

An optical model description of momentum transfer in relativistic heavy ion collisions, based upon composite particle multiple scattering theory, is presented. The imaginary component of the complex momentum transfer, which comes from the absorptive part of the optical potential, is identified as the longitudinal momentum downshift of the projectile. Predictions of fragment momentum distribution observables are made and compared with experimental data. Use of the model as a tool for estimating collision impact parameters is discussed.

Generation of three-dimensional optical cusp beams with ultrathin metasurfaces.

PubMed

Liu, Weiwei; Zhang, Yuchao; Gao, Jie; Yang, Xiaodong

2018-06-22

Cusp beams are one type of complex structured beams with unique multiple self-accelerating channels and needle-like field structures owning great potentials to advance applications such as particle micromanipulation and super-resolution imaging. The traditional method to generate optical catastrophe is based on cumbrous reflective diffraction optical elements, which makes optical system complicated and hinders the nanophotonics integration. Here we design geometric phase based ultrathin plasmonic metasurfaces made of nanoslit antennas to produce three-dimensional (3D) optical cusp beams with variable numbers of self-accelerating channels in a broadband wavelength range. The entire beam propagation profiles of the cusp beams generated from the metasurfaces are mapped theoretically and experimentally. The special self-accelerating behavior and caustics concentration property of the cups beams are also demonstrated. Our results provide great potentials for promoting metasurface-enabled compact photonic devices used in wide applications of light-matter interactions.

Design of a Pressure Sensor Based on Optical Fiber Bragg Grating Lateral Deformation

PubMed Central

Urban, Frantisek; Kadlec, Jaroslav; Vlach, Radek; Kuchta, Radek

2010-01-01

This paper describes steps involved in the design and realization of a new type of pressure sensor based on the optical fiber Bragg grating. A traditional pressure sensor has very limited usage in heavy industrial environments, particularly in explosive or electromagnetically noisy environments. Utilization of optics in these environments eliminates all surrounding influences. An initial motivation for our development was the research, experimental validation, and realization of a complex smart pressure sensor based on the optical principle. The main benefit of this solution consists of increasing sensitivity, resistance to electromagnetic interference, dimensions, and potential increased accuracy. PMID:22163521

Scattering of particles in the presence of harmonic confinement perturbed by a complex absorbing potential

NASA Astrophysics Data System (ADS)

Maghari, A.; Kermani, M. M.

2018-04-01

A system of two interacting atoms confined in 1D harmonic trap and perturbed by an absorbing boundary potential is studied using the Lippmann-Schwinger formalism. The atom-atom interaction potential was considered as a nonlocal separable model. The perturbed absorbing boundary potential was also assumed in the form of Scarf II complex absorbing potential. The model is used for the study of 1D optical lattices that support the trapping of a pair atom within a unit cell. Moreover, it allows to describe the scattering particles in a tight smooth trapping surface and to analyze the bound and resonance states. The analytical expressions for wavefunctions and transition matrix as well as the absorption probabilities are calculated. A demonstration of how the complex absorbing potential affecting the bound states and resonances of particles confined in a harmonic trap is described.

Replicative manufacturing of complex lighting optics by non-isothermal glass molding

NASA Astrophysics Data System (ADS)

Kreilkamp, Holger; Vu, Anh Tuan; Dambon, Olaf; Klocke, Fritz

2016-09-01

The advantages of LED lighting, especially its energy efficiency and the long service life have led to a wide distribution of LED technology in the world. However, in order to make fully use of the great potential that LED lighting offers, complex optics are required to distribute the emitted light from the LED efficiently. Nowadays, many applications use polymer optics which can be manufactured at low costs. However, due to ever increasing luminous power, polymer optics reach their technological limits. Due to its outstanding properties, especially its temperature resistance, resistance against UV radiation and its long term stability, glass is the alternative material of choice for the use in LED optics. This research is introducing a new replicative glass manufacturing approach, namely non-isothermal glass molding (NGM) which is able to manufacture complex lighting optics in high volumes at competitive prices. The integration of FEM simulation at the early stage of the process development is presented and helps to guarantee a fast development cycle. A coupled thermo-mechanical model is used to define the geometry of the glass preform as well as to define the mold surface geometry. Furthermore, simulation is used to predict main process outcomes, especially in terms of resulting form accuracy of the molded optics. Experiments conducted on a commercially available molding machine are presented to validate the developed simulation model. Finally, the influence of distinct parameters on important process outcomes like form accuracy, surface roughness, birefringence, etc. is discussed.

Brownian Motion in a Speckle Light Field: Tunable Anomalous Diffusion and Selective Optical Manipulation

PubMed Central

Volpe, Giorgio; Volpe, Giovanni; Gigan, Sylvain

2014-01-01

The motion of particles in random potentials occurs in several natural phenomena ranging from the mobility of organelles within a biological cell to the diffusion of stars within a galaxy. A Brownian particle moving in the random optical potential associated to a speckle pattern, i.e., a complex interference pattern generated by the scattering of coherent light by a random medium, provides an ideal model system to study such phenomena. Here, we derive a theory for the motion of a Brownian particle in a speckle field and, in particular, we identify its universal characteristic timescale. Based on this theoretical insight, we show how speckle light fields can be used to control the anomalous diffusion of a Brownian particle and to perform some basic optical manipulation tasks such as guiding and sorting. Our results might broaden the perspectives of optical manipulation for real-life applications. PMID:24496461

Systematic study of the elastic, optoelectronic, and thermoelectric behavior of MRh2O4 (M = Zn, Cd) based on first principles calculations

NASA Astrophysics Data System (ADS)

Abbas, Syed Adeel; Rashid, Muhammad; Faridi, Muhammad Ayub; Saddique, Muhammad Bilal; Mahmood, Asif; Ramay, Shahid Muhammad

2018-02-01

In the present study, we performed first principles total energy calculations to explore the electronic, elastic, optical, and thermoelectric behavior of MRh2O4(M = Zn, Cd) spinel oxides. We employed Perdew-Burke-Ernzerhof-sol as well as the modified Becke and Johnson potential to compute the elastic, optoelectronic, and thermoelectric behavior of MRh2O4(M = Zn, Cd). The optical behavior was investigated by calculating the complex dielectric constant, refractive index, optical reflectivity, absorption coefficient, and optical conductivity. All of the optical parameters indicated a shift to lower energies as the atomic size increased from Zn to Cd, thereby suggesting potential applications of the spinel oxides in optoelectronic device. Moreover, the thermoelectric properties of MRh2O4(M = Zn, Cd) spinel oxides were computed in terms of the electrical conductivity (σ), Seebeck coefficient (S), thermal conductivity (k), and power factor (σS2) using the BoltzTraP code.

Label-free optical detection of action potential in mammalian neurons (Conference Presentation)

NASA Astrophysics Data System (ADS)

Batabyal, Subrata; Satpathy, Sarmishtha; Bui, Loan; Kim, Young-Tae; Mohanty, Samarendra K.; Davé, Digant P.

2017-02-01

Electrophysiology techniques are the gold standard in neuroscience for studying functionality of a single neuron to a complex neuronal network. However, electrophysiology techniques are not flawless, they are invasive nature, procedures are cumbersome to implement with limited capability of being used as a high-throughput recording system. Also, long term studies of neuronal functionality with aid of electrophysiology is not feasible. Non-invasive stimulation and detection of neuronal electrical activity has been a long standing goal in neuroscience. Introduction of optogenetics has ushered in the era of non-invasive optical stimulation of neurons, which is revolutionizing neuroscience research. Optical detection of neuronal activity that is comparable to electro-physiology is still elusive. A number of optical techniques have been reported recording of neuronal electrical activity but none is capable of reliably measuring action potential spikes that is comparable to electro-physiology. Optical detection of action potential with voltage sensitive fluorescent reporters are potential alternatives to electrophysiology techniques. The heavily rely on secondary reporters, which are often toxic in nature with background fluorescence, with slow response and low SNR making them far from ideal. The detection of one shot (without averaging)-single action potential in a true label-free way has been elusive so far. In this report, we demonstrate the optical detection of single neuronal spike in a cultured mammalian neuronal network without using any exogenous labels. To the best of our knowledge, this is the first demonstration of label free optical detection of single action potentials in a mammalian neuronal network, which was achieved using a high-speed phase sensitive interferometer. We have carried out stimulation and inhibition of neuronal firing using Glutamate and Tetrodotoxin respectively to demonstrate the different outcome (stimulation and inhibition) revealed in optical signal. We hypothesize that the interrogating optical beam is modulated during neuronal firing by electro-motility driven membrane fluctuation in conjunction with electrical wave propagation in cellular system.

Optical network scaling: roles of spectral and spatial aggregation.

PubMed

Arık, Sercan Ö; Ho, Keang-Po; Kahn, Joseph M

2014-12-01

As the bit rates of routed data streams exceed the throughput of single wavelength-division multiplexing channels, spectral and spatial traffic aggregation become essential for optical network scaling. These aggregation techniques reduce network routing complexity by increasing spectral efficiency to decrease the number of fibers, and by increasing switching granularity to decrease the number of switching components. Spectral aggregation yields a modest decrease in the number of fibers but a substantial decrease in the number of switching components. Spatial aggregation yields a substantial decrease in both the number of fibers and the number of switching components. To quantify routing complexity reduction, we analyze the number of multi-cast and wavelength-selective switches required in a colorless, directionless and contentionless reconfigurable optical add-drop multiplexer architecture. Traffic aggregation has two potential drawbacks: reduced routing power and increased switching component size.

Analytical model and figures of merit for filtered Microwave Photonic Links.

PubMed

Gasulla, Ivana; Capmany, José

2011-09-26

The concept of filtered Microwave Photonic Links is proposed in order to provide the most general and versatile description of complex analog photonic systems. We develop a field propagation model where a global optical filter, characterized by its optical transfer function, embraces all the intermediate optical components in a linear link. We assume a non-monochromatic light source characterized by an arbitrary spectral distribution which has a finite linewidth spectrum and consider both intensity modulation and phase modulation with balanced and single detection. Expressions leading to the computation of the main figures of merit concerning the link gain, noise and intermodulation distortion are provided which, to our knowledge, are not available in the literature. The usefulness of this derivation resides in the capability to directly provide performance criteria results for complex links just by substituting in the overall closed-form formulas the numerical or measured optical transfer function characterizing the link. This theory is presented thus as a potential tool for a wide range of relevant microwave photonic application cases which is extendable to multiport radio over fiber systems. © 2011 Optical Society of America

Projecting light beams with 3D waveguide arrays

NASA Astrophysics Data System (ADS)

Crespi, Andrea; Bragheri, Francesca

2017-01-01

Free-space light beams with complex intensity patterns, or non-trivial phase structure, are demanded in diverse fields, ranging from classical and quantum optical communications, to manipulation and imaging of microparticles and cells. Static or dynamic spatial light modulators, acting on the phase or intensity of an incoming light wave, are the conventional choices to produce beams with such non-trivial characteristics. However, interfacing these devices with optical fibers or integrated optical circuits often requires difficult alignment or cumbersome optical setups. Here we explore theoretically and with numerical simulations the potentialities of directly using the output of engineered three-dimensional waveguide arrays, illuminated with linearly polarized light, to project light beams with peculiar structures. We investigate through a collection of illustrative configurations the far field distribution, showing the possibility to achieve orbital angular momentum, or to produce elaborate intensity or phase patterns with several singularity points. We also simulate the propagation of the projected beam, showing the possibility to concentrate light. We note that these devices should be at reach of current technology, thus perspectives are open for the generation of complex free-space optical beams from integrated waveguide circuits.

Optical properties of graphene, silicene, germanene, and stanene from IR to far UV - A first principles study

NASA Astrophysics Data System (ADS)

John, Rita; Merlin, Benita

2017-11-01

This study offers an analysis of optical properties of Graphene and its 2D analogues: Silicene, Germanene, and Stanene with the help of band structures based on Density Functional Theory. The complex dielectric function and complex refractive index are calculated in both parallel (||) and perpendicular (⊥) polarization directions of the electromagnetic field. From these calculated values, optical observables like absorption, reflection, optical conductivity, and electron loss function have been studied. The optical response of all materials is shifted from ultraviolet (UV) to infrared (IR) from graphene to stanene; Graphene is more into UV region and other materials in the IR and visible regions. The intensity of absorption is maximum for stanene. The real part of dielectric function reveals the existence of plasma frequency in the || polarization direction indicating the metal to dielectric transition except for graphene. Study on refractive index clearly displays the birefringence characteristics of all materials. Reflectivity is enhanced in the mid IR and visible regions when light is polarized in the || direction. The in-depth investigations arrive at fine results which would enable the prediction of their potential applications in the optical and optoelectronic industries.

Research in Optical Symbolic Tasks

DTIC Science & Technology

1989-11-29

November 1989. Specifically, we have concentrated on the following topics: complexity studies for optical neural and digital systems, architecture and...1989. Specifically, we hav, concentrated on the following topics: complexity studies for optical neural and digital systems, architecture and models for...Digital Systems 1.1 Digital Optical Parallel System Complexity Our study of digital optical system complexity has included a comparison of optical and

Flight behavior of the rhinoceros beetle Trypoxylus dichotomus during electrical nerve stimulation.

PubMed

Van Truong, Tien; Byun, Doyoung; Lavine, Laura Corley; Emlen, Douglas J; Park, Hoon Cheol; Kim, Min Jun

2012-09-01

Neuronal stimulation is an intricate part of understanding insect flight behavior and control insect itself. In this study, we investigated the effects of electrical pulses applied to the brain and basalar muscle of the rhinoceros beetle (Trypoxylus dichotomus). To understand specific neuronal stimulation mechanisms, responses and flight behavior of the beetle, four electrodes were implanted into the two optic lobes, the brain's central complex and the ventral nerve cord in the posterior pronotum. We demonstrated flight initiation, turning and cessation by stimulating the brain. The change undergone by the wing flapping in response to the electrical signal was analyzed from a sequence of images captured by a high-speed camera. Here, we provide evidence to distinguish the important differences between neuronal and muscular flight stimulations in beetles. We found that in the neural potential stimulation, both the hind wing and the elytron were suppressed. Interestingly, the beetle stopped flying whenever a stimulus potential was applied between the pronotum and one side of the optic lobe, or between the ventral nerve cord in the posterior pronotum and the central complex. In-depth experimentation demonstrated the effective of neural stimulation over muscle stimulation for flight control. During electrical stimulation of the optic lobes, the beetle performed unstable flight, resulting in alternating left and right turns. By applying the electrical signal into both the optic lobes and the central complex of the brain, we could precisely control the direction of the beetle flight. This work provides an insight into insect flight behavior for future development of insect-micro air vehicle.

All-optical phase modulation in a cavity-polariton Mach–Zehnder interferometer

PubMed Central

Sturm, C.; Tanese, D.; Nguyen, H.S.; Flayac, H.; Galopin, E.; Lemaître, A.; Sagnes, I.; Solnyshkov, D.; Amo, A.; Malpuech, G.; Bloch, J.

2014-01-01

Quantum fluids based on light is a highly developing research field, since they provide a nonlinear platform for developing optical functionalities and quantum simulators. An important issue in this context is the ability to coherently control the properties of the fluid. Here we propose an all-optical approach for controlling the phase of a flow of cavity-polaritons, making use of their strong interactions with localized excitons. Here we illustrate the potential of this method by implementing a compact exciton–polariton interferometer, which output intensity and polarization can be optically controlled. This interferometer is cascadable with already reported polariton devices and is promising for future polaritonic quantum optic experiments. Complex phase patterns could be also engineered using this optical method, providing a key tool to build photonic artificial gauge fields. PMID:24513781

Assessment of an approach to printed polymer lenses

NASA Astrophysics Data System (ADS)

Marasco, Peter L.; Foote, Bob

2017-05-01

Additive manufacturing is proving its relevancy across a wide spectrum of development, prototyping and manufacturing in the US. However, there is a desire to move the capability beyond modeling and structural components. The use of additive manufacturing techniques to fabricate low-cost optics and optical systems is highly desirable in a number of markets. But processes and techniques for successfully printing an optic are currently very new. This paper discusses early advances in printing optics suitable for commercial and military applications. Data from and analysis of early prototype lenses fabricated using one possible technique will be included and discussed. The potential for additive manufacturing of optics to open the design space for complex optics and reduce development time, lowering cost and speeding up time to market, will also be discussed.

Laser beam complex amplitude measurement by phase diversity.

PubMed

Védrenne, Nicolas; Mugnier, Laurent M; Michau, Vincent; Velluet, Marie-Thérèse; Bierent, Rudolph

2014-02-24

The control of the optical quality of a laser beam requires a complex amplitude measurement able to deal with strong modulus variations and potentially highly perturbed wavefronts. The method proposed here consists in an extension of phase diversity to complex amplitude measurements that is effective for highly perturbed beams. Named camelot for Complex Amplitude MEasurement by a Likelihood Optimization Tool, it relies on the acquisition and processing of few images of the beam section taken along the optical path. The complex amplitude of the beam is retrieved from the images by the minimization of a Maximum a Posteriori error metric between the images and a model of the beam propagation. The analytical formalism of the method and its experimental validation are presented. The modulus of the beam is compared to a measurement of the beam profile, the phase of the beam is compared to a conventional phase diversity estimate. The precision of the experimental measurements is investigated by numerical simulations.

Paraxial diffractive elements for space-variant linear transforms

NASA Astrophysics Data System (ADS)

Teiwes, Stephan; Schwarzer, Heiko; Gu, Ben-Yuan

1998-06-01

Optical linear transform architectures bear good potential for future developments of very powerful hybrid vision systems and neural network classifiers. The optical modules of such systems could be used as pre-processors to solve complex linear operations at very high speed in order to simplify an electronic data post-processing. However, the applicability of linear optical architectures is strongly connected with the fundamental question of how to implement a specific linear transform by optical means and physical imitations. The large majority of publications on this topic focusses on the optical implementation of space-invariant transforms by the well-known 4f-setup. Only few papers deal with approaches to implement selected space-variant transforms. In this paper, we propose a simple algebraic method to design diffractive elements for an optical architecture in order to realize arbitrary space-variant transforms. The design procedure is based on a digital model of scalar, paraxial wave theory and leads to optimal element transmission functions within the model. Its computational and physical limitations are discussed in terms of complexity measures. Finally, the design procedure is demonstrated by some examples. Firstly, diffractive elements for the realization of different rotation operations are computed and, secondly, a Hough transform element is presented. The correct optical functions of the elements are proved in computer simulation experiments.

Fluorescent Polymer-Single-Walled Carbon Nanotube Complexes with Charged and Noncharged Dendronized Perylene Bisimides for Bioimaging Studies.

PubMed

Huth, Katharina; Glaeske, Mareen; Achazi, Katharina; Gordeev, Georgy; Kumar, Shiv; Arenal, Raúl; Sharma, Sunil K; Adeli, Mohsen; Setaro, Antonio; Reich, Stephanie; Haag, Rainer

2018-06-05

Fluorescent nanomaterials are expected to revolutionize medical diagnostic, imaging, and therapeutic tools due to their superior optical and structural properties. Their inefficient water solubility, cell permeability, biodistribution, and high toxicity, however, limit the full potential of their application. To overcome these obstacles, a water-soluble, fluorescent, cytocompatible polymer-single-walled carbon nanotube (SWNT) complex is introduced for bioimaging applications. The supramolecular complex consists of an alkylated polymer conjugated with neutral hydroxylated or charged sulfated dendronized perylene bisimides (PBIs) and SWNTs as a general immobilization platform. The polymer backbone solubilizes the SWNTs, decorates them with fluorescent PBIs, and strongly improves their cytocompatibility by wrapping around the SWNT scaffold. In photophysical measurements and biological in vitro studies, sulfated complexes exhibit superior optical properties, cellular uptake, and intracellular staining over their hydroxylated analogs. A toxicity assay confirms the highly improved cytocompatibility of the polymer-wrapped SWNTs toward surfactant-solubilized SWNTs. In microscopy studies the complexes allow for the direct imaging of the SWNTs' cellular uptake via the PBI and SWNT emission using the 1st and 2nd optical window for bioimaging. These findings render the polymer-SWNT complexes with nanometer size, dual fluorescence, multiple charges, and high cytocompatibility as valuable systems for a broad range of fluorescence bioimaging studies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Computational adaptive optics for broadband interferometric tomography of tissues and cells

NASA Astrophysics Data System (ADS)

Adie, Steven G.; Mulligan, Jeffrey A.

2016-03-01

Adaptive optics (AO) can shape aberrated optical wavefronts to physically restore the constructive interference needed for high-resolution imaging. With access to the complex optical field, however, many functions of optical hardware can be achieved computationally, including focusing and the compensation of optical aberrations to restore the constructive interference required for diffraction-limited imaging performance. Holography, which employs interferometric detection of the complex optical field, was developed based on this connection between hardware and computational image formation, although this link has only recently been exploited for 3D tomographic imaging in scattering biological tissues. This talk will present the underlying imaging science behind computational image formation with optical coherence tomography (OCT) -- a beam-scanned version of broadband digital holography. Analogous to hardware AO (HAO), we demonstrate computational adaptive optics (CAO) and optimization of the computed pupil correction in 'sensorless mode' (Zernike polynomial corrections with feedback from image metrics) or with the use of 'guide-stars' in the sample. We discuss the concept of an 'isotomic volume' as the volumetric extension of the 'isoplanatic patch' introduced in astronomical AO. Recent CAO results and ongoing work is highlighted to point to the potential biomedical impact of computed broadband interferometric tomography. We also discuss the advantages and disadvantages of HAO vs. CAO for the effective shaping of optical wavefronts, and highlight opportunities for hybrid approaches that synergistically combine the unique advantages of hardware and computational methods for rapid volumetric tomography with cellular resolution.

Optical polarization: plenty of room for surprise

NASA Astrophysics Data System (ADS)

Chenault, David

2012-10-01

Solutions to difficult problems in complex environments frequently require methodical approaches and detailed research plans. Fortunately, there is still room for serendipity in disciplines that are relatively mature and well understood. As a case in point, optical sensors that exploit polarized light have matured greatly and the discipline of optical polarization has grown substantially in scope and applications over the last ten years. In spite of this increased understanding, polarization signatures are frequently not well understood. A good example is polarization in the animal kingdom. The potential for polarimetric monitoring of moose populations, and other applications, will be discussed.

Generating and Separating Twisted Light by gradient-rotation Split-Ring Antenna Metasurfaces.

PubMed

Zeng, Jinwei; Li, Ling; Yang, Xiaodong; Gao, Jie

2016-05-11

Nanoscale compact optical vortex generators promise substantially significant prospects in modern optics and photonics, leading to many advances in sensing, imaging, quantum communication, and optical manipulation. However, conventional vortex generators often suffer from bulky size, low vortex mode purity in the converted beam, or limited operation bandwidth. Here, we design and demonstrate gradient-rotation split-ring antenna metasurfaces as unique spin-to-orbital angular momentum beam converters to simultaneously generate and separate pure optical vortices in a broad wavelength range. Our proposed design has the potential for realizing miniaturized on-chip OAM-multiplexers, as well as enabling new types of metasurface devices for the manipulation of complex structured light beams.

Evolution of ring-field systems in microlithography

NASA Astrophysics Data System (ADS)

Williamson, David M.

1998-09-01

Offner's ring-field all-reflecting triplet was the first successful projection system used in microlithography. It evolved over several generations, increasing NA and field size, reducing the feature sizes printed from three down to one micron. Because of its relative simplicity, large field size and broad spectral bandwidth it became the dominant optical design used in microlithography until the early 1980's, when the demise of optical lithography was predicted. Rumours of the death of optics turned out to be exaggerated; what happened instead was a metamorphosis to more complex optical designs. A reduction ring-field system was developed, but the inevitable loss of concentricity led to a dramatic increase in complexity. Higher NA reduction projection optics have therefore been full-field, either all-refracting or catadioptric using a beamsplitter and a single mirror. At the present time, the terminal illness of optical lithography is once again being prognosed, but now at 0.1 micro feature sizes early in the next millenium. If optics has a future beyond that, it lies at wavelengths below the practical transmission cut-off of all refracting materials. Scanning all-reflecting ring-field systems are therefore poised for a resurgence, based on their well-established advantage of rotational symmetry and consequent small aberration variations over a small, annular field. This paper explores some such designs that potentially could take optical lithography down to the region of 0.025 micron features.

Unidirectional invisibility and non-reciprocal transmission in two and three dimensions.

PubMed

Loran, Farhang; Mostafazadeh, Ali

2016-07-01

We explore the phenomenon of unidirectional invisibility in two dimensions, examine its optical realizations and discuss its three-dimensional generalization. In particular, we construct an infinite class of unidirectionally invisible optical potentials that describe the scattering of normally incident transverse electric waves by an infinite planar slab with refractive-index modulations along both the normal directions to the electric field. A by-product of this investigation is a demonstration of non-reciprocal transmission in two dimensions. To elucidate this phenomenon, we state and prove a general reciprocity theorem that applies to quantum scattering theory of real and complex potentials in two and three dimensions.

Light-effect transistor (LET) with multiple independent gating controls for optical logic gates and optical amplification

NASA Astrophysics Data System (ADS)

Marmon, Jason; Rai, Satish; Wang, Kai; Zhou, Weilie; Zhang, Yong

The pathway for CMOS technology beyond the 5-nm technology node remains unclear for both physical and technological reasons. A new transistor paradigm is required. A LET (Marmon et. al., Front. Phys. 2016, 4, No. 8) offers electronic-optical hybridization at the component level, and is capable of continuing Moore's law to the quantum scale. A LET overcomes a FET's fabrication complexity, e.g., physical gate and doping, by employing optical gating and photoconductivity, while multiple independent, optical gates readily realize unique functionalities. We report LET device characteristics and novel digital and analog applications, such as optical logic gates and optical amplification. Prototype CdSe-nanowire-based LETs, incorporating an M-S-M structure, show output and transfer characteristics resembling advanced FETs, e.g., on/off ratios up to 106 with a source-drain voltage of 1.43V, gate-power of 260nW, and a subthreshold swing of 0.3nW/decade (excluding losses). A LET has potential for high-switching (THz) speeds and extremely low-switching energies (aJ) in the ballistic transport region. Our work offers new electronic-optical integration strategies for high speed and low energy computing approaches, which could potentially be extended to other materials and devices.

A fast low-power optical memory based on coupled micro-ring lasers

NASA Astrophysics Data System (ADS)

Hill, Martin T.; Dorren, Harmen J. S.; de Vries, Tjibbe; Leijtens, Xaveer J. M.; den Besten, Jan Hendrik; Smalbrugge, Barry; Oei, Yok-Siang; Binsma, Hans; Khoe, Giok-Djan; Smit, Meint K.

2004-11-01

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 × 40µm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20ps with 5.5fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.

Optical spectral singularities as threshold resonances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mostafazadeh, Ali

2011-04-15

Spectral singularities are among generic mathematical features of complex scattering potentials. Physically they correspond to scattering states that behave like zero-width resonances. For a simple optical system, we show that a spectral singularity appears whenever the gain coefficient coincides with its threshold value and other parameters of the system are selected properly. We explore a concrete realization of spectral singularities for a typical semiconductor gain medium and propose a method of constructing a tunable laser that operates at threshold gain.

University of South Carolina CB Support, Basic Research in Materials and Techniques for Optical Computing Standoff Sensors

DTIC Science & Technology

2004-10-01

chloroform-soaked swab prior to making electrical contact with directly related to the oxidation and reduction potential of the an alligator clip. In...other cases, no cleaning protocol was used emitting layers.’.’ Wrighton et al.𔃺 examined the cyclic and a direct connection via an alligator clip was...applied to optical spectra of complex mix- samples requires techniques of simple multivariate patterntame (gasoline, blood , environmental samples

Fiber Optic Strain Sensor for Planetary Gear Diagnostics

NASA Technical Reports Server (NTRS)

Kiddy, Jason S.; Lewicki, David G.; LaBerge, Kelsen E.; Ehinger, Ryan T.; Fetty, Jason

2011-01-01

This paper presents a new sensing approach for helicopter damage detection in the planetary stage of a helicopter transmission based on a fiber optic strain sensor array. Complete helicopter transmission damage detection has proven itself a difficult task due to the complex geometry of the planetary reduction stage. The crowded and complex nature of the gearbox interior does not allow for attachment of sensors within the rotating frame. Hence, traditional vibration-based diagnostics are instead based on measurements from externally mounted sensors, typically accelerometers, fixed to the gearbox exterior. However, this type of sensor is susceptible to a number of external disturbances that can corrupt the data, leading to false positives or missed detection of potentially catastrophic faults. Fiber optic strain sensors represent an appealing alternative to the accelerometer. Their small size and multiplexibility allows for potentially greater sensing resolution and accuracy, as well as redundancy, when employed as an array of sensors. The work presented in this paper is focused on the detection of gear damage in the planetary stage of a helicopter transmission using a fiber optic strain sensor band. The sensor band includes an array of 13 strain sensors, and is mounted on the ring gear of a Bell Helicopter OH-58C transmission. Data collected from the sensor array is compared to accelerometer data, and the damage detection results are presented

Photofunctional triplet excited states of cyclometalated Ir(III) complexes: beyond electroluminescence.

PubMed

You, Youngmin; Nam, Wonwoo

2012-11-07

The development of cyclometalated Ir(III) complexes has enabled important breakthroughs in electroluminescence because such complexes permit the efficient population of triplet excited states that give rise to luminescent transitions. The triplet states of Ir(III) complexes are advantageous over those of other transition metal complexes in that their electronic transitions and charge-transfer characteristics are tunable over wide ranges. These favorable properties suggest that Ir(III) complexes have significant potential in a variety of photofunctions other than electroluminescence. In this critical review, we describe recent photonic applications of novel Ir(III) complexes. Ir(III) complexes have been shown to affect the exciton statistics in the active layers of organic photovoltaic cells, thereby improving the photon-to-current conversion efficiencies. Nonlinear optical applications that take advantage of the strong charge-transfer properties of triplet transitions are also discussed. The tunability of the electrochemical potentials facilitates the development of efficient photocatalysis in the context of water photolysis or organic syntheses. The photoredox reactivities of Ir(III) complexes have been employed in studies of charge migration along DNA chains. The photoinduced cytotoxicity of Ir(III) complexes on live cells suggests that the complexes may be useful in photodynamic therapy. Potential biological applications of the complexes include phosphorescence labeling and sensing. Intriguing platforms based on cyclometalated Ir(III) complexes potentially provide novel protein tagging and ratiometric detection. We envision that future research into the photofunctionality of Ir(III) complexes will provide important breakthroughs in a variety of photonic applications.

Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde

NASA Astrophysics Data System (ADS)

Anitha, C.; Sheela, C. D.; Tharmaraj, P.; Sumathi, S.

2012-10-01

A series of metal(II) complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the azo Schiff base ligand 4-((E)-4-((E)-(4-chlorophenyl)diazenyl)-2-hydroxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (CDHBAP) and characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR, ESR and EI-mass), magnetic moment measurements, molar conductance, DNA, SEM, X-ray crystallography and fluorescence studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square pyramidal geometry for VO(II) and octahedral geometry for all the other complexes. The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied and implies that CDHBAP is coordinated to the metal ions in a neutral tridentate manner. The redox behavior of copper(II) and vanadyl(II) complexes have been studied by cyclic voltammetry. The nuclease activity of the above metal(II) complexes shows that the complexes cleave DNA. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species (Staphylococcus aureus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Shigella sonnie) and fungi (Candida albicans, Aspergillus niger, Rhizoctonia bataicola). Amikacin and Ketoconozole were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species. The second harmonic generation (SHG) efficiency of the ligand was measured and the NLO (non-linear optical) properties of the ligand are expected to result in the realization of advanced optical devices in optical fiber communication (OFC) and optical computing. The SEM image of the copper(II) complex implies that the size of the particles is 1 μm.

The optical characterization of organometallic complex thin films by spectroscopic ellipsometry and photovoltaic diode application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Özaydın, C.; Güllü, Ö., E-mail: omergullu@gmail.com; Pakma, O.

2016-05-15

Highlights: • Optical properties and thickness of the A novel organometallic complex (OMC) film were investigated by spectroscopic ellipsometry (SE). • Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated • This paper presents the I–V analysis of Au/OMC/n-Si MIS diode. • Current–voltage and photovoltaic properties of the diode were investigated. - Abstract: In this work, organometallic complex (OMC) films have been deposited onto glass or silicon substrates by spin coating technique and their photovoltaic application potential has been investigated. Optical properties and thickness of the film have been investigated by spectroscopic ellipsometry (SE). Also, transmittance spectrum has been taken by UV/vismore » spectrophotometer. The optical method has been used to determine the band gap value of the films. Also, Au/OMC/n-Si metal/interlayer/semiconductor (MIS) diode has been fabricated. Current–voltage and photovoltaic properties of the structure were investigated. The ideality factor (n) and barrier height (Φ{sub b}) values of the diode were found to be 2.89 and 0.79 eV, respectively. The device shows photovoltaic behavior with a maximum open-circuit voltage of 396 mV and a short circuit current of 33.8 μA under 300 W light.« less

A modular assembling platform for manufacturing of microsystems by optical tweezers

NASA Astrophysics Data System (ADS)

Ksouri, Sarah Isabelle; Aumann, Andreas; Ghadiri, Reza; Prüfer, Michael; Baer, Sebastian; Ostendorf, Andreas

2013-09-01

Due to the increased complexity in terms of materials and geometries for microsystems new assembling techniques are required. Assembling techniques from the semiconductor industry are often very specific and cannot fulfill all specifications in more complex microsystems. Therefore, holographic optical tweezers are applied to manipulate structures in micrometer range with highest flexibility and precision. As is well known non-spherical assemblies can be trapped and controlled by laser light and assembled with an additional light modulator application, where the incident laser beam is rearranged into flexible light patterns in order to generate multiple spots. The complementary building blocks are generated by a two-photon-polymerization process. The possibilities of manufacturing arbitrary microstructures and the potential of optical tweezers lead to the idea of combining manufacturing techniques with manipulation processes to "microrobotic" processes. This work presents the manipulation of generated complex microstructures with optical tools as well as a storage solution for 2PP assemblies. A sample holder has been developed for the manual feeding of 2PP building blocks. Furthermore, a modular assembling platform has been constructed for an `all-in-one' 2PP manufacturing process as a dedicated storage system. The long-term objective is the automation process of feeding and storage of several different 2PP micro-assemblies to realize an automated assembly process.

Rapid and prodium iodide-compatible optical clearing method for brain tissue based on sugar/sugar-alcohol

NASA Astrophysics Data System (ADS)

Yu, Tingting; Qi, Yisong; Wang, Jianru; Feng, Wei; Xu, Jianyi; Zhu, Jingtan; Yao, Yingtao; Gong, Hui; Luo, Qingming; Zhu, Dan

2016-08-01

The developed optical clearing methods show great potential for imaging of large-volume tissues, but these methods present some nonnegligible limitations such as complexity of implementation and long incubation times. In this study, we tried to screen out rapid optical clearing agents by means of molecular dynamical simulation and experimental demonstration. According to the optical clearing potential of sugar and sugar-alcohol, we further evaluated the improvement in the optical clearing efficacy of mouse brain samples, imaging depth, fluorescence preservation, and linear deformation. The results showed that drops of sorbitol, sucrose, and fructose could quickly make the mouse brain sample transparent within 1 to 2 min, and induce about threefold enhancement in imaging depth. The former two could evidently enhance the fluorescence intensity of green fluorescent protein (GFP) and prodium iodide (PI) nuclear dye. Fructose could significantly increase the fluorescence intensity of PI, but slightly decrease the fluorescence intensity of GFP. Even though the three agents caused some shrinkage in samples, the contraction in horizontal and longitudinal directions are almost the same.

Photonic jet etching: Justifying the shape of optical fiber tip

NASA Astrophysics Data System (ADS)

Abdurrochman, Andri; Zelgowski, Julien; Lecler, Sylvain; Mermet, Frédéric; Tumbelaka, Bernard; Fontaine, Joël

2016-02-01

Photonic jet (PJ) is a low diverging and highly concentrated beam in the shadow side of dielectric particle (cylinder or sphere). The concentration can be more than 200 times higher than the incidence wave. It is a non-resonance phenomenon in the near-field can propagate in a few wavelengths. Many potential applications have been proposed, including PJ etching. Hence, a guided-beam is considered increasing the PJ mobility control. While the others used a combination of classical optical fibers and spheres, we are concerned on a classical optical fiber with spherical tip to generate the PJ. This PJ driven waveguide has been realized using Gaussian mode beam inside the core. It has different variable parameters compared to classical PJ, which will be discussed in correlation with the etching demonstrations. The parameters dependency between the tip and PJ properties are complex; and theoretical aspect of this interaction will be exposed to justify the shape of our tip and optical fiber used in our demonstrations. Methods to achieve such a needed optical fiber tip will also be described. Finally the ability to generate PJ out of the shaped optical fiber will be experimentally demonstrated and the potential applications for material processing will be exposed.

Retinal optical coherence tomography image enhancement via shrinkage denoising using double-density dual-tree complex wavelet transform

PubMed Central

Mayer, Markus A.; Boretsky, Adam R.; van Kuijk, Frederik J.; Motamedi, Massoud

2012-01-01

Abstract. Image enhancement of retinal structures, in optical coherence tomography (OCT) scans through denoising, has the potential to aid in the diagnosis of several eye diseases. In this paper, a locally adaptive denoising algorithm using double-density dual-tree complex wavelet transform, a combination of the double-density wavelet transform and the dual-tree complex wavelet transform, is applied to reduce speckle noise in OCT images of the retina. The algorithm overcomes the limitations of commonly used multiple frame averaging technique, namely the limited number of frames that can be recorded due to eye movements, by providing a comparable image quality in significantly less acquisition time equal to an order of magnitude less time compared to the averaging method. In addition, improvements of image quality metrics and 5 dB increase in the signal-to-noise ratio are attained. PMID:23117804

Retinal optical coherence tomography image enhancement via shrinkage denoising using double-density dual-tree complex wavelet transform.

PubMed

Chitchian, Shahab; Mayer, Markus A; Boretsky, Adam R; van Kuijk, Frederik J; Motamedi, Massoud

2012-11-01

ABSTRACT. Image enhancement of retinal structures, in optical coherence tomography (OCT) scans through denoising, has the potential to aid in the diagnosis of several eye diseases. In this paper, a locally adaptive denoising algorithm using double-density dual-tree complex wavelet transform, a combination of the double-density wavelet transform and the dual-tree complex wavelet transform, is applied to reduce speckle noise in OCT images of the retina. The algorithm overcomes the limitations of commonly used multiple frame averaging technique, namely the limited number of frames that can be recorded due to eye movements, by providing a comparable image quality in significantly less acquisition time equal to an order of magnitude less time compared to the averaging method. In addition, improvements of image quality metrics and 5 dB increase in the signal-to-noise ratio are attained.

Optomechanical performance of 3D-printed mirrors with embedded cooling channels and substructures

NASA Astrophysics Data System (ADS)

Mici, Joni; Rothenberg, Bradley; Brisson, Erik; Wicks, Sunny; Stubbs, David M.

2015-09-01

Advances in 3D printing technology allow for the manufacture of topologically complex parts not otherwise feasible through conventional manufacturing methods. Maturing metal and ceramic 3D printing technologies are becoming more adept at printing complex shapes, enabling topologically intricate mirror substrates. One application area that can benefit from additive manufacturing is reflective optics used in high energy laser (HEL) systems that require materials with a low coefficient of thermal expansion (CTE), high specific stiffness, and (most importantly) high thermal conductivity to effectively dissipate heat from the optical surface. Currently, the limits of conventional manufacturing dictate the topology of HEL optics to be monolithic structures that rely on passive cooling mechanisms and high reflectivity coatings to withstand laser damage. 3D printing enables the manufacture of embedded cooling channels in metallic mirror substrates to allow for (1) active cooling and (2) tunable structures. This paper describes the engineering and analysis of an actively cooled composite optical structure to demonstrate the potential of 3D printing on the improvement of optomechanical systems.

Nanoparticle heterodimers: The role of size and interparticle gap distance on the optical response

NASA Astrophysics Data System (ADS)

Mokkath, Junais Habeeb

2018-05-01

Composite plasmonic nanostructures with controlled size, shape and relative arrangement is a subject of significant current research interest. Much of this is stimulated by the prospects by generating enormous near-field enhancements of the surface and interparticle gap regions for potential applications in surface-enhanced spectroscopies. In this manuscript, using time-dependent density functional theory (TDDFT) calculations, we investigate how the optical response in size matched homodimers and size mismatched heterodimers composed of Aluminum modify while varying the size and interparticle gap distances in the sub-nanometer range. Both systems show interesting optical response evolution. In particular, the size mismatched heterodimers show even more complex optical response evolution due to a symmetry-breaking in the system.

Hybrid optical (freeform) components--functionalization of nonplanar optical surfaces by direct picosecond laser ablation.

PubMed

Kleindienst, Roman; Kampmann, Ronald; Stoebenau, Sebastian; Sinzinger, Stefan

2011-07-01

The performance of optical systems is typically improved by increasing the number of conventionally fabricated optical components (spheres, aspheres, and gratings). This approach is automatically connected to a system enlargement, as well as potentially higher assembly and maintenance costs. Hybrid optical freeform components can help to overcome this trade-off. They merge several optical functions within fewer but more complex optical surfaces, e.g., elements comprising shallow refractive/reflective and high-frequency diffractive structures. However, providing the flexibility and precision essential for their realization is one of the major challenges in the field of optical component fabrication. In this article we present tailored integrated machining techniques suitable for rapid prototyping as well as the fabrication of molding tools for low-cost mass replication of hybrid optical freeform components. To produce the different feature sizes with optical surface quality, we successively combine mechanical machining modes (ultraprecision micromilling and fly cutting) with precisely aligned direct picosecond laser ablation in an integrated fabrication approach. The fabrication accuracy and surface quality achieved by our integrated fabrication approach are demonstrated with profilometric measurements and experimental investigations of the optical performance.

Assessment of spectroscopic parameters of solvated Eu(dmh)3 phen organometallic complex in various basic and acidic solvents.

PubMed

Chitnis, Dipti; Kalyani, N Thejo; Dhoble, Sanjay

2018-05-31

We report on the comprehension of novel europium activated hybrid organic Eu(dmh) 3 phen (Eu: europium, dmh: 2,6-dimethyl-3,5-heptanedione, phen: 1,10 phenanthroline) organo-metallic complexes, synthesized at different pH values by the solution technique. Photo physical properties of these complexes in various basic and acidic solvents were probed by UV-vis optical absorption and photoluminescence (PL) spectra. Minute differences in optical absorption peaks with variable optical densities were encountered with the variation in solvent from basic (chloroform, toluene, tetrahydrofuran) to acidic (acetic acid) media, revealing bathochromic shift in the absorption peaks. The PL spectra of the complex in various acidic and basic organic solvents revealed the position of the emission peak at 613 nm irrespective of the changes in solvents whereas the excitation spectrum almost matched with that of the UV-vis absorption data. The optical density was found to be maximum for the complex with pH 7.0 whereas it gradually decreased when pH was lowered to 6.0 or raised to 8.0 at an interval of 0.5, demonstrating its pH sensitive nature. Several spectroscopic parameters related to probability of transition such as absorbance A(λ), Napierian absorption coefficient α(λ), molecular absorption cross-section σ(λ), radiative lifetime (τ 0 ) and oscillator strength (f) were calculated from UV-vis spectra. The relative intensity ratio (R-ratio), calculated from the emission spectra was found to be almost the same in all the organic solvents. The optical energy gap, calculated for the designed complexes were found to be well in accordance with the ideal acceptance value of energy gap of the emissive materials used for fabrication of red organic light-emitting diode (OLED). The relation between Stoke's shift and solvent polarity function was established by Lippert-Mataga plot. This remarkable independence of the electronic absorption spectra of Eu complexes on the nature of the solvent with unique emission wavelength furnishes its potential to serve as a red light emitter for solution processed OLEDs, display panels and solid-state lighting. Copyright © 2018 John Wiley & Sons, Ltd.

MEMS for optical switching: technologies, applications, and perspectives

NASA Astrophysics Data System (ADS)

Lin, Lih-Y.; Goldstein, Evan L.

1999-09-01

Micro-electro-mechanical-systems (MEMS), due to their unique ability to integrate electrical, mechanical, and optical elements on a single chip, have recently begun to exhibit great potential for realizing optical components and subsystems in compact, lowcost form. Recently, this technology has been applied to wavelength-division-multiplexed (WDM) networks, and resulted in advances in several network elements, including switches, filters, modulators, and wavelength-add/drop multiplexers. Due largely to the exploding capacity demand arising from data traffic, the transmission capacity demanded of and available from WDM networks is anticipated to increase rapidly. For managing such networks, optical switching is of particular interest due to the fact that its complexity is essentially immune to steady advances in the per-channel bit-rate. We will review various micromachined optical-switching technologies, emphasizing studies of their reliability. We then summarizing recent progress in the free-space MEMS optical switch we have demonstrated.

MEMS for optical switching: technologies, applications, and perspectives

NASA Astrophysics Data System (ADS)

Lin, Lih-Yuan; Goldstein, Evan L.

1999-09-01

Micro-electro-mechanical-systems (MEMS), due to their unique ability to integrate electrical, mechanical, and optical elements on a single chip, have recently begun to exhibit great potential for realizing optical components and subsystems in compact, low-cost form. Recently, this technology has been applied to wavelength-division-multiplexed (WDM) networks, and resulted in advances in several network elements, including switches, filters, modulators, and wavelength-add/drop multiplexers. Due largely to the exploding capacity demand arising from data traffic, the transmission capacity demanded of and available from WDM networks is anticipated to increase rapidly. For managing such networks, optical switching is of particular interest due to the fact that its complexity is essentially immune to steady advances in the per-channel bit-rate. We will review various micromachined optical-switching technologies, emphasizing studies of their reliability. We then summarizing recent progress in the free-space MEMS optical switch we have demonstrated.

Optical radiation measurements and instrumentation.

PubMed

Andersen, F A; Landry, R J

1981-07-01

Accurate measurement of optical radiation is required when sources of optical radiation are used in biological research. Such measurement of broad-band noncoherent optical radiations usually must be performed by a highly trained specialist using sophisticated, complex, and expensive instruments. Presentation of the results of such measurement requires correct use of quantities and units with which many biological researchers are unfamiliar. The measurement process, quantities, units, measurement systems and instruments, and uncertainties associated with optical radiation measurements are reviewed in this paper. A conventional technique for evaluating the potential hazards associated with broad-band sources of optical radiation and a spectroradiometer developed to measure spectral quantities is described. A new prototype ultraviolet radiation hazard monitor which has recently been developed is also presented. This new instrument utilizes a spectrograph and a spectral weighting mechanical mask and provides a direct reading of the effective irradiance for wavelengths less than 315 nm.

Cell Signaling Experiments Driven by Optical Manipulation

PubMed Central

Difato, Francesco; Pinato, Giulietta; Cojoc, Dan

2013-01-01

Cell signaling involves complex transduction mechanisms in which information released by nearby cells or extracellular cues are transmitted to the cell, regulating fundamental cellular activities. Understanding such mechanisms requires cell stimulation with precise control of low numbers of active molecules at high spatial and temporal resolution under physiological conditions. Optical manipulation techniques, such as optical tweezing, mechanical stress probing or nano-ablation, allow handling of probes and sub-cellular elements with nanometric and millisecond resolution. PicoNewton forces, such as those involved in cell motility or intracellular activity, can be measured with femtoNewton sensitivity while controlling the biochemical environment. Recent technical achievements in optical manipulation have new potentials, such as exploring the actions of individual molecules within living cells. Here, we review the progress in optical manipulation techniques for single-cell experiments, with a focus on force probing, cell mechanical stimulation and the local delivery of active molecules using optically manipulated micro-vectors and laser dissection. PMID:23698758

Optical laboratory solution and error model simulation of a linear time-varying finite element equation

NASA Technical Reports Server (NTRS)

Taylor, B. K.; Casasent, D. P.

1989-01-01

The use of simplified error models to accurately simulate and evaluate the performance of an optical linear-algebra processor is described. The optical architecture used to perform banded matrix-vector products is reviewed, along with a linear dynamic finite-element case study. The laboratory hardware and ac-modulation technique used are presented. The individual processor error-source models and their simulator implementation are detailed. Several significant simplifications are introduced to ease the computational requirements and complexity of the simulations. The error models are verified with a laboratory implementation of the processor, and are used to evaluate its potential performance.

Birefringence and vascular imaging of in vivo human skin by Jones-matrix optical coherence tomography

NASA Astrophysics Data System (ADS)

Li, En; Makita, Shuichi; Hong, Young-Joo; Kasaragod, Deepa; Yasuno, Yoshiaki

2017-02-01

A customized 1310-nm Jones-matrix optical coherence tomography (JM-OCT) for dermatological investigation was constructed and used for in vivo normal human skin tissue imaging. This system can simultaneously measure the threedimensional depth-resolved local birefringence, complex-correlation based OCT angiography (OCT-A), degree-ofpolarization- uniformity (DOPU) and scattering OCT intensity. By obtaining these optical properties of tissue, the morphology, vasculature, and collagen content of skin can be deduced and visualized. Structures in the deep layers of the epithelium were observed with depth-resolved local birefringence and polarization uniformity images. These results suggest high diagnostic and investigative potential of JM-OCT for dermatology.

High transmittance optical films based on quantum dot doped nanoscale polymer dispersed liquid crystals

NASA Astrophysics Data System (ADS)

Gandhi, Sahil Sandesh; Chien, Liang-Chy

2016-04-01

We propose a simple way to fabricate highly transparent nanoscale polymer dispersed liquid crystal (nano-PDLC) films between glass substrates and investigate their incident angle dependent optical transmittance properties with both collimated and Lambertian intensity distribution light sources. We also demonstrate that doping nano-PDLC films with 0.1% InP/ZnS core/shell quantum dots (QD) results in a higher optical transmittance. This work lays the foundation for such nanostructured composites to potentially serve as roll-to-roll coatable light extraction or brightness enhancement films in emissive display applications, superior to complex nanocorrugation techniques proposed in the past.

Electron impact ionisation cross section for organoplatinum compounds

NASA Astrophysics Data System (ADS)

Mahato, Dibyendu; Naghma, Rahla; Alam, Mohammad Jane; Ahmad, Shabbir; Antony, Bobby

2016-11-01

This article reports electron impact ionisation cross sections for platinum-based drugs viz., cisplatin (H6N2Cl2Pt), carboplatin (C6H12N2O4Pt), oxaliplatin (C8H14N2O4Pt), nedaplatin (C2H8N2O3Pt) and satraplatin (C10H22ClN2O4Pt) complexes used in the cancer chemotherapy. The multi-scattering centre spherical complex optical potential formalism is used to obtain the inelastic cross section for these large molecules upon electron impact. The ionisation cross section is derived from the inelastic cross section employing complex scattering potential-ionisation contribution method. Comparison is made with previous results, where ever available and overall a reasonable agreement is observed. This is the first attempt to report total ionisation cross sections for nedaplatin and satraplatin complexes.

Optical solitons, nonlinear self-adjointness and conservation laws for the cubic nonlinear Shrödinger's equation with repulsive delta potential

NASA Astrophysics Data System (ADS)

Baleanu, Dumitru; Inc, Mustafa; Aliyu, Aliyu Isa; Yusuf, Abdullahi

2017-11-01

In this paper, the complex envelope function ansatz method is used to acquire the optical solitons to the cubic nonlinear Shrödinger's equation with repulsive delta potential (δ-NLSE). The method reveals dark and bright optical solitons. The necessary constraint conditions which guarantee the existence of the solitons are also presented. We studied the δ-NLSE by analyzing a system of partial differential equations (PDEs) obtained by decomposing the equation into real and imaginary components. We derive the Lie point symmetry generators of the system and prove that the system is nonlinearly self-adjoint with an explicit form of a differential substitution satisfying the nonlinear self-adjoint condition. Then we use these facts to establish a set of conserved vectors for the system using the general Cls theorem presented by Ibragimov. Some interesting figures for the acquired solutions are also presented.

First-Principle Study of the Optical Properties of Dilute-P GaN1-xPx Alloys.

PubMed

Borovac, Damir; Tan, Chee-Keong; Tansu, Nelson

2018-04-16

An investigation on the optical properties of dilute-P GaN 1-x P x alloys by First-Principle Density Functional Theory (DFT) methods is presented, for phosphorus (P) content varying from 0% up to 12.5%. Findings on the imaginary and real part of the dielectric function are analyzed and the results are compared with previously reported theoretical works on GaN. The complex refractive index, normal-incidence reflectivity and birefringence are presented and a difference in the refractive index in the visible regime between GaN and GaNP alloys of ~0.3 can be engineered by adding minute amounts of phosphorus, indicating strong potential for refractive index tunability. The optical properties of the GaN 1-x P x alloys indicate their strong potential for implementation in various III-nitride-based photonic waveguide applications and Distributed Bragg Reflectors (DBR).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet

The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observationsmore » for all the targets reported here, especially for the total cross section.« less

High-precision multiband spectroscopy of ultracold fermions in a nonseparable optical lattice

NASA Astrophysics Data System (ADS)

Fläschner, Nick; Tarnowski, Matthias; Rem, Benno S.; Vogel, Dominik; Sengstock, Klaus; Weitenberg, Christof

2018-05-01

Spectroscopic tools are fundamental for the understanding of complex quantum systems. Here, we demonstrate high-precision multiband spectroscopy in a graphenelike lattice using ultracold fermionic atoms. From the measured band structure, we characterize the underlying lattice potential with a relative error of 1.2 ×10-3 . Such a precise characterization of complex lattice potentials is an important step towards precision measurements of quantum many-body systems. Furthermore, we explain the excitation strengths into different bands with a model and experimentally study their dependency on the symmetry of the perturbation operator. This insight suggests the excitation strengths as a suitable observable for interaction effects on the eigenstates.

Peptide Beacons: A New Design for Polypeptide-Based Optical Biosensors

PubMed Central

Oh, Kenneth J.; Cash, Kevin J.; Hugenberg, Verena; Plaxco, Kevin W.

2008-01-01

Phage display and other in vitro selection techniques produce short polypeptides that tightly and specifically bind to any of a wide range of macromolecular targets. Here we demonstrate a potentially general means of converting such polypeptides into optical biosensors. The sensing architecture we have developed, termed peptide beacons, is based on the observation that, whereas short peptides are almost invariably unfolded and highly dynamic, they become rigid when complexed to their target. Using this effect to segregate a long-lived fluorophore from an electron transfer-based contact quencher, both covalently attached to the peptide, we have produced a robust optical sensor for anti-HIV antibodies. The binding-induced segregation of the fluorophore-quencher pair produces a six-fold increase in sensor emission, thus allowing us to readily detect as low as ∼250 pM of the target antibody. Because the sensor is based on binding-induced folding and a visible-light fluorophore, it is sufficiently selective to work directly in complex, contaminant-ridden samples such as saliva and blood. PMID:17461545

Extended Finite Element Method with Simplified Spherical Harmonics Approximation for the Forward Model of Optical Molecular Imaging

PubMed Central

Li, Wei; Yi, Huangjian; Zhang, Qitan; Chen, Duofang; Liang, Jimin

2012-01-01

An extended finite element method (XFEM) for the forward model of 3D optical molecular imaging is developed with simplified spherical harmonics approximation (SPN). In XFEM scheme of SPN equations, the signed distance function is employed to accurately represent the internal tissue boundary, and then it is used to construct the enriched basis function of the finite element scheme. Therefore, the finite element calculation can be carried out without the time-consuming internal boundary mesh generation. Moreover, the required overly fine mesh conforming to the complex tissue boundary which leads to excess time cost can be avoided. XFEM conveniences its application to tissues with complex internal structure and improves the computational efficiency. Phantom and digital mouse experiments were carried out to validate the efficiency of the proposed method. Compared with standard finite element method and classical Monte Carlo (MC) method, the validation results show the merits and potential of the XFEM for optical imaging. PMID:23227108

Extended finite element method with simplified spherical harmonics approximation for the forward model of optical molecular imaging.

PubMed

Li, Wei; Yi, Huangjian; Zhang, Qitan; Chen, Duofang; Liang, Jimin

2012-01-01

An extended finite element method (XFEM) for the forward model of 3D optical molecular imaging is developed with simplified spherical harmonics approximation (SP(N)). In XFEM scheme of SP(N) equations, the signed distance function is employed to accurately represent the internal tissue boundary, and then it is used to construct the enriched basis function of the finite element scheme. Therefore, the finite element calculation can be carried out without the time-consuming internal boundary mesh generation. Moreover, the required overly fine mesh conforming to the complex tissue boundary which leads to excess time cost can be avoided. XFEM conveniences its application to tissues with complex internal structure and improves the computational efficiency. Phantom and digital mouse experiments were carried out to validate the efficiency of the proposed method. Compared with standard finite element method and classical Monte Carlo (MC) method, the validation results show the merits and potential of the XFEM for optical imaging.

The Use of Computer-Aided Decision Support Systems for Complex Source Selection Decisions

DTIC Science & Technology

1989-09-01

unique low noise interferometer developed at Fusetech Inc. by using divided Fabry - Perot fiber optic cells, common- mode rejection, matched path lengths and...potential techniques for a demodulation scheme. They proposed a detailed investigation of the approaches as part of the program. For mine applications

Embodiment of Learning in Electro-Optical Signal Processors

NASA Astrophysics Data System (ADS)

Hermans, Michiel; Antonik, Piotr; Haelterman, Marc; Massar, Serge

2016-09-01

Delay-coupled electro-optical systems have received much attention for their dynamical properties and their potential use in signal processing. In particular, it has recently been demonstrated, using the artificial intelligence algorithm known as reservoir computing, that photonic implementations of such systems solve complex tasks such as speech recognition. Here, we show how the backpropagation algorithm can be physically implemented on the same electro-optical delay-coupled architecture used for computation with only minor changes to the original design. We find that, compared to when the backpropagation algorithm is not used, the error rate of the resulting computing device, evaluated on three benchmark tasks, decreases considerably. This demonstrates that electro-optical analog computers can embody a large part of their own training process, allowing them to be applied to new, more difficult tasks.

Embodiment of Learning in Electro-Optical Signal Processors.

PubMed

Hermans, Michiel; Antonik, Piotr; Haelterman, Marc; Massar, Serge

2016-09-16

Delay-coupled electro-optical systems have received much attention for their dynamical properties and their potential use in signal processing. In particular, it has recently been demonstrated, using the artificial intelligence algorithm known as reservoir computing, that photonic implementations of such systems solve complex tasks such as speech recognition. Here, we show how the backpropagation algorithm can be physically implemented on the same electro-optical delay-coupled architecture used for computation with only minor changes to the original design. We find that, compared to when the backpropagation algorithm is not used, the error rate of the resulting computing device, evaluated on three benchmark tasks, decreases considerably. This demonstrates that electro-optical analog computers can embody a large part of their own training process, allowing them to be applied to new, more difficult tasks.

Development of realtime connected element interferometry at the Goldstone Deep Space Communications Complex

NASA Technical Reports Server (NTRS)

Edwards, C. D.

1990-01-01

Connected-element interferometry (CEI) has the potential to provide high-accuracy angular spacecraft tracking on short baselines by making use of the very precise phase delay observable. Within the Goldstone Deep Space Communications Complex (DSCC), one of three tracking complexes in the NASA Deep Space Network, baselines of up to 21 km in length are available. Analysis of data from a series of short-baseline phase-delay interferometry experiments are presented to demonstrate the potential tracking accuracy on these baselines. Repeated differential observations of pairs of angularly close extragalactic radio sources were made to simulate differential spacecraft-quasar measurements. Fiber-optic data links and a correlation processor are currently being developed and installed at Goldstone for a demonstration of real-time CEI in 1990.

Realization of optical multimode TSV waveguides for Si-Interposer in 3D-chip-stacks

NASA Astrophysics Data System (ADS)

Killge, S.; Charania, S.; Richter, K.; Neumann, N.; Al-Husseini, Z.; Plettemeier, D.; Bartha, J. W.

2017-05-01

Optical connectivity has the potential to outperform copper-based TSVs in terms of bandwidth at the cost of more complexity due to the required electro-optical and opto-electrical conversion. The continuously increasing demand for higher bandwidth pushes the breakeven point for a profitable operation to shorter distances. To integrate an optical communication network in a 3D-chip-stack optical through-silicon vertical VIAs (TSV) are required. While the necessary effort for the electrical/optical and vice versa conversion makes it hard to envision an on-chip optical interconnect, a chip-to-chip optical link appears practicable. In general, the interposer offers the potential advantage to realize electro-optical transceivers on affordable expense by specific, but not necessarily CMOS technology. We investigated the realization and characterization of optical interconnects as a polymer based waveguide in high aspect ratio (HAR) TSVs proved on waferlevel. To guide the optical field inside a TSV as optical-waveguide or fiber, its core has to have a higher refractive index than the surrounding material. Comparing different material / technology options it turned out that thermal grown silicon dioxide (SiO2) is a perfect candidate for the cladding (nSiO2 = 1.4525 at 850 nm). In combination with SiO2 as the adjacent polymer layer, the negative resist SU-8 is very well suited as waveguide material (nSU-8 = 1.56) for the core. Here, we present the fabrication of an optical polymer based multimode waveguide in TSVs proved on waferlevel using SU-8 as core and SiO2 as cladding. The process resulted in a defect-free filling of waveguide TSVs with SU-8 core and SiO2 cladding up to aspect ratio (AR) 20:1 and losses less than 3 dB.

Polymer-stabilized liquid crystalline topological defect network for micro-pixelated optical devices

NASA Astrophysics Data System (ADS)

Araoka, Fumito; Le, Khoa V.; Fujii, Shuji; Orihara, Hiroshi; Sasaki, Yuji

2018-02-01

Spatially and temporally controlled topological defects in nematic liquid crystals (NLCs) are promising for its potential in optical applications. Utilization of self-organization is a key to fabricate complex micro- and nano-structures which are often difficult to obtain by conventional lithographic tools. Using photo-polymerization technique, here we show a polymer-stabilized NLC having a micro-pixelated structure of regularly ordered umbilical defects which are induced by an electric field. Due to the formation of polymer network, the self-organized pattern is kept stable without deterioration. Moreover, the polymer network allows to template other LCs whose optical properties can be tuned with external stimuli such as temperature and electric fields.

Unidirectional reflectionless light propagation at exceptional points

NASA Astrophysics Data System (ADS)

Huang, Yin; Shen, Yuecheng; Min, Changjun; Fan, Shanhui; Veronis, Georgios

2017-05-01

In this paper, we provide a comprehensive review of unidirectional reflectionless light propagation in photonic devices at exceptional points (EPs). EPs, which are branch point singularities of the spectrum, associated with the coalescence of both eigenvalues and corresponding eigenstates, lead to interesting phenomena, such as level repulsion and crossing, bifurcation, chaos, and phase transitions in open quantum systems described by non-Hermitian Hamiltonians. Recently, it was shown that judiciously designed photonic synthetic matters could mimic the complex non-Hermitian Hamiltonians in quantum mechanics and realize unidirectional reflection at optical EPs. Unidirectional reflectionlessness is of great interest for optical invisibility. Achieving unidirectional reflectionless light propagation could also be potentially important for developing optical devices, such as optical network analyzers. Here, we discuss unidirectional reflectionlessness at EPs in both parity-time (PT)-symmetric and non-PT-symmetric optical systems. We also provide an outlook on possible future directions in this field.

Miniature optical planar camera based on a wide-angle metasurface doublet corrected for monochromatic aberrations

PubMed Central

Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Horie, Yu; Han, Seunghoon; Faraon, Andrei

2016-01-01

Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They are poised to revolutionize optics by enabling complex low-cost systems where multiple metasurfaces are lithographically stacked and integrated with electronics. For imaging applications, metasurface stacks can perform sophisticated image corrections and can be directly integrated with image sensors. Here we demonstrate this concept with a miniature flat camera integrating a monolithic metasurface lens doublet corrected for monochromatic aberrations, and an image sensor. The doublet lens, which acts as a fisheye photographic objective, has a small f-number of 0.9, an angle-of-view larger than 60° × 60°, and operates at 850 nm wavelength with 70% focusing efficiency. The camera exhibits nearly diffraction-limited image quality, which indicates the potential of this technology in the development of optical systems for microscopy, photography, and computer vision. PMID:27892454

Miniature optical planar camera based on a wide-angle metasurface doublet corrected for monochromatic aberrations

NASA Astrophysics Data System (ADS)

Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Horie, Yu; Han, Seunghoon; Faraon, Andrei

2016-11-01

Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They are poised to revolutionize optics by enabling complex low-cost systems where multiple metasurfaces are lithographically stacked and integrated with electronics. For imaging applications, metasurface stacks can perform sophisticated image corrections and can be directly integrated with image sensors. Here we demonstrate this concept with a miniature flat camera integrating a monolithic metasurface lens doublet corrected for monochromatic aberrations, and an image sensor. The doublet lens, which acts as a fisheye photographic objective, has a small f-number of 0.9, an angle-of-view larger than 60° × 60°, and operates at 850 nm wavelength with 70% focusing efficiency. The camera exhibits nearly diffraction-limited image quality, which indicates the potential of this technology in the development of optical systems for microscopy, photography, and computer vision.

Ultra-precision fabrication of high density micro-optical backbone interconnections for data center and mobile application

NASA Astrophysics Data System (ADS)

Lohmann, U.; Jahns, J.; Wagner, T.; Werner, C.

2012-10-01

A microoptical 3D interconnection scheme and fabricated samples of this fiberoptical multi-channel interconnec- tion with an actual capacity of 144 channels were shown. Additionally the aspects of micrometer-fabrication of such microoptical interconnection modules in the view of alignment-tolerances were considered. For the realiza- tion of the interconnection schemes, the approach of planar-integrated free space optics (PIFSO) is used with its well known advantages. This approach offers the potential for complex interconnectivity, and yet compact size.

Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies.

PubMed

Vogel, Nicolas; Utech, Stefanie; England, Grant T; Shirman, Tanya; Phillips, Katherine R; Koay, Natalie; Burgess, Ian B; Kolle, Mathias; Weitz, David A; Aizenberg, Joanna

2015-09-01

Materials in nature are characterized by structural order over multiple length scales have evolved for maximum performance and multifunctionality, and are often produced by self-assembly processes. A striking example of this design principle is structural coloration, where interference, diffraction, and absorption effects result in vivid colors. Mimicking this emergence of complex effects from simple building blocks is a key challenge for man-made materials. Here, we show that a simple confined self-assembly process leads to a complex hierarchical geometry that displays a variety of optical effects. Colloidal crystallization in an emulsion droplet creates micron-sized superstructures, termed photonic balls. The curvature imposed by the emulsion droplet leads to frustrated crystallization. We observe spherical colloidal crystals with ordered, crystalline layers and a disordered core. This geometry produces multiple optical effects. The ordered layers give rise to structural color from Bragg diffraction with limited angular dependence and unusual transmission due to the curved nature of the individual crystals. The disordered core contributes nonresonant scattering that induces a macroscopically whitish appearance, which we mitigate by incorporating absorbing gold nanoparticles that suppress scattering and macroscopically purify the color. With increasing size of the constituent colloidal particles, grating diffraction effects dominate, which result from order along the crystal's curved surface and induce a vivid polychromatic appearance. The control of multiple optical effects induced by the hierarchical morphology in photonic balls paves the way to use them as building blocks for complex optical assemblies--potentially as more efficient mimics of structural color as it occurs in nature.

Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies

PubMed Central

Vogel, Nicolas; Utech, Stefanie; England, Grant T.; Shirman, Tanya; Phillips, Katherine R.; Koay, Natalie; Burgess, Ian B.; Kolle, Mathias; Weitz, David A.; Aizenberg, Joanna

2015-01-01

Materials in nature are characterized by structural order over multiple length scales have evolved for maximum performance and multifunctionality, and are often produced by self-assembly processes. A striking example of this design principle is structural coloration, where interference, diffraction, and absorption effects result in vivid colors. Mimicking this emergence of complex effects from simple building blocks is a key challenge for man-made materials. Here, we show that a simple confined self-assembly process leads to a complex hierarchical geometry that displays a variety of optical effects. Colloidal crystallization in an emulsion droplet creates micron-sized superstructures, termed photonic balls. The curvature imposed by the emulsion droplet leads to frustrated crystallization. We observe spherical colloidal crystals with ordered, crystalline layers and a disordered core. This geometry produces multiple optical effects. The ordered layers give rise to structural color from Bragg diffraction with limited angular dependence and unusual transmission due to the curved nature of the individual crystals. The disordered core contributes nonresonant scattering that induces a macroscopically whitish appearance, which we mitigate by incorporating absorbing gold nanoparticles that suppress scattering and macroscopically purify the color. With increasing size of the constituent colloidal particles, grating diffraction effects dominate, which result from order along the crystal’s curved surface and induce a vivid polychromatic appearance. The control of multiple optical effects induced by the hierarchical morphology in photonic balls paves the way to use them as building blocks for complex optical assemblies—potentially as more efficient mimics of structural color as it occurs in nature. PMID:26290583

Manipulation of long-term dynamics in a colloidal active matter system using speckle light fields

NASA Astrophysics Data System (ADS)

Pince, Ercag; Velu, Sabareesh K. P.; Callegari, Agnese; Elahi, Parviz; Gigan, Sylvain; Volpe, Giovanni; Volpe, Giorgio

Particles undergoing a stochastic motion within a disordered medium is a ubiquitous physical and biological phenomena. Examples can be given from organelles performing tasks in the cytoplasm to large animals moving in patchy environment. Here, we use speckle light fields to study the anomalous diffusion in an active matter system consisting of micron-sized silica particles(diameter 5 μm) and motile bacterial cells (E. coli). The speckle light fields are generated by mode mixing inside a multimode optical fiber where a small amount of incident laser power is needed to obtain an effective disordered optical landscape for the purpose of optical manipulation. We experimentally show how complex potentials contribute to the long-term dynamics of the active matter system and observed an enhanced diffusion of particles interacting with the active bacterial bath in the speckle light fields. We showed that this effect can be tuned and controlled by varying the intensity and the statistical properties of the speckle pattern. Potentially, these results could be of interest for many technological applications, such as the manipulation of microparticles inside optically disordered media of biological interest.

Ab-initio investigations for opto-electronic response of (Cd, Zn)Ga2Te4: Promising solar PV materials

NASA Astrophysics Data System (ADS)

Sahariya, Jagrati; Soni, Amit; Kumar, Pancham

2018-04-01

In this paper, the first principle calculations are performed to analyze the structural, electronic and optical behavior of promising solar materials (Cd,Zn)Ga2Te4. To perform these calculations we have used one of the most accurate Full Potential Linearized Augmented Plane Wave (FP-LAPW) method. The ground state properties of these compounds are confirmed over here after proper examination of energy and charge convergence using Perdew-Burke-Ernzerhof (PBE-sol) exchange correlation potential. The investigations performed such as energy band structure, Density of States (DOS), optical parameters like complex dielectric function and absorption co-efficient are discussed over here to understand the overall response of the chosen system.

Microscopic few-body and Gaussian-shaped density distributions for the analysis of the 6He exotic nucleus with different target nuclei

NASA Astrophysics Data System (ADS)

Aygun, M.; Kucuk, Y.; Boztosun, I.; Ibraheem, Awad A.

2010-12-01

The elastic scattering angular distributions of 6He projectile on different medium and heavy mass target nuclei including 12C, 27Al, 58Ni, 64Zn, 65Cu, 197Au, 208Pb and 209Bi have been examined by using the few-body and Gaussian-shaped density distributions at various energies. The microscopic real parts of the complex nuclear optical potential have been obtained by using the double-folding model for each of the density distributions and the phenomenological imaginary potentials have been taken as the Woods-Saxon type. Comparative results of the few-body and Gaussian-shaped density distributions together with the experimental data are presented within the framework of the optical model.

Finite element model for MOI applications using A-V formulation

NASA Astrophysics Data System (ADS)

Xuan, L.; Shanker, B.; Udpa, L.; Shih, W.; Fitzpatrick, G.

2001-04-01

Magneto-optic imaging (MOI) is a relatively new sensor application of an extension of bubble memory technology to NDT and produce easy-to-interpret, real time analog images. MOI systems use a magneto-optic (MO) sensor to produce analog images of magnetic flux leakage from surface and subsurface defects. The instrument's capability in detecting the relatively weak magnetic fields associated with subsurface defects depends on the sensitivity of the magneto-optic sensor. The availability of a theoretical model that can simulate the MOI system performance is extremely important for optimization of the MOI sensor and hardware system. A nodal finite element model based on magnetic vector potential formulation has been developed for simulating MOI phenomenon. This model has been used for predicting the magnetic fields in simple test geometry with corrosion dome defects. In the case of test samples with multiple discontinuities, a more robust model using the magnetic vector potential Ā and electrical scalar potential V is required. In this paper, a finite element model based on A-V formulation is developed to model complex circumferential crack under aluminum rivets in dimpled countersink.

Multi-tap complex-coefficient incoherent microwave photonic filters based on optical single-sideband modulation and narrow band optical filtering.

PubMed

Sagues, Mikel; García Olcina, Raimundo; Loayssa, Alayn; Sales, Salvador; Capmany, José

2008-01-07

We propose a novel scheme to implement tunable multi-tap complex coefficient filters based on optical single sideband modulation and narrow band optical filtering. A four tap filter is experimentally demonstrated to highlight the enhanced tuning performance provided by complex coefficients. Optical processing is performed by the use of a cascade of four phase-shifted fiber Bragg gratings specifically fabricated for this purpose.

Optical and electrochemical characteristics of Ir(III) complexes with metalated 4-(4-bromophenyl)-2-methyl-1,3-thiazole and isocyanide, ethylenediamine, and diethyldithiocarbamate ligands

NASA Astrophysics Data System (ADS)

Katlenok, E. A.; Kinzhalov, M. A.; Eremina, A. A.; Balashev, K. P.

2017-05-01

The influence of donor-acceptor properties of tert-butyl-, 2.6-dimethylphenyl-, and 4-bromophenyl-isocyanides (BuNC, XylNC, BpNC), ethylenediamine (En), and diethyldithiocarbamate ions (Dtc-) on the 1H and 13C NMR, IR, optical, and electrochemical characteristics of Ir(III) complexes with metalated 4-(4-bromophenyl)-2-methyl-1,3-thiazole is studied. Enhancement of the donor properties of BpNC, XylNC, BuNC, En, and Dtc- ligands leads to a bathochromic shift of metal-to-ligand charge transfer (MLCT) bands and to a decrease in the difference between the one-electron oxidation and reduction potentials of complexes. The bathochromic shift of the low-temperature phosphorescence of complexes in frozen (77 K) solutions with increasing donor properties of BpNC, XylNC, BuNC, En, and Dtc-ligands is caused by a decrease in the admixture of MLCT to the intraligand excited state of {Ir(bptz)2}. Quenching of the phosphorescence of complexes in liquid solutions is attributed to the thermally-induced population of excited d- d* states with subsequent nonradiative deactivation.

Synthesis, characterization and theoretical investigations of the structure, electronic properties and third-order nonlinearity optics (NLO) of M(DPIP)2

NASA Astrophysics Data System (ADS)

Li, Kang; Tang, Guodong; Kou, ShanShan; Culnane, Lance F.; Zhang, Yu; Song, Yinglin; Li, Rongqing; Wei, Changmei

2015-03-01

Three complexes of M(DPIP)2 (M = Cu, Co, Zn as 1, 2, 3) were synthesized and characterized by elemental analysis, IR, UV-Vis, thermogravimetry, and X-ray diffraction. Their nonlinear optical properties were measured by the Z-scan technique and yielded a normalized transmittance of about 70% for complex 1 (45 μJ pulse), and 93% for complex 3 (68 μJ pulse at the focus point). The nonlinear absorption coefficient, β, is 1.4 × 10-11 m/W for 1 and 5.6 × 10-13 m/W for 3, and the third-order nonlinear refraction index, n2, is 1.0 × 10-18 m2/W for 3. Complex 1 shows self-defocusing property, while complex 3 exhibits self-focusing property. The thermogravimetric results show that the frame structure of compounds 1-3 begin to collapse at 400, 250 and 280 °C, respectively, which suggests that they elicit excellent thermal stability. This research aims to provide better understanding of these compounds, and offer preliminary explanations for the significant differences between compounds 1-3, in order to potentially help in the designing of future novel materials with NLO properties.

Synthesis and Characterization of Electroresponsive Materials with Applications In: Part I. Second Harmonic Generation. Part II. Organic-Lanthanide Ion Complexes for Electroluminescence and Optical Amplifiers.

NASA Astrophysics Data System (ADS)

Claude, Charles

1995-01-01

Materials for optical waveguides were developed from two different approaches, inorganic-organic composites and soft gel polymers. Inorganic-organic composites were developed from alkoxysilane and organically modified silanes based on nonlinear optical chromophores. Organically modified silanes based on N-((3^' -trialkoxysilyl)propyl)-4-nitroaniline were synthesized and sol-gelled with trimethoxysilane. After a densification process at 190^circC with a corona discharge, the second harmonic of the film was measured with a Nd:YAG laser with a fundamental wavelength of 1064nm, d_{33} = 13pm/V. The decay of the second harmonic was expressed by a stretched bi-exponential equation. The decay time (tau _2) was equal to 3374 hours, and was comparable to nonlinear optical systems based on epoxy/Disperse Orange 1. The processing temperature of the organically modified silane was limited to 200^circC due to the decomposition of the organic chromophore. Soft gel polymers were synthesized and characterized for the development of optical waveguides with dc-electrical field assisted phase-matching. Polymers based on 4-nitroaniline terminated poly(ethylene oxide-co-propylene oxide) were shown to exhibit second harmonic generation that were optically phase-matched in an electrical field. The optical signals were stable and reproducible. Siloxane polymers modified with 1-mercapto-4-nitrobenzene and 1-mercapto-4-methylsulfonylstilbene nonlinear optical chromophores were synthesized. The physical and the linear and nonlinear optical properties of the polymers were characterized. Waveguides were developed from the polymers which were optically phase -matched and had an efficiency of 8.1%. The siloxane polymers exhibited optical phase-matching in an applied electrical field and can be used with a semiconductor laser. Organic lanthanide ion complexes for electroluminescence and optical amplifiers were synthesized and characterized. The complexes were characterized for their thermal and oxidative stability and for their optical properties. Organic-europium ion complexes based on derivatives of 2-benzoyl benzoate are stable to a temperature 70^circ C higher than the europium beta -diketonate complexes. The optical and fluorescence properties of the organic-europium ion complexes were characterized. The methoxy and the t-butyl derivatives of the europium 2-benzoylbenzoate complexes exhibited fluorescence quantum efficiencies that were comparable to europium tris(thenoyl trifluoroacetonate) in methylene chloride but the extinction coefficient was two-thirds of the europium thenoyltrifluoroacetonate complexes. The last complex characterized was the europium bis(diphenylphosphino)imine complex. The complex exhibited thermal stability to 550 ^circC under nitrogen.

Molecular and electronic structure of terminal and alkali metal-capped uranium(V) nitride complexes

PubMed Central

King, David M.; Cleaves, Peter A.; Wooles, Ashley J.; Gardner, Benedict M.; Chilton, Nicholas F.; Tuna, Floriana; Lewis, William; McInnes, Eric J. L.; Liddle, Stephen T.

2016-01-01

Determining the electronic structure of actinide complexes is intrinsically challenging because inter-electronic repulsion, crystal field, and spin–orbit coupling effects can be of similar magnitude. Moreover, such efforts have been hampered by the lack of structurally analogous families of complexes to study. Here we report an improved method to U≡N triple bonds, and assemble a family of uranium(V) nitrides. Along with an isoelectronic oxo, we quantify the electronic structure of this 5f1 family by magnetometry, optical and electron paramagnetic resonance (EPR) spectroscopies and modelling. Thus, we define the relative importance of the spin–orbit and crystal field interactions, and explain the experimentally observed different ground states. We find optical absorption linewidths give a potential tool to identify spin–orbit coupled states, and show measurement of UV···UV super-exchange coupling in dimers by EPR. We show that observed slow magnetic relaxation occurs via two-phonon processes, with no obvious correlation to the crystal field. PMID:27996007

Combined effects of nonparaxiality, optical activity, and walk-off on rogue wave propagation in optical fibers filled with chiral materials.

PubMed

Temgoua, D D Estelle; Tchokonte, M B Tchoula; Kofane, T C

2018-04-01

The generalized nonparaxial nonlinear Schrödinger (NLS) equation in optical fibers filled with chiral materials is reduced to the higher-order integrable Hirota equation. Based on the modified Darboux transformation method, the nonparaxial chiral optical rogue waves are constructed from the scalar model with modulated coefficients. We show that the parameters of nonparaxiality, third-order dispersion, and differential gain or loss term are the main keys to control the amplitude, linear, and nonlinear effects in the model. Moreover, the influence of nonparaxiality, optical activity, and walk-off effect are also evidenced under the defocusing and focusing regimes of the vector nonparaxial NLS equations with constant and modulated coefficients. Through an algorithm scheme of wider applicability on nonparaxial beam propagation methods, the most influential effect and the simultaneous controllability of combined effects are underlined, showing their properties and their potential applications in optical fibers and in a variety of complex dynamical systems.

Combined effects of nonparaxiality, optical activity, and walk-off on rogue wave propagation in optical fibers filled with chiral materials

NASA Astrophysics Data System (ADS)

Temgoua, D. D. Estelle; Tchokonte, M. B. Tchoula; Kofane, T. C.

2018-04-01

The generalized nonparaxial nonlinear Schrödinger (NLS) equation in optical fibers filled with chiral materials is reduced to the higher-order integrable Hirota equation. Based on the modified Darboux transformation method, the nonparaxial chiral optical rogue waves are constructed from the scalar model with modulated coefficients. We show that the parameters of nonparaxiality, third-order dispersion, and differential gain or loss term are the main keys to control the amplitude, linear, and nonlinear effects in the model. Moreover, the influence of nonparaxiality, optical activity, and walk-off effect are also evidenced under the defocusing and focusing regimes of the vector nonparaxial NLS equations with constant and modulated coefficients. Through an algorithm scheme of wider applicability on nonparaxial beam propagation methods, the most influential effect and the simultaneous controllability of combined effects are underlined, showing their properties and their potential applications in optical fibers and in a variety of complex dynamical systems.

Patterning via optical saturable transitions

NASA Astrophysics Data System (ADS)

Cantu, Precious

For the past 40 years, optical lithography has been the patterning workhorse for the semiconductor industry. However, as integrated circuits have become more and more complex, and as device geometries shrink, more innovative methods are required to meet these needs. In the far-field, the smallest feature that can be generated with light is limited to approximately half the wavelength. This, so called far-field diffraction limit or the Abbe limit (after Prof. Ernst Abbe who first recognized this), effectively prevents the use of long-wavelength photons >300nm from patterning nanostructures <100nm. Even with a 193nm laser source and extremely complicated processing, patterns below ˜20nm are incredibly challenging to create. Sources with even shorter wavelengths can potentially be used. However, these tend be much more expensive and of much lower brightness, which in turn limits their patterning speed. Multi-photon reactions have been proposed to overcome the diffraction limit. However, these require very large intensities for modest gain in resolution. Moreover, the large intensities make it difficult to parallelize, thus limiting the patterning speed. In this dissertation, a novel nanopatterning technique using wavelength-selective small molecules that undergo single-photon reactions, enabling rapid top-down nanopatterning over large areas at low-light intensities, thereby allowing for the circumvention of the far-field diffraction barrier is developed and experimentally verified. This approach, which I refer to as Patterning via Optical Saturable Transitions (POST) has the potential for massive parallelism, enabling the creation of nanostructures and devices at a speed far surpassing what is currently possible with conventional optical lithographic techniques. The fundamental understanding of this technique goes beyond optical lithography in the semiconductor industry and is applicable to any area that requires the rapid patterning of large-area two or three-dimensional complex geometries. At a basic level, this research intertwines the fields of electrochemistry, material science, electrical engineering, optics, physics, and mechanical engineering with the goal of developing a novel super-resolution lithographic technique.

Electron impact scattering study of hypohalous acids HOX (X = F, Cl, Br, I)

NASA Astrophysics Data System (ADS)

Yadav, Hitesh; Bhutadia, Harshad; Prajapati, Dinesh; Desai, Hardik; Vinodkumar, Minaxi; Vinodkumar, P. C.

2018-05-01

In this article we aim to report total cross sections (TCS) QT, total elastic cross sections (Qel), total inelastic cross sections (Qinel) i.e. (total ionizations cross sections (Qion)+total electronic excitation cross sections (Qexc)) from threshold of the target to 5000 eV energy range. We have used a well-defined theoretical methodology Spherical Complex Optical Potential (SCOP) to compute QT, Qel and Qinel and Complex Scattering Potential - ionization contribution (CSP - ic) method to report the (Qion). The cross-sectional data reported here for the Hypohalous Acids is for the first time and the present data can become a guideline for the experimentalist to study these targets.

Elastic light scattering from single cells: orientational dynamics in optical trap.

PubMed

Watson, Dakota; Hagen, Norbert; Diver, Jonathan; Marchand, Philippe; Chachisvilis, Mirianas

2004-08-01

Light-scattering diagrams (phase functions) from single living cells and beads suspended in an optical trap were recorded with 30-ms time resolution. The intensity of the scattered light was recorded over an angular range of 0.5-179.5 degrees using an optical setup based on an elliptical mirror and rotating aperture. Experiments revealed that light-scattering diagrams from biological cells exhibit significant and complex time dependence. We have attributed this dependence to the cell's orientational dynamics within the trap. We have also used experimentally measured phase function information to calculate the time dependence of the optical radiation pressure force on the trapped particle and show how it changes depending on the orientation of the particle. Relevance of these experiments to potential improvement in the sensitivity of label-free flow cytometry is discussed.

Nonlinear optical investigation of the Tris(2‧,2-bipyridyl)iron(II) tetrafluoroborate using z-scan technique

NASA Astrophysics Data System (ADS)

Zidan, M. D.; Al-Ktaifani, M. M.; Allahham, A.

2017-05-01

Z-scan measurements were performed with a CW diode laser at 635 nm to investigate the nonlinear optical properties of Tris(2‧,2-bipyridyl)iron(II) tetrafluoroborate in ethanol at two concentrations. Theoretical fit was carried out to evaluate the nonlinear absorption coefficient (β) and the negative nonlinear refractive index (n2) for the studied complex. Furthermore, the ground-state absorption cross sections (σg), the excited-state absorption cross sections (σex) and thermo-optic coefficient were also estimated. The investigations show large NLO response, which is predominantly associated with substantial conjugation between the aromatic ring π-electron system and d-electron set metal center. The obtained results give a strong indication that Tris(2‧,2-bipyridyl)iron(II) tetrafluoroborate have a potential application in optical domain.

Coarse graining of NN inelastic interactions up to 3 GeV: Repulsive versus structural core

NASA Astrophysics Data System (ADS)

Fernández-Soler, P.; Ruiz Arriola, E.

2017-07-01

The repulsive short-distance core is one of the main paradigms of nuclear physics which even seems confirmed by QCD lattice calculations. On the other hand nuclear potentials at short distances are motivated by high energy behavior where inelasticities play an important role. We analyze NN interactions up to 3 GeV in terms of simple coarse grained complex and energy dependent interactions. We discuss two possible and conflicting scenarios which share the common feature of a vanishing wave function at the core location in the particular case of S waves. We find that the optical potential with a repulsive core exhibits a strong energy dependence whereas the optical potential with the structural core is characterized by a rather adiabatic energy dependence which allows one to treat inelasticity perturbatively. We discuss the possible implications for nuclear structure calculations of both alternatives.

Dual-comb spectroscopy of water vapor with a free-running semiconductor disk laser.

PubMed

Link, S M; Maas, D J H C; Waldburger, D; Keller, U

2017-06-16

Dual-comb spectroscopy offers the potential for high accuracy combined with fast data acquisition. Applications are often limited, however, by the complexity of optical comb systems. Here we present dual-comb spectroscopy of water vapor using a substantially simplified single-laser system. Very good spectroscopy measurements with fast sampling rates are achieved with a free-running dual-comb mode-locked semiconductor disk laser. The absolute stability of the optical comb modes is characterized both for free-running operation and with simple microwave stabilization. This approach drastically reduces the complexity for dual-comb spectroscopy. Band-gap engineering to tune the center wavelength from the ultraviolet to the mid-infrared could optimize frequency combs for specific gas targets, further enabling dual-comb spectroscopy for a wider range of industrial applications. Copyright © 2017, American Association for the Advancement of Science.

All-optical pulse-echo ultrasound probe for intravascular imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Colchester, Richard J.; Noimark, Sacha; Mosse, Charles A.; Zhang, Edward Z.; Beard, Paul C.; Parkin, Ivan P.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

2016-02-01

High frequency ultrasound probes such as intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) catheters can be invaluable for guiding minimally invasive medical procedures in cardiology such as coronary stent placement and ablation. With current-generation ultrasound probes, ultrasound is generated and received electrically. The complexities involved with fabricating these electrical probes can result in high costs that limit their clinical applicability. Additionally, it can be challenging to achieve wide transmission bandwidths and adequate wideband reception sensitivity with small piezoelectric elements. Optical methods for transmitting and receiving ultrasound are emerging as alternatives to their electrical counterparts. They offer several distinguishing advantages, including the potential to generate and detect the broadband ultrasound fields (tens of MHz) required for high resolution imaging. In this study, we developed a miniature, side-looking, pulse-echo ultrasound probe for intravascular imaging, with fibre-optic transmission and reception. The axial resolution was better than 70 microns, and the imaging depth in tissue was greater than 1 cm. Ultrasound transmission was performed by photoacoustic excitation of a carbon nanotube/polydimethylsiloxane composite material; ultrasound reception, with a fibre-optic Fabry-Perot cavity. Ex vivo tissue studies, which included healthy swine tissue and diseased human tissue, demonstrated the strong potential of this technique. To our knowledge, this is the first study to achieve an all-optical pulse-echo ultrasound probe for intravascular imaging. The potential for performing all-optical B-mode imaging (2D and 3D) with virtual arrays of transmit/receive elements, and hybrid imaging with pulse-echo ultrasound and photoacoustic sensing are discussed.

Roadmap on neurophotonics

NASA Astrophysics Data System (ADS)

Cho, Yong Ku; Zheng, Guoan; Augustine, George J.; Hochbaum, Daniel; Cohen, Adam; Knöpfel, Thomas; Pisanello, Ferruccio; Pavone, Francesco S.; Vellekoop, Ivo M.; Booth, Martin J.; Hu, Song; Zhu, Jiang; Chen, Zhongping; Hoshi, Yoko

2016-09-01

Mechanistic understanding of how the brain gives rise to complex behavioral and cognitive functions is one of science’s grand challenges. The technical challenges that we face as we attempt to gain a systems-level understanding of the brain are manifold. The brain’s structural complexity requires us to push the limit of imaging resolution and depth, while being able to cover large areas, resulting in enormous data acquisition and processing needs. Furthermore, it is necessary to detect functional activities and ‘map’ them onto the structural features. The functional activity occurs at multiple levels, using electrical and chemical signals. Certain electrical signals are only decipherable with sub-millisecond timescale resolution, while other modes of signals occur in minutes to hours. For these reasons, there is a wide consensus that new tools are necessary to undertake this daunting task. Optical techniques, due to their versatile and scalable nature, have great potentials to answer these challenges. Optical microscopy can now image beyond the diffraction limit, record multiple types of brain activity, and trace structural features across large areas of tissue. Genetically encoded molecular tools opened doors to controlling and detecting neural activity using light in specific cell types within the intact brain. Novel sample preparation methods that reduce light scattering have been developed, allowing whole brain imaging in rodent models. Adaptive optical methods have the potential to resolve images from deep brain regions. In this roadmap article, we showcase a few major advances in this area, survey the current challenges, and identify potential future needs that may be used as a guideline for the next steps to be taken.

Roadmap on neurophotonics

PubMed Central

Cho, Yong Ku; Zheng, Guoan; Augustine, George J; Hochbaum, Daniel; Cohen, Adam; Knöpfel, Thomas; Pisanello, Ferruccio; Pavone, Francesco S; Vellekoop, Ivo M; Booth, Martin J; Hu, Song; Zhu, Jiang; Chen, Zhongping; Hoshi, Yoko

2017-01-01

Mechanistic understanding of how the brain gives rise to complex behavioral and cognitive functions is one of science’s grand challenges. The technical challenges that we face as we attempt to gain a systems-level understanding of the brain are manifold. The brain’s structural complexity requires us to push the limit of imaging resolution and depth, while being able to cover large areas, resulting in enormous data acquisition and processing needs. Furthermore, it is necessary to detect functional activities and ‘map’ them onto the structural features. The functional activity occurs at multiple levels, using electrical and chemical signals. Certain electrical signals are only decipherable with sub-millisecond timescale resolution, while other modes of signals occur in minutes to hours. For these reasons, there is a wide consensus that new tools are necessary to undertake this daunting task. Optical techniques, due to their versatile and scalable nature, have great potentials to answer these challenges. Optical microscopy can now image beyond the diffraction limit, record multiple types of brain activity, and trace structural features across large areas of tissue. Genetically encoded molecular tools opened doors to controlling and detecting neural activity using light in specific cell types within the intact brain. Novel sample preparation methods that reduce light scattering have been developed, allowing whole brain imaging in rodent models. Adaptive optical methods have the potential to resolve images from deep brain regions. In this roadmap article, we showcase a few major advances in this area, survey the current challenges, and identify potential future needs that may be used as a guideline for the next steps to be taken. PMID:28386392

FIRST PRINCIPLES STUDY ON ELECTRONIC AND OPTICAL PROPERTIES OF Al-DOPED γ-Ge3N4

NASA Astrophysics Data System (ADS)

Ding, Y. C.; Xiang, A. P.; Zhu, X. H.; Luo, J.; Hu, X. F.

2012-12-01

First principles study of the structural, electronic and optical properties of Al-doped γ-Ge3N4 with different concentration has been reported using the pseudo-potential plane wave method within the generalized gradient approximation (GGA). The binding energy and the formation energy suggest that Aluminum (Al) impurities prefer to substitute Ge at octahedral sites. Different doping concentrations are considered and the corresponding density of states (DOS) are analyzed. Calculated DOS indicates that there are holes in the top of the valance band after doping, meaning a p-type doping. We study the complex dielectric function, the absorption coefficient, and the electron energy loss spectra. It is demonstrated that for the low Al concentration, the material exhibits the dielectric behavior and for the high Al concentration, the material has possibilities to exhibit some metallic behavior. The γ-Ge3N4 doped with Al has a much higher static dielectric constant than undoped γ-Ge3N4, implying its potential applications in electronics and optics.

Semiconductor optoelectronic devices for free-space optical communications

NASA Technical Reports Server (NTRS)

Katz, J.

1983-01-01

The properties of individual injection lasers are reviewed, and devices of greater complexity are described. These either include or are relevant to monolithic integration configurations of the lasers with their electronic driving circuitry, power combining methods of semiconductor lasers, and electronic methods of steering the radiation patterns of semiconductor lasers and laser arrays. The potential of AlGaAs laser technology for free-space optical communications systems is demonstrated. These solid-state components, which can generate and modulate light, combine the power of a number of sources and perform at least part of the beam pointing functions. Methods are proposed for overcoming the main drawback of semiconductor lasers, that is, their inability to emit the needed amount of optical power in a single-mode operation.

Electro-optic chaotic system based on the reverse-time chaos theory and a nonlinear hybrid feedback loop.

PubMed

Jiang, Xingxing; Cheng, Mengfan; Luo, Fengguang; Deng, Lei; Fu, Songnian; Ke, Changjian; Zhang, Minming; Tang, Ming; Shum, Ping; Liu, Deming

2016-12-12

A novel electro-optic chaos source is proposed on the basis of the reverse-time chaos theory and an analog-digital hybrid feedback loop. The analog output of the system can be determined by the numeric states of shift registers, which makes the system robust and easy to control. The dynamical properties as well as the complexity dependence on the feedback parameters are investigated in detail. The correlation characteristics of the system are also studied. Two improving strategies which were established in digital field and analog field are proposed to conceal the time-delay signature. The proposed scheme has the potential to be used in radar and optical secure communication systems.

Enabling Characteristics Of Optical Autocovariance Lidar For Global Wind And Aerosol Profiling

NASA Astrophysics Data System (ADS)

Grund, C. J.; Stephens, M.; Lieber, M.; Weimer, C.

2008-12-01

Systematic global wind measurements with 70 km horizontal resolution and, depending on altitude from the PBL to stratosphere, 250m-2km vertical resolution and 0.5m/s - 2 m/s velocity precision are recognized as key to the understanding and monitoring of complex climate modulations, validation of models, and improved precision and range for weather forecasts. Optical Autocovariance Wind Lidar (OAWL) is a relatively new interferometric direct detection Doppler lidar approach that promises to meet the required wind profile resolution at substantial mass, cost, and power savings, and at reduced technical risk for a space-based system meeting the most demanding velocity precision and spatial and temporal resolution requirements. A proof of concept Optical Autocovariance Wind Lidar (OAWL) has been demonstrated, and a robust multi- wavelength, field-widened (more than 100 microR) lidar system suitable for high altitude (over 16km) aircraft demonstration is under construction. Other advantages of the OAWL technique include insensitivity to aerosol/molecular backscatter mixing ratio, freedom from complex receiver/transmitter optical frequency lock loops, prospects for practical continuous large-area coverage wind profiling from GEO, and the availability of simultaneous multiple wavelength High Spectral Resolution Lidar (OA-HSRL) for aerosol identification and optical property measurements. We will discuss theory, development and demonstration status, advantages, limitations, and space-based performance of OAWL and OA-HSRL, as well as the potential for combined mission synergies.

Multimodal Nonlinear Optical Microscopy

PubMed Central

Yue, Shuhua; Slipchenko, Mikhail N.; Cheng, Ji-Xin

2013-01-01

Because each nonlinear optical (NLO) imaging modality is sensitive to specific molecules or structures, multimodal NLO imaging capitalizes the potential of NLO microscopy for studies of complex biological tissues. The coupling of multiphoton fluorescence, second harmonic generation, and coherent anti-Stokes Raman scattering (CARS) has allowed investigation of a broad range of biological questions concerning lipid metabolism, cancer development, cardiovascular disease, and skin biology. Moreover, recent research shows the great potential of using CARS microscope as a platform to develop more advanced NLO modalities such as electronic-resonance-enhanced four-wave mixing, stimulated Raman scattering, and pump-probe microscopy. This article reviews the various approaches developed for realization of multimodal NLO imaging as well as developments of new NLO modalities on a CARS microscope. Applications to various aspects of biological and biomedical research are discussed. PMID:24353747

In Vivo Optical Imaging for Targeted Drug Kinetics and Localization for Oral Surgery and Super-Resolution, Facilitated by Printed Phantoms

NASA Astrophysics Data System (ADS)

Bentz, Brian Z.

Many human cancer cell types over-express folate receptors, and this provides an opportunity to develop targeted anti-cancer drugs. For these drugs to be effective, their kinetics must be well understood in vivo and in deep tissue where tumors occur. We demonstrate a method for imaging these parameters by incorporating a kinetic compartment model and fluorescence into optical diffusion tomography (ODT). The kinetics were imaged in a live mouse, and found to be in agreement with previous in vitro studies, demonstrating the validity of the method and its feasibility as an effective tool in preclinical drug development studies. Progress in developing optical imaging for biomedical applications requires customizable and often complex objects known as "phantoms" for testing and evaluation. We present new optical phantoms fabricated using inexpensive 3D printing methods with multiple materials, allowing for the placement of complex inhomogeneities in heterogeneous or anatomically realistic geometries, as opposed to previous phantoms which were limited to simple shapes formed by molds or machining. Furthermore, we show that Mie theory can be used to design the optical properties to match a target tissue. The phantom fabrication methods are versatile, can be applied to optical imaging methods besides diffusive imaging, and can be used in the calibration of live animal imaging data. Applications of diffuse optical imaging in the operating theater have been limited in part due to computational burden. We present an approach for the fast localization of arteries in the roof of the mouth that has the potential to reduce complications. Furthermore, we use the extracted position information to fabricate a custom surgical guide using 3D printing that could protect the arteries during surgery. The resolution of ODT is severely limited by the attenuation of high spatial frequencies. We present a super-resolution method achieved through the point localization of fluorescent inhomogeneities in a tissue-like scattering medium, and examine the localization uncertainty numerically and experimentally. Furthermore, we show numerical results for the localization of multiple fluorescent inhomogeneities by distinguishing them based on temporal characteristics. Potential applications include imaging neuron activation in the brain.

First principles study of structural, electronic and optical properties of perovskites CaZrO3 and CaHfO3 in cubic phase

NASA Astrophysics Data System (ADS)

Hoat, D. M.; Silva, J. F. Rivas; Blas, A. Méndez

2018-07-01

In this work, we present the first principles calculations for structural, electronic and optical properties of perovskites CaZrO3 and CaHfO3 using the full-potential linearized augmented plane wave method (FP-LAPW) within the framework of density functional theory (DFT) as implemented in WIEN2k package. The exchange-correlation potential is treated with local density approximation (LDA) and generalized gradient approximation (GGA-PBE and PBESol). Additionally, the Tran Blaha modified Becke-Johnson exchange potential (mBJ) also is employed for electronic and optical calculations due to that it gives very accurate band gap of solids. Our obtained structural parameters are in good agreement with experimental datas and other theoretical results. The energy band gap obtained with mBJ is 4.56 eV for CaZrO3 and 5.27 eV for CaHfO3. The hybridization of states of O atom with those of Zr and Hf atoms in CaZrO3 and CaHfO3, respectively, is observed. The spin-orbit coupling effect on electronic properties of considered compounds also is investigated. Finally, the linear optical properties of CaZrO3 and CaHfO3 are derived from their complex dielectric function calculated with mBJ potential for wide energy range up to 45 eV, and all of them analyzed in details.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa

Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They are poised to revolutionize optics by enabling complex low-cost systems where multiple metasurfaces are lithographically stacked and integrated with electronics. For imaging applications, metasurface stacks can perform sophisticated image corrections and can be directly integrated with image sensors. Here we demonstrate this concept with a miniature flat camera integrating a monolithic metasurface lens doublet corrected for monochromatic aberrations, and an image sensor. The doublet lens, which acts as a fisheye photographic objective, has a small f-number of 0.9, an angle-of-view larger than 60° ×more » 60°, and operates at 850 nm wavelength with 70% focusing efficiency. The camera exhibits nearly diffraction-limited image quality, which indicates the potential of this technology in the development of optical systems for microscopy, photography, and computer vision.« less

Lightning detection from Space Science and Applications Team review. [optical and radio frequency sensors

NASA Technical Reports Server (NTRS)

Few, A. A., Jr.

1981-01-01

The various needs for lightning data that exist among potential users of satellite lightning data were identified and systems were defined which utilize the optical and radio frequency radiations from lightning to serve as the satellite based lightning mapper. Three teams worked interactively with NASA to develop a system concept. An assessment of the results may be summarized as follows: (1) a small sensor system can be easily designed to operate on a geostationary satellite that can provide the bulk of the real time user requirements; (2) radio frequency systems in space may be feasible but would be much larger and more costly; RF technology for this problem lags the optical technology by years; and (3) a hybrid approach (optical in space and RF on the ground) would provide the most complete information but is probably unreasonably complex and costly at this time.

Computers and the design of ion beam optical systems

NASA Astrophysics Data System (ADS)

White, Nicholas R.

Advances in microcomputers have made it possible to maintain a library of advanced ion optical programs which can be used on inexpensive computer hardware, which are suitable for the design of a variety of ion beam systems including ion implanters, giving excellent results. This paper describes in outline the steps typically involved in designing a complete ion beam system for materials modification applications. Two computer programs are described which, although based largely on algorithms which have been in use for many years, make possible detailed beam optical calculations using microcomputers, specifically the IBM PC. OPTICIAN is an interactive first-order program for tracing beam envelopes through complex optical systems. SORCERY is a versatile program for solving Laplace's and Poisson's equations by finite difference methods using successive over-relaxation. Ion and electron trajectories can be traced through these potential fields, and plots of beam emittance obtained.

High-resolution 3D laser imaging based on tunable fiber array link

NASA Astrophysics Data System (ADS)

Zhao, Sisi; Ruan, Ningjuan; Yang, Song

2017-10-01

Airborne photoelectric reconnaissance system with the bore sight down to the ground is an important battlefield situational awareness system, which can be used for reconnaissance and surveillance of complex ground scene. Airborne 3D imaging Lidar system is recognized as the most potential candidates for target detection under the complex background, and is progressing in the directions of high resolution, long distance detection, high sensitivity, low power consumption, high reliability, eye safe and multi-functional. However, the traditional 3D laser imaging system has the disadvantages of lower imaging resolutions because of the small size of the existing detector, and large volume. This paper proposes a high resolution laser 3D imaging technology based on the tunable optical fiber array link. The echo signal is modulated by a tunable optical fiber array link and then transmitted to the focal plane detector. The detector converts the optical signal into electrical signals which is given to the computer. Then, the computer accomplishes the signal calculation and image restoration based on modulation information, and then reconstructs the target image. This paper establishes the mathematical model of tunable optical fiber array signal receiving link, and proposes the simulation and analysis of the affect factors on high density multidimensional point cloud reconstruction.

Structural, optoelectronic, and thermoelectric properties of AZn13 (A=Na, K, Ca, Sr, Ba) compounds

NASA Astrophysics Data System (ADS)

Basit, Abdul; Murtaza, G.; Mahmood, Asif; Yar, Abdullah; Muhammad, S.

2016-08-01

We report the structural, electronic, optical, and thermoelectric properties of the five cubic alkali-earth transition-metals AZn13 (A-Na, K, Ca, Sr, Ba) using density functional theory. Structural properties, electronic structures and optical behaviors are calculated explicitly via highly accurate contemporary full potential-linearized augmented plane wave (FP-LAPW) method. The investigated ground state data of these materials is quite close to the experimental information. The modified Becke-Johnson (mBJ) predicts the intermetallic nature of AZn13 (A-Na, K, Ca, Sr, Ba) materials. The complex dielectric function of these intermetallic compounds has been calculated and the observed noticeable peaks are examined through mBJ. With the help of complex dielectric function, the other important optical parameters like reflectivities, conductivities and refractive indices of AZn13 (A-Na, K, Ca, Sr, Ba) have been calculated as a function of energy. The optical response suggests that AZn13 (A-Na, K, Ca, Sr, Ba) compounds can be used for the optoelectronic devices. Further, the thermoelectric properties have been calculated through BoltzTraP program, the calculated values for different thermoelectric parameters recommend that these AZn13 (A-Na, K, Ca, Sr, Ba) materials are the suitable candidates for thermoelectric applications.

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation.

PubMed

Dini, Danilo; Calvete, Mário J F; Hanack, Michael

2016-11-23

The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the function of optical power limiting. All known mechanisms of optical limiting have been analyzed and discussed for the different types of materials.

Miniature optical planar camera based on a wide-angle metasurface doublet corrected for monochromatic aberrations

DOE PAGES

Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; ...

2016-11-28

Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They are poised to revolutionize optics by enabling complex low-cost systems where multiple metasurfaces are lithographically stacked and integrated with electronics. For imaging applications, metasurface stacks can perform sophisticated image corrections and can be directly integrated with image sensors. Here we demonstrate this concept with a miniature flat camera integrating a monolithic metasurface lens doublet corrected for monochromatic aberrations, and an image sensor. The doublet lens, which acts as a fisheye photographic objective, has a small f-number of 0.9, an angle-of-view larger than 60° ×more » 60°, and operates at 850 nm wavelength with 70% focusing efficiency. The camera exhibits nearly diffraction-limited image quality, which indicates the potential of this technology in the development of optical systems for microscopy, photography, and computer vision.« less

The potential benefits of photonics in the computing platform

NASA Astrophysics Data System (ADS)

Bautista, Jerry

2005-03-01

The increase in computational requirements for real-time image processing, complex computational fluid dynamics, very large scale data mining in the health industry/Internet, and predictive models for financial markets are driving computer architects to consider new paradigms that rely upon very high speed interconnects within and between computing elements. Further challenges result from reduced power requirements, reduced transmission latency, and greater interconnect density. Optical interconnects may solve many of these problems with the added benefit extended reach. In addition, photonic interconnects provide relative EMI immunity which is becoming an increasing issue with a greater dependence on wireless connectivity. However, to be truly functional, the optical interconnect mesh should be able to support arbitration, addressing, etc. completely in the optical domain with a BER that is more stringent than "traditional" communication requirements. Outlined are challenges in the advanced computing environment, some possible optical architectures and relevant platform technologies, as well roughly sizing these opportunities which are quite large relative to the more "traditional" optical markets.

Synthesis, characterization and theoretical investigations of the structure, electronic properties and third-order nonlinearity optics (NLO) of M(DPIP)₂.

PubMed

Li, Kang; Tang, Guodong; Kou, ShanShan; Culnane, Lance F; Zhang, Yu; Song, Yinglin; Li, Rongqing; Wei, Changmei

2015-03-15

Three complexes of M(DPIP)2 (M=Cu, Co, Zn as 1, 2, 3) were synthesized and characterized by elemental analysis, IR, UV-Vis, thermogravimetry, and X-ray diffraction. Their nonlinear optical properties were measured by the Z-scan technique and yielded a normalized transmittance of about 70% for complex 1 (45 μJ pulse), and 93% for complex 3 (68 μJ pulse at the focus point). The nonlinear absorption coefficient, β, is 1.4×10(-11) m/W for 1 and 5.6×10(-13) m/W for 3, and the third-order nonlinear refraction index, n2, is 1.0×10(-18) m(2)/W for 3. Complex 1 shows self-defocusing property, while complex 3 exhibits self-focusing property. The thermogravimetric results show that the frame structure of compounds 1-3 begin to collapse at 400, 250 and 280°C, respectively, which suggests that they elicit excellent thermal stability. This research aims to provide better understanding of these compounds, and offer preliminary explanations for the significant differences between compounds 1-3, in order to potentially help in the designing of future novel materials with NLO properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Calculation of total and ionization cross sections for electron scattering by primary benzene compounds

NASA Astrophysics Data System (ADS)

Singh, Suvam; Naghma, Rahla; Kaur, Jaspreet; Antony, Bobby

2016-07-01

The total and ionization cross sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic cross sections. The total ionization cross section is estimated from total inelastic cross section using the complex scattering potential-ionization contribution method. In the present article, the first theoretical calculations for electron impact total and ionization cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total cross section.

Development of Moire machine vision

NASA Technical Reports Server (NTRS)

Harding, Kevin G.

1987-01-01

Three dimensional perception is essential to the development of versatile robotics systems in order to handle complex manufacturing tasks in future factories and in providing high accuracy measurements needed in flexible manufacturing and quality control. A program is described which will develop the potential of Moire techniques to provide this capability in vision systems and automated measurements, and demonstrate artificial intelligence (AI) techniques to take advantage of the strengths of Moire sensing. Moire techniques provide a means of optically manipulating the complex visual data in a three dimensional scene into a form which can be easily and quickly analyzed by computers. This type of optical data manipulation provides high productivity through integrated automation, producing a high quality product while reducing computer and mechanical manipulation requirements and thereby the cost and time of production. This nondestructive evaluation is developed to be able to make full field range measurement and three dimensional scene analysis.

Development of Moire machine vision

NASA Astrophysics Data System (ADS)

Harding, Kevin G.

1987-10-01

Three dimensional perception is essential to the development of versatile robotics systems in order to handle complex manufacturing tasks in future factories and in providing high accuracy measurements needed in flexible manufacturing and quality control. A program is described which will develop the potential of Moire techniques to provide this capability in vision systems and automated measurements, and demonstrate artificial intelligence (AI) techniques to take advantage of the strengths of Moire sensing. Moire techniques provide a means of optically manipulating the complex visual data in a three dimensional scene into a form which can be easily and quickly analyzed by computers. This type of optical data manipulation provides high productivity through integrated automation, producing a high quality product while reducing computer and mechanical manipulation requirements and thereby the cost and time of production. This nondestructive evaluation is developed to be able to make full field range measurement and three dimensional scene analysis.

All-optical control of light on a graphene-on-silicon nitride chip using thermo-optic effect.

PubMed

Qiu, Ciyuan; Yang, Yuxing; Li, Chao; Wang, Yifang; Wu, Kan; Chen, Jianping

2017-12-06

All-optical signal processing avoids the conversion between optical signals and electronic signals and thus has the potential to achieve a power efficient photonic system. Micro-scale all-optical devices for light manipulation are the key components in the all-optical signal processing and have been built on the semiconductor platforms (e.g., silicon and III-V semiconductors). However, the two-photon absorption (TPA) effect and the free-carrier absorption (FCA) effect in these platforms deteriorate the power handling and limit the capability to realize complex functions. Instead, silicon nitride (Si 3 N 4 ) provides a possibility to realize all-optical large-scale integrated circuits due to its insulator nature without TPA and FCA. In this work, we investigate the physical dynamics of all-optical control on a graphene-on-Si 3 N 4 chip based on thermo-optic effect. In the experimental demonstration, a switching response time constant of 253.0 ns at a switching energy of ~50 nJ is obtained with a device dimension of 60 μm × 60 μm, corresponding to a figure of merit (FOM) of 3.0 nJ mm. Detailed coupled-mode theory based analysis on the thermo-optic effect of the device has been performed.

Excited state electron and energy relays in supramolecular dinuclear complexes revealed by ultrafast optical and X-ray transient absorption spectroscopy.

PubMed

Hayes, Dugan; Kohler, Lars; Hadt, Ryan G; Zhang, Xiaoyi; Liu, Cunming; Mulfort, Karen L; Chen, Lin X

2018-01-28

The kinetics of photoinduced electron and energy transfer in a family of tetrapyridophenazine-bridged heteroleptic homo- and heterodinuclear copper(i) bis(phenanthroline)/ruthenium(ii) polypyridyl complexes were studied using ultrafast optical and multi-edge X-ray transient absorption spectroscopies. This work combines the synthesis of heterodinuclear Cu(i)-Ru(ii) analogs of the homodinuclear Cu(i)-Cu(i) targets with spectroscopic analysis and electronic structure calculations to first disentangle the dynamics at individual metal sites by taking advantage of the element and site specificity of X-ray absorption and theoretical methods. The excited state dynamical models developed for the heterodinuclear complexes are then applied to model the more challenging homodinuclear complexes. These results suggest that both intermetallic charge and energy transfer can be observed in an asymmetric dinuclear copper complex in which the ground state redox potentials of the copper sites are offset by only 310 meV. We also demonstrate the ability of several of these complexes to effectively and unidirectionally shuttle energy between different metal centers, a property that could be of great use in the design of broadly absorbing and multifunctional multimetallic photocatalysts. This work provides an important step toward developing both a fundamental conceptual picture and a practical experimental handle with which synthetic chemists, spectroscopists, and theoreticians may collaborate to engineer cheap and efficient photocatalytic materials capable of performing coulombically demanding chemical transformations.

Coherent multi-dimensional spectroscopy at optical frequencies in a single beam with optical readout

NASA Astrophysics Data System (ADS)

Seiler, Hélène; Palato, Samuel; Kambhampati, Patanjali

2017-09-01

Ultrafast coherent multi-dimensional spectroscopies form a powerful set of techniques to unravel complex processes, ranging from light-harvesting, chemical exchange in biological systems to many-body interactions in quantum-confined materials. Yet these spectroscopies remain complex to implement at the high frequencies of vibrational and electronic transitions, thereby limiting their widespread use. Here we demonstrate the feasibility of two-dimensional spectroscopy at optical frequencies in a single beam. Femtosecond optical pulses are spectrally broadened to a relevant bandwidth and subsequently shaped into phase coherent pulse trains. By suitably modulating the phases of the pulses within the beam, we show that it is possible to directly read out the relevant optical signals. This work shows that one needs neither complex beam geometries nor complex detection schemes in order to measure two-dimensional spectra at optical frequencies. Our setup provides not only a simplified experimental design over standard two-dimensional spectrometers but its optical readout also enables novel applications in microscopy.

A new Cu–cysteamine complex: structure and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Lun; Chen, Wei; Schatte, Gabriele

2014-06-07

Here we report the structure and optical properties of a new Cu–cysteamine complex (Cu–Cy) with a formula of Cu3Cl(SR)2 (R ¼ CH2CH2NH2). This Cu–Cy has a different structure from a previous Cu–Cy complex, in which both thio and amine groups from cysteamine bond with copper ions. Single-crystal X-ray diffraction and solid-state nuclear magnetic resonance results show that the oxidation state of copper in Cu3Cl(SR)2 is +1 rather than +2. Further, Cu3Cl(SR)2 has been observed to show intense photoluminescence and X-ray excited luminescence. More interesting is that Cu3Cl(SR)2 particles can produce singlet oxygen under irradiation by light or X-ray. This indicatesmore » that Cu3Cl(SR)2 is a new photosensitizer that can be used for deep cancer treatment as X-ray can penetrate soft tissues. All these findings mean that Cu3Cl(SR)2 is a new material with potential applications for lighting, radiation detection and cancer treatment.« less

Digital adaptive optics line-scanning confocal imaging system.

PubMed

Liu, Changgeng; Kim, Myung K

2015-01-01

A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

The role of metals and dithiolate ligands on structural, electronic and optical properties of [M(bipyridine)(dithiolate)] complexes: A theoretical study

NASA Astrophysics Data System (ADS)

Samiee, Sepideh; Taghvaeian, Samira

2018-06-01

A series of [M(diimine)(dithiolate)] complexes of general formula [M(bpy)(dithiolate)] {bpy = 2,2‧-bipyridine;dithiolate = 1,2-benzenedithiolate (bdt2-), 3,4-toluenedithiolate (tdt2-) and 4-cyanobenzene-1,2-dithiolate (cbdt2-); M = Ni(II), Pd(II) and Pt(II)} have been studied by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The geometries, stabilities, electronic structures, optical absorption spectra in different phases as well as thermodynamic parameters are explored. The changes of metal ion center and dithiolate ligands on some molecular properties are also discussed. These calculated results are in good agreement with the experimental data. The bonding analyses show that the Msbnd S bond is covalent so that always polarized towards sulfur atom, whereas the Msbnd N bond exhibits a considerable amount of electrostatic interaction. Detailed NBO analysis indicates that these complexes can be easily oxidized than reduced, and acts as the reducing agent. The HOMO-LUMO energy gaps of all complexes under study are founded about 2 eV and the strong absorption from 400 to 700 nm which match with the solar spectra very well. Besides, the simulated absorption spectra are in accordance with the trends of energy gaps. Comparison of the absorption spectra in dichloromethane solution with those in gas phase show that the solvatochromic effect. The order of magnitude for light harvesting efficiencies (LHE) of all complexes is Pt > Pd > Ni and cbdt2- > bdt2- > tdt2-. Our results confirm the effect and role of metals and dithiolate ligands on enhancing the optical properties of these complexes. Thus, the result of this work can serve as a rational tool for the design and synthesis of diimine-dithiolate complexes and broadens the scope for further investigations into potential dyes for use in the field of dye-sensitized solar cells (DSSC).

Nonlinear optical properties and excited state dynamics of sandwich-type mixed (phthalocyaninato)(Schiff-base) triple-decker complexes: Effect of rare earth atom

NASA Astrophysics Data System (ADS)

Li, Zhongguo; Gao, Feng; Xiao, Zhengguo; Wu, Xingzhi; Zuo, Jinglin; Song, Yinglin

2018-07-01

The third-order nonlinear optical properties of two di-lanthanide (Ln = Tb and Dy) sandwich complexes with mixed phthalocyanine and Schiff-base ligands were studied using Z-scan technique at 532 nm with 20 ps and 4 ns pulses. Both complexes exhibit reverse saturable absorption and self-focusing effect in ps regime, while the second-order hyperpolarizability decreases from Dy to Tb. Interestingly, the Tb triple-decker complexes show larger nonlinear absorption than Dy complexes on ns timescale. The time-resolved pump-probe measurements demonstrate that the nonlinear optical response was caused by excited-state mechanism related to the five-level model, while the singlet state lifetime of Dy complexes is 3 times shorter than that of Tb complexes. Our results indicate the lanthanide ions play a critical role in the photo-physical properties of triple-decker phthalocyanine complexes for their application as optical limiting materials.

Optical versus tactile geometry measurement: alternatives or counterparts

NASA Astrophysics Data System (ADS)

Lehmann, Peter

2003-05-01

This contribution deals with measuring strategies and methods for the determination of several geometrical features, covering the surface micro-topography and the form of mechanical objects. The measuring principles used in optical surface metrology include optical focusing profilers, confocal point measuring and areal measuring sensors as well as interferometrical principles such as white light interferometry and speckle techniques. In comparison with stylus instruments optical techniques provide certain advantages such as a fast data acquisition, in-process applicability or contactless measurement. However, the frequency response characteristics of optical and tactile measurement differ significantly. In addition, optical sensors are commonly more influenced by critical geometrical conditions and optical properties of an object. For precise form measurement mechanical instruments dominate till now. One reason for this may be, that commonly the complete 360 degrees geometry of the measuring object has to be analyzed. Another point is that optical principles such as form measuring interferometry fail in cases of complex object geometry or rougher object surfaces. Other methods, e.g. fringe projection or digital holography, till now do not meet the accuracy demands of precision engineered workpieces. Hence, a combination of mechanical concepts and optical sensors represents an interesting potential for current and future measuring tasks, which require high accuracy and maximum flexibility.

High-Resolution Two-Dimensional Optical Spectroscopy of Electron Spins

NASA Astrophysics Data System (ADS)

Salewski, M.; Poltavtsev, S. V.; Yugova, I. A.; Karczewski, G.; Wiater, M.; Wojtowicz, T.; Yakovlev, D. R.; Akimov, I. A.; Meier, T.; Bayer, M.

2017-07-01

Multidimensional coherent optical spectroscopy is one of the most powerful tools for investigating complex quantum mechanical systems. While it was conceived decades ago in magnetic resonance spectroscopy using microwaves and radio waves, it has recently been extended into the visible and UV spectral range. However, resolving MHz energy splittings with ultrashort laser pulses still remains a challenge. Here, we analyze two-dimensional Fourier spectra for resonant optical excitation of resident electrons to localized trions or donor-bound excitons in semiconductor nanostructures subject to a transverse magnetic field. Particular attention is devoted to Raman coherence spectra, which allow one to accurately evaluate tiny splittings of the electron ground state and to determine the relaxation times in the electron spin ensemble. A stimulated steplike Raman process induced by a sequence of two laser pulses creates a coherent superposition of the ground-state doublet which can be retrieved only optically because of selective excitation of the same subensemble with a third pulse. This provides the unique opportunity to distinguish between different complexes that are closely spaced in energy in an ensemble. The related experimental demonstration is based on photon-echo measurements in an n -type CdTe /(Cd ,Mg )Te quantum-well structure detected by a heterodyne technique. The difference in the sub-μ eV range between the Zeeman splittings of donor-bound electrons and electrons localized at potential fluctuations can be resolved even though the homogeneous linewidth of the optical transitions is larger by 2 orders of magnitude.

Fabrication and application of heterogeneous printed mouse phantoms for whole animal optical imaging

PubMed Central

Bentz, Brian Z.; Chavan, Anmol V.; Lin, Dergan; Tsai, Esther H. R.; Webb, Kevin J.

2017-01-01

This work demonstrates the usefulness of 3D printing for optical imaging applications. Progress in developing optical imaging for biomedical applications requires customizable and often complex objects for testing and evaluation. There is therefore high demand for what have become known as tissue-simulating “phantoms.” We present a new optical phantom fabricated using inexpensive 3D printing methods with multiple materials, allowing for the placement of complex inhomogeneities in complex or anatomically realistic geometries, as opposed to previous phantoms, which were limited to simple shapes formed by molds or machining. We use diffuse optical imaging to reconstruct optical parameters in 3D space within a printed mouse to show the applicability of the phantoms for developing whole animal optical imaging methods. This phantom fabrication approach is versatile, can be applied to optical imaging methods besides diffusive imaging, and can be used in the calibration of live animal imaging data. PMID:26835763

Solitonic dynamics and excitations of the nonlinear Schrödinger equation with third-order dispersion in non-Hermitian PT-symmetric potentials.

PubMed

Chen, Yong; Yan, Zhenya

2016-03-22

Solitons are of the important significant in many fields of nonlinear science such as nonlinear optics, Bose-Einstein condensates, plamas physics, biology, fluid mechanics, and etc. The stable solitons have been captured not only theoretically and experimentally in both linear and nonlinear Schrödinger (NLS) equations in the presence of non-Hermitian potentials since the concept of the parity-time -symmetry was introduced in 1998. In this paper, we present novel bright solitons of the NLS equation with third-order dispersion in some complex -symmetric potentials (e.g., physically relevant -symmetric Scarff-II-like and harmonic-Gaussian potentials). We find stable nonlinear modes even if the respective linear -symmetric phases are broken. Moreover, we also use the adiabatic changes of the control parameters to excite the initial modes related to exact solitons to reach stable nonlinear modes. The elastic interactions of two solitons are exhibited in the third-order NLS equation with -symmetric potentials. Our results predict the dynamical phenomena of soliton equations in the presence of third-order dispersion and -symmetric potentials arising in nonlinear fiber optics and other physically relevant fields.

Solitonic dynamics and excitations of the nonlinear Schrödinger equation with third-order dispersion in non-Hermitian PT-symmetric potentials

PubMed Central

Chen, Yong; Yan, Zhenya

2016-01-01

Solitons are of the important significant in many fields of nonlinear science such as nonlinear optics, Bose-Einstein condensates, plamas physics, biology, fluid mechanics, and etc. The stable solitons have been captured not only theoretically and experimentally in both linear and nonlinear Schrödinger (NLS) equations in the presence of non-Hermitian potentials since the concept of the parity-time -symmetry was introduced in 1998. In this paper, we present novel bright solitons of the NLS equation with third-order dispersion in some complex -symmetric potentials (e.g., physically relevant -symmetric Scarff-II-like and harmonic-Gaussian potentials). We find stable nonlinear modes even if the respective linear -symmetric phases are broken. Moreover, we also use the adiabatic changes of the control parameters to excite the initial modes related to exact solitons to reach stable nonlinear modes. The elastic interactions of two solitons are exhibited in the third-order NLS equation with -symmetric potentials. Our results predict the dynamical phenomena of soliton equations in the presence of third-order dispersion and -symmetric potentials arising in nonlinear fiber optics and other physically relevant fields. PMID:27002543

Higher-order rogue wave-like solutions for a nonautonomous nonlinear Schrödinger equation with external potentials

NASA Astrophysics Data System (ADS)

Liu, Lei; Tian, Bo; Wu, Xiao-Yu; Sun, Yan

2018-02-01

Under investigation in this paper is the higher-order rogue wave-like solutions for a nonautonomous nonlinear Schrödinger equation with external potentials which can be applied in the nonlinear optics, hydrodynamics, plasma physics and Bose-Einstein condensation. Based on the Kadomtsev-Petviashvili hierarchy reduction, we construct the Nth order rogue wave-like solutions in terms of the Gramian under the integrable constraint. With the help of the analytic and graphic analysis, we exhibit the first-, second- and third-order rogue wave-like solutions through the different dispersion, nonlinearity and linear potential coefficients. We find that only if the dispersion and nonlinearity coefficients are proportional to each other, heights of the background of those rogue waves maintain unchanged with time increasing. Due to the existence of complex parameters, such nonautonomous rogue waves in the higher-order cases have more complex features than those in the lower.

Parasitic light scattered by complex optical coatings: modelization and metrology

NASA Astrophysics Data System (ADS)

Zerrad, Myriam; Lequime, Michel; Liukaityte, Simona; Amra, Claude

2017-12-01

Optical components realized for space applications have to be mastered in term of parasitic light. This paper present the last improvements performed at the Institute Fresnel to predict and measure scattering losses of optical components with a special care to complex optical coatings. Agreement between numerical models and metrology is now excellent. Some examples will be presented.

Transmission of RF Signals Over Optical Fiber for Avionics Applications

NASA Technical Reports Server (NTRS)

Slaveski, Filip; Sluss, James, Jr.; Atiquzzaman, Mohammed; Hung, Nguyen; Ngo, Duc

2002-01-01

During flight, aircraft avionics transmit and receive RF signals to/from antennas over coaxial cables. As the density and complexity of onboard avionics increases, the electromagnetic interference (EM) environment degrades proportionately, leading to decreasing signal-to-noise ratios (SNRs) and potential safety concerns. The coaxial cables are inherently lossy, limiting the RF signal bandwidth while adding considerable weight. To overcome these limitations, we have investigated a fiber optic communications link for aircraft that utilizes wavelength division multiplexing (WDM) to support the simultaneous transmission of multiple signals (including RF) over a single optical fiber. Optical fiber has many advantages over coaxial cable, particularly lower loss, greater bandwidth, and immunity to EM. In this paper, we demonstrate that WDM can be successfully used to transmit multiple RF signals over a single optical fiber with no appreciable signal degradation. We investigate the transmission of FM and AM analog modulated signals, as well as FSK digital modulated signals, over a fiber optic link (FOL) employing WDM. We present measurements of power loss, delay, SNR, carrier-to-noise ratio (CNR), total harmonic distortion (THD), and bit error rate (BER). Our experimental results indicate that WDM is a fiber optic technology suitable for avionics applications.

Tunable Metasurface and Flat Optical Zoom Lens on a Stretchable Substrate.

PubMed

Ee, Ho-Seok; Agarwal, Ritesh

2016-04-13

A mechanically reconfigurable metasurface that can continuously tune the wavefront is demonstrated in the visible frequency range by changing the lattice constant of a complex Au nanorod array fabricated on a stretchable polydimethylsiloxane substrate. It is shown that the anomalous refraction angle of visible light at 632.8 nm interacting with the tunable metasurface can be adjusted from 11.4° to 14.9° by stretching the substrate by ∼30%. An ultrathin flat 1.7× zoom lens whose focal length can continuously be changed from 150 to 250 μm is realized, which also demonstrates the potential of utilizing metasurfaces for reconfigurable flat optics.

Digital imaging technology assessment: Digital document storage project

NASA Technical Reports Server (NTRS)

1989-01-01

An ongoing technical assessment and requirements definition project is examining the potential role of digital imaging technology at NASA's STI facility. The focus is on the basic components of imaging technology in today's marketplace as well as the components anticipated in the near future. Presented is a requirement specification for a prototype project, an initial examination of current image processing at the STI facility, and an initial summary of image processing projects at other sites. Operational imaging systems incorporate scanners, optical storage, high resolution monitors, processing nodes, magnetic storage, jukeboxes, specialized boards, optical character recognition gear, pixel addressable printers, communications, and complex software processes.

First principles study on structural, electronic and optical properties of Ga1-xBxP ternary alloys (x = 0, 0.25, 0.5, 0.75 and 1)

NASA Astrophysics Data System (ADS)

Hoat, D. M.; Rivas Silva, J. F.; Méndez Blas, A.

2018-07-01

The structural, electronic and optical properties of GaP, BP binary compounds and their ternary alloys Ga1-xBxP (x = 0.25, 0.5 and 0.75) have been studied by full-potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory (DFT) as implemented in WIEN2k package. Local density approximation (LDA) and generalized gradient approximation (GGA) as proposed by Perdew-Burke-Ernzerhof (PBE), Wu-Cohen (WC) and PBE for solid (PBESol) were used for treatment of exchange-correlation effect in calculations. Additionally, the Tran-Blaha modified Becke-Johnson (mBJ) potential was also employed for electronic and optical calculations due to that it gives very accurate band gap of solids. As B concentration increases, the lattice constant reduces and the energy band gap firstly decreases for small composition x and then it shows increasing trend until pure BP. Our results show that the indirect-direct band gap transition can be reached from x = 0.33. The linear optical properties, such as reflectivity, absorption coefficient, refractive index and optical conductivity of binary compounds and ternary alloys were derived from their calculated complex dielectric function in wide energy range up to 30 eV, and the alloying effect on these properties was also analyzed in detail.

Photonic Integrated Circuit (PIC) Device Structures: Background, Fabrication Ecosystem, Relevance to Space Systems Applications, and Discussion of Related Radiation Effects

NASA Technical Reports Server (NTRS)

Alt, Shannon

2016-01-01

Electronic integrated circuits are considered one of the most significant technological advances of the 20th century, with demonstrated impact in their ability to incorporate successively higher numbers transistors and construct electronic devices onto a single CMOS chip. Photonic integrated circuits (PICs) exist as the optical analog to integrated circuits; however, in place of transistors, PICs consist of numerous scaled optical components, including such "building-block" structures as waveguides, MMIs, lasers, and optical ring resonators. The ability to construct electronic and photonic components on a single microsystems platform offers transformative potential for the development of technologies in fields including communications, biomedical device development, autonomous navigation, and chemical and atmospheric sensing. Developing on-chip systems that provide new avenues for integration and replacement of bulk optical and electro-optic components also reduces size, weight, power and cost (SWaP-C) limitations, which are important in the selection of instrumentation for specific flight projects. The number of applications currently emerging for complex photonics systems-particularly in data communications-warrants additional investigations when considering reliability for space systems development. This Body of Knowledge document seeks to provide an overview of existing integrated photonics architectures; the current state of design, development, and fabrication ecosystems in the United States and Europe; and potential space applications, with emphasis given to associated radiation effects and reliability.

UV-Vis spectrophotometry of quinone flow battery electrolyte for in situ monitoring and improved electrochemical modeling of potential and quinhydrone formation.

PubMed

Tong, Liuchuan; Chen, Qing; Wong, Andrew A; Gómez-Bombarelli, Rafael; Aspuru-Guzik, Alán; Gordon, Roy G; Aziz, Michael J

2017-12-06

Quinone-based aqueous flow batteries provide a potential opportunity for large-scale, low-cost energy storage due to their composition from earth abundant elements, high aqueous solubility, reversible redox kinetics and their chemical tunability such as reduction potential. In an operating flow battery utilizing 9,10-anthraquinone-2,7-disulfonic acid, the aggregation of an oxidized quinone and a reduced hydroquinone to form a quinhydrone dimer causes significant variations from ideal solution behavior and of optical absorption from the Beer-Lambert law. We utilize in situ UV-Vis spectrophotometry to establish (a), quinone, hydroquinone and quinhydrone molar attenuation profiles and (b), an equilibrium constant for formation of the quinhydrone dimer (K QHQ ) ∼ 80 M -1 . We use the molar optical attenuation profiles to identify the total molecular concentration and state of charge at arbitrary mixtures of quinone and hydroquinone. We report density functional theory calculations to support the quinhydrone UV-Vis measurements and to provide insight into the dimerization conformations. We instrument a quinone-bromine flow battery with a Pd-H reference electrode in order to demonstrate how complexation in both the negative (quinone) and positive (bromine) electrolytes directly impacts measured half-cell and full-cell voltages. This work shows how accounting for electrolyte complexation improves the accuracy of electrochemical modeling of flow battery electrolytes.

Tutorial: Integrated-photonic switching structures

NASA Astrophysics Data System (ADS)

Soref, Richard

2018-02-01

Recent developments in waveguided 2 × 2 and N × M photonic switches are reviewed, including both broadband and narrowband resonant devices for the Si, InP, and AlN platforms. Practical actuation of switches by electro-optical and thermo-optical techniques is discussed. Present datacom-and-computing applications are reviewed, and potential applications are proposed for chip-scale photonic and optoelectronic integrated switching networks. Potential is found in the reconfigurable, programmable "mesh" switches that enable a promising group of applications in new areas beyond those in data centers and cloud servers. Many important matrix switches use gated semiconductor optical amplifiers. The family of broadband, directional-coupler 2 × 2 switches featuring two or three side-coupled waveguides deserves future experimentation, including devices that employ phase-change materials. The newer 2 × 2 resonant switches include standing-wave resonators, different from the micro-ring traveling-wave resonators. The resonant devices comprise nanobeam interferometers, complex-Bragg interferometers, and asymmetric contra-directional couplers. Although the fast, resonant devices offer ultralow switching energy, ˜1 fJ/bit, they have limitations. They require several trade-offs when deployed, but they do have practical application.

Possibilities of lasers within NOTES.

PubMed

Stepp, Herbert; Sroka, Ronald

2010-10-01

Lasers possess unique properties that render them versatile light sources particularly for NOTES. Depending on the laser light sources used, diagnostic as well as therapeutic purposes can be achieved. The diagnostic potential offered by innovative concepts such as new types of ultra-thin endoscopes and optical probes supports the physician with optical information of ultra-high resolution, tissue discrimination and manifold types of fluorescence detection. In addition, the potential 3-D capability promises enhanced recognition of tissue type and pathological status. These diagnostic techniques might enable or at least contribute to accurate and safe procedures within the spatial restrictions inherent with NOTES. The therapeutic potential ranges from induction of phototoxic effects over tissue welding, coagulation and tissue cutting to stone fragmentation. As proven in many therapeutic laser endoscopic treatment concepts, laser surgery is potentially bloodless and transmits the energy without mechanical forces. Specialized NOTES endoscopes will likely incorporate suitable probes for improving diagnostic procedures, laser fibres with advantageous light delivery possibility or innovative laser beam manipulation systems. NOTES training centres may support the propagation of the complex handling and the safety aspects for clinical use to the benefit of the patient.

Structural, electronic, and optical properties of representative Cu-flavonoid complexes.

PubMed

Lekka, Ch E; Ren, Jun; Meng, Sheng; Kaxiras, Efthimios

2009-05-07

We present density functional theory (DFT) results on the structural, electronic, and optical properties of Cu-flavonoid complexes for molar ratios 1:1, 1:2, and 1:3. We find that the preferred chelating site is close to the 4-oxo group and in particular the 3-4 site followed by the 3'-4' dihydroxy group in ring B. For the Cu-quercetin complexes, the large bathochromic shift of the first absorbance band upon complexation, which is in good agreement with experimental UV-vis spectra, results from the reduction of the electronic energy gap. The HOMO states for these complexes are characterized by pi-bonding between the Cu d orbitals and the C, O p orbitals except for the case of 1:1 complex (spin minority), which corresponds to sigma-type bonds. The LUMO states are attributed to the contribution of Cu p(z) orbitals. Consequently, the main features of the first optical absorption maxima are essentially due to pi --> pi transitions, while the 1:1 complex exhibits also sigma --> pi transitions. Our optical absorption calculations based on time-dependent DFT demonstrate that the 1:1 complex is responsible for the spectroscopic features at pH 5.5, whereas the 1:2 complex is mainly the one responsible for the characteristic spectra at pH 7.4. These theoretical predictions explain in detail the behavior of the optical absorption for the Cu-flavonoid complexes observed in experiments and are thus useful in elucidating the complexation mechanism and antioxidant activity of flavonoids.

Electron impact ionization of cycloalkanes, aldehydes, and ketones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Dhanoj; Antony, Bobby, E-mail: bka.ism@gmail.com

The theoretical calculations of electron impact total ionization cross section for cycloalkane, aldehyde, and ketone group molecules are undertaken from ionization threshold to 2 keV. The present calculations are based on the spherical complex optical potential formalism and complex scattering potential ionization contribution method. The results of most of the targets studied compare fairly well with the recent measurements, wherever available and the cross sections for many targets are predicted for the first time. The correlation between the peak of ionization cross sections with number of target electrons and target parameters is also reported. It was found that the crossmore » sections at their maximum depend linearly with the number of target electrons and with other target parameters, confirming the consistency of the values reported here.« less

Direct Nanoscale Characterization of Submolecular Mobility in Complex Organic Non-linear Optical Systems

NASA Astrophysics Data System (ADS)

Knorr, Daniel; Gray, Tomoko; Kim, Tae-Dong; Luo, Jingdong; Jen, Alex; Overney, Rene

2008-03-01

For organic non-linear optical (NLO) materials composed of intricate molecular building blocks, the challenge is to deduce meaningful molecular scale mobility information to understand complex relaxation and phase behavior. This is crucial, as the process of achieving a robust acentric alignment strongly depends on the availability of inter- and intra-molecular mobilities outside the temperature range of the device operation window. Here, we introduce a nanoscale methodology based on scanning probe microscopy that provides direct insight into structural relaxations and shows great potential to direct material design of sophisticated macromolecules. It also offers a means by which mesoscale dynamics and cooperativity involved in relaxation processes can be quantified in terms of dynamic entropy and enthalpy. This study demonstrates this methodology to describe the mesocale dynamics of two systems (1) organic networking dendronized NLO molecular glasses that self-assemble into physically linked polymers due to quadrupolar phenyl-perfluorophenyl interactions and (2) dendronized side-chain electro-optic (EO) polymers. For the self assembling glasses, the degree of intermolecular cooperativity can be deduced using this methodology, while for the dendronized side-chain polymers, specific side chain mobilities are exploited to improve EO properties.

Precise replication of antireflective nanostructures from biotemplates

NASA Astrophysics Data System (ADS)

Gao, Hongjun; Liu, Zhongfan; Zhang, Jin; Zhang, Guoming; Xie, Guoyong

2007-03-01

The authors report herein a new type of nanonipple structures on the cicada's eye and the direct structural replication of the complex micro- and nanostructures for potential functional emulation. A two-step direct molding process is developed to replicate these natural micro- and nanostructures using epoxy resin with high fidelity, which demonstrates a general way of fabricating functional nanostructures by direct replication of natural biotemplates via a suitable physicochemical process. Measurements of spectral reflectance showed that this kind of replicated nanostructure has remarkable antireflective property, suggestive of its potential applications to optical devices.

Human lateral geniculate nucleus and visual cortex respond to screen flicker.

PubMed

Krolak-Salmon, Pierre; Hénaff, Marie-Anne; Tallon-Baudry, Catherine; Yvert, Blaise; Guénot, Marc; Vighetto, Alain; Mauguière, François; Bertrand, Olivier

2003-01-01

The first electrophysiological study of the human lateral geniculate nucleus (LGN), optic radiation, striate, and extrastriate visual areas is presented in the context of presurgical evaluation of three epileptic patients (Patients 1, 2, and 3). Visual-evoked potentials to pattern reversal and face presentation were recorded with depth intracranial electrodes implanted stereotactically. For Patient 1, electrode anatomical registration, structural magnetic resonance imaging, and electrophysiological responses confirmed the location of two contacts in the geniculate body and one in the optic radiation. The first responses peaked approximately 40 milliseconds in the LGN in Patient 1 and 60 milliseconds in the V1/V2 complex in Patients 2 and 3. Moreover, steady state visual-evoked potentials evoked by the unperceived but commonly experienced video-screen flicker were recorded in the LGN, optic radiation, and V1/V2 visual areas. This study provides topographic and temporal propagation characteristics of steady state visual-evoked potentials along human visual pathways. We discuss the possible relationship between the oscillating signal recorded in subcortical and cortical areas and the electroencephalogram abnormalities observed in patients suffering from photosensitive epilepsy, particularly video-game epilepsy. The consequences of high temporal frequency visual stimuli delivered by ubiquitous video screens on epilepsy, headaches, and eyestrain must be considered.

Integrated coherent matter wave circuits

DOE PAGES

Ryu, C.; Boshier, M. G.

2015-09-21

An integrated coherent matter wave circuit is a single device, analogous to an integrated optical circuit, in which coherent de Broglie waves are created and then launched into waveguides where they can be switched, divided, recombined, and detected as they propagate. Applications of such circuits include guided atom interferometers, atomtronic circuits, and precisely controlled delivery of atoms. We report experiments demonstrating integrated circuits for guided coherent matter waves. The circuit elements are created with the painted potential technique, a form of time-averaged optical dipole potential in which a rapidly moving, tightly focused laser beam exerts forces on atoms through theirmore » electric polarizability. Moreover, the source of coherent matter waves is a Bose–Einstein condensate (BEC). Finally, we launch BECs into painted waveguides that guide them around bends and form switches, phase coherent beamsplitters, and closed circuits. These are the basic elements that are needed to engineer arbitrarily complex matter wave circuitry.« less

Statistical estimation of the potential possibilities for panoramic hydro-optic laser sensing

NASA Astrophysics Data System (ADS)

Shamanaev, Vitalii S.; Lisenko, Andrey A.

2017-11-01

For statistical estimation of the potential possibilities of the lidar with matrix photodetector placed on board an aircraft, the nonstationary equation of laser sensing of a complex multicomponent sea water medium is solved by the Monte Carlo method. The lidar return power is estimated for various optical sea water characteristics in the presence of solar background radiation. For clear waters and brightness of external background illumination of 50, 1, and 10-3 W/(m2ṡμmṡsr), the signal/noise ratio (SNR) exceeds 10 to water depths h = 45-50 m. For coastal waters, SNR >= 10 for h = 17-24 m, whereas for turbid sea waters, SNR >= 10 only to depths h = 8-12 m. Results of statistical simulation have shown that the lidar system with optimal parameters can be used for water sensing to depths of 50 m.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryu, C.; Boshier, M. G.

An integrated coherent matter wave circuit is a single device, analogous to an integrated optical circuit, in which coherent de Broglie waves are created and then launched into waveguides where they can be switched, divided, recombined, and detected as they propagate. Applications of such circuits include guided atom interferometers, atomtronic circuits, and precisely controlled delivery of atoms. We report experiments demonstrating integrated circuits for guided coherent matter waves. The circuit elements are created with the painted potential technique, a form of time-averaged optical dipole potential in which a rapidly moving, tightly focused laser beam exerts forces on atoms through theirmore » electric polarizability. Moreover, the source of coherent matter waves is a Bose–Einstein condensate (BEC). Finally, we launch BECs into painted waveguides that guide them around bends and form switches, phase coherent beamsplitters, and closed circuits. These are the basic elements that are needed to engineer arbitrarily complex matter wave circuitry.« less

Complex Light

NASA Astrophysics Data System (ADS)

Secor, Jeff; Alfano, Robert; Ashrafi, Solyman

2017-01-01

The emerging field of complex light-the study and application of custom light beams with tailored intensity, polarization or phase-is a focal point for fundamental breakthroughs in optical science. As this review will show, those advances in fundamental understanding, coupled with the latest developments in complex light generation, are translating into a range of diverse and cross-disciplinary applications that span microscopy, high-data-rate communications, optical trapping and quantum optics. We can expect more twists along the way, too, as researchers seek to manipulate and control the propagation speed of complex light beams, while others push the more exotic possibilities afforded by complex light in quantum-entanglement experiments.

Sapphire implant based neuro-complex for deep-lying brain tumors phototheranostics

NASA Astrophysics Data System (ADS)

Sharova, A. S.; Maklygina, YU S.; Yusubalieva, G. M.; Shikunova, I. A.; Kurlov, V. N.; Loschenov, V. B.

2018-01-01

The neuro-complex as a combination of sapphire implant optical port and osteoplastic biomaterial "Collapan" as an Aluminum phthalocyanine nanoform photosensitizer (PS) depot was developed within the framework of this study. The main goals of such neuro-complex are to provide direct access of laser radiation to the brain tissue depth and to transfer PS directly to the pathological tissue location that will allow multiple optical phototheranostics of the deep-lying tumor region without repeated surgical intervention. The developed complex spectral-optical properties research was carried out by photodiagnostics method using the model sample: a brain tissue phantom. The optical transparency of sapphire implant allows obtaining a fluorescent signal with high accuracy, comparable to direct measurement "in contact" with the tissue.

Novel C12orf65 mutations in patients with axonal neuropathy and optic atrophy.

PubMed

Tucci, Arianna; Liu, Yo-Tsen; Preza, Elisabeth; Pitceathly, Robert D S; Chalasani, Annapurna; Plagnol, Vincent; Land, John M; Trabzuni, Daniah; Ryten, Mina; Jaunmuktane, Zane; Reilly, Mary M; Brandner, Sebastian; Hargreaves, Iain; Hardy, John; Singleton, Andrew B; Abramov, Andrey Y; Houlden, Henry

2014-05-01

Charcot-Marie Tooth disease (CMT) forms a clinically and genetically heterogeneous group of disorders. Although a number of disease genes have been identified for CMT, the gene discovery for some complex form of CMT has lagged behind. The association of neuropathy and optic atrophy (also known as CMT type 6) has been described with autosomaldominant, recessive and X-linked modes of inheritance. Mutations in Mitofusin 2 have been found to cause dominant forms of CMT6. Phosphoribosylpyrophosphate synthetase-I mutations cause X-linked CMT6, but until now, mutations in the recessive forms of disease have never been identified. We here describe a family with three affected individuals who inherited in an autosomal recessive fashion a childhood onset neuropathy and optic atrophy. Using homozygosity mapping in the family and exome sequencing in two affected individuals we identified a novel protein-truncating mutation in the C12orf65 gene, which encodes for a protein involved in mitochondrial translation. Using a variety of methods we investigated the possibility of mitochondrial impairment in the patients cell lines. We described a large consanguineous family with neuropathy and optic atrophy carrying a loss of function mutation in the C12orf65 gene. We report mitochondrial impairment in the patients cell lines, followed by multiple lines of evidence which include decrease of complex V activity and stability (blue native gel assay), decrease in mitochondrial respiration rate and reduction of mitochondrial membrane potential. This work describes a mutation in the C12orf65 gene that causes recessive form of CMT6 and confirms the role of mitochondrial dysfunction in this complex axonal neuropathy.

Reference data set of volcanic ash physicochemical and optical properties

NASA Astrophysics Data System (ADS)

Vogel, A.; Diplas, S.; Durant, A. J.; Azar, A. S.; Sunding, M. F.; Rose, W. I.; Sytchkova, A.; Bonadonna, C.; Krüger, K.; Stohl, A.

2017-09-01

Uncertainty in the physicochemical and optical properties of volcanic ash particles creates errors in the detection and modeling of volcanic ash clouds and in quantification of their potential impacts. In this study, we provide a data set that describes the physicochemical and optical properties of a representative selection of volcanic ash samples from nine different volcanic eruptions covering a wide range of silica contents (50-80 wt % SiO2). We measured and calculated parameters describing the physical (size distribution, complex shape, and dense-rock equivalent mass density), chemical (bulk and surface composition), and optical (complex refractive index from ultraviolet to near-infrared wavelengths) properties of the volcanic ash and classified the samples according to their SiO2 and total alkali contents into the common igneous rock types basalt to rhyolite. We found that the mass density ranges between ρ = 2.49 and 2.98 g/cm3 for rhyolitic to basaltic ash types and that the particle shape varies with changing particle size (d < 100 μm). The complex refractive indices in the wavelength range between λ = 300 nm and 1500 nm depend systematically on the composition of the samples. The real part values vary from n = 1.38 to 1.66 depending on ash type and wavelength and the imaginary part values from k = 0.00027 to 0.00268. We place our results into the context of existing data and thus provide a comprehensive data set that can be used for future and historic eruptions, when only basic information about the magma type producing the ash is known.

Excited state electron and energy relays in supramolecular dinuclear complexes revealed by ultrafast optical and X-ray transient absorption spectroscopy

DOE PAGES

Hayes, Dugan; Kohler, Lars; Hadt, Ryan G.; ...

2017-11-28

Here, the kinetics of photoinduced electron and energy transfer in a family of tetrapyridophenazine-bridged heteroleptic homo- and heterodinuclear copper(I) bis(phenanthroline)/ruthenium(II) polypyridyl complexes were studied using ultrafast optical and multi-edge X-ray transient absorption spectroscopies. This work combines the synthesis of heterodinuclear Cu(I)–Ru(II) analogs of the homodinuclear Cu(I)–Cu(I) targets with spectroscopic analysis and electronic structure calculations to first disentangle the dynamics at individual metal sites by taking advantage of the element and site specificity of X-ray absorption and theoretical methods. The excited state dynamical models developed for the heterodinuclear complexes are then applied to model the more challenging homodinuclear complexes. These resultsmore » suggest that both intermetallic charge and energy transfer can be observed in an asymmetric dinuclear copper complex in which the ground state redox potentials of the copper sites are offset by only 310 meV. We also demonstrate the ability of several of these complexes to effectively and unidirectionally shuttle energy between different metal centers, a property that could be of great use in the design of broadly absorbing and multifunctional multimetallic photocatalysts. This work provides an important step toward developing both a fundamental conceptual picture and a practical experimental handle with which synthetic chemists, spectroscopists, and theoreticians may collaborate to engineer cheap and efficient photocatalytic materials capable of performing coulombically demanding chemical transformations.« less

Excited state electron and energy relays in supramolecular dinuclear complexes revealed by ultrafast optical and X-ray transient absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, Dugan; Kohler, Lars; Hadt, Ryan G.

Here, the kinetics of photoinduced electron and energy transfer in a family of tetrapyridophenazine-bridged heteroleptic homo- and heterodinuclear copper(I) bis(phenanthroline)/ruthenium(II) polypyridyl complexes were studied using ultrafast optical and multi-edge X-ray transient absorption spectroscopies. This work combines the synthesis of heterodinuclear Cu(I)–Ru(II) analogs of the homodinuclear Cu(I)–Cu(I) targets with spectroscopic analysis and electronic structure calculations to first disentangle the dynamics at individual metal sites by taking advantage of the element and site specificity of X-ray absorption and theoretical methods. The excited state dynamical models developed for the heterodinuclear complexes are then applied to model the more challenging homodinuclear complexes. These resultsmore » suggest that both intermetallic charge and energy transfer can be observed in an asymmetric dinuclear copper complex in which the ground state redox potentials of the copper sites are offset by only 310 meV. We also demonstrate the ability of several of these complexes to effectively and unidirectionally shuttle energy between different metal centers, a property that could be of great use in the design of broadly absorbing and multifunctional multimetallic photocatalysts. This work provides an important step toward developing both a fundamental conceptual picture and a practical experimental handle with which synthetic chemists, spectroscopists, and theoreticians may collaborate to engineer cheap and efficient photocatalytic materials capable of performing coulombically demanding chemical transformations.« less

Complex interferometry potential in case of sufficiently stable diagnostic system

NASA Astrophysics Data System (ADS)

Kalal, M.

2016-06-01

Classical interferometry is one of the key methods among active optical diagnostics. Its more advanced version, which allows recording and subsequent reconstruction of up to three sets of data using just one data object —a complex interferogram—was developed in the past and became known as complex interferometry. Employing this diagnostics, not only the usual phase shift, but also the amplitude of the probing beam as well as the fringe contrast (leading directly to the phase shift time derivative) can be reconstructed simultaneously from such a complex interferogram. In this paper it will be demonstrated that even in the case of a not particularly good diagnostic beam quality these three quantities can be reconstructed with a high degree of accuracy provided both the diagnostic beam as well as the corresponding optical line feature a reasonable stability. Such stability requirement is important as in an ideal case four shots need to be gradually recorded (one by one): the signal complex interferogram, the reference interferogram as well as the intensity structures of the signal and reference part of the diagnostic beam. Two examples of complex interferograms obtained in experiments will be analyzed: the laser produced plasma (spark in the air) and the high pressure gas jet. A general ray-tracing based iterative algorithm will be outlined in order to increase a precision of the index of refraction spatial profile taking into account refraction effects (omitted in the Abel inversion) and employing the original reconstructed phase shift and amplitude.

The applicability of physical optics in the millimetre and sub-millimetre spectral region. Part I: The ray tracing with diffraction on facets method

NASA Astrophysics Data System (ADS)

Baran, A. J.; Hesse, Evelyn; Sourdeval, Odran

2017-03-01

Future satellite missions, from 2022 onwards, will obtain near-global measurements of cirrus at microwave and sub-millimetre frequencies. To realise the potential of these observations, fast and accurate light-scattering methods are required to calculate scattered millimetre and sub-millimetre intensities from complex ice crystals. Here, the applicability of the ray tracing with diffraction on facets method (RTDF) in predicting the bulk scalar optical properties and phase functions of randomly oriented hexagonal ice columns and hexagonal ice aggregates at millimetre frequencies is investigated. The applicability of RTDF is shown to be acceptable down to size parameters of about 18, between the frequencies of 243 and 874 GHz. It is demonstrated that RTDF is generally well within about 10% of T-matrix solutions obtained for the scalar optical properties assuming hexagonal ice columns. Moreover, on replacing electromagnetic scalar optical property solutions obtained for the hexagonal ice aggregate with the RTDF counterparts at size parameter values of about 18 or greater, the bulk scalar optical properties can be calculated to generally well within ±5% of an electromagnetic-based database. The RTDF-derived bulk scalar optical properties result in brightness temperature errors to generally within about ±4 K at 874 GHz. Differing microphysics assumptions can easily exceed such errors. Similar findings are found for the bulk scattering phase functions. This finding is owing to the scattering solutions being dominated by the processes of diffraction and reflection, both being well described by RTDF. The impact of centimetre-sized complex ice crystals on interpreting cirrus polarisation measurements at sub-millimetre frequencies is discussed.

Tunable liquid optics: electrowetting-controlled liquid mirrors based on self-assembled Janus tiles.

PubMed

Bucaro, Michael A; Kolodner, Paul R; Taylor, J Ashley; Sidorenko, Alex; Aizenberg, Joanna; Krupenkin, Tom N

2009-04-09

In this paper, we describe a tunable, high-reflectivity optofluidic device based on self-assembly of anisotropically functionalized hexagonal micromirrors (Janus tiles) on the surface of an oil droplet to create a concave liquid mirror. The liquid mirror is deposited on a patterned transparent electrode that allows the focal length and axial position to be electrically controlled. The mirror is mechanically robust and retains its integrity even at high levels of vibrational excitation of the interface. The use of reflection instead of refraction overcomes the limited available refractive-index contrast between pairs of density-matched liquids, allowing stronger focusing than is possible for a liquid lens of the same geometry. This approach is compatible with optical instruments that could provide novel functionality-for example, a dynamic 3D projector, i.e., a light source which can scan an image onto a moving, nonplanar focal surface. Janus tiles with complex optical properties can be manufactured using our approach, thus potentially enabling a wide range of novel optical elements.

Tunable liquid optics: electrowetting-controlled liquid mirrors based on self-assembled Janus tiles

NASA Astrophysics Data System (ADS)

Krupenkin, Tom; Bucaro, Mike; Kolodner, Paul; Taylor, Ashley; Sidorenko, Alex; Aizenberg, Joanna

2009-03-01

In this work we describe a tunable, high-reflectivity optofluidic device based on self-assembly of anisotropically-functionalized hexagonal micromirrors (Janus tiles) on the surface of an oil droplet to create a concave liquid mirror. The liquid mirror is deposited on a patterned transparent electrode that allows the focal length and axial position to be electrically controlled. The mirror is mechanically robust and retains its integrity even at high levels of vibrational excitation of the interface. The use of reflection instead of refraction overcomes the limited available refractive-index contrast between pairs of density-matched liquids, allowing stronger focusing than is possible for a liquid lens of the same geometry. This approach is compatible with optical instruments that could provide novel functionality - for example, a dynamic 3D projector; i.e., a light source which can scan an image onto a moving, non-planar focal surface. Janus tiles with complex optical properties can be manufactured using our approach, thus potentially enabling a wide range of novel optical elements.

Diagnosis of basal cell carcinoma by two photon excited fluorescence combined with lifetime imaging

NASA Astrophysics Data System (ADS)

Fan, Shunping; Peng, Xiao; Liu, Lixin; Liu, Shaoxiong; Lu, Yuan; Qu, Junle

2014-02-01

Basal cell carcinoma (BCC) is the most common type of human skin cancer. The traditional diagnostic procedure of BCC is histological examination with haematoxylin and eosin staining of the tissue biopsy. In order to reduce complexity of the diagnosis procedure, a number of noninvasive optical methods have been applied in skin examination, for example, multiphoton tomography (MPT) and fluorescence lifetime imaging microscopy (FLIM). In this study, we explored two-photon optical tomography of human skin specimens using two-photon excited autofluorescence imaging and FLIM. There are a number of naturally endogenous fluorophores in skin sample, such as keratin, melanin, collagen, elastin, flavin and porphyrin. Confocal microscopy was used to obtain structures of the sample. Properties of epidermic and cancer cells were characterized by fluorescence emission spectra, as well as fluorescence lifetime imaging. Our results show that two-photon autofluorescence lifetime imaging can provide accurate optical biopsies with subcellular resolution and is potentially a quantitative optical diagnostic method in skin cancer diagnosis.

Stable dissipative optical vortex clusters by inhomogeneous effective diffusion.

PubMed

Li, Huishan; Lai, Shiquan; Qui, Yunli; Zhu, Xing; Xie, Jianing; Mihalache, Dumitru; He, Yingji

2017-10-30

We numerically show the generation of robust vortex clusters embedded in a two-dimensional beam propagating in a dissipative medium described by the generic cubic-quintic complex Ginzburg-Landau equation with an inhomogeneous effective diffusion term, which is asymmetrical in the two transverse directions and periodically modulated in the longitudinal direction. We show the generation of stable optical vortex clusters for different values of the winding number (topological charge) of the input optical beam. We have found that the number of individual vortex solitons that form the robust vortex cluster is equal to the winding number of the input beam. We have obtained the relationships between the amplitudes and oscillation periods of the inhomogeneous effective diffusion and the cubic gain and diffusion (viscosity) parameters, which depict the regions of existence and stability of vortex clusters. The obtained results offer a method to form robust vortex clusters embedded in two-dimensional optical beams, and we envisage potential applications in the area of structured light.

Reversible optical switching of highly confined phonon-polaritons with an ultrathin phase-change material

NASA Astrophysics Data System (ADS)

Li, Peining; Yang, Xiaosheng; Maß, Tobias W. W.; Hanss, Julian; Lewin, Martin; Michel, Ann-Katrin U.; Wuttig, Matthias; Taubner, Thomas

2016-08-01

Surface phonon-polaritons (SPhPs), collective excitations of photons coupled with phonons in polar crystals, enable strong light-matter interaction and numerous infrared nanophotonic applications. However, as the lattice vibrations are determined by the crystal structure, the dynamical control of SPhPs remains challenging. Here, we realize the all-optical, non-volatile, and reversible switching of SPhPs by controlling the structural phase of a phase-change material (PCM) employed as a switchable dielectric environment. We experimentally demonstrate optical switching of an ultrathin PCM film (down to 7 nm, <λ/1,200) with single laser pulses and detect ultra-confined SPhPs (polariton wavevector kp > 70k0, k0 = 2π/λ) in quartz. Our proof of concept allows the preparation of all-dielectric, rewritable SPhP resonators without the need for complex fabrication methods. With optimized materials and parallelized optical addressing we foresee application potential for switchable infrared nanophotonic elements, for example, imaging elements such as superlenses and hyperlenses, as well as reconfigurable metasurfaces and sensors.

Complex and oriented ZnO nanostructures.

PubMed

Tian, Zhengrong R; Voigt, James A; Liu, Jun; McKenzie, Bonnie; McDermott, Matthew J; Rodriguez, Mark A; Konishi, Hiromi; Xu, Huifang

2003-12-01

Extended and oriented nanostructures are desirable for many applications, but direct fabrication of complex nanostructures with controlled crystalline morphology, orientation and surface architectures remains a significant challenge. Here we report a low-temperature, environmentally benign, solution-based approach for the preparation of complex and oriented ZnO nanostructures, and the systematic modification of their crystal morphology. Using controlled seeded growth and citrate anions that selectively adsorb on ZnO basal planes as the structure-directing agent, we prepared large arrays of oriented ZnO nanorods with controlled aspect ratios, complex film morphologies made of oriented nanocolumns and nanoplates (remarkably similar to biomineral structures in red abalone shells) and complex bilayers showing in situ column-to-rod morphological transitions. The advantages of some of these ZnO structures for photocatalytic decompositions of volatile organic compounds were demonstrated. The novel ZnO nanostructures are expected to have great potential for sensing, catalysis, optical emission, piezoelectric transduction, and actuations.

Structural, thermal, optical and nonlinear optical properties of ethylenediaminium picrate single crystals

NASA Astrophysics Data System (ADS)

Indumathi, C.; T. C., Sabari Girisun; Anitha, K.; Alfred Cecil Raj, S.

2017-07-01

A new organic optical limiting material, ethylenediaminium picrate (EDAPA) was synthesized through acid base reaction and grown as single crystals by solvent evaporation method. Single crystal XRD analysis showed that EDAPA crystallizes in orthorhombic system with Cmca as space group. The formation of charge transfer complex during the reaction of ethylenediamine and picric acid was strongly evident through the recorded Fourier Transform Infra Red (FTIR), Raman and Nuclear Magnetic Resonance (NMR) spectrum. Thermal (TG-DTA and DSC) curves indicated that the material possesses high thermal stability with decomposition temperature at 243 °C. Optical (UV-Visible-NIR) analysis showed that the grown crystal was found to be transparent in the entire visible and NIR region. Z-scan studies with intense short pulse (532 nm, 5 ns, 100 μJ) excitations, revealed that EDAPA exhibited two photon absorption behaviour and the nonlinear absorption coefficient was found to be two orders of magnitude higher than some of the known optical limiter like Cu nano glasses. EDAPA exhibited a strong optical limiting action with low limiting threshold which make them a potential candidate for eye and photosensitive component protection against intense short pulse lasers.

Overview of selected seminal optical science and photonics processes in nature

NASA Astrophysics Data System (ADS)

Alfano, Robert R.

2016-03-01

This presentation gives an overview on some of seminal research in optical science, condensed matter physics, biophysics, biology, biomedical, nonlinear optics, and structure light propagation and interactions at CCNY and GTE Labs over past 46 years. The advent of ultrafast laser pulses with picosecond and femtosecond pulses and optical spectroscopy (label free native fluorescence and Raman) has led to unravel some of mysteries in the molecular world leading to breakthroughs in various areas of science and medicine. The following topics are discussed: white light continuum called now Supercontinuum (SC); first direct measurement of Optical Phonon's lifetimes; first observation of creation of daughter vibrations in time from excited mother vibration in liquids; first direct measurement of creation and decay of Spin Angular Momentum of electrons in GaAs where picosecond Circular Polarized Light carrying Optical Spin Angular Momentum is generated; Pulse break up into ballistic, snake and diffusive components in scattering media such as um beads and tissues; and use of optical spectroscopy for first cancer detection in label free tissues. Most recently, advances in Biomedical Optics showed that Tryptophan as a key biomarker for aggressive cancers; there are three new optical windows with the Golden window #3 the best for penetrating tissue from 1600 nm to 1800 nm; Complex light with OAM offers potential deeper tissue penetration and Resonance Raman excited using magic 532 nm wavelength in tissues.

Implementing digital holograms to create and measure complex-plane optical fields

NASA Astrophysics Data System (ADS)

Dudley, Angela; Majola, Nombuso; Chetty, Naven; Forbes, Andrew

2016-02-01

The coherent superposition of a Gaussian beam with an optical vortex can be mathematically described to occupy the complex plane. We provide a simple analogy between the mathematics, in the form of the complex plane, and the visual representation of these two superimposed optical fields. We provide detailed instructions as to how one can experimentally produce, measure, and control these fields with the use of digital holograms encoded on a spatial light modulator.

Potential for integrated optical circuits in advanced aircraft with fiber optic control and monitoring systems

NASA Astrophysics Data System (ADS)

Baumbick, Robert J.

1991-02-01

Fiber optic technology is expected to be used in future advanced weapons platforms as well as commercial aerospace applications. Fiber optic waveguides will be used to transmit noise free high speed data between a multitude of computers as well as audio and video information to the flight crew. Passive optical sensors connected to control computers with optical fiber interconnects will serve both control and monitoring functions. Implementation of fiber optic technology has already begun. Both the military and NASA have several programs in place. A cooperative program called FOCSI (Fiber Optic Control System Integration) between NASA Lewis and the NAVY to build environmentally test and flight demonstrate sensor systems for propul sion and flight control systems is currently underway. Integrated Optical Circuits (IOC''s) are also being given serious consideration for use in advanced aircraft sys tems. IOC''s will result in miniaturization and localization of components to gener ate detect optical signals and process them for use by the control computers. In some complex systems IOC''s may be required to perform calculations optically if the technology is ready replacing some of the electronic systems used today. IOC''s are attractive because they will result in rugged components capable of withstanding severe environments in advanced aerospace vehicles. Manufacturing technology devel oped for microelectronic integrated circuits applied to IOC''s will result in cost effective manufacturing. This paper reviews the current FOCSI program and describes the role of IOC''s in FOCSI applications.

Direct writing of fiber optic components in photonic crystal fibers and other specialty fibers

NASA Astrophysics Data System (ADS)

Fernandes, Luis Andre; Sezerman, Omur; Best, Garland; Ng, Mi Li; Kane, Saidou

2016-04-01

Femtosecond direct laser writing has recently shown great potential for the fabrication of complex integrated devices in the cladding of optical fibers. Such devices have the advantage of requiring no bulk optical components and no breaks in the fiber path, thus reducing the need for complicated alignment, eliminating contamination, and increasing stability. This technology has already found applications using combinations of Bragg gratings, interferometers, and couplers for the fabrication of optical filters, sensors, and power monitors. The femtosecond laser writing method produces a local modification of refractive index through non-linear absorption of the ultrafast laser pulses inside the dielectric material of both the core and cladding of the fiber. However, fiber geometries that incorporate air or hollow structures, such as photonic crystal fibers (PCFs), still present a challenge since the index modification regions created by the writing process cannot be generated in the hollow regions of the fiber. In this work, the femtosecond laser method is used together with a pre-modification method that consists of partially collapsing the hollow holes using an electrical arc discharge. The partial collapse of the photonic band gap structure provides a path for femtosecond laser written waveguides to couple light from the core to the edge of the fiber for in-line power monitoring. This novel approach is expected to have applications in other specialty fibers such as suspended core fibers and can open the way for the integration of complex devices and facilitate miniaturization of optical circuits to take advantage of the particular characteristics of the PCFs.

Catalytic Asymmetric Synthesis of Butenolides and Butyrolactones

PubMed Central

2017-01-01

γ-Butenolides, γ-butyrolactones, and derivatives, especially in enantiomerically pure form, constitute the structural core of numerous natural products which display an impressive range of biological activities which are important for the development of novel physiological and therapeutic agents. Furthermore, optically active γ-butenolides and γ-butyrolactones serve also as a prominent class of chiral building blocks for the synthesis of diverse biological active compounds and complex molecules. Taking into account the varying biological activity profiles and wide-ranging structural diversity of the optically active γ-butenolide or γ-butyrolactone structure, the development of asymmetric synthetic strategies for assembling such challenging scaffolds has attracted major attention from synthetic chemists in the past decade. This review offers an overview of the different enantioselective synthesis of γ-butenolides and γ-butyrolactones which employ catalytic amounts of metal complexes or organocatalysts, with emphasis focused on the mechanistic issues that account for the observed stereocontrol of the representative reactions, as well as practical applications and synthetic potentials. PMID:28640622

Dynamic Network Analysis for Robust Uncertainty Management

DTIC Science & Technology

2010-03-01

complex networks since a set of modules could be a lot simpler than a collection of entangled individual agents (22). The simplification may be...nanomaterials and photonic crystals with desired material prop- 233 C.l. FAST GENERATION OF POTENTIALS FOR SELF-ASSEMBLY OF PARTICLES erties [14-21...prescribed geometry and structure is highly motivated by the desire to produce photonic crystals with specified optical properties. Also, we intend to

Scattering and radiative properties of complex soot and soot-containing particles

NASA Astrophysics Data System (ADS)

Liu, L.; Mishchenko, M. I.; Mackowski, D. W.; Dlugach, J.

2012-12-01

Tropospheric soot and soot containing aerosols often exhibit nonspherical overall shapes and complex morphologies. They can externally, semi-externally, and internally mix with other aerosol species. This poses a tremendous challenge in particle characterization, remote sensing, and global climate modeling studies. To address these challenges, we used the new numerically exact public-domain Fortran-90 code based on the superposition T-matrix method (STMM) and other theoretical models to analyze the potential effects of aggregation and heterogeneity on light scattering and absorption by morphologically complex soot containing particles. The parameters we computed include the whole scattering matrix elements, linear depolarization ratios, optical cross-sections, asymmetry parameters, and single scattering albedos. It is shown that the optical characteristics of soot and soot containing aerosols very much depend on particle sizes, compositions, and aerosol overall shapes. The soot particle configurations and heterogeneities can have a substantial effect that can result in a significant enhancement of extinction and absorption relative to those computed from the Lorenz-Mie theory. Meanwhile the model calculated information combined with in-situ and remote sensed data can be used to constrain soot particle shapes and sizes which are much needed in climate models.

A Facile CD Protocol for Rapid Determination of Enantiomeric Excess and Concentration of Chiral Primary Amines

PubMed Central

Nieto, Sonia; Dragna, Justin M.; Anslyn, Eric V.

2010-01-01

A protocol for the rapid determination of the absolute configuration and enantiomeric excess of α-chiral primary amines with potential applications in asymmetric reaction discovery has been developed. The protocol requires derivatization of α-chiral primary amines via condensation with pyridine carboxaldehyde to quantitatively yield the corresponding imine. The Cu(I) complex with 2,2'-bis (diphenylphosphino)-1,1'-dinaphthyl (BINAP -CuI) with the imine yields a metal-to-ligand-charge-transfer band (MLCT) in the visible region of the circular dichroism spectrum upon binding. Diastereomeric host-guest complexes give CD signals of the same signs, but different amplitudes, allowing for differentiation of enantiomers. Processing the primary optical data from the CD spectrum with linear discriminant analysis (LDA) allows for the determination of absolute configuration and identification of the amines, and processing with a supervised multi-layer perceptron artifical neural network (MLP-ANN) allows for the simultaneous determination of ee and concentration. The primary optical data necessary to determine the ee of unknown samples is obtained in 2 minutes per sample. To demonstrate the utility of the protocol in asymmetric reaction discovery, the ee's and concentrations for an asymmetric metal catalyzed reaction are determined. The potential of the protocol's application in high-throughput screening (HTS) of ee is discussed. PMID:19946914

Angular selective window systems: Assessment of technical potential for energy savings

DOE PAGES

Fernandes, Luis L.; Lee, Eleanor S.; McNeil, Andrew; ...

2014-10-16

Static angular selective shading systems block direct sunlight and admit daylight within a specific range of incident solar angles. The objective of this study is to quantify their potential to reduce energy use and peak demand in commercial buildings using state-of-the art whole-building computer simulation software that allows accurate modeling of the behavior of optically-complex fenestration systems such as angular selective systems. Three commercial systems were evaluated: a micro-perforated screen, a tubular shading structure, and an expanded metal mesh. This evaluation was performed through computer simulation for multiple climates (Chicago, Illinois and Houston, Texas), window-to-wall ratios (0.15-0.60), building codes (ASHRAEmore » 90.1-2004 and 2010) and lighting control configurations (with and without). The modeling of the optical complexity of the systems took advantage of the development of state-of-the-art versions of the EnergyPlus, Radiance and Window simulation tools. Results show significant reductions in perimeter zone energy use; the best system reached 28% and 47% savings, respectively without and with daylighting controls (ASHRAE 90.1-2004, south facade, Chicago,WWR=0.45). As a result, angular selectivity and thermal conductance of the angle-selective layer, as well as spectral selectivity of low-emissivity coatings, were identified as factors with significant impact on performance.« less

Iron-dextran complex: geometrical structure and magneto-optical features.

PubMed

Graczykowski, Bartłomiej; Dobek, Andrzej

2011-11-15

Molecular mass of the iron-dextran complex (M(w)=1133 kDa), diameter of its particles (∼8.3 nm) and the content of iron ions in the complex core (N(Fe)=6360) were determined by static light scattering, measurements of refractive index increment and the Cotton-Mouton effect in solution. The known number of iron ions permitted the calculation of the permanent magnetic dipole moment value to be μ(Fe)=3.17×10(-18) erg Oe(-1) and the determination of anisotropy of linear magneto-optical polarizabilities components as Δχ=9.2×10(-21) cm(3). Knowing both values and the value of the mean linear optical polarizability α=7.3×10(-20) cm(3), it was possible to show that the total measured CM effect was due to the reorientation of the permanent and the induced magnetic dipole moments of the complex. Analysis of the measured magneto-optical birefringence indicated very small optical anisotropy of linear optical polarizability components, κ(α), which suggested a homogeneous structure of particles of spherical symmetry. Copyright © 2011 Elsevier Inc. All rights reserved.

Two dimensional thermo-optic beam steering using a silicon photonic optical phased array

NASA Astrophysics Data System (ADS)

Mahon, Rita; Preussner, Marcel W.; Rabinovich, William S.; Goetz, Peter G.; Kozak, Dmitry A.; Ferraro, Mike S.; Murphy, James L.

2016-03-01

Components for free space optical communication terminals such as lasers, amplifiers, and receivers have all seen substantial reduction in both size and power consumption over the past several decades. However, pointing systems, such as fast steering mirrors and gimbals, have remained large, slow and power-hungry. Optical phased arrays provide a possible solution for non-mechanical beam steering devices that can be compact and lower in power. Silicon photonics is a promising technology for phased arrays because it has the potential to scale to many elements and may be compatible with CMOS technology thereby enabling batch fabrication. For most free space optical communication applications, two-dimensional beam steering is needed. To date, silicon photonic phased arrays have achieved two-dimensional steering by combining thermo-optic steering, in-plane, with wavelength tuning by means of an output grating to give angular tuning, out-of-plane. While this architecture might work for certain static communication links, it would be difficult to implement for moving platforms. Other approaches have required N2 controls for an NxN element phased array, which leads to complexity. Hence, in this work we demonstrate steering using the thermo-optic effect for both dimensions with a simplified steering mechanism requiring only two control signals, one for each steering dimension.

Noninvasive identification of bladder cancer with subsurface backscattered light

NASA Astrophysics Data System (ADS)

Bigio, Irving J.; Mourant, Judith R.; Boyer, James D.; Johnson, Tamara M.; Shimada, Tsutomu; Conn, Richard L.

1994-05-01

We have developed and are testing early prototypes of an optical biopsy system (OBS) for detection of cancer and other tissue pathologies. The OBS invokes a unique approach to optical diagnosis of tissue pathologies based on the elastic scattering properties, over a wide range of wavelengths, of the microscopic structure of the tissue. Absorption bands in the tissue also add useful complexity to the spectral data collected. The data acquisition and storage/display time with the OBS instrument is approximately 1 second. Thus, in addition to the reduced invasiveness of this technique compared with current state-of- the-art methods, the OBS offers the possibility of impressively faster diagnostic assessment. The OBS employs a small fiber-optic probe that is amendable to use with any endoscope, catheter or hypodermic, or to direct surface examination (e.g., as in skin cancer or cervical cancer). We report here specifically on its potential application in the detection of bladder cancer.

A study of photon propagation in free-space based on hybrid radiosity-radiance theorem.

PubMed

Chen, Xueli; Gao, Xinbo; Qu, Xiaochao; Liang, Jimin; Wang, Lin; Yang, Da'an; Garofalakis, Anikitos; Ripoll, Jorge; Tian, Jie

2009-08-31

Noncontact optical imaging has attracted increasing attention in recent years due to its significant advantages on detection sensitivity, spatial resolution, image quality and system simplicity compared with contact measurement. However, photon transport simulation in free-space is still an extremely challenging topic for the complexity of the optical system. For this purpose, this paper proposes an analytical model for photon propagation in free-space based on hybrid radiosity-radiance theorem (HRRT). It combines Lambert's cosine law and the radiance theorem to handle the influence of the complicated lens and to simplify the photon transport process in the optical system. The performance of the proposed model is evaluated and validated with numerical simulations and physical experiments. Qualitative comparison results of flux distribution at the detector are presented. In particular, error analysis demonstrates the feasibility and potential of the proposed model for simulating photon propagation in free-space.

Rich stochastic dynamics of co-doped Er:Yb fluorescence upconversion nanoparticles in the presence of thermal, non-conservative, harmonic and optical forces

NASA Astrophysics Data System (ADS)

Nome, Rene A.; Sorbello, Cecilia; Jobbágy, Matías; Barja, Beatriz C.; Sanches, Vitor; Cruz, Joyce S.; Aguiar, Vinicius F.

2017-03-01

The stochastic dynamics of individual co-doped Er:Yb upconversion nanoparticles (UCNP) were investigated from experiments and simulations. The UCNP were characterized by high-resolution scanning electron microscopy, dynamic light scattering, and zeta potential measurements. Single UCNP measurements were performed by fluorescence upconversion micro-spectroscopy and optical trapping. The mean-square displacement (MSD) from single UCNP exhibited a time-dependent diffusion coefficient which was compared with Brownian dynamics simulations of a viscoelastic model of harmonically bound spheres. Experimental time-dependent two-dimensional trajectories of individual UCNP revealed correlated two-dimensional nanoparticle motion. The measurements were compared with stochastic trajectories calculated in the presence of a non-conservative rotational force field. Overall, the complex interplay of UCNP adhesion, thermal fluctuations and optical forces led to a rich stochastic behavior of these nanoparticles.

CRISTAPRESS: an optical cell for structure development in high-pressure crystallization.

PubMed

Boyer, S A E; Fournier, F E J; Gandin, Ch-A; Haudin, J-M

2014-01-01

An original optical high-pressure cell, named CRISTAPRESS, has been especially designed to investigate phase transitions of complex liquids, i.e., polymers, polymer blends, nano-composites, etc. The design of the cell is based on the optical properties of morphological entities through in situ light depolarizing microscopic observations. Pressure up to 200 MPa with a fine temperature control up to 300 °C can be applied. A striking advantage of this cell is the possibility to select the pressure transmitting medium that can be water, silicone oil, a fluid in the supercritical state, etc. The potential of the novel technique was demonstrated by carrying out time-resolved measurements during polymer crystallization induced by water pressure. These preliminary experimental investigations permit to discriminate the role of the barometric and thermal histories on the kinetics of polymer growth, as well as on the subsequent morphologies. It should lead to new reliable crystallization kinetics models.

Three-Particle Complexes in Two-Dimensional Semiconductors

NASA Astrophysics Data System (ADS)

Ganchev, Bogdan; Drummond, Neil; Aleiner, Igor; Fal'ko, Vladimir

2015-03-01

We evaluate binding energies of trions X±, excitons bound by a donor or acceptor charge XD (A ) , and overcharged acceptors or donors in two-dimensional atomic crystals by mapping the three-body problem in two dimensions onto one particle in a three-dimensional potential treatable by a purposely developed boundary-matching-matrix method. We find that in monolayers of transition metal dichalcogenides the dissociation energy of X± is typically much larger than that of localized exciton complexes, so that trions are more resilient to heating, despite the fact that their recombination line in optics is less redshifted from the exciton line than the line of XD (A ) .

Single-sensor system for spatially resolved, continuous, and multiparametric optical mapping of cardiac tissue

PubMed Central

Lee, Peter; Bollensdorff, Christian; Quinn, T. Alexander; Wuskell, Joseph P.; Loew, Leslie M.; Kohl, Peter

2011-01-01

Background Simultaneous optical mapping of multiple electrophysiologically relevant parameters in living myocardium is desirable for integrative exploration of mechanisms underlying heart rhythm generation under normal and pathophysiologic conditions. Current multiparametric methods are technically challenging, usually involving multiple sensors and moving parts, which contributes to high logistic and economic thresholds that prevent easy application of the technique. Objective The purpose of this study was to develop a simple, affordable, and effective method for spatially resolved, continuous, simultaneous, and multiparametric optical mapping of the heart, using a single camera. Methods We present a new method to simultaneously monitor multiple parameters using inexpensive off-the-shelf electronic components and no moving parts. The system comprises a single camera, commercially available optical filters, and light-emitting diodes (LEDs), integrated via microcontroller-based electronics for frame-accurate illumination of the tissue. For proof of principle, we illustrate measurement of four parameters, suitable for ratiometric mapping of membrane potential (di-4-ANBDQPQ) and intracellular free calcium (fura-2), in an isolated Langendorff-perfused rat heart during sinus rhythm and ectopy, induced by local electrical or mechanical stimulation. Results The pilot application demonstrates suitability of this imaging approach for heart rhythm research in the isolated heart. In addition, locally induced excitation, whether stimulated electrically or mechanically, gives rise to similar ventricular propagation patterns. Conclusion Combining an affordable camera with suitable optical filters and microprocessor-controlled LEDs, single-sensor multiparametric optical mapping can be practically implemented in a simple yet powerful configuration and applied to heart rhythm research. The moderate system complexity and component cost is destined to lower the threshold to broader application of functional imaging and to ease implementation of more complex optical mapping approaches, such as multiparametric panoramic imaging. A proof-of-principle application confirmed that although electrically and mechanically induced excitation occur by different mechanisms, their electrophysiologic consequences downstream from the point of activation are not dissimilar. PMID:21459161

Heuristic modelling of laser written mid-infrared LiNbO₃ stressed-cladding waveguides.

PubMed

Nguyen, Huu-Dat; Ródenas, Airán; Vázquez de Aldana, Javier R; Martínez, Javier; Chen, Feng; Aguiló, Magdalena; Pujol, Maria Cinta; Díaz, Francesc

2016-04-04

Mid-infrared lithium niobate cladding waveguides have great potential in low-loss on-chip non-linear optical instruments such as mid-infrared spectrometers and frequency converters, but their three-dimensional femtosecond-laser fabrication is currently not well understood due to the complex interplay between achievable depressed index values and the stress-optic refractive index changes arising as a function of both laser fabrication parameters, and cladding arrangement. Moreover, both the stress-field anisotropy and the asymmetric shape of low-index tracks yield highly birefringent waveguides not useful for most applications where controlling and manipulating the polarization state of a light beam is crucial. To achieve true high performance devices a fundamental understanding on how these waveguides behave and how they can be ultimately optimized is required. In this work we employ a heuristic modelling approach based on the use of standard optical characterization data along with standard computational numerical methods to obtain a satisfactory approximate solution to the problem of designing realistic laser-written circuit building-blocks, such as straight waveguides, bends and evanescent splitters. We infer basic waveguide design parameters such as the complex index of refraction of laser-written tracks at 3.68 µm mid-infrared wavelengths, as well as the cross-sectional stress-optic index maps, obtaining an overall waveguide simulation that closely matches the measured mid-infrared waveguide properties in terms of anisotropy, mode field distributions and propagation losses. We then explore experimentally feasible waveguide designs in the search of a single-mode low-loss behaviour for both ordinary and extraordinary polarizations. We evaluate the overall losses of s-bend components unveiling the expected radiation bend losses of this type of waveguides, and finally showcase a prototype design of a low-loss evanescent splitter. Developing a realistic waveguide model with which robust waveguide designs can be developed will be key for exploiting the potential of the technology.

Coupled counterrotating polariton condensates in optically defined annular potentials

PubMed Central

Dreismann, Alexander; Cristofolini, Peter; Balili, Ryan; Christmann, Gabriel; Pinsker, Florian; Berloff, Natasha G.; Hatzopoulos, Zacharias; Savvidis, Pavlos G.; Baumberg, Jeremy J.

2014-01-01

Polariton condensates are macroscopic quantum states formed by half-matter half-light quasiparticles, thus connecting the phenomena of atomic Bose–Einstein condensation, superfluidity, and photon lasing. Here we report the spontaneous formation of such condensates in programmable potential landscapes generated by two concentric circles of light. The imposed geometry supports the emergence of annular states that extend up to 100 μm, yet are fully coherent and exhibit a spatial structure that remains stable for minutes at a time. These states exhibit a petal-like intensity distribution arising due to the interaction of two superfluids counterpropagating in the circular waveguide defined by the optical potential. In stark contrast to annular modes in conventional lasing systems, the resulting standing wave patterns exhibit only minimal overlap with the pump laser itself. We theoretically describe the system using a complex Ginzburg–Landau equation, which indicates why the condensate wants to rotate. Experimentally, we demonstrate the ability to precisely control the structure of the petal condensates both by carefully modifying the excitation geometry as well as perturbing the system on ultrafast timescales to reveal unexpected superfluid dynamics. PMID:24889642

Excited-state vibronic wave-packet dynamics in H2 probed by XUV transient four-wave mixing

NASA Astrophysics Data System (ADS)

Cao, Wei; Warrick, Erika R.; Fidler, Ashley; Leone, Stephen R.; Neumark, Daniel M.

2018-02-01

The complex behavior of a molecular wave packet initiated by an extreme ultraviolet (XUV) pulse is investigated with noncollinear wave mixing spectroscopy. A broadband XUV pulse spanning 12-16 eV launches a wave packet in H2 comprising a coherent superposition of multiple electronic and vibrational levels. The molecular wave packet evolves freely until a delayed few-cycle optical laser pulse arrives to induce nonlinear signals in the XUV via four-wave mixing (FWM). The angularly resolved FWM signals encode rich energy exchange processes between the optical laser field and the XUV-excited molecule. The noncollinear geometry enables spatial separation of ladder and V- or Λ-type transitions induced by the optical field. Ladder transitions, in which the energy exchange with the optical field is around 3 eV, appear off axis from the incident XUV beam. Each vibrationally revolved FWM line probes a different part of the wave packet in energy, serving as a promising tool for energetic tomography of molecular wave packets. V- or Λ-type transitions, in which the energy exchange is well under 1 eV, result in on-axis nonlinear signals. The first-order versus third-order interference of the on-axis signal serves as a mapping tool of the energy flow pathways. Intra- and interelectronic potential energy curve transitions are decisively identified. The current study opens possibilities for accessing complete dynamic information in XUV-excited complex systems.

Detecting ecological change on coral reefs

NASA Astrophysics Data System (ADS)

Dustan, P.

2011-12-01

Remote sensing offers the potential to observe the response of coral reef ecosystems to environmental perturbations on a geographical scale not previously accessible. However, coral reef environments are optically, spatially, and temporally complex habitats which all present significant challenges for extracting meaningful information. Virtually every member of the reef community possesses some degree of photosynthetic capability. The community thus generates a matrix of fine scale features with bio-optical signatures that blend as the scale of observation increases. Furthermore, to have any validity, the remotely sensed signal must be "calibrated" to the bio-optics of the reef, a difficult and resource intensive process due to a convergence of photosynthetic light harvesting by green, red, and brown algal pigment systems. To make matters more complex, reefs are overlain by a seawater skin with its own set of hydrological optical challenges. Rather than concentrating on classification, my research has attempted to track change by following the variation in geo-referenced pixel brightness over time with a technique termed temporal texture. Environmental periodicities impart a phenology to the variation in brightness and departures from the norm are easily detected as statistical outliers. This opens the door to using current orbiting technology to efficiently examine large areas of sea for change. If hot spots are detected, higher resolution sensors and field studies can be focused as resources permit. While this technique does not identify the type of change, it is sensitive, simple to compute, easy to automate and grounded in ecological niche theory

Advanced optic fabrication using ultrafast laser radiation

NASA Astrophysics Data System (ADS)

Taylor, Lauren L.; Qiao, Jun; Qiao, Jie

2016-03-01

Advanced fabrication and finishing techniques are desired for freeform optics and integrated photonics. Methods including grinding, polishing and magnetorheological finishing used for final figuring and polishing of such optics are time consuming, expensive, and may be unsuitable for complex surface features while common photonics fabrication techniques often limit devices to planar geometries. Laser processing has been investigated as an alternative method for optic forming, surface polishing, structure writing, and welding, as direct tuning of laser parameters and flexible beam delivery are advantageous for complex freeform or photonics elements and material-specific processing. Continuous wave and pulsed laser radiation down to the nanosecond regime have been implemented to achieve nanoscale surface finishes through localized material melting, but the temporal extent of the laser-material interaction often results in the formation of a sub-surface heat affected zone. The temporal brevity of ultrafast laser radiation can allow for the direct vaporization of rough surface asperities with minimal melting, offering the potential for smooth, final surface quality with negligible heat affected material. High intensities achieved in focused ultrafast laser radiation can easily induce phase changes in the bulk of materials for processing applications. We have experimentally tested the effectiveness of ultrafast laser radiation as an alternative laser source for surface processing of monocrystalline silicon. Simulation of material heating associated with ultrafast laser-material interaction has been performed and used to investigate optimized processing parameters including repetition rate. The parameter optimization process and results of experimental processing will be presented.

Arsenic complexes optical signatures in As-doped HgCdTe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gemain, F.; Robin, I. C.; Brochen, S.

2013-04-08

In this paper, the optical signatures of arsenic complexes in As-doped HgCdTe samples grown by molecular beam epitaxy are clearly identified using comparison between photoluminescence spectra, Extended X-Ray Absorption Fine Structure, and Hall measurements. The ionization energies of the different complexes are measured both by photoluminescence and Hall measurements.

Electrochemical analysis of the corrosion inhibition effect of trypsin complex on the pitting corrosion of 420 martensitic stainless steel in 2M H2SO4 solution.

PubMed

Loto, Roland Tolulope

2018-01-01

Inhibition effect of trypsin complex (TC) on the pitting corrosion of martensitic stainless steel (type 420) in 1M H2SO4 solution was studied with potentiodynamic polarization, open circuit potential measurement and optical microscopy. TC reduced the corrosion rate of the steel with maximum inhibition efficiency of 80.75%. Corrosion potential shifted anodically due to the electrochemical action of TC. The pitting potential increased from 1.088VAg/AgCl (3M) at 0% TC to 1.365VAg/AgCl(3M) at 4% TC. TC shifts the open circuit corrosion potential from -0.270s at 0% TC concentration to -0.255V at 5% TC. The compound completely adsorbed onto the steel according to Langmuir, Frumkin and Temkin isotherms. ATF-FTIR spectroscopy confirmed the inhibition mode to be through surface coverage. Thermodynamic calculations showed physisorption molecular interaction. Corrosion pits are present on the uninhibited 420 morphology in comparison to TC inhibited surface which slightly deteriorated.

Electrochemical analysis of the corrosion inhibition effect of trypsin complex on the pitting corrosion of 420 martensitic stainless steel in 2M H2SO4 solution

PubMed Central

Loto, Roland Tolulope

2018-01-01

Inhibition effect of trypsin complex (TC) on the pitting corrosion of martensitic stainless steel (type 420) in 1M H2SO4 solution was studied with potentiodynamic polarization, open circuit potential measurement and optical microscopy. TC reduced the corrosion rate of the steel with maximum inhibition efficiency of 80.75%. Corrosion potential shifted anodically due to the electrochemical action of TC. The pitting potential increased from 1.088VAg/AgCl (3M) at 0% TC to 1.365VAg/AgCl(3M) at 4% TC. TC shifts the open circuit corrosion potential from -0.270s at 0% TC concentration to -0.255V at 5% TC. The compound completely adsorbed onto the steel according to Langmuir, Frumkin and Temkin isotherms. ATF-FTIR spectroscopy confirmed the inhibition mode to be through surface coverage. Thermodynamic calculations showed physisorption molecular interaction. Corrosion pits are present on the uninhibited 420 morphology in comparison to TC inhibited surface which slightly deteriorated. PMID:29672541

Practical guidelines for implementing adaptive optics in fluorescence microscopy

NASA Astrophysics Data System (ADS)

Wilding, Dean; Pozzi, Paolo; Soloviev, Oleg; Vdovin, Gleb; Verhaegen, Michel

2018-02-01

In life sciences, interest in the microscopic imaging of increasingly complex three dimensional samples, such as cell spheroids, zebrafish embryos, and in vivo applications in small animals, is growing quickly. Due to the increasing complexity of samples, more and more life scientists are considering the implementation of adaptive optics in their experimental setups. While several approaches to adaptive optics in microscopy have been reported, it is often difficult and confusing for the microscopist to choose from the array of techniques and equipment. In this poster presentation we offer a small guide to adaptive optics providing general guidelines for successful adaptive optics implementation.

Rectangular QPSK for generation of optical eight-ary phase-shift keying.

PubMed

Lu, Guo-Wei; Sakamoto, Takahide; Kawanishi, Tetsuya

2011-09-12

Quadrature phase-shift keying (QPSK) is usually generated using an in-phase/quadrature (IQ) modulator in a balanced driving-condition, showing a square-shape constellation in complex plane. This conventional QPSK is referred to as square QPSK (S-QPSK) in this paper. On the other hand, when an IQ modulator is driven in an un-balanced manner with different amplitudes in in-phase (I) and quadrature (Q) branches, a rectangular QPSK (R-QPSK) could be synthesized. The concept of R-QPSK is proposed for the first time and applied to optical eight-ary phase-shift keying (8PSK) transmitter. By cascading an S-QPSK and an R-QPSK, an optical 8PSK could be synthesized. The transmitter configuration is based on two cascaded IQ modulators, which also could be used to generate other advanced multi-level formats like quadrature amplitude modulation (QAM) when different driving and bias conditions are applied. Therefore, the proposed transmitter structure has potential to be deployed as a versatile transmitter for synthesis of several different multi-level modulation formats for the future dynamic optical networks. A 30-Gb/s optical 8PSK is experimentally demonstrated using the proposed solution.

Speckle-field digital holographic microscopy.

PubMed

Park, YongKeun; Choi, Wonshik; Yaqoob, Zahid; Dasari, Ramachandra; Badizadegan, Kamran; Feld, Michael S

2009-07-20

The use of coherent light in conventional holographic phase microscopy (HPM) poses three major drawbacks: poor spatial resolution, weak depth sectioning, and fixed pattern noise due to unwanted diffraction. Here, we report a technique which can overcome these drawbacks, but maintains the advantage of phase microscopy - high contrast live cell imaging and 3D imaging. A speckle beam of a complex spatial pattern is used for illumination to reduce fixed pattern noise and to improve optical sectioning capability. By recording of the electric field of speckle, we demonstrate high contrast 3D live cell imaging without the need for axial scanning - neither objective lens nor sample stage. This technique has great potential in studying biological samples with improved sensitivity, resolution and optical sectioning capability.

Study on combined polishing process of aspherical aluminum mirrors

NASA Astrophysics Data System (ADS)

Deng, Jinqiu; Peng, Xiaoqiang; Hu, Hao; Ge, Kunpeng

2017-10-01

The aluminum mirrors are widely used as important optical components in some vital fields such as astronomical instruments or military installations due to the unique advantages of aluminum alloy. In order to simplify the structure of optical system and improve the performance at the same time, it's a tendency that the optics will be designed to aspherical or other freeform shapes. However, the traditional techniques are falling to have adequate abilities to deal with the increasing demands of aluminum optics. For example, the tool marks leaved on the surface from single point diamond turning (SPDT) has obvious adverse effects to optical system. The deterministic and sub-aperture polishing process has showed the potential to fabricate complex shapes over the few years. But it's still recognized as a problem to polish bare aluminum directly because of its soft surface and active chemical characteristics. Therefore, a combination of magnetorheological finishing (MRF) and small tool polishing (STP) is applied to obtain high performance aluminum optics in this paper. A paraboloid aluminum mirror was polished with this proposed method, and the results showed that the surface texture of the sample is restrained from rms 0.409λ (λ=632.8nm) to rms 0.025λ, and the surface roughness is improved from average Ra 6 7nm to Ra 3 4nm.

Electron-induced scattering dynamics of Boron, Aluminium and Gallium trihalides in the intermediate energy domain

NASA Astrophysics Data System (ADS)

Verma, Pankaj; Alam, Mohammad Jane; Ahmad, Shabbir; Antony, Bobby

2018-05-01

This article is focused on the calculation of electron-induced ionisation and total scattering cross sections by Boron, Aluminium and Gallium trihalide molecules in the intermediate energy domain. The computational formalism, spherical complex optical potential has been employed for the study of these two scattering cross sections. The ionisation cross section has been derived from the inelastic cross section using a semi-empirical method called complex scattering potential-ionisation contribution (CSP-ic) method. We have also calculated the ionisation cross section using the BEB theory with Hartree-Fock and density functional theory (DFT- ωB97XD) orbitals so that a comparison can be made with the cross sections predicted by CSP-ic method. For this theoretical study, we have also calculated polarisability and bond length of some targets which were not found in literature using DFT/B3LYP in Gaussian 09 software.

Strong Plasmonic Enhancement of a Single Peridinin-Chlorophyll a-Protein Complex on DNA Origami-Based Optical Antennas.

PubMed

Kaminska, Izabela; Bohlen, Johann; Mackowski, Sebastian; Tinnefeld, Philip; Acuna, Guillermo P

2018-02-27

In this contribution, we fabricate hybrid constructs based on a natural light-harvesting complex, peridinin-chlorophyll a-protein, coupled to dimer optical antennas self-assembled with the help of the DNA origami technique. This approach enables controlled positioning of individual complexes at the hotspot of the optical antennas based on large, colloidal gold and silver nanoparticles. Our approach allows us to selectively excite the different pigments present in the harvesting complex, reaching a fluorescence enhancement of 500-fold. This work expands the range of self-assembled functional hybrid constructs for harvesting sunlight and can be further developed for other pigment-proteins and proteins.

Structured Light-Matter Interactions Enabled By Novel Photonic Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Litchinitser, Natalia; Feng, Liang

The synergy of complex materials and complex light is expected to add a new dimension to the science of light and its applications [1]. The goal of this program is to investigate novel phenomena emerging at the interface of these two branches of modern optics. While metamaterials research was largely focused on relatively “simple” linearly or circularly polarized light propagation in “complex” nanostructured, carefully designed materials with properties not found in nature, many singular optics studies addressed “complex” structured light transmission in “simple” homogeneous, isotropic, nondispersive transparent media, where both spin and orbital angular momentum are independently conserved. However, ifmore » both light and medium are complex so that structured light interacts with a metamaterial whose optical materials properties can be designed at will, the spin or angular momentum can change, which leads to spin-orbit interaction and many novel optical phenomena that will be studied in the proposed project. Indeed, metamaterials enable unprecedented control over light propagation, opening new avenues for using spin and quantum optical phenomena, and design flexibility facilitating new linear and nonlinear optical properties and functionalities, including negative index of refraction, magnetism at optical frequencies, giant optical activity, subwavelength imaging, cloaking, dispersion engineering, and unique phase-matching conditions for nonlinear optical interactions. In this research program we focused on structured light-matter interactions in complex media with three particularly remarkable properties that were enabled only with the emergence of metamaterials: extreme anisotropy, extreme material parameters, and magneto-electric coupling–bi-anisotropy and chirality.« less

Feasibility study in the application of optical signal analysis to non-destructive testing of complex structures

NASA Technical Reports Server (NTRS)

Baker, B.; Brown, H.

1974-01-01

Advantages of the large time bandwidth product of optical processing are presented. Experiments were performed to study the feasibility of the use of optical spectral analysis for detection of flaws in structural elements excited by random noise. Photographic and electronic methods of comparison of complex spectra were developed. Limitations were explored, and suggestions for further work are offered.

Optical characterization and bandgap engineering of flat and wrinkle-textured FA0.83Cs0.17Pb(I1-xBrx)3 perovskite thin films

NASA Astrophysics Data System (ADS)

Tejada, A.; Braunger, S.; Korte, L.; Albrecht, S.; Rech, B.; Guerra, J. A.

2018-05-01

The complex refractive indices of formamidinium cesium lead mixed-halide [FA0.83Cs0.17Pb(I1- xBrx)3] perovskite thin films of compositions ranging from x = 0 to 0.4, with both flat and wrinkle-textured surface topographies, are reported. The films are characterized using a combination of variable angle spectroscopic ellipsometry and spectral transmittance in the wavelength range of 190 nm to 850 nm. Optical constants, film thicknesses and roughness layers are obtained point-by-point by minimizing a global error function, without using optical dispersion models, and including topographical information supplied by a laser confocal microscope. To evaluate the bandgap engineering potential of the material, the optical bandgaps and Urbach energies are then accurately determined by applying a band fluctuation model for direct semiconductors, which considers both the Urbach tail and the fundamental band-to-band absorption region in a single equation. With this information, the composition yielding the optimum bandgap of 1.75 eV for a Si-perovskite tandem solar cell is determined.

Ultrafast optical excitations in supramolecular metallacycles with charge transfer properties.

PubMed

Flynn, Daniel C; Ramakrishna, Guda; Yang, Hai-Bo; Northrop, Brian H; Stang, Peter J; Goodson, Theodore

2010-02-03

New organometallic materials such as two-dimensional metallacycles and three-dimensional metallacages are important for the development of novel optical, electronic, and energy related applications. In this article, the ultrafast dynamics of two different platinum-containing metallacycles have been investigated by femtosecond fluorescence upconversion and transient absorption. These measurements were carried out in an effort to probe the charge transfer dynamics and the rate of intersystem crossing in metallacycles of different geometries and dimensions. The processes of ultrafast intersystem crossing and charge transfer vary between the two different classes of metallacyclic systems studied. For rectangular anthracene-containing metallacycles, the electronic coupling between adjacent ligands was relatively weak, whereas for the triangular phenanthrene-containing structures, there was a clear interaction between the conjugated ligand and the metal complex center. The transient lifetimes increased with increasing conjugation in that case. The results show that differences in the dimensionality and structure of metallacycles result in different optical properties, which may be utilized in the design of nonlinear optical materials and potential new, longer-lived excited state materials for further electronic applications.

Energy-efficient spatial-domain-based hybrid multidimensional coded-modulations enabling multi-Tb/s optical transport.

PubMed

Djordjevic, Ivan B

2011-08-15

In addition to capacity, the future high-speed optical transport networks will also be constrained by energy consumption. In order to solve the capacity and energy constraints simultaneously, in this paper we propose the use of energy-efficient hybrid D-dimensional signaling (D>4) by employing all available degrees of freedom for conveyance of the information over a single carrier including amplitude, phase, polarization and orbital angular momentum (OAM). Given the fact that the OAM eigenstates, associated with the azimuthal phase dependence of the complex electric field, are orthogonal, they can be used as basis functions for multidimensional signaling. Since the information capacity is a linear function of number of dimensions, through D-dimensional signal constellations we can significantly improve the overall optical channel capacity. The energy-efficiency problem is solved, in this paper, by properly designing the D-dimensional signal constellation such that the mutual information is maximized, while taking the energy constraint into account. We demonstrate high-potential of proposed energy-efficient hybrid D-dimensional coded-modulation scheme by Monte Carlo simulations. © 2011 Optical Society of America

Precision molding of advanced glass optics: innovative production technology for lens arrays and free form optics

NASA Astrophysics Data System (ADS)

Pongs, Guido; Bresseler, Bernd; Bergs, Thomas; Menke, Gert

2012-10-01

Today isothermal precision molding of imaging glass optics has become a widely applied and integrated production technology in the optical industry. Especially in consumer electronics (e.g. digital cameras, mobile phones, Blu-ray) a lot of optical systems contain rotationally symmetrical aspherical lenses produced by precision glass molding. But due to higher demands on complexity and miniaturization of optical elements the established process chain for precision glass molding is not sufficient enough. Wafer based molding processes for glass optics manufacturing become more and more interesting for mobile phone applications. Also cylindrical lens arrays can be used in high power laser systems. The usage of unsymmetrical free-form optics allows an increase of efficiency in optical laser systems. Aixtooling is working on different aspects in the fields of mold manufacturing technologies and molding processes for extremely high complex optical components. In terms of array molding technologies, Aixtooling has developed a manufacturing technology for the ultra-precision machining of carbide molds together with European partners. The development covers the machining of multi lens arrays as well as cylindrical lens arrays. The biggest challenge is the molding of complex free-form optics having no symmetrical axis. A comprehensive CAD/CAM data management along the entire process chain is essential to reach high accuracies on the molded lenses. Within a national funded project Aixtooling is working on a consistent data handling procedure in the process chain for precision molding of free-form optics.

Theranostic Nanoshells: From Probe Design to Imaging and Treatment of Cancer

PubMed Central

Bardhan, Rizia; Lal, Surbhi; Joshi, Amit; Halas, Naomi J.

2013-01-01

CONSPECTUS Recent advances in theranostics have expanded our ability to design and construct multifunctional nanoparticles that will ultimately allow us to image and treat diseases in a single clinical procedure. Theranostic nanoparticles, combining targeting, therapeutic and diagnostic functions within a single nanoscale complex, have emerged as a result of this confluence of nanoscience and biomedicine. The theranostic capabilities of gold nanoshells -spherical, silica core, gold shell nanoparticles- have attracted tremendous attention over the past decade as nanoshells have emerged as a promising tool for cancer therapy and bioimaging enhancement. This account examines the design and synthesis of nanoshell-based theranostic agents, their plasmon-derived optical properties and their corresponding applications. Nanoshells illuminated with resonant light are either strong optical absorbers or scatterers, properties which give rise to their unique capabilities. In this account, we discuss the underlying physical principles contributing to the photothermal response of nanoshells. We elucidate the photophysics of nanoshell-induced fluorescence enhancement of weak near-infrared fluorophores. We then describe the application of nanoshells as a contrast agent for optical coherence tomography of breast carcinoma cells in vivo. We also examine the recent progress of nanoshells as a multimodal theranostic probe for near-infrared fluorescence and magnetic resonance imaging (MRI) combined with photothermal ablation of cancer cells. The design and preparation of nanoshell complexes is discussed, and their ability to enhance the photoluminescence of fluorophores while incorporating MR contrast is described. We show the theranostic potential of the multimodal nanoshells in vivo for imaging subcutaneous breast cancer tumors in animal models and their biodistribution in various tissues. We then discuss the potential of nanoshells as light-triggered gene therapy vectors. The plasmonic properties of nanoshells make them highly effective as light controlled delivery vectors, adding temporal control to the spatial control characteristic of nanoparticle-based gene therapy approaches. We describe the fabrication of DNA-conjugated nanoshell complexes and compare the efficiency of light-induced and thermally-induced DNA release of DNA. We examine light-triggered release of DAPI (4',6-diamidino-2-phenylindole) molecules, which bind reversibly to double-stranded DNA, to visualize intracellular light-induced release. Finally, we look at future prospects of nanoshell-based theranostics, the potential impact and near-term challenges of theranostic nanomedicine in the next decade. PMID:21612199

Research on a solid state-streak camera based on an electro-optic crystal

NASA Astrophysics Data System (ADS)

Wang, Chen; Liu, Baiyu; Bai, Yonglin; Bai, Xiaohong; Tian, Jinshou; Yang, Wenzheng; Xian, Ouyang

2006-06-01

With excellent temporal resolution ranging from nanosecond to sub-picoseconds, a streak camera is widely utilized in measuring ultrafast light phenomena, such as detecting synchrotron radiation, examining inertial confinement fusion target, and making measurements of laser-induced discharge. In combination with appropriate optics or spectroscope, the streak camera delivers intensity vs. position (or wavelength) information on the ultrafast process. The current streak camera is based on a sweep electric pulse and an image converting tube with a wavelength-sensitive photocathode ranging from the x-ray to near infrared region. This kind of streak camera is comparatively costly and complex. This paper describes the design and performance of a new-style streak camera based on an electro-optic crystal with large electro-optic coefficient. Crystal streak camera accomplishes the goal of time resolution by direct photon beam deflection using the electro-optic effect which can replace the current streak camera from the visible to near infrared region. After computer-aided simulation, we design a crystal streak camera which has the potential of time resolution between 1ns and 10ns.Some further improvements in sweep electric circuits, a crystal with a larger electro-optic coefficient, for example LN (γ 33=33.6×10 -12m/v) and the optimal optic system may lead to better time resolution less than 1ns.

Nanoimprint of a 3D structure on an optical fiber for light wavefront manipulation.

PubMed

Calafiore, Giuseppe; Koshelev, Alexander; Allen, Frances I; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

2016-09-16

Integration of complex photonic structures onto optical fiber facets enables powerful platforms with unprecedented optical functionalities. Conventional nanofabrication technologies, however, do not permit viable integration of complex photonic devices onto optical fibers owing to their low throughput and high cost. In this paper we report the fabrication of a three-dimensional structure achieved by direct nanoimprint lithography on the facet of an optical fiber. Nanoimprint processes and tools were specifically developed to enable a high lithographic accuracy and coaxial alignment of the optical device with respect to the fiber core. To demonstrate the capability of this new approach, a 3D beam splitter has been designed, imprinted and optically characterized. Scanning electron microscopy and optical measurements confirmed the good lithographic capabilities of the proposed approach as well as the desired optical performance of the imprinted structure. The inexpensive solution presented here should enable advancements in areas such as integrated optics and sensing, achieving enhanced portability and versatility of fiber optic components.

Exploitation of molecular mobilities for advanced organic optoelectronic and photonic nano-materials

NASA Astrophysics Data System (ADS)

Gray, Tomoko O.

Electro-optically active organic materials have shown great potential in advanced technologies such as ultrafast electro-optical switches for broadband communication, light-emitting diodes, and photovoltaic cells. Currently, the maturity of chemical synthesis enables a sophisticated integration of the active elements into complex macromolecules. Also, the structure-property relationships of the isolated single electrically/optically active elements are well established. Unfortunately, such correlations involving single molecule are not applicable to complex unstructured condensed systems, in which unique mesoscale properties and complex dynamics of super-/supra-molecular structures are present. Our current challenge arises, in particular, from a deficiency of appropriate characterization tools that close the gap between phenomenological measurements and theoretical models. This work addresses submolecular mobilities relevant for opto-electronic functionalities of photoluminescent polymers and non-linear optical (NLO) materials. Thereby, I will introduce novel nanoscale thermomechanical characterization tools that are based on scanning force microscopy. From nanoscale thermomechanical measurements sub-/super-molecular mobilities of novel optoelectronic materials can be inferred and to some degree controlled. For instance, we have explored interfacial constraints as a engineering tool to control molecular mobility. This will be illustrated with electroluminescent polymers, which are prone to undesired pi-pi aggregation due to the rod-like structure---intrinsic to all conjugated polymers. The nanoscale confinement is used to reduced chain mobility, and thus, hinders undesired aggregation, and consequently, yields superior spectral stability. From the nanomaterial design perspective, I will also address mobility control with targeted molecular designs. This involves two classes of novel NLO materials, side-chain dendronized polymers and self-assembling molecular glasses. The side-chain dendronized polymers are, due to the structural complexity, self-constrained systems. Our thermomechanical investigations identified that a local relaxation mode associated to the NLO side-chain is the critical design parameter in yielding high mobility to the active element. Relaxation processes of the self-assembling molecular glasses are discussed from a thermodynamic perspective involving both enthalpic and entropic contributions, considering the very special nature of interactions for the NLO molecular glasses, i.e., the formation and dissociation of phenyl/perfluorophenyl quadrupol pairs.

Structural, spectral, NLO and MEP analysis of the [MgO2Ti2(OPri)6], [MgO2Ti2(OPri)2(acac)4] and [MgO2Ti2(OPri)2(bzac)4] by DFT method

NASA Astrophysics Data System (ADS)

Sayin, Koray; Karakaş, Duran

2015-06-01

Quantum chemical calculations are performed on [MgO2Ti2(OPri)6] and [MgO2Ti2(OPri)2(L)4] complexes. L is acetylacetonate (acac) and benzoylacetonate (bzac) anion. The crystal structures of these complexes have not been obtained as experimentally but optimized structures of these complexes are obtained as theoretically in this study. Universal force field (UFF) and DFT/B3LYP method are used to obtain optimized structures. Theoretical spectral analysis (IR, 1H and 13C NMR) is compared with their experimental values. A good agreement is found between experimental and theoretical spectral analysis. These results mean that the optimized structures of mentioned complexes are appropriate. Additionally, the active sites of mentioned complexes are determined by molecular electrostatic potential (MEP) diagrams and non-linear optical (NLO) properties are investigated.

Synthesis, characterization and solid-state properties of [Zn(Hdmmthiol)2]\\cdot2H2O complex

NASA Astrophysics Data System (ADS)

Dagdelen, Fethi; Aydogdu, Yildirim; Dey, Kamalendu; Biswas, Susobhan

2016-05-01

The zinc(II) complex with tridentate thiohydrazone ligand have been prepared by metal template reaction. The metal template reaction was used to prepare the zinc (II) complex with tridentate thiohydrazone ligand. The reaction of diacetylmonoxime and, morpholine N-thiohydrazidewith Zn(OAc)2 \\cdot2H2O under reflux yielded the formation of the [Zn(Hdmmthiol )2]\\cdot2H2O complex. The complex was characterized by a combination of protocols including elemental analysis, UV+vis, FT-IR, TG and PXRD. The temperature dependence of the electrical conductivity and the optical property of the [Zn(Hdmmthiol )2] \\cdot2H2O complex is called H2dammthiol was studied. Powder X-ray diffraction (PXRD) method was used to investigate the crystal structure of the sample. The zinc complex was shown to be a member of the triclinic system. The zinc complex was determined to have n-type conductivity as demonstrated in the hot probe measurements. The complex was determined to display direct optical transition with band gaps of 2.52eV as determined by the optical absorption analysis.

DFT Study of Optical Properties of Pt-based Complexes

NASA Astrophysics Data System (ADS)

Oprea, Corneliu I.; Dumbravǎ, Anca; Moscalu, Florin; Nicolaides, Atnanassios; Gîrţu, Mihai A.

2010-01-01

We report Density Functional Theory (DFT) calculations providing the geometrical and electronic structures, as well as the vibrational and optical properties of the homologous series of Pt-pyramidalized olefin complexes (CH2)n-(C8H10)Pt(PH3)2, where n = 0, 1, and 2, in their neutral and oxidized states. All complexes were geometry optimized for the singlet ground state in vacuum using DFT methods with B3LYP exchange-correlation functional and the Effective Core Potential LANL2DZ basis set, within the frame of Gaussian03 quantum chemistry package. We find the coordination geometry of Pt to be distorted square planar, with dihedral angles ranging from 0°, for n = 0 and 1, which have C2V symmetry to 3.4°, for n = 2 with C2 symmetry. The Mulliken charge analysis allows a discussion of the oxidation state of the Pt ion. Electronic transitions were calculated at the same level of theory by means of Time Dependant-DFT. For n = 2 the electronic absorption bands are located in the UV region of the spectrum, the transitions being assigned to metal to ligand charge transfers. The relevance of these Pt-based compounds as possible pigments for dye-sensitized solar cells is discussed.

Uncooled infrared imaging using bimaterial microcantilever arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grbovic, Dragoslav; Lavrik, Nickolay V; Rajic, Slobodan

2006-01-01

We report on the fabrication and characterization of microcantilever based uncooled focal plane array (FPA) for infrared imaging. By combining a streamlined design of microcantilever thermal transducers with a highly efficient optical readout, we minimized the fabrication complexity while achieving a competitive level of imaging performance. The microcantilever FPAs were fabricated using a straightforward fabrication process that involved only three photolithographic steps (i.e. three masks). A designed and constructed prototype of an IR imager employed a simple optical readout based on a noncoherent low-power light source. The main figures of merit of the IR imager were found to be comparablemore » to those of uncooled MEMS infrared detectors with substantially higher degree of fabrication complexity. In particular, the NETD and the response time of the implemented MEMS IR detector were measured to be as low as 0.5K and 6 ms, respectively. The potential of the implemented designs can also be concluded from the fact that the constructed prototype enabled IR imaging of close to room temperature objects without the use of any advanced data processing. The most unique and practically valuable feature of the implemented FPAs, however, is their scalability to high resolution formats, such as 2000x2000, without progressively growing device complexity and cost.« less

Basic optics of effect materials.

PubMed

Jones, Steven A

2010-01-01

Effect materials derive their color and effect primarily from thin-film interference. Effect materials have evolved over the decades from simple guanine crystals to the complex multilayer optical structures of today. The development of new complex effect materials requires an understanding of the optics of effect materials. Such an understanding would also benefit the cosmetic formulator as these new effect materials are introduced. The root of this understanding begins with basic optics. This paper covers the nature of light, interference of waves, thin-film interference, color from interference, and color travel.

New trends in the optical and electronic applications of polymers containing transition-metal complexes.

PubMed

Liu, Shu-Juan; Chen, Yang; Xu, Wen-Juan; Zhao, Qiang; Huang, Wei

2012-04-13

Polymers containing transition-metal complexes exhibit excellent optical and electronic properties, which are different from those of polymers with a pure organic skeleton and combine the advantages of both polymers and metal complexes. Hence, research about this class of polymers has attracted more and more interest in recent years. Up to now, a number of novel polymers containing transition-metal complexes have been exploited, and significant advances in their optical and electronic applications have been achieved. In this article, we summarize some new research trends in the applications of this important class of optoelectronic polymers, such as chemo/biosensors, electronic memory devices and photovoltaic devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application and Miniaturization of Linear and Nonlinear Raman Microscopy for Biomedical Imaging

NASA Astrophysics Data System (ADS)

Mittal, Richa

Current diagnostics for several disorders rely on surgical biopsy or evaluation of ex vivo bodily fluids, which have numerous drawbacks. We evaluated the potential for vibrational techniques (both linear and nonlinear Raman) as a reliable and noninvasive diagnostic tool. Raman spectroscopy is an optical technique for molecular analysis that has been used extensively in various biomedical applications. Based on demonstrated capabilities of Raman spectroscopy we evaluated the potential of the technique for providing a noninvasive diagnosis of mucopolysaccharidosis (MPS). These studies show that Raman spectroscopy can detect subtle changes in tissue biochemistry. In applications where sub-micrometer visualization of tissue compositional change is required, a transition from spectroscopy to high quality imaging is necessary. Nonlinear vibrational microscopy is sensitive to the same molecular vibrations as linear Raman, but features fast imaging capabilities. Coherent Raman scattering when combined with other nonlinear optical (NLO) techniques (like two-photon excited fluorescence and second harmonic generation) forms a collection of advanced optical techniques that provide noninvasive chemical contrast at submicron resolution. This capability to examine tissues without external molecular agents is driving the NLO approach towards clinical applications. However, the unique imaging capabilities of NLO microscopy are accompanied by complex instrument requirements. Clinical examination requires portable imaging systems for rapid inspection of tissues. Optical components utilized in NLO microscopy would then need substantial miniaturization and optimization to enable in vivo use. The challenges in designing compact microscope objective lenses and laser beam scanning mechanisms are discussed. The development of multimodal NLO probes for imaging oral cavity tissue is presented. Our prototype has been examined for ex vivo tissue imaging based on intrinsic fluorescence and SHG contrast. These studies show a potential for multiphoton compact probes to be used for real time imaging in the clinic.

Mechanistic insights into energy conservation by flavin-based electron bifurcation.

PubMed

Lubner, Carolyn E; Jennings, David P; Mulder, David W; Schut, Gerrit J; Zadvornyy, Oleg A; Hoben, John P; Tokmina-Lukaszewska, Monika; Berry, Luke; Nguyen, Diep M; Lipscomb, Gina L; Bothner, Brian; Jones, Anne K; Miller, Anne-Frances; King, Paul W; Adams, Michael W W; Peters, John W

2017-06-01

The recently realized biochemical phenomenon of energy conservation through electron bifurcation provides biology with an elegant means to maximize utilization of metabolic energy. The mechanism of coordinated coupling of exergonic and endergonic oxidation-reduction reactions by a single enzyme complex has been elucidated through optical and paramagnetic spectroscopic studies revealing unprecedented features. Pairs of electrons are bifurcated over more than 1 volt of electrochemical potential by generating a low-potential, highly energetic, unstable flavin semiquinone and directing electron flow to an iron-sulfur cluster with a highly negative potential to overcome the barrier of the endergonic half reaction. The unprecedented range of thermodynamic driving force that is generated by flavin-based electron bifurcation accounts for unique chemical reactions that are catalyzed by these enzymes.

Sequential double second-order nonlinear optical switch by an acido-triggered photochromic cyclometallated platinum(II) complex.

PubMed

Boixel, Julien; Guerchais, Véronique; Le Bozec, Hubert; Chantzis, Agisilaos; Jacquemin, Denis; Colombo, Alessia; Dragonetti, Claudia; Marinotto, Daniele; Roberto, Dominique

2015-05-07

An unprecedented DTE-based Pt(II) complex, 2(o), which stands as the first example of a sequential double nonlinear optical switch, induced first by protonation and next upon irradiation with UV light is presented.

Solid-state polymerisation via [2+2] cycloaddition reaction involving coordination polymers.

PubMed

Medishetty, Raghavender; Park, In-Hyeok; Lee, Shim Sung; Vittal, Jagadese J

2016-03-14

Highly crystalline metal ions containing organic polymers are potentially useful to manipulate the magnetic and optical properties to make advanced multifunctional materials. However, it is challenging to synthesise monocrystalline metal complexes of organic polymers and single-phase hybrid materials made up of both coordination and organic polymers by traditional solution crystallisation. This requires an entirely different approach in the solid-state by thermal or photo polymerisation of the ligands. Among the photochemical methods available, [2+2] cycloaddition reaction has been recently employed to generate cyclobutane based coordination polymers from the metal complexes. Cyclobutane polymers have also been integrated into coordination polymers in this way. Recent advancements in the construction of polymeric chains of cyclobutane rings through photo-dimerisation reaction in the monocrystalline solids containing metal complexes, coordination polymers and metal-organic framework structures are discussed here.

Implementation of a Si/SiC hybrid optically controlled high-power switching device

NASA Astrophysics Data System (ADS)

Bhadri, Prashant; Ye, Kuntao; Guliants, E.; Beyette, Fred R., Jr.

2002-03-01

The ever-increasing performance and economy of operation requirements placed on commercial and military transport aircraft are resulting in very complex systems. As a result, the use of fiber optic component technology has lead to high data throughput, immunity to EMI, reduced certification and maintenance costs and reduced weight features. In particular, in avionic systems, data integrity and high data rates are necessary for stable flight control. Fly-by-Light systems that use optical signals to actuate the flight control surfaces of an aircraft have been suggested as a solution to the EMI problem in avionic systems. Current fly-by-light systems are limited by the lack of optically activated high-power switching devices. The challenge has been the development of an optoelectronic switching technology that can withstand the high power and harsh environmental conditions common in a flight surface actuation system. Wide bandgap semiconductors such as Silicon Carbide offer the potential to overcome both the temperature and voltage blocking limitations that inhibit the use of Silicon. Unfortunately, SiC is not optically active at the near IR wavelengths where communications grade light sources are readily available. Thus, we have proposed a hybrid device that combines a silicon based photoreceiver model with a SiC power transistor. When illuminated with the 5mW optical control signal the silicon chip produces a 15mA drive current for a SiC Darlington pair. The SiC Darlington pair then produces a 150 A current that is suitable for driving an electric motor with sufficient horsepower to actuate the control surfaces on an aircraft. Further, when the optical signal is turned off, the SiC is capable of holding off a 270 V potential to insure that the motor drive current is completely off. We present in this paper the design and initial tests from a prototype device that has recently been fabricated.

Human umbilical cord blood mononuclear cells and chorionic plate-derived mesenchymal stem cells promote axon survival in a rat model of optic nerve crush injury

PubMed Central

CHUNG, SOKJOONG; RHO, SEUNGSOO; KIM, GIJIN; KIM, SO-RA; BAEK, KWANG-HYUN; KANG, MYUNGSEO; LEW, HELEN

2016-01-01

The use of mesenchymal stem cells (MSCs) in cell therapy in regenerative medicine has great potential, particularly in the treatment of nerve injury. Umbilical cord blood (UCB) reportedly contains stem cells, which have been widely used as a hematopoietic source and may have therapeutic potential for neurological impairment. Although ongoing research is dedicated to the management of traumatic optic nerve injury using various measures, novel therapeutic strategies based on the complex underlying mechanisms responsible for optic nerve injury, such as inflammation and/or ischemia, are required. In the present study, a rat model of optic nerve crush (ONC) injury was established in order to examine the effects of transplanting human chorionic plate-derived MSCs (CP-MSCs) isolated from the placenta, as well as human UCB mononuclear cells (CB-MNCs) on compressed rat optic nerves. Expression markers for inflammation, apoptosis, and optic nerve regeneration were analyzed, as well as the axon survival rate by direct counting. Increased axon survival rates were observed following the injection of CB-MNCs at at 1 week post-transplantation compared with the controls. The levels of growth-associated protein-43 (GAP-43) were increased after the injection of CB-MNCs or CP-MSCs compared with the controls, and the expression levels of hypoxia-inducible factor-1α (HIF-1α) were also significantly increased following the injection of CB-MNCs or CP-MSCs. ERM-like protein (ERMN) and SLIT-ROBO Rho GTPase activating protein 2 (SRGAP2) were found to be expressed in the optic nerves of the CP-MSC-injected rats with ONC injury. The findings of our study suggest that the administration of CB-MNCs or CP-MSCs may promote axon survival through systemic concomitant mechanisms involving GAP-43 and HIF-1α. Taken together, these findings provide further understanding of the mechanisms repsonsible for optic nerve injury and may aid in the development of novel cell-based therapeutic strategies with future applications in regenerative medicine, particularly in the management of optic nerve disorders. PMID:26986762

DFT and TD-DFT calculations of metallotetraphenylporphyrin and metallotetraphenylporphyrin fullerene complexes as potential dye sensitizers for solar cells

NASA Astrophysics Data System (ADS)

El Mahdy, A. M.; Halim, Shimaa Abdel; Taha, H. O.

2018-05-01

Density functional theory (DFT) and time-dependent DFT calculations have been employed to model metallotetraphenylporphyrin dyes and metallotetraphenylporphyrin -fullerene complexes in order to investigate the geometries, electronic structures, the density of states, non-linear optical properties (NLO), IR-vis spectra, molecular electrostatic potential contours, and electrophilicity. To calculate the excited states of the tetraphenyl porphyrin analogs, time-dependent density functional theory (TD-DFT) are used. Their UV-vis spectra were also obtained and a comparison with available experimental and theoretical results is included. The results reveal that the metal and the tertiary butyl groups of the dyes are electron donors, and the tetraphenylporphyrin rings are electron acceptors. The HOMOs of the dyes fall within the (TiO2)60 and Ti38O76 band gaps and support the issue of typical interfacial electron transfer reaction. The resulting potential drop of Mn-TPP-C60 increased by ca. 3.50% under the effect of the tertiary butyl groups. The increase in the potential drop indicates that the tertiary butyl complexes could be a better choice for the strong operation of the molecular rectifiers. The introduction of metal atom and tertiary butyl groups to the tetraphenyl porphyrin moiety leads to a stronger response to the external electric field and induces higher photo-to-current conversion efficiency. This also shifts the absorption in the dyes and makes them potential candidates for harvesting light in the entire visible and near IR region for photovoltaic applications.

Synthesis, spectroscopic studies, DFT calculations, electrochemical evaluation, BSA binding and molecular docking of an aroylhydrazone -based cis-dioxido Mo(VI) complex

NASA Astrophysics Data System (ADS)

Mohamadi, Maryam; Faghih-Mirzaei, Ehsan; Ebrahimipour, S. Yousef; Sheikhshoaie, Iran; Haase, Wolfgang; Foro, Sabine

2017-07-01

A cis-dioxido Mo(VI) complex, [MoO2(L)(MeOH)], [L2-: (3-methoxy-2-oxidobenzylidene) benzohydrazonate], has been synthesized and characterized using physicochemical and spectroscopic techniques including elemental analysis, FT-IR, 1HNMR, UV-Vis spectroscopy, molar conductivity and single crystal X-ray diffraction. DFT calculations in the ground state of the complex were carried out using hybrid functional B3LYP with DGDZVP as basis set. Non-linear optical properties including electric dipole moment (μ), polarizability (α) and molecular first hyperpolarizability (β) of the compound were also computed. The values of linear polarizability and first hyperpolarizability obtained for the studied molecule indicated that the compound could be a good candidate of nonlinear optical materials. TD-DFT calculation and molecular electrostatic potential (MEP) were also performed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the complex at different temperatures have been calculated. The interaction of a synthesized complex, with bovine serum albumin was also thoroughly investigated using experimental and theoretical studies. UV-Vis absorption and fluorescence quenching techniques were used to determine the binding parameters as well as the mechanism of the interaction. The values of binding constants were in the range of 104-105 M-1 demonstrating a moderate interaction between the synthesized complex and BSA making the protein suitable for transportation and delivery of the compound. Thermodynamic parameters were also indicating a binding through van der Waals force or hydrogen bond of [MoO2(L)(MeOH)] to BSA. The results obtained from docking studies were consistent to those obtained from experimental studies.

Excited state electron and energy relays in supramolecular dinuclear complexes revealed by ultrafast optical and X-ray transient absorption spectroscopy† †Electronic supplementary information (ESI) available: Synthesis schemes, experimental methods, NMR spectra, X-ray crystallographic information, emission spectra, cyclic voltammetry, electronic structure calculations, data analysis and numerical methods, and other additional figures. CCDC 1561879. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04055e

PubMed Central

Kohler, Lars; Hadt, Ryan G.; Zhang, Xiaoyi; Liu, Cunming

2017-01-01

The kinetics of photoinduced electron and energy transfer in a family of tetrapyridophenazine-bridged heteroleptic homo- and heterodinuclear copper(i) bis(phenanthroline)/ruthenium(ii) polypyridyl complexes were studied using ultrafast optical and multi-edge X-ray transient absorption spectroscopies. This work combines the synthesis of heterodinuclear Cu(i)–Ru(ii) analogs of the homodinuclear Cu(i)–Cu(i) targets with spectroscopic analysis and electronic structure calculations to first disentangle the dynamics at individual metal sites by taking advantage of the element and site specificity of X-ray absorption and theoretical methods. The excited state dynamical models developed for the heterodinuclear complexes are then applied to model the more challenging homodinuclear complexes. These results suggest that both intermetallic charge and energy transfer can be observed in an asymmetric dinuclear copper complex in which the ground state redox potentials of the copper sites are offset by only 310 meV. We also demonstrate the ability of several of these complexes to effectively and unidirectionally shuttle energy between different metal centers, a property that could be of great use in the design of broadly absorbing and multifunctional multimetallic photocatalysts. This work provides an important step toward developing both a fundamental conceptual picture and a practical experimental handle with which synthetic chemists, spectroscopists, and theoreticians may collaborate to engineer cheap and efficient photocatalytic materials capable of performing coulombically demanding chemical transformations. PMID:29629153

Determining the magnitude and direction of photoinduced ligand field switching in photochromic metal-organic complexes: molybdenum-tetracarbonyl spirooxazine complexes.

PubMed

Paquette, Michelle M; Patrick, Brian O; Frank, Natia L

2011-07-06

The ability to optically switch or tune the intrinsic properties of transition metals (e.g., redox potentials, emission/absorption energies, and spin states) with photochromic metal-ligand complexes is an important strategy for developing "smart" materials. We have described a methodology for using metal-carbonyl complexes as spectroscopic probes of ligand field changes associated with light-induced isomerization of photochromic ligands. Changes in ligand field between the ring-closed spirooxazine (SO) and ring-opened photomerocyanine (PMC) forms of photochromic azahomoadamantyl and indolyl phenanthroline-spirooxazine ligands are demonstrated through FT-IR, (13)C NMR, and computational studies of their molybdenum-tetracarbonyl complexes. The frontier molecular orbitals (MOs) of the SO and PMC forms differ considerably in both electron density distributions and energies. Of the multiple π* MOs in the SO and PMC forms of the ligands, the LUMO+1, a pseudo-b(1)-symmetry phenanthroline-based MO, mixes primarily with the Mo(CO)(4) fragment and provides the major pathway for Mo(d)→phen(π*) backbonding. The LUMO+1 is found to be 0.2-0.3 eV lower in energy in the SO form relative to the PMC form, suggesting that the SO form is a better π-acceptor. Light-induced isomerization of the photochromic ligands was therefore found to lead to changes in the energies of their frontier MOs, which in turn leads to changes in π-acceptor ability and ligand field strength. Ligand field changes associated with photoisomerizable ligands allow tuning of excited-state and ground-state energies that dictate energy/electron transfer, optical/electrical properties, and spin states of a metal center upon photoisomerization, positioning photochromic ligand-metal complexes as promising targets for smart materials.

Sedimentation Velocity Analysis of Large Oligomeric Chromatin Complexes Using Interference Detection.

PubMed

Rogge, Ryan A; Hansen, Jeffrey C

2015-01-01

Sedimentation velocity experiments measure the transport of molecules in solution under centrifugal force. Here, we describe a method for monitoring the sedimentation of very large biological molecular assemblies using the interference optical systems of the analytical ultracentrifuge. The mass, partial-specific volume, and shape of macromolecules in solution affect their sedimentation rates as reflected in the sedimentation coefficient. The sedimentation coefficient is obtained by measuring the solute concentration as a function of radial distance during centrifugation. Monitoring the concentration can be accomplished using interference optics, absorbance optics, or the fluorescence detection system, each with inherent advantages. The interference optical system captures data much faster than these other optical systems, allowing for sedimentation velocity analysis of extremely large macromolecular complexes that sediment rapidly at very low rotor speeds. Supramolecular oligomeric complexes produced by self-association of 12-mer chromatin fibers are used to illustrate the advantages of the interference optics. Using interference optics, we show that chromatin fibers self-associate at physiological divalent salt concentrations to form structures that sediment between 10,000 and 350,000S. The method for characterizing chromatin oligomers described in this chapter will be generally useful for characterization of any biological structures that are too large to be studied by the absorbance optical system. © 2015 Elsevier Inc. All rights reserved.

Cytochrome bc1 complexes of microorganisms.

PubMed Central

Trumpower, B L

1990-01-01

The cytochrome bc1 complex is the most widely occurring electron transfer complex capable of energy transduction. Cytochrome bc1 complexes are found in the plasma membranes of phylogenetically diverse photosynthetic and respiring bacteria, and in the inner mitochondrial membrane of all eucaryotic cells. In all of these species the bc1 complex transfers electrons from a low-potential quinol to a higher-potential c-type cytochrome and links this electron transfer to proton translocation. Most bacteria also possess alternative pathways of quinol oxidation capable of circumventing the bc1 complex, but these pathways generally lack the energy-transducing, protontranslocating activity of the bc1 complex. All cytochrome bc1 complexes contain three electron transfer proteins which contain four redox prosthetic groups. These are cytochrome b, which contains two b heme groups that differ in their optical and thermodynamic properties; cytochrome c1, which contains a covalently bound c-type heme; and a 2Fe-2S iron-sulfur protein. The mechanism which links proton translocation to electron transfer through these proteins is the proton motive Q cycle, and this mechanism appears to be universal to all bc1 complexes. Experimentation is currently focused on understanding selected structure-function relationships prerequisite for these redox proteins to participate in the Q-cycle mechanism. The cytochrome bc1 complexes of mitochondria differ from those of bacteria, in that the former contain six to eight supernumerary polypeptides, in addition to the three redox proteins common to bacteria and mitochondria. These extra polypeptides are encoded in the nucleus and do not contain redox prosthetic groups. The functions of the supernumerary polypeptides of the mitochondrial bc1 complexes are generally not known and are being actively explored by genetically manipulating these proteins in Saccharomyces cerevisiae. Images PMID:2163487

The molecular basis of retinal ganglion cell death in glaucoma.

PubMed

Almasieh, Mohammadali; Wilson, Ariel M; Morquette, Barbara; Cueva Vargas, Jorge Luis; Di Polo, Adriana

2012-03-01

Glaucoma is a group of diseases characterized by progressive optic nerve degeneration that results in visual field loss and irreversible blindness. A crucial element in the pathophysiology of all forms of glaucoma is the death of retinal ganglion cells (RGCs), a population of CNS neurons with their soma in the inner retina and axons in the optic nerve. Strategies that delay or halt RGC loss have been recognized as potentially beneficial to preserve vision in glaucoma; however, the success of these approaches depends on an in-depth understanding of the mechanisms that lead to RGC dysfunction and death. In recent years, there has been an exponential increase in valuable information regarding the molecular basis of RGC death stemming from animal models of acute and chronic optic nerve injury as well as experimental glaucoma. The emerging landscape is complex and points at a variety of molecular signals - acting alone or in cooperation - to promote RGC death. These include: axonal transport failure, neurotrophic factor deprivation, toxic pro-neurotrophins, activation of intrinsic and extrinsic apoptotic signals, mitochondrial dysfunction, excitotoxic damage, oxidative stress, misbehaving reactive glia and loss of synaptic connectivity. Collectively, this body of work has considerably updated and expanded our view of how RGCs might die in glaucoma and has revealed novel, potential targets for neuroprotection. Copyright © 2011. Published by Elsevier Ltd.

Examples of Current and Future Uses of Neural-Net Image Processing for Aerospace Applications

NASA Technical Reports Server (NTRS)

Decker, Arthur J.

2004-01-01

Feed forward artificial neural networks are very convenient for performing correlated interpolation of pairs of complex noisy data sets as well as detecting small changes in image data. Image-to-image, image-to-variable and image-to-index applications have been tested at Glenn. Early demonstration applications are summarized including image-directed alignment of optics, tomography, flow-visualization control of wind-tunnel operations and structural-model-trained neural networks. A practical application is reviewed that employs neural-net detection of structural damage from interference fringe patterns. Both sensor-based and optics-only calibration procedures are available for this technique. These accomplishments have generated the knowledge necessary to suggest some other applications for NASA and Government programs. A tomography application is discussed to support Glenn's Icing Research tomography effort. The self-regularizing capability of a neural net is shown to predict the expected performance of the tomography geometry and to augment fast data processing. Other potential applications involve the quantum technologies. It may be possible to use a neural net as an image-to-image controller of an optical tweezers being used for diagnostics of isolated nano structures. The image-to-image transformation properties also offer the potential for simulating quantum computing. Computer resources are detailed for implementing the black box calibration features of the neural nets.

Quantifying sub-pixel urban impervious surface through fusion of optical and inSAR imagery

USGS Publications Warehouse

Yang, L.; Jiang, L.; Lin, H.; Liao, M.

2009-01-01

In this study, we explored the potential to improve urban impervious surface modeling and mapping with the synergistic use of optical and Interferometric Synthetic Aperture Radar (InSAR) imagery. We used a Classification and Regression Tree (CART)-based approach to test the feasibility and accuracy of quantifying Impervious Surface Percentage (ISP) using four spectral bands of SPOT 5 high-resolution geometric (HRG) imagery and three parameters derived from the European Remote Sensing (ERS)-2 Single Look Complex (SLC) SAR image pair. Validated by an independent ISP reference dataset derived from the 33 cm-resolution digital aerial photographs, results show that the addition of InSAR data reduced the ISP modeling error rate from 15.5% to 12.9% and increased the correlation coefficient from 0.71 to 0.77. Spatially, the improvement is especially noted in areas of vacant land and bare ground, which were incorrectly mapped as urban impervious surfaces when using the optical remote sensing data. In addition, the accuracy of ISP prediction using InSAR images alone is only marginally less than that obtained by using SPOT imagery. The finding indicates the potential of using InSAR data for frequent monitoring of urban settings located in cloud-prone areas.

Magneto-optical absorption in semiconducting spherical quantum dots: Influence of the dot-size, confining potential, and magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kushwaha, Manvir S.

2014-12-15

Semiconducting quantum dots – more fancifully dubbed artificial atoms – are quasi-zero dimensional, tiny, man-made systems with charge carriers completely confined in all three dimensions. The scientific quest behind the synthesis of quantum dots is to create and control future electronic and optical nanostructures engineered through tailoring size, shape, and composition. The complete confinement – or the lack of any degree of freedom for the electrons (and/or holes) – in quantum dots limits the exploration of spatially localized elementary excitations such as plasmons to direct rather than reciprocal space. Here we embark on a thorough investigation of the magneto-optical absorptionmore » in semiconducting spherical quantum dots characterized by a confining harmonic potential and an applied magnetic field in the symmetric gauge. This is done within the framework of Bohm-Pines’ random-phase approximation that enables us to derive and discuss the full Dyson equation that takes proper account of the Coulomb interactions. As an application of our theoretical strategy, we compute various single-particle and many-particle phenomena such as the Fock-Darwin spectrum; Fermi energy; magneto-optical transitions; probability distribution; and the magneto-optical absorption in the quantum dots. It is observed that the role of an applied magnetic field on the absorption spectrum is comparable to that of a confining potential. Increasing (decreasing) the strength of the magnetic field or the confining potential is found to be analogous to shrinking (expanding) the size of the quantum dots: resulting into a blue (red) shift in the absorption spectrum. The Fermi energy diminishes with both increasing magnetic-field and dot-size; and exhibits saw-tooth-like oscillations at large values of field or dot-size. Unlike laterally confined quantum dots, both (upper and lower) magneto-optical transitions survive even in the extreme instances. However, the intra-Landau level transitions are seen to be forbidden. The spherical quantum dots have an edge over the strictly two-dimensional quantum dots in that the additional (magnetic) quantum number makes the physics richer (but complex). A deeper grasp of the Coulomb blockade, quantum coherence, and entanglement can lead to a better insight into promising applications involving lasers, detectors, storage devices, and quantum computing.« less

Optogenetic micro-electrocorticography for modulating and localizing cerebral cortex activity

PubMed Central

Richner, Thomas J.; Thongpang, Sanitta; Brodnick, Sarah K.; Schendel, Amelia A.; Falk, Ryan W.; Krugner-Higby, Lisa A.; Pashaie, Ramin; Williams, Justin C.

2014-01-01

Objective Spatial localization of neural activity from within the brain with electrocorticography (ECoG) and electroencephalography (EEG) remains a challenge in clinical and research settings, and while microfabricated ECoG (micro-ECoG) array technology continues to improve, complimentary methods to simultaneously modulate cortical activity while recording are needed. Approach We developed a neural interface utilizing optogenetics, cranial windowing, and micro-ECoG arrays fabricated on a transparent polymer. This approach enabled us to directly modulate neural activity at known locations around micro-ECoG arrays in mice expressing Channelrhodopsin-2 (ChR2). We applied photostimuli varying in time, space and frequency to the cortical surface, and we targeted multiple depths within the cortex using an optical fiber while recording micro-ECoG signals. Main Results Negative potentials of up to 1.5 mV were evoked by photostimuli applied to the entire cortical window, while focally applied photostimuli evoked spatially localized micro-ECoG potentials. Two simultaneously applied focal stimuli could be separated, depending on the distance between them. Photostimuli applied within the cortex with an optical fiber evoked more complex micro-ECoG potentials with multiple positive and negative peaks whose relative amplitudes depended on the depth of the fiber. Significance Optogenetic ECoG has potential applications in the study of epilepsy, cortical dynamics, and neuroprostheses. PMID:24445482

Spectrodirectional Investigation of a Geometric-Optical Canopy Reflectance Model by Laboratory Simulation

NASA Astrophysics Data System (ADS)

Stanford, Adam Christopher

Canopy reflectance models (CRMs) can accurately estimate vegetation canopy biophysical-structural information such as Leaf Area Index (LAI) inexpensively using satellite imagery. The strict physical basis which geometric-optical CRMs employ to mathematically link canopy bidirectional reflectance and structure allows for the tangible replication of a CRM's geometric abstraction of a canopy in the laboratory, enabling robust CRM validation studies. To this end, the ULGS-2 goniometer was used to obtain multiangle, hyperspectral (Spectrodirectional) measurements of a specially-designed tangible physical model forest, developed based upon the Geometric-Optical Mutual Shadowing (GOMS) CRM, at three different canopy cover densities. GOMS forward-modelled reflectance values had high levels of agreement with ULGS-2 measurements, with obtained reflectance RMSE values ranging from 0.03% to 0.1%. Canopy structure modelled via GOMS Multiple-Forward-Mode (MFM) inversion had varying levels of success. The methods developed in this thesis can potentially be extended to more complex CRMs through the implementation of 3D printing.

Automatic optical detection and classification of marine animals around MHK converters using machine vision

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brunton, Steven

Optical systems provide valuable information for evaluating interactions and associations between organisms and MHK energy converters and for capturing potentially rare encounters between marine organisms and MHK device. The deluge of optical data from cabled monitoring packages makes expert review time-consuming and expensive. We propose algorithms and a processing framework to automatically extract events of interest from underwater video. The open-source software framework consists of background subtraction, filtering, feature extraction and hierarchical classification algorithms. This principle classification pipeline was validated on real-world data collected with an experimental underwater monitoring package. An event detection rate of 100% was achieved using robustmore » principal components analysis (RPCA), Fourier feature extraction and a support vector machine (SVM) binary classifier. The detected events were then further classified into more complex classes – algae | invertebrate | vertebrate, one species | multiple species of fish, and interest rank. Greater than 80% accuracy was achieved using a combination of machine learning techniques.« less

Amplified Sensitivity of Nitrogen-Vacancy Spins in Nanodiamonds Using All-Optical Charge Readout.

PubMed

Hopper, David A; Grote, Richard R; Parks, Samuel M; Bassett, Lee C

2018-04-23

Nanodiamonds containing nitrogen-vacancy (NV) centers offer a versatile platform for sensing applications spanning from nanomagnetism to in vivo monitoring of cellular processes. In many cases, however, weak optical signals and poor contrast demand long acquisition times that prevent the measurement of environmental dynamics. Here, we demonstrate the ability to perform fast, high-contrast optical measurements of charge distributions in ensembles of NV centers in nanodiamonds and use the technique to improve the spin-readout signal-to-noise ratio through spin-to-charge conversion. A study of 38 nanodiamonds with sizes ranging between 20 and 70 nm, each hosting a small ensemble of NV centers, uncovers complex, multiple time scale dynamics due to radiative and nonradiative ionization and recombination processes. Nonetheless, the NV-containing nanodiamonds universally exhibit charge-dependent photoluminescence contrasts and the potential for enhanced spin readout using spin-to-charge conversion. We use the technique to speed up a T 1 relaxometry measurement by a factor of 5.

In Situ Optical Mapping of Voltage and Calcium in the Heart

PubMed Central

Ewart, Paul; Ashley, Euan A.; Loew, Leslie M.; Kohl, Peter; Bollensdorff, Christian; Woods, Christopher E.

2012-01-01

Electroanatomic mapping the interrelation of intracardiac electrical activation with anatomic locations has become an important tool for clinical assessment of complex arrhythmias. Optical mapping of cardiac electrophysiology combines high spatiotemporal resolution of anatomy and physiological function with fast and simultaneous data acquisition. If applied to the clinical setting, this could improve both diagnostic potential and therapeutic efficacy of clinical arrhythmia interventions. The aim of this study was to explore this utility in vivo using a rat model. To this aim, we present a single-camera imaging and multiple light-emitting-diode illumination system that reduces economic and technical implementation hurdles to cardiac optical mapping. Combined with a red-shifted calcium dye and a new near-infrared voltage-sensitive dye, both suitable for use in blood-perfused tissue, we demonstrate the feasibility of in vivo multi-parametric imaging of the mammalian heart. Our approach combines recording of electrophysiologically-relevant parameters with observation of structural substrates and is adaptable, in principle, to trans-catheter percutaneous approaches. PMID:22876327

Electro-optical muzzle flash detection

NASA Astrophysics Data System (ADS)

Krieg, Jürgen; Eisele, Christian; Seiffer, Dirk

2016-10-01

Localizing a shooter in a complex scenario is a difficult task. Acoustic sensors can be used to detect blast waves. Radar technology permits detection of the projectile. A third method is to detect the muzzle flash using electro-optical devices. Detection of muzzle flash events is possible with focal plane arrays, line and single element detectors. In this paper, we will show that the detection of a muzzle flash works well in the shortwave infrared spectral range. Important for the acceptance of an operational warning system in daily use is a very low false alarm rate. Using data from a detector with a high sampling rate the temporal signature of a potential muzzle flash event can be analyzed and the false alarm rate can be reduced. Another important issue is the realization of an omnidirectional view required on an operational level. It will be shown that a combination of single element detectors and simple optics in an appropriate configuration is a capable solution.

Five chiral Cd(II) complexes with dual chiral components: Effect of positional isomerism, luminescence and SHG response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Lin, E-mail: lcheng@seu.edu.cn; Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, Southeast University, Nanjing 211189; Wang, Jun

2015-01-15

Five chiral Cd(II) complexes with dual chiral components have been synthesized by using a series of (1R,2R)–N{sup 1},N{sup 2}-bis(pyridinylmethyl)cyclohexane-1,2-diamine ligands with different N-positions of pyridyl rings and Cd(NO{sub 3}){sub 2}. The circular dichroism (CD) spectra and second-harmonic generation (SHG) efficiency measurements confirmed that they are of structural chirality in the bulk samples. The luminescent properties indicated that they may have potential applications as optical materials. The formation of discrete mononuclear and binuclear complexes, and one-dimensional chains may be attributed to positional isomerism of the ligands. - Graphical abstract: Five chiral Cd(II) complexes with dual chiral components have been synthesized bymore » using a series of chiral ligands with different N-positions of pyridyl rings. - Highlights: • Five chiral Cd(II) complexes with dual chiral components have been synthesized. • CD spectra and SHG efficiency of the bulk samples have been measured. • The complexes display luminescent properties.« less

How nonlinear optics can merge interferometry for high resolution imaging

NASA Astrophysics Data System (ADS)

Ceus, D.; Reynaud, F.; Tonello, A.; Delage, L.; Grossard, L.

2017-11-01

High resolution stellar interferometers are very powerful efficient instruments to get a better knowledge of our Universe through the spatial coherence analysis of the light. For this purpose, the optical fields collected by each telescope Ti are mixed together. From the interferometric pattern, two expected information called the contrast Cij and the phase information φij are extracted. These information lead to the Vij, called the complex visibility, with Vij=Cijexp(jφij). For each telescope doublet TiTj, it is possible to get a complex visibility Vij. The Zernike Van Cittert theorem gives a relationship between the intensity distribution of the object observed and the complex visibility. The combination of the acquired complex visibilities and a reconstruction algorithm allows imaging reconstruction. To avoid lots of technical difficulties related to infrared optics (components transmission, thermal noises, thermal cooling…), our team proposes to explore the possibility of using nonlinear optical techniques. This is a promising alternative detection technique for detecting infrared optical signals. This way, we experimentally demonstrate that frequency conversion does not result in additional bias on the interferometric data supplied by a stellar interferometer. In this presentation, we report on wavelength conversion of the light collected by each telescope from the infrared domain to the visible. The interferometric pattern is observed in the visible domain with our, so called, upconversion interferometer. Thereby, one can benefit from mature optical components mainly used in optical telecommunications (waveguide, coupler, multiplexer…) and efficient low-noise detection schemes up to the single-photon counting level.

Simulation and performance evaluation of fiber optic sensor for detection of hepatic malignancies in human liver tissues

NASA Astrophysics Data System (ADS)

Sharma, Anuj K.; Gupta, Jyoti; Basu, Rikmantra

2018-01-01

A fiber optic sensor is proposed for the identification of healthy and cancerous liver tissues through determination of their corresponding refractive index values. Existing experimental results describing variation of complex refractive index of liver tissues in near infrared (NIR) spectral region are considered for theoretical calculations. The intensity interrogation method with chalcogenide fiber is considered. The sensor's performance is closely analyzed in terms of its sensitivity at multiple operating wavelengths falling in NIR region. Operating at shorter NIR wavelengths leads to greater sensitivity. The effect of design parameters (sensing region length and fiber core diameter), different launching conditions, and fiber glass materials on sensor's performance is examined. The proposed sensor has the potential to provide high sensitivity of liver tissue detection.

Fluorescence fluctuations analysis in nanoapertures: physical concepts and biological applications.

PubMed

Lenne, Pierre-François; Rigneault, Hervé; Marguet, Didier; Wenger, Jérôme

2008-11-01

During the past years, nanophotonics has provided new approaches to study the biological processes below the optical diffraction limit. How single molecules diffuse, bind and assemble can be studied now at the nanometric level, not only in solutions but also in complex and crowded environments such as in live cells. In this context fluorescence fluctuations spectroscopy is a unique tool since it has proven to be easy to use in combination with nanostructures, which are able to confine light in nanometric volumes. We review here recent advances in fluorescence fluctuations' analysis below the optical diffraction limit with a special focus on nanoapertures milled in metallic films. We discuss applications in the field of single-molecule detection, DNA sequencing and membrane organization, and underscore some potential perspectives of this new emerging technology.

Optimized optical clearing method for imaging central nervous system

NASA Astrophysics Data System (ADS)

Yu, Tingting; Qi, Yisong; Gong, Hui; Luo, Qingming; Zhu, Dan

2015-03-01

The development of various optical clearing methods provides a great potential for imaging entire central nervous system by combining with multiple-labelling and microscopic imaging techniques. These methods had made certain clearing contributions with respective weaknesses, including tissue deformation, fluorescence quenching, execution complexity and antibody penetration limitation that makes immunostaining of tissue blocks difficult. The passive clarity technique (PACT) bypasses those problems and clears the samples with simple implementation, excellent transparency with fine fluorescence retention, but the passive tissue clearing method needs too long time. In this study, we not only accelerate the clearing speed of brain blocks but also preserve GFP fluorescence well by screening an optimal clearing temperature. The selection of proper temperature will make PACT more applicable, which evidently broaden the application range of this method.

Chaos in Dirac Electron Optics: Emergence of a Relativistic Quantum Chimera.

PubMed

Xu, Hong-Ya; Wang, Guang-Lei; Huang, Liang; Lai, Ying-Cheng

2018-03-23

We uncover a remarkable quantum scattering phenomenon in two-dimensional Dirac material systems where the manifestations of both classically integrable and chaotic dynamics emerge simultaneously and are electrically controllable. The distinct relativistic quantum fingerprints associated with different electron spin states are due to a physical mechanism analogous to a chiroptical effect in the presence of degeneracy breaking. The phenomenon mimics a chimera state in classical complex dynamical systems but here in a relativistic quantum setting-henceforth the term "Dirac quantum chimera," associated with which are physical phenomena with potentially significant applications such as enhancement of spin polarization, unusual coexisting quasibound states for distinct spin configurations, and spin selective caustics. Experimental observations of these phenomena are possible through, e.g., optical realizations of ballistic Dirac fermion systems.

Inverse design of near unity efficiency perfectly vertical grating couplers

NASA Astrophysics Data System (ADS)

Michaels, Andrew; Yablonovitch, Eli

2018-02-01

Efficient coupling between integrated optical waveguides and optical fibers is essential to the success of integrated photonics. While many solutions exist, perfectly vertical grating couplers which scatter light out of a waveguide in the direction normal to the waveguide's top surface are an ideal candidate due to their potential to reduce packaging complexity. Designing such couplers with high efficiency, however, has proven difficult. In this paper, we use electromagnetic inverse design techniques to optimize a high efficiency two-layer perfectly vertical silicon grating coupler. Our base design achieves a chip-to-fiber coupling efficiency of over 99% (-0.04 dB) at 1550 nm. Using this base design, we apply subsequent constrained optimizations to achieve vertical couplers with over 96% efficiency which are fabricable using a 65 nm process.

Hybrid Toffoli gate on photons and quantum spins

PubMed Central

Luo, Ming-Xing; Ma, Song-Ya; Chen, Xiu-Bo; Wang, Xiaojun

2015-01-01

Quantum computation offers potential advantages in solving a number of interesting and difficult problems. Several controlled logic gates, the elemental building blocks of quantum computer, have been realized with various physical systems. A general technique was recently proposed that significantly reduces the realization complexity of multiple-control logic gates by harnessing multi-level information carriers. We present implementations of a key quantum circuit: the three-qubit Toffoli gate. By exploring the optical selection rules of one-sided optical microcavities, a Toffoli gate may be realized on all combinations of photon and quantum spins in the QD-cavity. The three general controlled-NOT gates are involved using an auxiliary photon with two degrees of freedom. Our results show that photons and quantum spins may be used alternatively in quantum information processing. PMID:26568078

Hybrid Toffoli gate on photons and quantum spins.

PubMed

Luo, Ming-Xing; Ma, Song-Ya; Chen, Xiu-Bo; Wang, Xiaojun

2015-11-16

Quantum computation offers potential advantages in solving a number of interesting and difficult problems. Several controlled logic gates, the elemental building blocks of quantum computer, have been realized with various physical systems. A general technique was recently proposed that significantly reduces the realization complexity of multiple-control logic gates by harnessing multi-level information carriers. We present implementations of a key quantum circuit: the three-qubit Toffoli gate. By exploring the optical selection rules of one-sided optical microcavities, a Toffoli gate may be realized on all combinations of photon and quantum spins in the QD-cavity. The three general controlled-NOT gates are involved using an auxiliary photon with two degrees of freedom. Our results show that photons and quantum spins may be used alternatively in quantum information processing.

Chaos in Dirac Electron Optics: Emergence of a Relativistic Quantum Chimera

NASA Astrophysics Data System (ADS)

Xu, Hong-Ya; Wang, Guang-Lei; Huang, Liang; Lai, Ying-Cheng

2018-03-01

We uncover a remarkable quantum scattering phenomenon in two-dimensional Dirac material systems where the manifestations of both classically integrable and chaotic dynamics emerge simultaneously and are electrically controllable. The distinct relativistic quantum fingerprints associated with different electron spin states are due to a physical mechanism analogous to a chiroptical effect in the presence of degeneracy breaking. The phenomenon mimics a chimera state in classical complex dynamical systems but here in a relativistic quantum setting—henceforth the term "Dirac quantum chimera," associated with which are physical phenomena with potentially significant applications such as enhancement of spin polarization, unusual coexisting quasibound states for distinct spin configurations, and spin selective caustics. Experimental observations of these phenomena are possible through, e.g., optical realizations of ballistic Dirac fermion systems.

Global Coordinates and Exact Aberration Calculations Applied to Physical Optics Modeling of Complex Optical Systems

NASA Astrophysics Data System (ADS)

Lawrence, G.; Barnard, C.; Viswanathan, V.

1986-11-01

Historically, wave optics computer codes have been paraxial in nature. Folded systems could be modeled by "unfolding" the optical system. Calculation of optical aberrations is, in general, left for the analyst to do with off-line codes. While such paraxial codes were adequate for the simpler systems being studied 10 years ago, current problems such as phased arrays, ring resonators, coupled resonators, and grazing incidence optics require a major advance in analytical capability. This paper describes extension of the physical optics codes GLAD and GLAD V to include a global coordinate system and exact ray aberration calculations. The global coordinate system allows components to be positioned and rotated arbitrarily. Exact aberrations are calculated for components in aligned or misaligned configurations by using ray tracing to compute optical path differences and diffraction propagation. Optical path lengths between components and beam rotations in complex mirror systems are calculated accurately so that coherent interactions in phased arrays and coupled devices may be treated correctly.

Elegant Gaussian beams for enhanced optical manipulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alpmann, Christina, E-mail: c.alpmann@uni-muenster.de; Schöler, Christoph; Denz, Cornelia

2015-06-15

Generation of micro- and nanostructured complex light beams attains increasing impact in photonics and laser applications. In this contribution, we demonstrate the implementation and experimental realization of the relatively unknown, but highly versatile class of complex-valued Elegant Hermite- and Laguerre-Gaussian beams. These beams create higher trapping forces compared to standard Gaussian light fields due to their propagation changing properties. We demonstrate optical trapping and alignment of complex functional particles as nanocontainers with standard and Elegant Gaussian light beams. Elegant Gaussian beams will inspire manifold applications in optical manipulation, direct laser writing, or microscopy, where the design of the point-spread functionmore » is relevant.« less

An Anatomically Constrained Model for Path Integration in the Bee Brain.

PubMed

Stone, Thomas; Webb, Barbara; Adden, Andrea; Weddig, Nicolai Ben; Honkanen, Anna; Templin, Rachel; Wcislo, William; Scimeca, Luca; Warrant, Eric; Heinze, Stanley

2017-10-23

Path integration is a widespread navigational strategy in which directional changes and distance covered are continuously integrated on an outward journey, enabling a straight-line return to home. Bees use vision for this task-a celestial-cue-based visual compass and an optic-flow-based visual odometer-but the underlying neural integration mechanisms are unknown. Using intracellular electrophysiology, we show that polarized-light-based compass neurons and optic-flow-based speed-encoding neurons converge in the central complex of the bee brain, and through block-face electron microscopy, we identify potential integrator cells. Based on plausible output targets for these cells, we propose a complete circuit for path integration and steering in the central complex, with anatomically identified neurons suggested for each processing step. The resulting model circuit is thus fully constrained biologically and provides a functional interpretation for many previously unexplained architectural features of the central complex. Moreover, we show that the receptive fields of the newly discovered speed neurons can support path integration for the holonomic motion (i.e., a ground velocity that is not precisely aligned with body orientation) typical of bee flight, a feature not captured in any previously proposed model of path integration. In a broader context, the model circuit presented provides a general mechanism for producing steering signals by comparing current and desired headings-suggesting a more basic function for central complex connectivity, from which path integration may have evolved. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gold nanoparticles as a factor of influence on doxorubicin-bovine serum albumin complex

NASA Astrophysics Data System (ADS)

Goncharenko, N. A.; Pavlenko, O. L.; Dmytrenko, O. P.; Kulish, M. P.; Lopatynskyi, A. M.; Chegel, V. I.

2018-04-01

The interaction between doxorubicin (Dox) and bovine serum albumin (BSA) complex with gold nanoparticles (AuNPs) was investigated by optical spectroscopy. The optical absorption of Dox and BSA solutions was studied. The formation of Dox-BSA complexes with a binding constant K = 7.56 × 106 M-2 and the number of binding sites n = 2 was found out. With pH 6.9, the concentration of complexes is an order of magnitude lower than the concentration of unbound antibiotic molecules. Optical absorption in solutions of Dox-BSA conjugates in the presence of AuNPs undergoes a significant rearrangement, which manifests the changes in the magnitude of the hydrophobic interaction of BSA with Dox, changes in the conformational state of antibiotic, and, as a consequence, a plasmon-induced change in the mechanism of complex formation. The aggregation of the Dox-AuNPs conjugate depends on the presence and concentration of BSA and in the case of formation of the Dox-BSA complex is minimal.

Argand-plane vorticity singularities in complex scalar optical fields: an experimental study using optical speckle.

PubMed

Rothschild, Freda; Bishop, Alexis I; Kitchen, Marcus J; Paganin, David M

2014-03-24

The Cornu spiral is, in essence, the image resulting from an Argand-plane map associated with monochromatic complex scalar plane waves diffracting from an infinite edge. Argand-plane maps can be useful in the analysis of more general optical fields. We experimentally study particular features of Argand-plane mappings known as "vorticity singularities" that are associated with mapping continuous single-valued complex scalar speckle fields to the Argand plane. Vorticity singularities possess a hierarchy of Argand-plane catastrophes including the fold, cusp and elliptic umbilic. We also confirm their connection to vortices in two-dimensional complex scalar waves. The study of vorticity singularities may also have implications for higher-dimensional fields such as coherence functions and multi-component fields such as vector and spinor fields.

Huygens' optical vector wave field synthesis via in-plane electric dipole metasurface.

PubMed

Park, Hyeonsoo; Yun, Hansik; Choi, Chulsoo; Hong, Jongwoo; Kim, Hwi; Lee, Byoungho

2018-04-16

We investigate Huygens' optical vector wave field synthesis scheme for electric dipole metasurfaces with the capability of modulating in-plane polarization and complex amplitude and discuss the practical issues involved in realizing multi-modulation metasurfaces. The proposed Huygens' vector wave field synthesis scheme identifies the vector Airy disk as a synthetic unit element and creates a designed vector optical field by integrating polarization-controlled and complex-modulated Airy disks. The metasurface structure for the proposed vector field synthesis is analyzed in terms of the signal-to-noise ratio of the synthesized field distribution. The design of practical metasurface structures with true vector modulation capability is possible through the analysis of the light field modulation characteristics of various complex modulated geometric phase metasurfaces. It is shown that the regularization of meta-atoms is a key factor that needs to be considered in field synthesis, given that it is essential for a wide range of optical field synthetic applications, including holographic displays, microscopy, and optical lithography.

Charge-transfer optical absorption mechanism of DNA:Ag-nanocluster complexes

NASA Astrophysics Data System (ADS)

Longuinhos, R.; Lúcio, A. D.; Chacham, H.; Alexandre, S. S.

2016-05-01

Optical properties of DNA:Ag-nanoclusters complexes have been successfully applied experimentally in Chemistry, Physics, and Biology. Nevertheless, the mechanisms behind their optical activity remain unresolved. In this work, we present a time-dependent density functional study of optical absorption in DNA:Ag4. In all 23 different complexes investigated, we obtain new absorption peaks in the visible region that are not found in either the isolated Ag4 or isolated DNA base pairs. Absorption from red to green are predominantly of charge-transfer character, from the Ag4 to the DNA fragment, while absorption in the blue-violet range are mostly associated to electronic transitions of a mixed character, involving either DNA-Ag4 hybrid orbitals or intracluster orbitals. We also investigate the role of exchange-correlation functionals in the calculated optical spectra. Significant differences are observed between the calculations using the PBE functional (without exact exchange) and the CAM-B3LYP functional (which partly includes exact exchange). Specifically, we observe a tendency of charge-transfer excitations to involve purines bases, and the PBE spectra error is more pronounced in the complexes where the Ag cluster is bound to the purines. Finally, our results also highlight the importance of adding both the complementary base pair and the sugar-phosphate backbone in order to properly characterize the absorption spectrum of DNA:Ag complexes.

Charge-transfer optical absorption mechanism of DNA:Ag-nanocluster complexes.

PubMed

Longuinhos, R; Lúcio, A D; Chacham, H; Alexandre, S S

2016-05-01

Optical properties of DNA:Ag-nanoclusters complexes have been successfully applied experimentally in Chemistry, Physics, and Biology. Nevertheless, the mechanisms behind their optical activity remain unresolved. In this work, we present a time-dependent density functional study of optical absorption in DNA:Ag_{4}. In all 23 different complexes investigated, we obtain new absorption peaks in the visible region that are not found in either the isolated Ag_{4} or isolated DNA base pairs. Absorption from red to green are predominantly of charge-transfer character, from the Ag_{4} to the DNA fragment, while absorption in the blue-violet range are mostly associated to electronic transitions of a mixed character, involving either DNA-Ag_{4} hybrid orbitals or intracluster orbitals. We also investigate the role of exchange-correlation functionals in the calculated optical spectra. Significant differences are observed between the calculations using the PBE functional (without exact exchange) and the CAM-B3LYP functional (which partly includes exact exchange). Specifically, we observe a tendency of charge-transfer excitations to involve purines bases, and the PBE spectra error is more pronounced in the complexes where the Ag cluster is bound to the purines. Finally, our results also highlight the importance of adding both the complementary base pair and the sugar-phosphate backbone in order to properly characterize the absorption spectrum of DNA:Ag complexes.

Reconfigurable optical implementation of quantum complex networks

NASA Astrophysics Data System (ADS)

Nokkala, J.; Arzani, F.; Galve, F.; Zambrini, R.; Maniscalco, S.; Piilo, J.; Treps, N.; Parigi, V.

2018-05-01

Network theory has played a dominant role in understanding the structure of complex systems and their dynamics. Recently, quantum complex networks, i.e. collections of quantum systems arranged in a non-regular topology, have been theoretically explored leading to significant progress in a multitude of diverse contexts including, e.g., quantum transport, open quantum systems, quantum communication, extreme violation of local realism, and quantum gravity theories. Despite important progress in several quantum platforms, the implementation of complex networks with arbitrary topology in quantum experiments is still a demanding task, especially if we require both a significant size of the network and the capability of generating arbitrary topology—from regular to any kind of non-trivial structure—in a single setup. Here we propose an all optical and reconfigurable implementation of quantum complex networks. The experimental proposal is based on optical frequency combs, parametric processes, pulse shaping and multimode measurements allowing the arbitrary control of the number of the nodes (optical modes) and topology of the links (interactions between the modes) within the network. Moreover, we also show how to simulate quantum dynamics within the network combined with the ability to address its individual nodes. To demonstrate the versatility of these features, we discuss the implementation of two recently proposed probing techniques for quantum complex networks and structured environments.

Repulsive nature of optical potentials for high-energy heavy-ion scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furumoto, T.; Sakuragi, Y.; Yamamoto, Y.

2010-10-15

The recent works by the present authors predicted that the real part of heavy-ion optical potentials changes its character from attraction to repulsion around the incident energy per nucleon E/A=200-300 MeV on the basis of the complex G-matrix interaction and the double-folding model (DFM) and revealed that the three-body force plays an important role there. In the present paper, we have precisely analyzed the energy dependence of the calculated DFM potentials and its relation to the elastic-scattering angular distributions in detail in the case of the {sup 12}C+{sup 12}C system in the energy range of E/A=100-400 MeV. The tensor forcemore » contributes substantially to the energy dependence of the real part of the DFM potentials and plays an important role to lower the attractive-to-repulsive transition energy. The nearside and farside (N/F) decompositions of the elastic-scattering amplitudes clarify the close relation between the attractive-to-repulsive transition of the potentials and the characteristic evolution of the calculated angular distributions with the increase of the incident energy. Based on the present analysis, we propose experimental measurements for the predicted strong diffraction phenomena of the elastic-scattering angular distribution caused by the N/F interference around the attractive-to-repulsive transition energy together with the reduced diffractions below and above the transition energy.« less

Optical properties, excitation energy and primary charge transfer in photosystem II: theory meets experiment.

PubMed

Renger, Thomas; Schlodder, Eberhard

2011-01-01

In this review we discuss structure-function relationships of the core complex of photosystem II, as uncovered from analysis of optical spectra of the complex and its subunits. Based on descriptions of optical difference spectra including site directed mutagenesis we propose a revision of the multimer model of the symmetrically arranged reaction center pigments, described by an asymmetric exciton Hamiltonian. Evidence is provided for the location of the triplet state, the identity of the primary electron donor, the localization of the cation and the secondary electron transfer pathway in the reaction center. We also discuss the stationary and time-dependent optical properties of the CP43 and CP47 subunits and the excitation energy transfer and trapping-by-charge-transfer kinetics in the core complex. Copyright © 2011 Elsevier B.V. All rights reserved.

Enhanced nonlinear optical responses in donor-acceptor ionic complexes via photo induced energy transfer.

PubMed

Mamidala, Venkatesh; Polavarapu, Lakshminarayana; Balapanuru, Janardhan; Loh, Kian Ping; Xu, Qing-Hua; Ji, Wei

2010-12-06

By complexion of donor and acceptor using ionic interactions, the enhanced nonlinear optical responses of donor-acceptor ionic complexes in aqueous solution were studied with 7-ns laser pulses at 532 nm. The optical limiting performance of negatively charged gold nanoparticles or graphene oxide (Acceptor) was shown to be improved significantly when they were mixed with water-soluble, positively-charged porphyrin (Donor) derivative. In contrast, no enhancement was observed when mixing with negatively-charged porphyrin. Transient absorption studies of the donor-acceptor complexes confirmed that the addition of energy transfer pathway were responsible for excited-state deactivation, which results in the observed enhancement. Fluence, angle-dependent scattering and time correlated single photon counting measurements suggested that the enhanced nonlinear scattering due to faster nonradiative decay should play a major role in the enhanced optical limiting responses.

Wavefront correction and high-resolution in vivo OCT imaging with an objective integrated multi-actuator adaptive lens.

PubMed

Bonora, Stefano; Jian, Yifan; Zhang, Pengfei; Zam, Azhar; Pugh, Edward N; Zawadzki, Robert J; Sarunic, Marinko V

2015-08-24

Adaptive optics is rapidly transforming microscopy and high-resolution ophthalmic imaging. The adaptive elements commonly used to control optical wavefronts are liquid crystal spatial light modulators and deformable mirrors. We introduce a novel Multi-actuator Adaptive Lens that can correct aberrations to high order, and which has the potential to increase the spread of adaptive optics to many new applications by simplifying its integration with existing systems. Our method combines an adaptive lens with an imaged-based optimization control that allows the correction of images to the diffraction limit, and provides a reduction of hardware complexity with respect to existing state-of-the-art adaptive optics systems. The Multi-actuator Adaptive Lens design that we present can correct wavefront aberrations up to the 4th order of the Zernike polynomial characterization. The performance of the Multi-actuator Adaptive Lens is demonstrated in a wide field microscope, using a Shack-Hartmann wavefront sensor for closed loop control. The Multi-actuator Adaptive Lens and image-based wavefront-sensorless control were also integrated into the objective of a Fourier Domain Optical Coherence Tomography system for in vivo imaging of mouse retinal structures. The experimental results demonstrate that the insertion of the Multi-actuator Objective Lens can generate arbitrary wavefronts to correct aberrations down to the diffraction limit, and can be easily integrated into optical systems to improve the quality of aberrated images.

Comparisons between real and complex Gauss wavelet transform methods of three-dimensional shape reconstruction

NASA Astrophysics Data System (ADS)

Xu, Luopeng; Dan, Youquan; Wang, Qingyuan

2015-10-01

The continuous wavelet transform (CWT) introduces an expandable spatial and frequency window which can overcome the inferiority of localization characteristic in Fourier transform and windowed Fourier transform. The CWT method is widely applied in the non-stationary signal analysis field including optical 3D shape reconstruction with remarkable performance. In optical 3D surface measurement, the performance of CWT for optical fringe pattern phase reconstruction usually depends on the choice of wavelet function. A large kind of wavelet functions of CWT, such as Mexican Hat wavelet, Morlet wavelet, DOG wavelet, Gabor wavelet and so on, can be generated from Gauss wavelet function. However, so far, application of the Gauss wavelet transform (GWT) method (i.e. CWT with Gauss wavelet function) in optical profilometry is few reported. In this paper, the method using GWT for optical fringe pattern phase reconstruction is presented first and the comparisons between real and complex GWT methods are discussed in detail. The examples of numerical simulations are also given and analyzed. The results show that both the real GWT method along with a Hilbert transform and the complex GWT method can realize three-dimensional surface reconstruction; and the performance of reconstruction generally depends on the frequency domain appearance of Gauss wavelet functions. For the case of optical fringe pattern of large phase variation with position, the performance of real GWT is better than that of complex one due to complex Gauss series wavelets existing frequency sidelobes. Finally, the experiments are carried out and the experimental results agree well with our theoretical analysis.

A cobalt (II) complex with 6-methylpicolinate: Synthesis, characterization, second- and third-order nonlinear optical properties, and DFT calculations

NASA Astrophysics Data System (ADS)

Altürk, Sümeyye; Avcı, Davut; Tamer, Ömer; Atalay, Yusuf; Şahin, Onur

2016-11-01

A cobalt(II) complex of 6-methylpicolinic acid, [Co(6-Mepic)2(H2O)2]·2H2O, was prepared and fully determined by single crystal X-ray crystal structure analysis as well as FT-IR, FT-Raman. UV-vis spectra were recorded within different solvents, to illustrate electronic transitions and molecular charge transfer within complex 1. The coordination sphere of complex 1 is a distorted octahedron according to single crystal X-ray results. Moreover, DFT (density functional theory) calculations with HSEH1PBE/6-311 G(d,p) level were carried out to back up the experimental results, and form base for future work in advanced level. Hyperconjugative interactions, intramolecular charge transfer (ICT), molecular stability and bond strength were researched by the using natural bond orbital (NBO) analysis. X-ray and NBO analysis results demonsrate that O-H···O hydrogen bonds between the water molecules and carboxylate oxygen atoms form a 2D supramolecular network, and also adjacent 2D networks connected by C-H···π and π···π interactions to form a 3D supramolecular network. Additionally, the second- and third-order nonlinear optical parameters of complex 1 were computed at DFT/HSEH1PBE/6-311 G(d,p) level. The refractive index (n) was calculated by using the Lorentz-Lorenz equation in order to investigate polarization behavior of complex 1 in different solvent polarities. The first-order static hyperpolarizability (β) value is found to be lower than pNA value because of the inversion symmetry around Co (II). But the second-order static hyperpolarizability (γ) value is 2.45 times greater than pNA value (15×10-30 esu). According to these results, Co(II) complex can be considered as a candidate to NLO material. Lastly molecular electrostatic potential (MEP), frontier molecular orbital energies and related molecular parameters for complex 1 were evaluated.

The under-pressure behaviour of mechanical, electronic and optical properties of calcium titanate and its ground state thermoelectric response

NASA Astrophysics Data System (ADS)

Noor, N. A.; Alay-e-Abbas, S. M.; Hassan, M.; Mahmood, I.; Alahmed, Z. A.; Reshak, A. H.

2017-08-01

In this study, the elastic, electronic, optical and thermoelectric properties of CaTiO3 perovskite oxide have been investigated using first-principles calculations. The generalised gradient approximation (GGA) has been employed for evaluating structural and elastic properties, while the modified Becke Johnson functional is used for studying the optical response of this compound. In addition to ground state physical properties, we also investigate the effects of pressure (0, 30, 60, 90 and 120 GPa) on the electronic structure of CaTiO3. The application of pressure from 0 to 90 GPa shows that the indirect band gap (Γ-M) of CaTiO3 increases with increasing pressure and at 120 GPa it spontaneously decreases transforming cubic CaTiO3 to a direct (Γ-Γ) band gap material. The complex dielectric function and some optical parameters are also investigated under the application of pressures. All the calculated optical properties have been found to exhibit a shift to the higher energies with the increase of applied pressure suggesting potential optoelectronic device applications of CaTiO3. The thermoelectric properties of CaTiO3 have been computed at 0 GPa in terms of electrical conductivity, thermal conductivity and Seebeck coefficient.

Liquid Crystal Spatial Light Modulators for Simulating Zonal Multifocal Lenses.

PubMed

Li, Yiyu; Bradley, Arthur; Xu, Renfeng; Kollbaum, Pete S

2017-09-01

To maximize efficiency of the normally lengthy and costly multizone lens design and testing process, it is advantageous to evaluate the potential efficacy of a design as thoroughly as possible prior to lens fabrication and on-eye testing. The current work describes an ex vivo approach of optical design testing. The aim of this study was to describe a system capable of examining the optical characteristics of multizone bifocal and multifocal optics by subaperture stitching using liquid crystal technologies. A liquid crystal spatial light modulator (SLM) was incorporated in each of two channels to generate complementary subapertures by amplitude modulation. Additional trial lenses and phase plates were placed in pupil conjugate planes of either channel to integrate the desired bifocal and multifocal optics once the two optical paths were recombined. A high-resolution Shack-Hartmann aberrometer was integrated to measure the optics of the dual-channel system. Power and wavefront error maps as well as point spread functions were measured and computed for each of three multizone multifocal designs. High transmission modulation was achieved by introducing half-wavelength optical path differences to create two- and five-zone bifocal apertures. Dual-channel stitching revealed classic annular rings in the point spread functions generated from two-zone designs when the outer annular optic was defocused. However, low efficiency of the SLM prevented us from simultaneously measuring the eye + simulator aberrations, and the higher-order diffraction patterns generated by the cellular structure of the liquid crystal arrays limited the visual field to ±0.45 degrees. The system successfully simulated bifocal and multifocal simultaneous lenses allowing for future evaluation of both objective and subjective evaluation of complex optical designs. However, low efficiency and diffraction phenomena of the SLM limit the utility of this technology for simulating multizone and multifocal optics.

Overcoming Dynamic Disturbances in Imaging Systems

NASA Technical Reports Server (NTRS)

Young, Eric W.; Dente, Gregory C.; Lyon, Richard G.; Chesters, Dennis; Gong, Qian

2000-01-01

We develop and discuss a methodology with the potential to yield a significant reduction in complexity, cost, and risk of space-borne optical systems in the presence of dynamic disturbances. More robust systems almost certainly will be a result as well. Many future space-based and ground-based optical systems will employ optical control systems to enhance imaging performance. The goal of the optical control subsystem is to determine the wavefront aberrations and remove them. Ideally reducing an aberrated image of the object under investigation to a sufficiently clear (usually diffraction-limited) image. Control will likely be distributed over several elements. These elements may include telescope primary segments, telescope secondary, telescope tertiary, deformable mirror(s), fine steering mirror(s), etc. The last two elements, in particular, may have to provide dynamic control. These control subsystems may become elaborate indeed. But robust system performance will require evaluation of the image quality over a substantial range and in a dynamic environment. Candidate systems for improvement in the Earth Sciences Enterprise could include next generation Landsat systems or atmospheric sensors for dynamic imaging of individual, severe storms. The technology developed here could have a substantial impact on the development of new systems in the Space Science Enterprise; such as the Next Generation Space Telescope(NGST) and its follow-on the Next NGST. Large Interferometric Systems of non-zero field, such as Planet Finder and Submillimeter Probe of the Evolution of Cosmic Structure, could benefit. These systems most likely will contain large, flexible optomechanical structures subject to dynamic disturbance. Furthermore, large systems for high resolution imaging of planets or the sun from space may also benefit. Tactical and Strategic Defense systems will need to image very small targets as well and could benefit from the technology developed here. We discuss a novel speckle imaging technique with the potential to separate dynamic aberrations from static aberrations. Post-processing of a set of image data, using an algorithm based on this technique, should work for all but the lowest light levels and highest frequency dynamic environments. This technique may serve to reduce the complexity of the control system and provide for robust, fault-tolerant, reduced risk operation. For a given object, a short exposure image is "frozen" on the focal plane in the presence of the environmental disturbance (turbulence, jitter, etc.). A key factor is that this imaging data exhibits frame-to-frame linear shift invariance. Therefore, although the Point Spread Function is varying from frame to frame, the source is fixed; and each short exposure contains object spectrum data out to the diffraction limit of the imaging system. This novel speckle imaging technique uses the Knox-Thompson method. The magnitude of the complex object spectrum is straightforward to determine by well-established approaches. The phase of the complex object spectrum is decomposed into two parts. One is a single-valued function determined by the divergence of the optical phase gradient. The other is a multi-valued function determined by the circulation of the optical phase gradient-"hidden phase." Finite difference equations are developed for the phase. The novelty of this approach is captured in the inclusion of this "hidden phase." This technique allows the diffraction-limited reconstruction of the object from the ensemble of short exposure frames while simultaneously estimating the phase as a function of time from a set of exposures.

Overcoming Dynamic Disturbances in Imaging Systems

NASA Technical Reports Server (NTRS)

Young, Eric W.; Dente, Gregory C.; Lyon, Richard G.; Chesters, Dennis; Gong, Qian

2000-01-01

We develop and discuss a methodology with the potential to yield a significant reduction in complexity, cost, and risk of space-borne optical systems in the presence of dynamic disturbances. More robust systems almost certainly will be a result as well. Many future space-based and ground-based optical systems will employ optical control systems to enhance imaging performance. The goal of the optical control subsystem is to determine the wavefront aberrations and remove them. Ideally reducing an aberrated image of the object under investigation to a sufficiently clear (usually diffraction-limited) image. Control will likely be distributed over several elements. These elements may include telescope primary segments, telescope secondary, telescope tertiary, deformable mirror(s), fine steering mirror(s), etc. The last two elements, in particular, may have to provide dynamic control. These control subsystems may become elaborate indeed. But robust system performance will require evaluation of the image quality over a substantial range and in a dynamic environment. Candidate systems for improvement in the Earth Sciences Enterprise could include next generation Landsat systems or atmospheric sensors for dynamic imaging of individual, severe storms. The technology developed here could have a substantial impact on the development of new systems in the Space Science Enterprise; such as the Next Generation Space Telescope(NGST) and its follow-on the Next NGST. Large Interferometric Systems of non-zero field, such as Planet Finder and Submillimeter Probe of the Evolution of Cosmic Structure, could benefit. These systems most likely will contain large, flexible optormechanical structures subject to dynamic disturbance. Furthermore, large systems for high resolution imaging of planets or the sun from space may also benefit. Tactical and Strategic Defense systems will need to image very small targets as well and could benefit from the technology developed here. We discuss a novel speckle imaging technique with the potential to separate dynamic aberrations from static aberrations. Post-processing of a set of image data, using an algorithm based on this technique, should work for all but the lowest light levels and highest frequency dynamic environments. This technique may serve to reduce the complexity of the control system and provide for robust, fault-tolerant, reduced risk operation. For a given object, a short exposure image is "frozen" on the focal plane in the presence of the environmental disturbance (turbulence, jitter, etc.). A key factor is that this imaging data exhibits frame-to-frame linear shift invariance. Therefore, although the Point Spread Function is varying from frame to frame, the source is fixed; and each short exposure contains object spectrum data out to the diffraction limit of the imaging system. This novel speckle imaging technique uses the Knox-Thompson method. The magnitude of the complex object spectrum is straightforward to determine by well-established approaches. The phase of the complex object spectrum is decomposed into two parts. One is a single-valued function determined by the divergence of the optical phase gradient. The other is a multi-valued function determined by, the circulation of the optical phase gradient-"hidden phase." Finite difference equations are developed for the phase. The novelty of this approach is captured in the inclusion of this "hidden phase." This technique allows the diffraction-limited reconstruction of the object from the ensemble of short exposure frames while simultaneously estimating the phase as a function of time from a set of exposures.

Millisecond infrared laser pulses depolarize and elicit action potentials on in-vitro dorsal root ganglion neurons

PubMed Central

Paris, Lambert; Marc, Isabelle; Charlot, Benoit; Dumas, Michel; Valmier, Jean; Bardin, Fabrice

2017-01-01

This work focuses on the optical stimulation of dorsal root ganglion (DRG) neurons through infrared laser light stimulation. We show that a few millisecond laser pulse at 1875 nm induces a membrane depolarization, which was observed by the patch-clamp technique. This stimulation led to action potentials firing on a minority of neurons beyond an energy threshold. A depolarization without action potential was observed for the majority of DRG neurons, even beyond the action potential energy threshold. The use of ruthenium red, a thermal channel blocker, stops the action potential generation, but has no effects on membrane depolarization. Local temperature measurements reveal that the depolarization amplitude is sensitive to the amplitude of the temperature rise as well as to the time rate of change of temperature, but in a way which may not fully follow a photothermal capacitive mechanism, suggesting that more complex mechanisms are involved. PMID:29082085

Scalable modulation technology and the tradeoff of reach, spectral efficiency, and complexity

NASA Astrophysics Data System (ADS)

Bosco, Gabriella; Pilori, Dario; Poggiolini, Pierluigi; Carena, Andrea; Guiomar, Fernando

2017-01-01

Bandwidth and capacity demand in metro, regional, and long-haul networks is increasing at several tens of percent per year, driven by video streaming, cloud computing, social media and mobile applications. To sustain this traffic growth, an upgrade of the widely deployed 100-Gbit/s long-haul optical systems, based on polarization multiplexed quadrature phase-shift keying (PM-QPSK) modulation format associated with coherent detection and digital signal processing (DSP), is mandatory. In fact, optical transport techniques enabling a per-channel bit rate beyond 100 Gbit/s have recently been the object of intensive R and D activities, aimed at both improving the spectral efficiency and lowering the cost per bit in fiber transmission systems. In this invited contribution, we review the different available options to scale the per-channel bit-rate to 400 Gbit/s and beyond, i.e. symbol-rate increase, use of higher-order quadrature amplitude modulation (QAM) modulation formats and use of super-channels with DSP-enabled spectral shaping and advanced multiplexing technologies. In this analysis, trade-offs of system reach, spectral efficiency and transceiver complexity are addressed. Besides scalability, next generation optical networks will require a high degree of flexibility in the transponders, which should be able to dynamically adapt the transmission rate and bandwidth occupancy to the light path characteristics. In order to increase the flexibility of these transponders (often referred to as "flexponders"), several advanced modulation techniques have recently been proposed, among which sub-carrier multiplexing, hybrid formats (over time, frequency and polarization), and constellation shaping. We review these techniques, highlighting their limits and potential in terms of performance, complexity and flexibility.

New solutions to realize complex optical systems by a combination of diffractive and refractive optical components

NASA Astrophysics Data System (ADS)

Brunner, Robert; Steiner, Reinhard; Dobschal, Hans-Juergen; Martin, Dietrich; Burkhardt, Matthias; Helgert, Michael

2003-11-01

Diffractive optical elements (DOEs) have a great potential in the complete or partial substitution of refractive or reflective optical elements in imaging systems. The greater design flexibility compared to an all-refractive/reflective solution allows a more convenient realization of the optical systems and additionally opens up new possibilities for optimizing the performance or compactness. To demonstrate the opportunities of the hybrid optical concept we discuss different imaging systems for various applications. We present the lens design of a hybrid microscope objective which is especially applicable for wafer inspection technologies. Meeting the requirements for such a system used in the deep-UV regime (248 nm) is very challenging. The short wavelength limits the material selection and demands cement free optical groups. The additional requirement of an autofocus system, working at a wavelength in the near infrared region, is fulfilled by the special combination of two selected and adjusted DOEs. Furthermore, we discuss the opportunities of the hybrid concept c of a slit lamp used for ophthalmologic examinations. The DOEs are the basic elements of this hybrid concept. We demonstrate that holographic lithography is an appropriate technology to realize a wide variety of elements with different profile geometries. We address in particular the additional possibilities of an UV-laser system as an exposure tool. Additionally to the high spatial frequencies, the 266 nm exposure wavelength allows the use of novel photo resists with advantageous development behavior.

On the influence of lipid-induced optical anisotropy for the bioimaging of exo- or endocytosis with interference microscopic imaging.

PubMed

Marques, D; Miranda, A; Silva, A G; Munro, P R T; DE Beule, P A A

2018-05-01

Some implementations of interference microscopy imaging use digital holographic measurements of complex scattered fields to reconstruct three-dimensional refractive index maps of weakly scattering, semi-transparent objects, frequently encountered in biological investigations. Reconstruction occurs through application of the object scattering potential which assumes an isotropic refractive index throughout the object. Here, we demonstrate that this assumption can in some circumstances be invalid for biological imaging due to the presence of lipid-induced optical anisotropy. We show that the nanoscale organization of lipids in the observation of cellular endocytosis with polarized light induces a significant change in far-field scattering. We obtain this result by presenting a general solution to Maxwell's equations describing light scattering of core-shell particles near an isotropic substrate covered with an anisotropic thin film. This solution is based on an extension of the Bobbert-Vlieger solution for particle scattering near a substrate delivering an exact solution to the scattering problem in the near field as well as far field. By applying this solution to study light scattering by a lipid vesicle near a lipid bilayer, whereby the lipids are represented through a biaxial optical model, we conclude through ellipsometry concepts that effective amounts of lipid-induced optical anisotropy significantly alter far-field optical scattering in respect to an equivalent optical model that neglects the presence of optical anisotropy. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

A method of rapidly evaluating image quality of NED optical system

NASA Astrophysics Data System (ADS)

Sun, Qi; Qiu, Chuankai; Yang, Huan

2014-11-01

In recent years, with the development of technology of micro-display, advanced optics and the software and hardware, near-to-eye display ( NED) optical system will have a wide range of potential applications in the fields of amusement and virtual reality. However, research on the evaluating image quality of this kind optical system is comparatively lagging behind. Although now there are some methods and equipment for evaluation, they can't be applied in commercial production because of their complex operation and inaccuracy. In this paper, an academic method is proposed and a Rapid Evaluation System (RES) is designed to evaluate the image of optical system rapidly and exactly. Firstly, a set of parameters that eyes are sensitive to and also express the quality of system should be extracted and quantized to be criterion, so the evaluation standards can be established. Then, some parameters can be detected by RES consisted of micro-display, CCD camera and computer and so on. By process of scaling, the measuring results of the RES are exact and creditable, relationship between object measurement, subjective evaluation and the RES will be established. After that, image quality of optical system can be evaluated just by detecting parameters of that. The RES is simple and the results of evaluation are exact and keeping with human vision. So the method can be used not only for optimizing design of optical system, but also for evaluation in commercial production.

A High-Performance Optical Memory Array Based on Inhomogeneity of Organic Semiconductors.

PubMed

Pei, Ke; Ren, Xiaochen; Zhou, Zhiwen; Zhang, Zhichao; Ji, Xudong; Chan, Paddy Kwok Leung

2018-03-01

Organic optical memory devices keep attracting intensive interests for diverse optoelectronic applications including optical sensors and memories. Here, flexible nonvolatile optical memory devices are developed based on the bis[1]benzothieno[2,3-d;2',3'-d']naphtho[2,3-b;6,7-b']dithiophene (BBTNDT) organic field-effect transistors with charge trapping centers induced by the inhomogeneity (nanosprouts) of the organic thin film. The devices exhibit average mobility as high as 7.7 cm 2 V -1 s -1 , photoresponsivity of 433 A W -1 , and long retention time for more than 6 h with a current ratio larger than 10 6 . Compared with the standard floating gate memory transistors, the BBTNDT devices can reduce the fabrication complexity, cost, and time. Based on the reasonable performance of the single device on a rigid substrate, the optical memory transistor is further scaled up to a 16 × 16 active matrix array on a flexible substrate with operating voltage less than 3 V, and it is used to map out 2D optical images. The findings reveal the potentials of utilizing [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives as organic semiconductors for high-performance optical memory transistors with a facile structure. A detailed study on the charge trapping mechanism in the derivatives of BTBT materials is also provided, which is closely related to the nanosprouts formed inside the organic active layer. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical delay encoding for fast timing and detector signal multiplexing in PET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grant, Alexander M.; Levin, Craig S., E-mail: cslevin@stanford.edu; Molecular Imaging Program at Stanford

2015-08-15

Purpose: The large number of detector channels in modern positron emission tomography (PET) scanners poses a challenge in terms of readout electronics complexity. Multiplexing schemes are typically implemented to reduce the number of physical readout channels, but often result in performance degradation. Novel methods of multiplexing in PET must be developed to avoid this data degradation. The preservation of fast timing information is especially important for time-of-flight PET. Methods: A new multiplexing scheme based on encoding detector interaction events with a series of extremely fast overlapping optical pulses with precise delays is demonstrated in this work. Encoding events in thismore » way potentially allows many detector channels to be simultaneously encoded onto a single optical fiber that is then read out by a single digitizer. A two channel silicon photomultiplier-based prototype utilizing this optical delay encoding technique along with dual threshold time-over-threshold is demonstrated. Results: The optical encoding and multiplexing prototype achieves a coincidence time resolution of 160 ps full width at half maximum (FWHM) and an energy resolution of 13.1% FWHM at 511 keV with 3 × 3 × 5 mm{sup 3} LYSO crystals. All interaction information for both detectors, including timing, energy, and channel identification, is encoded onto a single optical fiber with little degradation. Conclusions: Optical delay encoding and multiplexing technology could lead to time-of-flight PET scanners with fewer readout channels and simplified data acquisition systems.« less

Integrated modeling: a look back

NASA Astrophysics Data System (ADS)

Briggs, Clark

2015-09-01

This paper discusses applications and implementation approaches used for integrated modeling of structural systems with optics over the past 30 years. While much of the development work focused on control system design, significant contributions were made in system modeling and computer-aided design (CAD) environments. Early work appended handmade line-of-sight models to traditional finite element models, such as the optical spacecraft concept from the ACOSS program. The IDEAS2 computational environment built in support of Space Station collected a wider variety of existing tools around a parametric database. Later, IMOS supported interferometer and large telescope mission studies at JPL with MATLAB modeling of structural dynamics, thermal analysis, and geometric optics. IMOS's predecessor was a simple FORTRAN command line interpreter for LQG controller design with additional functions that built state-space finite element models. Specialized language systems such as CAESY were formulated and prototyped to provide more complex object-oriented functions suited to control-structure interaction. A more recent example of optical modeling directly in mechanical CAD is used to illustrate possible future directions. While the value of directly posing the optical metric in system dynamics terms is well understood today, the potential payoff is illustrated briefly via project-based examples. It is quite likely that integrated structure thermal optical performance (STOP) modeling could be accomplished in a commercial off-the-shelf (COTS) tool set. The work flow could be adopted, for example, by a team developing a small high-performance optical or radio frequency (RF) instrument.

Plastic scintillators with high loading of one or more metal carboxylates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cherepy, Nerine; Sanner, Robert Dean

According to one embodiment, a method includes incorporating a metal carboxylate complex into a polymeric matrix to form an optically transparent material. According to another embodiment, a material includes at least one metal carboxylate complex incorporated into a polymeric matrix, where the material is optically transparent.

Large aspheric optics for high-power, high-energy laser

NASA Astrophysics Data System (ADS)

Geyl, Roland; Houbre, Francois

2001-12-01

SAGEM, within its REOSC high performance optics product line, has developed through the years a specific knowledge in large plano, spherical and aspherical optics for high energy or high power laser. This paper is aimed to illustrate the application of aspheric optics for such laser application with several examples of increasing optical surface complexity.

Hierarchical ferroelectric and ferrotoroidic polarizations coexistent in nano-metamaterials

PubMed Central

Shimada, Takahiro; Lich, Le Van; Nagano, Koyo; Wang, Jie; Kitamura, Takayuki

2015-01-01

Tailoring materials to obtain unique, or significantly enhanced material properties through rationally designed structures rather than chemical constituents is principle of metamaterial concept, which leads to the realization of remarkable optical and mechanical properties. Inspired by the recent progress in electromagnetic and mechanical metamaterials, here we introduce the concept of ferroelectric nano-metamaterials, and demonstrate through an experiment in silico with hierarchical nanostructures of ferroelectrics using sophisticated real-space phase-field techniques. This new concept enables variety of unusual and complex yet controllable domain patterns to be achieved, where the coexistence between hierarchical ferroelectric and ferrotoroidic polarizations establishes a new benchmark for exploration of complexity in spontaneous polarization ordering. The concept opens a novel route to effectively tailor domain configurations through the control of internal structure, facilitating access to stabilization and control of complex domain patterns that provide high potential for novel functionalities. A key design parameter to achieve such complex patterns is explored based on the parity of junctions that connect constituent nanostructures. We further highlight the variety of additional functionalities that are potentially obtained from ferroelectric nano-metamaterials, and provide promising perspectives for novel multifunctional devices. This study proposes an entirely new discipline of ferroelectric nano-metamaterials, further driving advances in metamaterials research. PMID:26424484

Luminescent molecular rods - transition-metal alkynyl complexes.

PubMed

Yam, Vivian Wing-Wah; Wong, Keith Man-Chung

2005-01-01

A number of transition-metal complexes have been reported to exhibit rich luminescence, usually originating from phosphorescence. Such luminescence properties of the triplet excited state with a large Stoke's shift, long lifetime, high luminescence quantum yield as well as lower excitation energy, are envisaged to serve as an ideal candidate in the area of potential applications for chemosensors, dye-sensitized solar cells, flat panel displays, optics, new materials and biological sciences. Organic alkynes (poly-ynes), with extended or conjugatedπ-systems and rigid structure with linear geometry, have become a significant research area due to their novel electronic and physical properties and their potential applications in nanotechnology. Owing to the presence of unsaturated sp-hybridized carbon atoms, the alkynyl unit can serve as a versatile building block in the construction of alkynyl transition-metal complexes, not only throughσ-bonding but also viaπ-bonding interactions. By incorporation of linear alkynyl groups into luminescent transition-metal complexes, the alkynyl moiety with goodσ-donor,π-donor andπ-acceptor abilities is envisaged to tune or perturb the emission behaviors, including emission energy (color), intensity and lifetime by its role as an auxiliary ligand as well as to govern the emission origin from its direct involvement. This review summarizes recent efforts on the synthesis of luminescent rod-like alkynyl complexes with different classes of transition metals and details the effects of the introduction of alkynyl groups on the luminescence properties of the complexes.

Peptide aptamer-assisted immobilization of green fluorescent protein for creating biomolecule-complexed carbon nanotube device

NASA Astrophysics Data System (ADS)

Nii, Daisuke; Nozawa, Yosuke; Miyachi, Mariko; Yamanoi, Yoshinori; Nishihara, Hiroshi; Tomo, Tatsuya; Shimada, Yuichiro

2017-10-01

Carbon nanotubes are a novel material for next-generation applications. In this study, we generated carbon nanotube and green fluorescent protein (GFP) conjugates using affinity binding peptides. The carbon nanotube-binding motif was introduced into the N-terminus of the GFP through molecular biology methods. Multiple GFPs were successfully aligned on a single-walled carbon nanotube via the molecular recognition function of the peptide aptamer, which was confirmed through transmission electron microscopy and optical analysis. Fluorescence spectral analysis results also suggested that the carbon nanotube-GFP complex was autonomously formed with orientation and without causing protein denaturation during immobilization. This simple process has a widespread potential for fabricating carbon nanotube-biomolecule hybrid devices.

Real-time generation of the Wigner distribution of complex functions using phase conjugation in photorefractive materials.

PubMed

Sun, P C; Fainman, Y

1990-09-01

An optical processor for real-time generation of the Wigner distribution of complex amplitude functions is introduced. The phase conjugation of the input signal is accomplished by a highly efficient self-pumped phase conjugator based on a 45 degrees -cut barium titanate photorefractive crystal. Experimental results on the real-time generation of Wigner distribution slices for complex amplitude two-dimensional optical functions are presented and discussed.

A new mixed-ligand copper(II) complex of (E)-N";-(2-hydroxybenzylidene) acetohydrazide: Synthesis, characterization, NLO behavior, DFT calculation and biological activities

NASA Astrophysics Data System (ADS)

Yousef Ebrahimipour, S.; Sheikhshoaie, Iran; Crochet, Aurelien; Khaleghi, Moj; Fromm, Katharina M.

2014-08-01

A tridentate hydrazone Schiff base ligand, (E)-N";-(2-hydroxybenzylidene)acetohydrazide [HL], and its mixed-ligand Cu(II) complex [CuL(phen)], have been synthesized and characterized by elemental analyses, FT-IR, molar conductivity, UV-Vis spectroscopy. The structure of the complex has been determined by X-ray diffraction. This complex has square pyramidal geometry and the positions around central atom are occupied with donor atoms of Schiff base ligand and two nitrogens of 1,10-phenanthroline. Computational studies of compounds were performed by using DFT calculations. The linear polarizabilities and first hyperpolarizabilities of the studied molecules indicate that these compounds can be good candidates of nonlinear optical materials. It is in accordance with experimental data. In addition, invitro antimicrobial results show that these compounds specially [CuL(phen)] have great potential of antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes bacteria and antifungal activity against Candida Albicans in comparison to some standard drugs.

Portable Optical Epidural Needle-A CMOS-Based System Solution and Its Circuit Design

PubMed Central

Gong, Cihun-Siyong Alex; Lin, Shih-Pin; Mandell, M. Susan; Tsou, Mei-Yung; Chang, Yin; Ting, Chien-Kun

2014-01-01

Epidural anesthesia is a common anesthesia method yet up to 10% of procedures fail to provide adequate analgesia. This is usually due to misinterpreting the tactile information derived from the advancing needle through the complex tissue planes. Incorrect placement also can cause dural puncture and neural injury. We developed an optic system capable of reliably identifying tissue planes surrounding the epidural space. However the new technology was too large and cumbersome for practical clinical use. We present a miniaturized version of our optic system using chip technology (first generation CMOS-based system) for logic functions. The new system was connected to an alarm that was triggered once the optic properties of the epidural were identified. The aims of this study were to test our miniaturized system in a porcine model and describe the technology to build this new clinical tool. Our system was tested in a porcine model and identified the epidural space in the lumbar, low and high thoracic regions of the spine. The new technology identified the epidural space in all but 1 of 46 attempts. Experimental results from our fabricated integrated circuit and animal study show the new tool has future clinical potential. PMID:25162150

Adaptive optics with pupil tracking for high resolution retinal imaging

PubMed Central

Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

2012-01-01

Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics. PMID:22312577

Adaptive optics with pupil tracking for high resolution retinal imaging.

PubMed

Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

2012-02-01

Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

Identifying Corresponding Patches in SAR and Optical Images With a Pseudo-Siamese CNN

NASA Astrophysics Data System (ADS)

Hughes, Lloyd H.; Schmitt, Michael; Mou, Lichao; Wang, Yuanyuan; Zhu, Xiao Xiang

2018-05-01

In this letter, we propose a pseudo-siamese convolutional neural network (CNN) architecture that enables to solve the task of identifying corresponding patches in very-high-resolution (VHR) optical and synthetic aperture radar (SAR) remote sensing imagery. Using eight convolutional layers each in two parallel network streams, a fully connected layer for the fusion of the features learned in each stream, and a loss function based on binary cross-entropy, we achieve a one-hot indication if two patches correspond or not. The network is trained and tested on an automatically generated dataset that is based on a deterministic alignment of SAR and optical imagery via previously reconstructed and subsequently co-registered 3D point clouds. The satellite images, from which the patches comprising our dataset are extracted, show a complex urban scene containing many elevated objects (i.e. buildings), thus providing one of the most difficult experimental environments. The achieved results show that the network is able to predict corresponding patches with high accuracy, thus indicating great potential for further development towards a generalized multi-sensor key-point matching procedure. Index Terms-synthetic aperture radar (SAR), optical imagery, data fusion, deep learning, convolutional neural networks (CNN), image matching, deep matching

Label-free optical biosensors based on aptamer-functionalized porous silicon scaffolds.

PubMed

Urmann, Katharina; Walter, Johanna-Gabriela; Scheper, Thomas; Segal, Ester

2015-02-03

A proof-of-concept for a label-free and reagentless optical biosensing platform based on nanostructured porous silicon (PSi) and aptamers is presented in this work. Aptamers are oligonucleotides (single-stranded DNA or RNA) that can bind their targets with high affinity and specificity, making them excellent recognition elements for biosensor design. Here we describe the fabrication and characterization of aptamer-conjugated PSi biosensors, where a previously characterized his-tag binding aptamer (6H7) is used as model system. Exposure of the aptamer-functionalized PSi to the target proteins as well as to complex fluids (i.e., bacteria lysates containing target proteins) results in robust and well-defined changes in the PSi optical interference spectrum, ascribed to specific aptamer-protein binding events occurring within the nanoscale pores, monitored in real time. The biosensors show exceptional stability and can be easily regenerated by a short rinsing step for multiple biosensing analyses. This proof-of-concept study demonstrates the possibility of designing highly stable and specific label-free optical PSi biosensors, employing aptamers as capture probes, holding immense potential for application in detection of a broad range of targets, in a simple yet reliable manner.

Experimental Evaluation of the "Polished Panel Optical Receiver" Concept on the Deep Space Network's 34 Meter Antenna

NASA Technical Reports Server (NTRS)

Vilnrotter, Victor A.

2012-01-01

The potential development of large aperture ground-based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation proposes to polish the aluminum reflector panels of 34-meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by even state-of-the-art polished aluminum panels. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. A custom designed aluminum panel has been mounted on the 34 meter research antenna at Deep-Space Station 13 (DSS-13), and a remotely controlled CCD camera with a large CCD sensor in a weather-proof container has been installed next to the subreflector, pointed directly at the custom polished panel. Using the planet Jupiter as the optical point-source, the point-spread function (PSF) generated by the polished panel has been characterized, the array data processed to determine the center of the intensity distribution, and expected communications performance of the proposed polished panel optical receiver has been evaluated.

Modeling of optical quadrature microscopy for imaging mouse embryos

NASA Astrophysics Data System (ADS)

Warger, William C., II; DiMarzio, Charles A.

2008-02-01

Optical quadrature microscopy (OQM) has been shown to provide the optical path difference through a mouse embryo, and has led to a novel method to count the total number of cells further into development than current non-toxic imaging techniques used in the clinic. The cell counting method has the potential to provide an additional quantitative viability marker for blastocyst transfer during in vitro fertilization. OQM uses a 633 nm laser within a modified Mach-Zehnder interferometer configuration to measure the amplitude and phase of the signal beam that travels through the embryo. Four cameras preceded by multiple beamsplitters record the four interferograms that are used within a reconstruction algorithm to produce an image of the complex electric field amplitude. Here we present a model for the electric field through the primary optical components in the imaging configuration and the reconstruction algorithm to calculate the signal to noise ratio when imaging mouse embryos. The model includes magnitude and phase errors in the individual reference and sample paths, fixed pattern noise, and noise within the laser and detectors. This analysis provides the foundation for determining the imaging limitations of OQM and the basis to optimize the cell counting method in order to introduce additional quantitative viability markers.

Spin-orbit-coupled fermions in an optical lattice clock

NASA Astrophysics Data System (ADS)

Kolkowitz, S.; Bromley, S. L.; Bothwell, T.; Wall, M. L.; Marti, G. E.; Koller, A. P.; Zhang, X.; Rey, A. M.; Ye, J.

2017-02-01

Engineered spin-orbit coupling (SOC) in cold-atom systems can enable the study of new synthetic materials and complex condensed matter phenomena. However, spontaneous emission in alkali-atom spin-orbit-coupled systems is hindered by heating, limiting the observation of many-body effects and motivating research into potential alternatives. Here we demonstrate that spin-orbit-coupled fermions can be engineered to occur naturally in a one-dimensional optical lattice clock. In contrast to previous SOC experiments, here the SOC is both generated and probed using a direct ultra-narrow optical clock transition between two electronic orbital states in 87Sr atoms. We use clock spectroscopy to prepare lattice band populations, internal electronic states and quasi-momenta, and to produce spin-orbit-coupled dynamics. The exceptionally long lifetime of the excited clock state (160 seconds) eliminates decoherence and atom loss from spontaneous emission at all relevant experimental timescales, allowing subsequent momentum- and spin-resolved in situ probing of the SOC band structure and eigenstates. We use these capabilities to study Bloch oscillations, spin-momentum locking and Van Hove singularities in the transition density of states. Our results lay the groundwork for using fermionic optical lattice clocks to probe new phases of matter.

Local motion compensation in image sequences degraded by atmospheric turbulence: a comparative analysis of optical flow vs. block matching methods

NASA Astrophysics Data System (ADS)

Huebner, Claudia S.

2016-10-01

As a consequence of fluctuations in the index of refraction of the air, atmospheric turbulence causes scintillation, spatial and temporal blurring as well as global and local image motion creating geometric distortions. To mitigate these effects many different methods have been proposed. Global as well as local motion compensation in some form or other constitutes an integral part of many software-based approaches. For the estimation of motion vectors between consecutive frames simple methods like block matching are preferable to more complex algorithms like optical flow, at least when challenged with near real-time requirements. However, the processing power of commercially available computers continues to increase rapidly and the more powerful optical flow methods have the potential to outperform standard block matching methods. Therefore, in this paper three standard optical flow algorithms, namely Horn-Schunck (HS), Lucas-Kanade (LK) and Farnebäck (FB), are tested for their suitability to be employed for local motion compensation as part of a turbulence mitigation system. Their qualitative performance is evaluated and compared with that of three standard block matching methods, namely Exhaustive Search (ES), Adaptive Rood Pattern Search (ARPS) and Correlation based Search (CS).

Action Potential Dynamics in Fine Axons Probed with an Axonally Targeted Optical Voltage Sensor.

PubMed

Ma, Yihe; Bayguinov, Peter O; Jackson, Meyer B

2017-01-01

The complex and malleable conduction properties of axons determine how action potentials propagate through extensive axonal arbors to reach synaptic terminals. The excitability of axonal membranes plays a major role in neural circuit function, but because most axons are too thin for conventional electrical recording, their properties remain largely unexplored. To overcome this obstacle, we used a genetically encoded hybrid voltage sensor (hVOS) harboring an axonal targeting motif. Expressing this probe in transgenic mice enabled us to monitor voltage changes optically in two populations of axons in hippocampal slices, the large axons of dentate granule cells (mossy fibers) in the stratum lucidum of the CA3 region and the much finer axons of hilar mossy cells in the inner molecular layer of the dentate gyrus. Action potentials propagated with distinct velocities in each type of axon. Repetitive firing broadened action potentials in both populations, but at an intermediate frequency the degree of broadening differed. Repetitive firing also attenuated action potential amplitudes in both mossy cell and granule cell axons. These results indicate that the features of use-dependent action potential broadening, and possible failure, observed previously in large nerve terminals also appear in much finer unmyelinated axons. Subtle differences in the frequency dependences could influence the propagation of activity through different pathways to excite different populations of neurons. The axonally targeted hVOS probe used here opens up the diverse repertoire of neuronal processes to detailed biophysical study.

Nonlinear network model analysis of vibrational energy transfer and localisation in the Fenna-Matthews-Olson complex

NASA Astrophysics Data System (ADS)

Morgan, Sarah E.; Cole, Daniel J.; Chin, Alex W.

2016-11-01

Collective protein modes are expected to be important for facilitating energy transfer in the Fenna-Matthews-Olson (FMO) complex of photosynthetic green sulphur bacteria, however to date little work has focussed on the microscopic details of these vibrations. The nonlinear network model (NNM) provides a computationally inexpensive approach to studying vibrational modes at the microscopic level in large protein structures, whilst incorporating anharmonicity in the inter-residue interactions which can influence protein dynamics. We apply the NNM to the entire trimeric FMO complex and find evidence for the existence of nonlinear discrete breather modes. These modes tend to transfer energy to the highly connected core pigments, potentially opening up alternative excitation energy transfer routes through their influence on pigment properties. Incorporating localised modes based on these discrete breathers in the optical spectra calculations for FMO using ab initio site energies and excitonic couplings can substantially improve their agreement with experimental results.

Real-time optical correlator using computer-generated holographic filter on a liquid crystal light valve

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin; Yu, Jeffrey

1990-01-01

Limitations associated with the binary phase-only filter often used in optical correlators are presently circumvented in the writing of complex-valued data on a gray-scale spatial light modulator through the use of a computer-generated hologram (CGH) algorithm. The CGH encodes complex-valued data into nonnegative real CGH data in such a way that it may be encoded in any of the available gray-scale spatial light modulators. A CdS liquid-crystal light valve is used for the complex-valued CGH encoding; computer simulations and experimental results are compared, and the use of such a CGH filter as the synapse hologram in a holographic optical neural net is discussed.

Mechanistic insights into energy conservation by flavin-based electron bifurcation

DOE PAGES

Lubner, Carolyn E.; Jennings, David P.; Mulder, David W.; ...

2017-04-10

The recently realized biochemical phenomenon of energy conservation through electron bifurcation provides biology with an elegant means to maximize utilization of metabolic energy. The mechanism of coordinated coupling of exergonic and endergonic oxidation-reduction reactions by a single enzyme complex has been elucidated through optical and paramagnetic spectroscopic studies revealing unprecedented features. Pairs of electrons are bifurcated over more than 1 volt of electrochemical potential by generating a low-potential, highly energetic, unstable flavin semiquinone and directing electron flow to an iron-sulfur cluster with a highly negative potential to overcome the barrier of the endergonic half reaction. As a result, the unprecedentedmore » range of thermodynamic driving force that is generated by flavin-based electron bifurcation accounts for unique chemical reactions that are catalyzed by these enzymes.« less

Mechanistic insights into energy conservation by flavin-based electron bifurcation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lubner, Carolyn E.; Jennings, David P.; Mulder, David W.

The recently realized biochemical phenomenon of energy conservation through electron bifurcation provides biology with an elegant means to maximize utilization of metabolic energy. The mechanism of coordinated coupling of exergonic and endergonic oxidation-reduction reactions by a single enzyme complex has been elucidated through optical and paramagnetic spectroscopic studies revealing unprecedented features. Pairs of electrons are bifurcated over more than 1 volt of electrochemical potential by generating a low-potential, highly energetic, unstable flavin semiquinone and directing electron flow to an iron-sulfur cluster with a highly negative potential to overcome the barrier of the endergonic half reaction. As a result, the unprecedentedmore » range of thermodynamic driving force that is generated by flavin-based electron bifurcation accounts for unique chemical reactions that are catalyzed by these enzymes.« less

Two-harmonic complex spectral-domain optical coherence tomography using achromatic sinusoidal phase modulation

NASA Astrophysics Data System (ADS)

Lu, Sheng-Hua; Huang, Siang-Ru; Chou, Che-Chung

2018-03-01

We resolve the complex conjugate ambiguity in spectral-domain optical coherence tomography (SD-OCT) by using achromatic two-harmonic method. Unlike previous researches, the optical phase of the fiber interferometer is modulated by an achromatic phase shifter based on an optical delay line. The achromatic phase modulation leads to a wavelength-independent scaling coefficient for the two harmonics. Dividing the mean absolute value of the first harmonic by that of the second harmonic in a B-scan interferogram directly gives the scaling coefficient. It greatly simplifies the determination of the magnitude ratio between the two harmonics without the need of third harmonic and cumbersome iterative calculations. The inverse fast Fourier transform of the complex-valued interferogram constructed with the scaling coefficient, first and second harmonics yields a full-range OCT image. Experimental results confirm the effectiveness of the proposed achromatic two-harmonic technique for suppressing the mirror artifacts in SD-OCT images.

Effects of Doping Ratio of Cobalt and Iron on the Structure and Optical Properties of Bi3.25La0.75Fe(x)Co(1-x)Ti2O12 (X = 0, 0.25, 0.5, 0.75, 1).

PubMed

Song, Myoung Geun; Han, Jun Young; Bark, Chung Wung

2015-10-01

The wide band gap of complex oxides is one of the major obstacles limiting their use in photovoltaic cells. To identify an effective route for tailoring the band gap of complex oxides, this study examined the effects of cobalt and iron doping on lanthanum-modified Bi4Ti3O2-based oxides synthesized using a solid reaction. The structural and optical properties were analyzed by X-ray diffraction and ultraviolet-visible absorption spectroscopy. As a result, the optimal iron to cobalt doping ratio in bismuth titanate powder resulted in an ~1.8 eV decrease in the optical band gap. This new route to reduce the optical bandgap can be adapted to the synthesis of other complex oxides.

All-fibre optical gating system for measuring a complex-shaped periodic broadband signal with picosecond resolution in a nanosecond time window

NASA Astrophysics Data System (ADS)

Andrianov, A. V.

2018-04-01

We have developed an optical gating system for continuously monitoring a complex-shaped periodic optical signal with picosecond resolution in a nanosecond time window using an all-fibre optical gate in the form of a nonlinear loop mirror and a passively mode-locked femtosecond laser. The distinctive features of the system are the possibility of characterizing signals with a very large spectral bandwidth, the possibility of using a gating pulse source with a wavelength falling in the band of the signal under study and its all-fibre design with the use of standard fibres and telecom components.

Application of Peterson's stray light model to complex optical instruments

NASA Astrophysics Data System (ADS)

Fray, S.; Goepel, M.; Kroneberger, M.

2016-07-01

Gary L. Peterson (Breault Research Organization) presented a simple analytical model for in- field stray light evaluation of axial optical systems. We exploited this idea for more complex optical instruments of the Meteosat Third Generation (MTG) mission. For the Flexible Combined Imager (FCI) we evaluated the in-field stray light of its three-mirroranastigmat telescope, while for the Infrared Sounder (IRS) we performed an end-to-end analysis including the front telescope, interferometer and back telescope assembly and the cold optics. A comparison to simulations will be presented. The authors acknowledge the support by ESA and Thales Alenia Space through the MTG satellites program.

Annular beam shaping system for advanced 3D laser brazing

NASA Astrophysics Data System (ADS)

Pütsch, Oliver; Stollenwerk, Jochen; Kogel-Hollacher, Markus; Traub, Martin

2012-10-01

As laser brazing benefits from advantages such as smooth joints and small heat-affected zones, it has become established as a joining technology that is widely used in the automotive industry. With the processing of complex-shaped geometries, recent developed brazing heads suffer, however, from the need for continuous reorientation of the optical system and/or limited accessibility due to lateral wire feeding. This motivates the development of a laser brazing head with coaxial wire feeding and enhanced functionality. An optical system is designed that allows to generate an annular intensity distribution in the working zone. The utilization of complex optical components avoids obscuration of the optical path by the wire feeding. The new design overcomes the disadvantages of the state-of-the-art brazing heads with lateral wire feeding and benefits from the independence of direction while processing complex geometries. To increase the robustness of the brazing process, the beam path also includes a seam tracking system, leading to a more challenging design of the whole optical train. This paper mainly discusses the concept and the optical design of the coaxial brazing head, and also presents the results obtained with a prototype and selected application results.

Imaging Voltage in Genetically Defined Neuronal Subpopulations with a Cre Recombinase-Targeted Hybrid Voltage Sensor.

PubMed

Bayguinov, Peter O; Ma, Yihe; Gao, Yu; Zhao, Xinyu; Jackson, Meyer B

2017-09-20

Genetically encoded voltage indicators create an opportunity to monitor electrical activity in defined sets of neurons as they participate in the complex patterns of coordinated electrical activity that underlie nervous system function. Taking full advantage of genetically encoded voltage indicators requires a generalized strategy for targeting the probe to genetically defined populations of cells. To this end, we have generated a mouse line with an optimized hybrid voltage sensor (hVOS) probe within a locus designed for efficient Cre recombinase-dependent expression. Crossing this mouse with Cre drivers generated double transgenics expressing hVOS probe in GABAergic, parvalbumin, and calretinin interneurons, as well as hilar mossy cells, new adult-born neurons, and recently active neurons. In each case, imaging in brain slices from male or female animals revealed electrically evoked optical signals from multiple individual neurons in single trials. These imaging experiments revealed action potentials, dynamic aspects of dendritic integration, and trial-to-trial fluctuations in response latency. The rapid time response of hVOS imaging revealed action potentials with high temporal fidelity, and enabled accurate measurements of spike half-widths characteristic of each cell type. Simultaneous recording of rapid voltage changes in multiple neurons with a common genetic signature offers a powerful approach to the study of neural circuit function and the investigation of how neural networks encode, process, and store information. SIGNIFICANCE STATEMENT Genetically encoded voltage indicators hold great promise in the study of neural circuitry, but realizing their full potential depends on targeting the sensor to distinct cell types. Here we present a new mouse line that expresses a hybrid optical voltage sensor under the control of Cre recombinase. Crossing this line with Cre drivers generated double-transgenic mice, which express this sensor in targeted cell types. In brain slices from these animals, single-trial hybrid optical voltage sensor recordings revealed voltage changes with submillisecond resolution in multiple neurons simultaneously. This imaging tool will allow for the study of the emergent properties of neural circuits and permit experimental tests of the roles of specific types of neurons in complex circuit activity. Copyright © 2017 the authors 0270-6474/17/379305-15$15.00/0.

Complex approach to the investigation of short fiber-optic comunication lines

NASA Astrophysics Data System (ADS)

Sukhoivanov, I. A.; Kontar', A. A.; Kublik, A. V.; Makarevich, V. S.

The paper proposes a method of complex measurements based on the consideration of the parameters of all the elements used in a specific multimode fiber-optic communication line. It is shown that the error in measuring losses in waveguides up to 20 m long can reach a value of 60 percent.

Birefringence measurement in complex optical systems

NASA Astrophysics Data System (ADS)

Knell, Holger; Heuck, Hans-Martin

2017-06-01

State of the art optical systems become more complex. There are more lenses required in the optical design and optical coatings have more layers. These complex designs are prone to induce more thermal stress into the optical system which causes birefringence. In addition, there is a certain degree of freedom required to meet optical specifications during the assembly process. The mechanical fixation of these degrees of freedom can also lead to mechanical stress in the optical system and therefore to birefringence. To be able to distinguish those two types of stress a method to image the birefringence in the optical system is required. In the proposed setup light is polarized by a circular polarization filter and then is transmitted through a rotatable linear retarder and the tested optical system. The light then is reflected on the same path by a mirror. After the light passes the circular polarization filter on the way back, the intensity is recorded. When the rotatable retarder is rotated, the recorded intensity is modulated depending on the birefringence of the tested optical system. This modulation can be analyzed in Fourier domain and the linear retardance angle between the slow and the fast axis as well as the angle of the fast axis can be calculated. The retardance distribution over the pupil of the optical system then can be analyzed using Zernike decomposition. From the Zernike decomposition, the origin of the birefringence can be identified. Since it is required to quantify small amounts of retardance well below 10nm, the birefringence of the measurement system must be characterized before the measurement and considered in the calculation of the resulting birefringence. Temperature change of the measurement system still can produce measurement artifacts in the calculated result, which must also be compensated for.

PROBLEMS OF THE OPTICAL MODEL FOR DEUTERONS. I. PARAMETERS OF THE OPTICAL POTENTIAL (in Polish)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grotowski, K.

1963-01-01

S>Problems concerning the optical model are discussed. Some special properties of deuterons as projectiles influence the optical model describing their interaction with nuclei. Several experiments were performed to obtain parameters of the optical model potential. (auth)

3D-printed optical active components

NASA Astrophysics Data System (ADS)

Suresh Nair, S.; Nuding, J.; Heinrich, A.

2018-02-01

Additive Manufacturing (AM) has the potential to become a powerful tool in the realization of complex optical components. The primary advantage that meets the eye, is that fabrication of geometrically complicated optical structures is made easier in AM as compared to the conventional fabrication methods (using molds for instance). But this is not the only degree of freedom that AM has to offer. With the multitude of materials suitable for AM in the market, it is possible to introduce functionality into the components one step before fabrication: by altering the raw material. A passive example would be to use materials with varying properties together, in a single manufacturing step, constructing samples with localized refractive indices for instance. An active approach is to blend in materials with distinct properties into the photopolymer resin and manufacturing with this composite material. Our research is currently focused in this direction, with the desired optical property to be introduced being Photoluminescence. Formation of nanocomposite mixtures to produce samples is the current approach. With this endeavor, new sensor systems can be realized, which may be used to measure the absorption spectra of biological samples. Thereby the sample compartment, the optics and the spectral light source (different quantum dots) are 3D-printed in one run. This component can be individually adapted to the biological sample with respect to wavelength, optical and mechanical properties. Here we would like to present our work on the additive manufacturing of an active optical component. Based on the stereolithography method, a monolithic optical component was 3D-printed, showing light emission at different defined wavelengths due to UV excited quantum dots inside the 3D-printed optics.

Robust optical wireless links over turbulent media using diversity solutions

NASA Astrophysics Data System (ADS)

Moradi, Hassan

Free-space optic (FSO) technology, i.e., optical wireless communication (OWC), is widely recognized as superior to radio frequency (RF) in many aspects. Visible and invisible optical wireless links solve first/last mile connectivity problems and provide secure, jam-free communication. FSO is license-free and delivers high-speed data rates in the order of Gigabits. Its advantages have fostered significant research efforts aimed at utilizing optical wireless communication, e.g. visible light communication (VLC), for high-speed, secure, indoor communication under the IEEE 802.15.7 standard. However, conventional optical wireless links demand precise optical alignment and suffer from atmospheric turbulence. When compared with RF, they suffer a low degree of reliability and lack robustness. Pointing errors cause optical transceiver misalignment, adversely affecting system reliability. Furthermore, atmospheric turbulence causes irradiance fluctuations and beam broadening of transmitted light. Innovative solutions to overcome limitations on the exploitation of high-speed optical wireless links are greatly needed. Spatial diversity is known to improve RF wireless communication systems. Similar diversity approaches can be adapted for FSO systems to improve its reliability and robustness; however, careful diversity design is needed since FSO apertures typically remain unbalanced as a result of FSO system sensitivity to misalignment. Conventional diversity combining schemes require persistent aperture monitoring and repetitive switching, thus increasing FSO implementation complexities. Furthermore, current RF diversity combining schemes may not be optimized to address the issue of unbalanced FSO receiving apertures. This dissertation investigates two efficient diversity combining schemes for multi-receiving FSO systems: switched diversity combining and generalized selection combining. Both can be exploited to reduce complexity and improve combining efficiency. Unlike maximum ratio combing, equal gain combining, and selective combining, switched diversity simplifies receiver design by avoiding unnecessary switching among receiving apertures. The most significant advantage of generalized combining is its ability to exclude apertures with low quality that could potentially affect the resultant output signal performance. This dissertation also investigates mobile FSO by considering a multi-receiving system in which all receiving FSO apertures are circularly placed on a platform. System mobility and performance are analyzed. Performance results confirm improvements when using angular diversity and generalized selection combining. The precis of this dissertation establishes the foundation of reliable FSO communications using efficient diversity-based solutions. Performance parameters are analyzed mathematically, and then evaluated using computer simulations. A testbed prototype is developed to facilitate the evaluation of optical wireless links via lab experiments.

A study of a self diagnostic platform for the detection of A2 biomarker for Leishmania donovani

NASA Astrophysics Data System (ADS)

Roche, Philip J. R.; Cheung, Maurice C.; Najih, Mohamed; McCall, Laura-Isobel; Fakih, Ibrahim; Chodavarapu, Vamsy P.; Ward, Brian; Ndao, Momar; Kirk, Andrew G.

2012-03-01

Visceral leishmaniasis (L.donovani) is a protozoan infection that attacks mononuclear phagocytes and causes the liver and spleen damage that can cause death. The investigation presented is a proof of concept development applying a plasmonic diagnostic platform with simple microfluidic sample delivery and optical readout. An immune-assay method is applied to the quantification of A2 protein, a highly immunogenic biomarker for the pathogen. Quantification of A2 was performed in the ng/ml range, analysis by ELISA suggested that a limit of 0.1ng/ml of A2 is approximate to 1 pathogen per ml and the sensing system shows the potential to deliver a similar level of quantification. Significant reduction in assay complexity as further enzyme linked enhancement is not required when applying a plasmonic methodology to an immunoassay. The basic instrumentation required for a portable device and potential dual optical readout where both plasmonic and photoluminescent response are assessed and investigated including consideration of the application of the device to testing where non-literate communication of results is considered and issues of performance are addressed.

Disentangling the major source areas for an intense aerosol advection in the Central Mediterranean on the basis of Potential Source Contribution Function modeling of chemical and size distribution measurements

NASA Astrophysics Data System (ADS)

Petroselli, Chiara; Crocchianti, Stefano; Moroni, Beatrice; Castellini, Silvia; Selvaggi, Roberta; Nava, Silvia; Calzolai, Giulia; Lucarelli, Franco; Cappelletti, David

2018-05-01

In this paper, we combined a Potential Source Contribution Function (PSCF) analysis of daily chemical aerosol composition data with hourly aerosol size distributions with the aim to disentangle the major source areas during a complex and fast modulating advection event impacting on Central Italy in 2013. Chemical data include an ample set of metals obtained by Proton Induced X-ray Emission (PIXE), main soluble ions from ionic chromatography and elemental and organic carbon (EC, OC) obtained by thermo-optical measurements. Size distributions have been recorded with an optical particle counter for eight calibrated size classes in the 0.27-10 μm range. We demonstrated the usefulness of the approach by the positive identification of two very different source areas impacting during the transport event. In particular, biomass burning from Eastern Europe and desert dust from Sahara sources have been discriminated based on both chemistry and size distribution time evolution. Hourly BT provided the best results in comparison to 6 h or 24 h based calculations.

Advancing the Theory of Nuclear Reactions with Rare Isotopes: From the Laboratory to the Cosmos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elster, Charlotte

2015-06-01

The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. Ohio University concentrates its efforts on the first part of the mission. Since direct measurements are often not feasible, indirect methods, e.g. (d,p) reactions, should be used. Those (d,p) reactions may be viewed as three-body reactions and described with Faddeev techniques. Faddeev equations in momentum space have a long tradition of utilizing separable interactions in ordermore » to arrive at sets of coupled integral equations in one variable. While there exist several separable representations for the nucleon-nucleon interaction, the optical potential between a neutron (proton) and a nucleus is not readily available in separable form. For this reason we first embarked in introducing a separable representation for complex phenomenological optical potentials of Woods-Saxon type.« less

Upgrade of optical WDM transport systems introducing linerates at 40 Gbit/s per channel

NASA Astrophysics Data System (ADS)

Schneiders, Malte; Vorbeck, Sascha; Aust, Nora

2006-10-01

Driven by high growth rates of internet traffic the question of upgrading existing optical metro-, regio- and long haul transport networks introducing 40 Gbit/s/λ is one of the most important questions today and in the near future. Current WDM Systems in photonic networks are commonly operated at linerates of 2.5 and 10 Gbit/s/λ. Induced by market analyses and the historical development of transport systems some work has already been carried out to evaluate update scenarios from 10 to 40 Gbit/s channel data rates. Due to the inherent quadruplication of the bandwidth per channel, limitations due to linear and non-linear transmission impairments become stronger resulting in a highly increased complexity of link engineering, potentially increasing the capital and operational expenditures. A lot of work is therefore in progress, which targets at the relaxation of constraints for 40 Gbit/s transmission to find the most efficient upgrade strategies. One approach towards an increased robustness against signal distortions is the introduction of more advanced modulation formats. Different modulation schemes show strongly different optical WDM transmission characteristics. The choice of the appropriate format does not only depend on the technical requirements, but also on economical considerations as an increased transmitter- and receiver-complexity will drive the transponder price. This article presents investigations on different modulation formats for the upgrade of existing metro-/ regio and long haul transport networks. Tolerances and robustness against the main degrading effects dispersion, noise and nonlinearities are considered together with mitigation strategies like the adaptation of dispersion maps. Results from numerical simulations are provided for some of the most promising modulation formats like NRZ, RZ, CS-RZ, Optical Duobinary and DPSK.

Differences in Optic Nerve Head, Retinal Nerve Fiber Layer, and Ganglion Cell Complex Parameters Between Caucasian and Chinese Subjects.

PubMed

Chansangpetch, Sunee; Huang, Guofu; Coh, Paul; Oldenburg, Catherine; Amoozgar, Behzad; He, Mingguang; Lin, Shan C

2018-04-01

To compare optic nerve head, peripapillary retinal nerve fiber layer (pRNFL), and ganglion cell complex (GCC) parameters between Caucasian and ethnic Chinese. Normal subjects above 40 years old and self-identified as being Caucasian and Chinese were recruited. They were evaluated with spectral-domain optical coherence tomography (RTVue-100). Parameters related to the optic nerve head, pRNFL, and GCC analysis protocols were acquired. Multivariable linear regression was performed adjusting for potential confounders. Data from 116 Caucasian and 130 Chinese subjects were available for analysis. Mean age of all participants was 66.72 (SD 10.82) years. There were statistically significant differences for disc area (DA), area cup-to-disc, vertical cup-to-disc, and cup volume (P=0.02, 0.004, 0.02, and 0.03, respectively), greater in Chinese. After adjusting for age, sex, axial length (AL), intraocular pressure (IOP), DA, and GCC thickness, Chinese subjects had significantly greater thickness in all pRNFL parameters (mean differences ranged between 4.29 and 9.93 μm; all P<0.001) except the nasal quadrant. GCC outcomes were also adjusted for DA and pRNFL; Caucasians had significantly higher average GCC and inferior GCC (mean difference 2.97 and 3.45 μm, respectively; P<0.01), whereas the Chinese group had significantly higher ganglion cell global loss volume (mean difference 2.47 %, P<0.001). This study suggests there is significantly greater pRNFL thickness in Chinese, which were independent of age, AL, IOP, and DA, and possibly greater GCC in Caucasians after adjustment for age, AL, IOP, DA, and pRNFL thickness.

Lanthanide binding and IgG affinity construct: Potential applications in solution NMR, MRI, and luminescence microscopy

PubMed Central

Barb, Adam W; Ho, Tienhuei Grace; Flanagan-Steet, Heather; Prestegard, James H

2012-01-01

Paramagnetic lanthanide ions when bound to proteins offer great potential for structural investigations that utilize solution nuclear magnetic resonance spectroscopy, magnetic resonance imaging, or optical microscopy. However, many proteins do not have native metal ion binding sites and engineering a chimeric protein to bind an ion while retaining affinity for a protein of interest represents a significant challenge. Here we report the characterization of an immunoglobulin G-binding protein redesigned to include a lanthanide binding motif in place of a loop between two helices (Z-L2LBT). It was shown to bind Tb3+ with 130 nM affinity. Ions such as Dy3+, Yb3+, and Ce3+ produce paramagnetic effects on NMR spectra and the utility of these effects is illustrated by their use in determining a structural model of the metal-complexed Z-L2LBT protein and a preliminary characterization of the dynamic distribution of IgG Fc glycan positions. Furthermore, this designed protein is demonstrated to be a novel IgG-binding reagent for magnetic resonance imaging (Z-L2LBT:Gd3+ complex) and luminescence microscopy (Z-L2LBT: Tb3+ complex). PMID:22851279

Luminescent Dinuclear Ruthenium Terpyridine Complexes with a Bis-Phenylbenzimidazole Spacer.

PubMed

Mondal, Debiprasad; Biswas, Sourav; Paul, Animesh; Baitalik, Sujoy

2017-07-17

A conjugated bis-terpyridine bridging ligand, 2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-6-(2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1H-benzo[d]imidazol-6-yl)-1H-benzo[d] imidazole (tpy-BPhBzimH 2 -tpy), was designed in this work by covalent coupling of 3,3'-diaminobenzidine and two 4'-(p-formylphenyl)-2,2':6',2″-terpyridine units to synthesize a new series of bimetallic Ru(II)-terpyridine light-harvesting complexes. Photophysical and electrochemical properties were modulated by the variation of the terminal ligands in the complexes. The new compounds were thoroughly characterized by 1 H NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. Absorption spectra of the complexes consist of very strong ligand-centered π-π* and n-π* transitions in the UV, metal-to-ligand, and intraligand charge transfer bands in the visible regions. Steady-state and time-resolved emission spectral measurements indicate that the complexes exhibit moderately intense luminescence at room temperature within the spectral domain of 653-687 nm having luminescence lifetimes in the range between 6.3 and 55.2 ns, depending upon terminal tridentate ligand and solvent. Variable-temperature luminescence measurements suggest substantial increase of the energy gap between luminescent 3 metal-to-ligand charge transfer state and nonluminescent 3 metal centered in the complexes compared to the parent [Ru(tpy) 2 ] 2+ . Each of the three bimetallic complexes exhibits only one reversible couple in the positive potential window with almost no detectable splitting corresponding to simultaneous oxidation of the two remote Ru centers. All the complexes possess a number of imidazole NH protons, which became sufficiently acidic upon metal ion coordination. By utilizing these NH protons, we thoroughly studied anion recognition properties of the complexes in pure organic as well as predominantly aqueous media through multiple optical channels and spectroscopic methods. Finally computation investigations employing density functional theory (DFT) and time-dependent DFT were done to examine the electronic structures of the complexes and accurate assignment of experimentally observed optical spectral bands.

Receiver bandwidth effects on complex modulation and detection using directly modulated lasers.

PubMed

Yuan, Feng; Che, Di; Shieh, William

2016-05-01

Directly modulated lasers (DMLs) have long been employed for short- and medium-reach optical communications due to their low cost. Recently, a new modulation scheme called complex modulated DMLs has been demonstrated showing a significant optical signal to noise ratio sensitivity enhancement compared with the traditional intensity-only detection scheme. However, chirp-induced optical spectrum broadening is inevitable in complex modulated systems, which may imply a need for high-bandwidth receivers. In this Letter, we study the impact of receiver bandwidth effects on the performance of complex modulation and coherent detection systems based on DMLs. We experimentally demonstrate that such systems exhibit a reasonable tolerance for the reduced receiver bandwidth. For 10 Gbaud 4-level pulse amplitude modulation signals, the required electrical bandwidth is as low as 8.5 and 7.5 GHz for 7% and 20% forward error correction, respectively. Therefore, it is feasible to realize DML-based complex modulated systems using cost-effective receivers with narrow bandwidth.

Disentanglement in bipartite continuous-variable systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbosa, F. A. S.; Coelho, A. S.; Nussenzveig, P.

2011-11-15

Entanglement in bipartite continuous-variable systems is investigated in the presence of partial losses such as those introduced by a realistic quantum communication channel, e.g., by propagation in an optical fiber. We find that entanglement can vanish completely for partial losses, in a situation reminiscent of so-called entanglement sudden death. Even states with extreme squeezing may become separable after propagation in lossy channels. Having in mind the potential applications of such entangled light beams to optical communications, we investigate the conditions under which entanglement can survive for all partial losses. Different loss scenarios are examined, and we derive criteria to testmore » the robustness of entangled states. These criteria are necessary and sufficient for Gaussian states. Our study provides a framework to investigate the robustness of continuous-variable entanglement in more complex multipartite systems.« less

Measuring the complex optical conductivity of graphene by Fabry-Pérot reflectance spectroscopy [Determination of the optical index for few-layer graphene by reflectivity spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghamsari, Behnood G.; Tosado, Jacob; Yamamoto, Mahito

Here, we have experimentally studied the optical refractive index of few-layer graphene through reflection spectroscopy at visible wavelengths. A laser scanning microscope (LSM) with a coherent supercontinuum laser source measured the reflectivity of an exfoliated graphene flake on a Si/SiO 2 substrate, containing monolayer, bilayer and trilayer areas, as the wavelength of the laser was varied from 545nm to 710nm. The complex refractive index of few-layer graphene, n-ik, was extracted from the reflectivity contrast to the bare substrate and the Fresnel reflection theory. Since the SiO 2 thickness enters to the modeling as a parameter, it was precisely measured atmore » the location of the sample. It was found that a common constant optical index cannot explain the wavelength-dependent reflectivity data for single-, double- and three-layer graphene simultaneously, but rather each individual few-layer graphene possesses a unique optical index whose complex values were precisely and accurately determined from the experimental data.« less

Measuring the complex optical conductivity of graphene by Fabry-Pérot reflectance spectroscopy [Determination of the optical index for few-layer graphene by reflectivity spectroscopy

DOE PAGES

Ghamsari, Behnood G.; Tosado, Jacob; Yamamoto, Mahito; ...

2016-09-29

Here, we have experimentally studied the optical refractive index of few-layer graphene through reflection spectroscopy at visible wavelengths. A laser scanning microscope (LSM) with a coherent supercontinuum laser source measured the reflectivity of an exfoliated graphene flake on a Si/SiO 2 substrate, containing monolayer, bilayer and trilayer areas, as the wavelength of the laser was varied from 545nm to 710nm. The complex refractive index of few-layer graphene, n-ik, was extracted from the reflectivity contrast to the bare substrate and the Fresnel reflection theory. Since the SiO 2 thickness enters to the modeling as a parameter, it was precisely measured atmore » the location of the sample. It was found that a common constant optical index cannot explain the wavelength-dependent reflectivity data for single-, double- and three-layer graphene simultaneously, but rather each individual few-layer graphene possesses a unique optical index whose complex values were precisely and accurately determined from the experimental data.« less

Education kits for fiber optics, optoelectronics, and optical communications

NASA Astrophysics Data System (ADS)

Hájek, Martin; Švrček, Miroslav

2007-04-01

Our company MIKROKOM, s.r.o. is engaged for many years in development of education equipment and kits for fiber optics, optoelectronics and optical communications. We would like to inform competitors of conference about results of this long-time development. Requirements on education kits and equipment in a modern and dynamic area as is optical communications and fiber optics are quite difficult. The education kits should to clearly introduce students to given issue - the most important physical principles and technical approaches, but it should to introduce also to new and modern technologies, which are quickly changing and developing. On the other hand should be these tools and kits reasonable for the schools. In our paper we would like to describe possible ways of development of this education kits and equipment and present our results of long-time work, which covers very wide range. On the one hand we developed equipment and kits for clear demonstration of physical effects using plastic optical fibers POF, next we prepare kits with a glass fibers, which are the most used fibers in practice and after as much as the kits, which covers broad range of passive and active elements of the optical networks and systems and which makes possible to create complex optical transmission connection. This kind of systems with using corresponding tools and equipment introduce the students to properties, manipulation, measurement and usage of optical fibers, traces and many active and passive components. Furthermore, with using different sorts of optical sources, photodetectors, fiber optics couplers etc., students can get acquainted with all optoelectronics transmission system, which uses different sorts of signals. Special part will be devoted also to effort mentioned before - to implement modern technologies such as e.g. Wavelength Division Multiplex (WDM) into the education kits. Our presentation will inform auditors about development of mentioned education kits and equipment and about their potentials and practical utility at school education.

Meta-q-plate for complex beam shaping

PubMed Central

Ji, Wei; Lee, Chun-Hong; Chen, Peng; Hu, Wei; Ming, Yang; Zhang, Lijian; Lin, Tsung-Hsien; Chigrinov, Vladimir; Lu, Yan-Qing

2016-01-01

Optical beam shaping plays a key role in optics and photonics. In this work, meta-q-plate featured by arbitrarily space-variant optical axes is proposed and demonstrated via liquid crystal photoalignment based on a polarization-sensitive alignment agent and a dynamic micro-lithography system. Meta-q-plates with multiple-, azimuthally/radially variant topological charges and initial azimuthal angles are fabricated. Accordingly, complex beams with elliptical, asymmetrical, multi-ringed and hurricane transverse profiles are generated, making the manipulation of optical vortex up to an unprecedented flexibility. The evolution, handedness and Michelson interferogram of the hurricane one are theoretically analysed and experimentally verified. The design facilitates the manipulation of polarization and spatial degrees of freedom of light in a point-to-point manner. The realization of meta-q-plate drastically enhances the capability of beam shaping and may pave a bright way towards optical manipulations, OAM based informatics, quantum optics and other fields. PMID:27149897

Geometrically complex 3D-printed phantoms for diffuse optical imaging.

PubMed

Dempsey, Laura A; Persad, Melissa; Powell, Samuel; Chitnis, Danial; Hebden, Jeremy C

2017-03-01

Tissue-equivalent phantoms that mimic the optical properties of human and animal tissues are commonly used in diffuse optical imaging research to characterize instrumentation or evaluate an image reconstruction method. Although many recipes have been produced for generating solid phantoms with specified absorption and transport scattering coefficients at visible and near-infrared wavelengths, the construction methods are generally time-consuming and are unable to create complex geometries. We present a method of generating phantoms using a standard 3D printer. A simple recipe was devised which enables printed phantoms to be produced with precisely known optical properties. To illustrate the capability of the method, we describe the creation of an anatomically accurate, tissue-equivalent premature infant head optical phantom with a hollow brain space based on MRI atlas data. A diffuse optical image of the phantom is acquired when a high contrast target is inserted into the hollow space filled with an aqueous scattering solution.

Encoding Schemes For A Digital Optical Multiplier Using The Modified Signed-Digit Number Representation

NASA Astrophysics Data System (ADS)

Lasher, Mark E.; Henderson, Thomas B.; Drake, Barry L.; Bocker, Richard P.

1986-09-01

The modified signed-digit (MSD) number representation offers full parallel, carry-free addition. A MSD adder has been described by the authors. This paper describes how the adder can be used in a tree structure to implement an optical multiply algorithm. Three different optical schemes, involving position, polarization, and intensity encoding, are proposed for realizing the trinary logic system. When configured in the generic multiplier architecture, these schemes yield the combinatorial logic necessary to carry out the multiplication algorithm. The optical systems are essentially three dimensional arrangements composed of modular units. Of course, this modularity is important for design considerations, while the parallelism and noninterfering communication channels of optical systems are important from the standpoint of reduced complexity. The authors have also designed electronic hardware to demonstrate and model the combinatorial logic required to carry out the algorithm. The electronic and proposed optical systems will be compared in terms of complexity and speed.

Geometrically complex 3D-printed phantoms for diffuse optical imaging

PubMed Central

Dempsey, Laura A.; Persad, Melissa; Powell, Samuel; Chitnis, Danial; Hebden, Jeremy C.

2017-01-01

Tissue-equivalent phantoms that mimic the optical properties of human and animal tissues are commonly used in diffuse optical imaging research to characterize instrumentation or evaluate an image reconstruction method. Although many recipes have been produced for generating solid phantoms with specified absorption and transport scattering coefficients at visible and near-infrared wavelengths, the construction methods are generally time-consuming and are unable to create complex geometries. We present a method of generating phantoms using a standard 3D printer. A simple recipe was devised which enables printed phantoms to be produced with precisely known optical properties. To illustrate the capability of the method, we describe the creation of an anatomically accurate, tissue-equivalent premature infant head optical phantom with a hollow brain space based on MRI atlas data. A diffuse optical image of the phantom is acquired when a high contrast target is inserted into the hollow space filled with an aqueous scattering solution. PMID:28663863

Meta-q-plate for complex beam shaping.

PubMed

Ji, Wei; Lee, Chun-Hong; Chen, Peng; Hu, Wei; Ming, Yang; Zhang, Lijian; Lin, Tsung-Hsien; Chigrinov, Vladimir; Lu, Yan-Qing

2016-05-06

Optical beam shaping plays a key role in optics and photonics. In this work, meta-q-plate featured by arbitrarily space-variant optical axes is proposed and demonstrated via liquid crystal photoalignment based on a polarization-sensitive alignment agent and a dynamic micro-lithography system. Meta-q-plates with multiple-, azimuthally/radially variant topological charges and initial azimuthal angles are fabricated. Accordingly, complex beams with elliptical, asymmetrical, multi-ringed and hurricane transverse profiles are generated, making the manipulation of optical vortex up to an unprecedented flexibility. The evolution, handedness and Michelson interferogram of the hurricane one are theoretically analysed and experimentally verified. The design facilitates the manipulation of polarization and spatial degrees of freedom of light in a point-to-point manner. The realization of meta-q-plate drastically enhances the capability of beam shaping and may pave a bright way towards optical manipulations, OAM based informatics, quantum optics and other fields.

Multislice does it all—calculating the performance of nanofocusing X-ray optics

DOE PAGES

Li, Kenan; Wojcik, Michael; Jacobsen, Chris

2017-01-23

Here, we describe an approach to calculating the optical performance of a wide range of nanofocusing X-ray optics using multislice scalar wave propagation with a complex X-ray refractive index. This approach produces results indistinguishable from methods such as coupled wave theory, and it allows one to reproduce other X-ray optical phenomena such as grazing incidence reflectivity where the direction of energy flow is changed significantly. Just as finite element analysis methods allow engineers to compute the thermal and mechanical responses of arbitrary structures too complex to model by analytical approaches, multislice propagation can be used to understand the properties ofmore » the real-world optics of finite extent and with local imperfections, allowing one to better understand the limits to nanoscale X-ray imaging.« less

Development of the local magnification method for quantitative evaluation of endoscope geometric distortion

NASA Astrophysics Data System (ADS)

Wang, Quanzeng; Cheng, Wei-Chung; Suresh, Nitin; Hua, Hong

2016-05-01

With improved diagnostic capabilities and complex optical designs, endoscopic technologies are advancing. As one of the several important optical performance characteristics, geometric distortion can negatively affect size estimation and feature identification related diagnosis. Therefore, a quantitative and simple distortion evaluation method is imperative for both the endoscopic industry and the medical device regulatory agent. However, no such method is available yet. While the image correction techniques are rather mature, they heavily depend on computational power to process multidimensional image data based on complex mathematical model, i.e., difficult to understand. Some commonly used distortion evaluation methods, such as the picture height distortion (DPH) or radial distortion (DRAD), are either too simple to accurately describe the distortion or subject to the error of deriving a reference image. We developed the basic local magnification (ML) method to evaluate endoscope distortion. Based on the method, we also developed ways to calculate DPH and DRAD. The method overcomes the aforementioned limitations, has clear physical meaning in the whole field of view, and can facilitate lesion size estimation during diagnosis. Most importantly, the method can facilitate endoscopic technology to market and potentially be adopted in an international endoscope standard.

Atomic scale origins of sub-band gap optical absorption in gold-hyperdoped silicon

NASA Astrophysics Data System (ADS)

Ferdous, Naheed; Ertekin, Elif

2018-05-01

Gold hyperdoped silicon exhibits room temperature sub band gap optical absorption, with potential applications as infrared absorbers/detectors and impurity band photovoltaics. We use first-principles density functional theory to establish the origins of the sub band gap response. Substitutional gold AuSi and substitutional dimers AuSi - AuSi are found to be the energetically preferred defect configurations, and AuSi gives rise to partially filled mid-gap defect bands well offset from the band edges. AuSi is predicted to offer substantial sub-band gap absorption, exceeding that measured in prior experiments by two orders of magnitude for similar Au concentration. This suggests that in experimentally realized systems, in addition to AuSi, the implanted gold is accommodated by the lattice in other ways, including other defect complexes and gold precipitates. We further identify that it is energetically favorable for isolated AuSi to form AuSi - AuSi, which by contrast do not exhibit mid-gap states. The formation of dimers and other complexes could serve as nuclei in the earliest stages of Au precipitation, which may be responsible for the observed rapid deactivation of sub-band gap response upon annealing.

Optical scanning tests of complex CMOS microcircuits

NASA Technical Reports Server (NTRS)

Levy, M. E.; Erickson, J. J.

1977-01-01

The new test method was based on the use of a raster-scanned optical stimulus in combination with special electrical test procedures. The raster-scanned optical stimulus was provided by an optical spot scanner, an instrument that combines a scanning optical microscope with electronic instrumentation to process and display the electric photoresponse signal induced in a device that is being tested.

Dielectric response of crystalline tris(acetylacetonato)cobalt(III) films grown on Si substrate for low- k dielectric applications

NASA Astrophysics Data System (ADS)

Dakhel, A. A.; Ali-Mohamed, A. Y.

2008-01-01

Thin films of the complex tris(acetylacetonato)cobalt(III) [abb. Co(acac) 3] were deposited in vacuum on glass and p-Si substrates for optical and dielectric studies. The samples were characterised by X-ray diffraction and fluorescence methods as well as optical absorption spectroscopy. The prepared films show a polycrystalline of monoclinic P2 1/ c structure. The optical absorption spectrum of the prepared film was not exactly fit to that of the molecular one. The energy of the optical absorption onset of the Co(acac) 3 film was calculated by using usual solid-state methods. For electrical measurements on the complex as insulator, samples in the form of metal-insulator-semiconductor (MIS) structure were prepared and characterised by measurement of the capacitance as a function of gate voltage at 1 MHz. The frequency dependence of the complex dielectric constant of the complex was studied in the frequency range (1-1000 kHz) in the temperature range (294-323 K). The experimental results were analysed in the framework of Debye single relaxation model. Generally, the present study shows that a film of complex Co(acac) 3 grown on Si substrate is a promising candidate for low- k dielectric applications, it displays low- k value around 1.7 at high frequencies.

Potential of mid IR spectroscopy in the rapid label free identification of skin malignancies

NASA Astrophysics Data System (ADS)

Kastl, Lena; Kemper, Björn; Lloyd, Gavin R.; Nallala, Jayakrupakar; Stone, Nick; Naranjo, Valery; Penaranda, Francisco; Schnekenburger, Jürgen

2016-03-01

The rapid inspection of suspicious skin lesions for pathological cell types is the objective of optical point of care diagnostics technologies. A marker free fast diagnosis of skin malignancies would overcome the limitations of the current gold standard surgical biopsy. The time consuming and costly biopsy procedure requires the inspection of each sample by a trained pathologist, which limits the analysis of potentially malignant lesions. Optical technologies like RAMAN or infrared spectroscopy, which provide both, localization and chemical information, can be used to differentiate malignant from healthy tissue by the analysis of multi cell structures and cell type specific spectra. We here report the application of midIR spectroscopy towards fast and reliable skin diagnostics. Within the European research project MINERVA we developed standardized in vitro skin systems with increasing complexity, from single skin cell types as fibroblasts, keratinocytes and melanoma cells, to mixtures of these and finally three dimensional human skin equivalents. The standards were characterized in the established midIR range and also with newly developed systems for fast imaging up to 12 μm. The analysis of the spectra by novel data processing algorithms demonstrated the clear separation of all cell types, especially the tumor cells. The signals from single cell layers were sufficient for cell type differentiation. We have compared different midIR systems and found all of them suitable for specific cell type identification. Our data demonstrate the potential of midIR spectroscopy for fast image acquisition and an improved data processing as sensitive and specific optical biopsy technology.

Bioinspired Omnidirectional Self-Stable Reflectors with Multiscale Hierarchical Structures.

PubMed

Han, Zhiwu; Mu, Zhengzhi; Li, Bo; Feng, Xiaoming; Wang, Ze; Zhang, Junqiu; Niu, Shichao; Ren, Luquan

2017-08-30

Structured surfaces, demonstrating various wondrous physicochemical performances, are ubiquitous phenomena in nature. Butterfly wings with impressive structural colors are an interesting example for multiscale hierarchical structures (MHSs). However, most natural structural colors are relatively unstable and highly sensitive to incident angles, which limit their potential practical applications to a certain extent. Here, we reported a bioinspired color reflector with omnidirectional reflective self-stable (ORS) properties, which is inspired by the wing scales of Papilio palinurus butterfly. Through experimental exploration and theoretical analysis, it was found that the vivid colors of such butterfly wings are structure-based and possess novel ORS properties, which attributes to the multiple optical actions between light and the complex structures coupling the inverse opal-like structures (IOSs) and stacked lamellar ridges (SLRs). On the basis of this, we designed and successfully fabricated the SiO 2 -based bioinspired color reflectors (BCRs) through a facile and effective biotemplate method. It was confirmed that the MHSs in biotemplate are inherited by the obtained SiO 2 -based BCRs. More importantly, the SiO 2 -based BCRs also demonstrated the similar ORS properties in a wide wavelength range. We forcefully anticipate that the reported MHS-based ORS performance discovered in butterfly wing scales here could offer new thoughts for scientists to solve unstable reflection issues in particular optical field. The involved biotemplate fabrication method offers a facile and effective strategy for fabricating functional nanomaterials or bioinspired nanodevices with 3D complex nanostructures, such as structured optical devices, displays, and optoelectronic equipment.

Elucidating the Complex Lineshapes Resulting from the Highly Sensitive, Ion Selective, Technique Nice-Ohvms

NASA Astrophysics Data System (ADS)

Hodges, James N.; Siller, Brian; McCall, Benjamin J.

2015-06-01

The technique Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy, or NICE-OHVMS, has been used to great effect to precisely and accurately measure a variety of molecular ion transitions from species such as H_3^+, CH_5^+, HeH^+, and HCO^+, achieving MHz or in some cases sub-MHz uncertainty. It is a powerful technique, but a complete theoretical understanding of the complex NICE-OHVMS lineshape is needed to fully unlock its potential. NICE-OHVMS is the direct result of the combination of the highly sensitive spectroscopic technique Noise Immune Cavity Enhanced Optical Heterodyne Molecular Spectroscopy(NICE-OHMS) with Velocity Modulation Spectroscopy(VMS), applying the most sensitive optical detection method with ion species selectivity. The theoretical underpinnings of NICE-OHMS lineshapes are well established, as are those of VMS. This presentation is the logical extension of those two preceding bodies of work. Simulations of NICE-OHVMS lineshapes under a variety of conditions and fits of experimental data to the model are presented. The significance and accuracy of the various inferred parameters, along with the prospect of using them to extract additional information from observed transitions, are discussed. J.~N. Hodges, et al. J. Chem. Phys. (2013), 139, 164201. A.~J. Perry, et al. J. Chem. Phys. (2014), 141, 101101. K.~N. Crabtree, et al. Chem. Phys. Lett. (2012), 551, 1-6. F.~M. Schmidt, et al. J. Opt. Soc. Amer. A (2008), 24, 1392--1405. J.~W. Farley, J. Chem. Phys. (1991), 95, 5590--5602.

Ultra-short FBG based distributed sensing using shifted optical Gaussian filters and microwave-network analysis.

PubMed

Cheng, Rui; Xia, Li; Sima, Chaotan; Ran, Yanli; Rohollahnejad, Jalal; Zhou, Jiaao; Wen, Yongqiang; Yu, Can

2016-02-08

Ultrashort fiber Bragg gratings (US-FBGs) have significant potential as weak grating sensors for distributed sensing, but the exploitation have been limited by their inherent broad spectra that are undesirable for most traditional wavelength measurements. To address this, we have recently introduced a new interrogation concept using shifted optical Gaussian filters (SOGF) which is well suitable for US-FBG measurements. Here, we apply it to demonstrate, for the first time, an US-FBG-based self-referencing distributed optical sensing technique, with the advantages of adjustable sensitivity and range, high-speed and wide-range (potentially >14000 με) intensity-based detection, and resistance to disturbance by nonuniform parameter distribution. The entire system is essentially based on a microwave network, which incorporates the SOGF with a fiber delay-line between the two arms. Differential detections of the cascaded US-FBGs are performed individually in the network time-domain response which can be obtained by analyzing its complex frequency response. Experimental results are presented and discussed using eight cascaded US-FBGs. A comprehensive numerical analysis is also conducted to assess the system performance, which shows that the use of US-FBGs instead of conventional weak FBGs could significantly improve the power budget and capacity of the distributed sensing system while maintaining the crosstalk level and intensity decay rate, providing a promising route for future sensing applications.

Optical isomer separation of potential analgesic drug candidates by using capillary electrophoresis.

PubMed

Ferrara, G; Santagati, N A; Aturki, Z; Fanali, S

1999-09-01

Using cyclodextrin capillary zone electrophoresis (CD-CZE), baseline separation of synthetic potential analgesic drug diastereoisomer candidates 6,11-dimethyl-1,2,3,4,5,6-hexahydro-3-[(2'-methoxycarbonyl-2'-phenylc yclopropyl)methyl]-2,6-methano-3-benzazocin-8-ol (MPCB) and 6,11-dimethyl-1,2,3,4,5,6-hexahydro-3-[[2'-methoxycarbonyl-2'(4-chloroph enyl)cyclopropyl]methyl]-2,6-methano-3-benzazocin-8-ol (CCB) was achieved. Among the cyclodextrins tested (hydroxypropyl-, carboxymethyl- and sulfobutyl-beta-cyclodextrin (HP-beta-CD, CM-beta-CD and SBE-beta-CD)) SBE-beta-CD was found to be the most effective complexing agent, allowing good optical isomer separation. Resolution was also influenced by the CD concentration, pH of the buffer and presence of organic modifier in the background electrolyte. The optimum experimental conditions for the separation of studied analgesic drugs were found using 25 mM borate buffer at pH 9 containing 40 mM of SBE-beta-CD and 20% v/v of methanol. Using the above-mentioned background electrolyte, it was also possible to separate, in the same run, the enantiomers of normetazocine (NMZ) as well as the optical isomers of (+/-)-cis-2-chloromethyl-1-phenyl cyclopropancarboxylic acid methyl ester (PCE) or (+/-)-cis-2-chloromethyl-1-(4-chlorophenyl)cyclopropancarboxylic acid methyl ester (CPCE) reagents used in the synthesis of the studied analgesic drugs).

Nondestructive sensing technologies using micro-optical elements for applications in the NIR-MIR spectral regions

NASA Astrophysics Data System (ADS)

Otto, Thomas; Saupe, Ray; Bruch, Reinhard F.; Fritzsch, Uwe; Stock, Volker; Gessner, Thomas; Afanasyeva, Natalia I.

2001-11-01

The field of microtechnology is an important industrial and scientific resource for the 21st century. There is a great interest in spectroscopic sensors in the near and middle infrared (NIR-MIR) wavelength regions (1 - 2.5 micrometers ; 2.5 - 4.5 micrometers ; 4 - 6 micrometers ). The potential for cheap and small devices for nondestructive, remote sensing techniques at a molecular level has stimulated the design and development of more compact analyzer systems. Therefore we will try to build analyzers using micro optical components such as micromirrors and embossed micro gratings optimized for the above mentioned spectral ranges. Potentially, infrared sensors can be used for rapid nondestructive diagnostics of surfaces, liquids, gases, polymers and complex biological systems including proteins, blood, cells and cellular debris as well as body tissue. Furthermore, NIR-MIR microsensing spectroscopy will be utilized to monitor the chemical composition of petrochemical products like gasoline and diesel. In addition, miniature analyzers will be used for rapid measuring of food, in particular oil, starch and meat. In this paper we will present an overview of several new approaches for subsurface and surface sensing technologies based on the integration of optical micro devices, the most promising sensors for biomedical, environmental and industrial applications, data processing and evaluation algorithms for classification of the results. Both scientific and industrial applications will be discussed.

Unified analysis of ensemble and single-complex optical spectral data from light-harvesting complex-2 chromoproteins for gaining deeper insight into bacterial photosynthesis

NASA Astrophysics Data System (ADS)

Pajusalu, Mihkel; Kunz, Ralf; Rätsep, Margus; Timpmann, Kõu; Köhler, Jürgen; Freiberg, Arvi

2015-11-01

Bacterial light-harvesting pigment-protein complexes are very efficient at converting photons into excitons and transferring them to reaction centers, where the energy is stored in a chemical form. Optical properties of the complexes are known to change significantly in time and also vary from one complex to another; therefore, a detailed understanding of the variations on the level of single complexes and how they accumulate into effects that can be seen on the macroscopic scale is required. While experimental and theoretical methods exist to study the spectral properties of light-harvesting complexes on both individual complex and bulk ensemble levels, they have been developed largely independently of each other. To fill this gap, we simultaneously analyze experimental low-temperature single-complex and bulk ensemble optical spectra of the light-harvesting complex-2 (LH2) chromoproteins from the photosynthetic bacterium Rhodopseudomonas acidophila in order to find a unique theoretical model consistent with both experimental situations. The model, which satisfies most of the observations, combines strong exciton-phonon coupling with significant disorder, characteristic of the proteins. We establish a detailed disorder model that, in addition to containing a C2-symmetrical modulation of the site energies, distinguishes between static intercomplex and slow conformational intracomplex disorders. The model evaluations also verify that, despite best efforts, the single-LH2-complex measurements performed so far may be biased toward complexes with higher Huang-Rhys factors.

Unified analysis of ensemble and single-complex optical spectral data from light-harvesting complex-2 chromoproteins for gaining deeper insight into bacterial photosynthesis.

PubMed

Pajusalu, Mihkel; Kunz, Ralf; Rätsep, Margus; Timpmann, Kõu; Köhler, Jürgen; Freiberg, Arvi

2015-01-01

Bacterial light-harvesting pigment-protein complexes are very efficient at converting photons into excitons and transferring them to reaction centers, where the energy is stored in a chemical form. Optical properties of the complexes are known to change significantly in time and also vary from one complex to another; therefore, a detailed understanding of the variations on the level of single complexes and how they accumulate into effects that can be seen on the macroscopic scale is required. While experimental and theoretical methods exist to study the spectral properties of light-harvesting complexes on both individual complex and bulk ensemble levels, they have been developed largely independently of each other. To fill this gap, we simultaneously analyze experimental low-temperature single-complex and bulk ensemble optical spectra of the light-harvesting complex-2 (LH2) chromoproteins from the photosynthetic bacterium Rhodopseudomonas acidophila in order to find a unique theoretical model consistent with both experimental situations. The model, which satisfies most of the observations, combines strong exciton-phonon coupling with significant disorder, characteristic of the proteins. We establish a detailed disorder model that, in addition to containing a C_{2}-symmetrical modulation of the site energies, distinguishes between static intercomplex and slow conformational intracomplex disorders. The model evaluations also verify that, despite best efforts, the single-LH2-complex measurements performed so far may be biased toward complexes with higher Huang-Rhys factors.

Membrane potential dynamics of axons in cultured hippocampal neurons probed by second-harmonic-generation imaging

NASA Astrophysics Data System (ADS)

Nuriya, Mutsuo; Yasui, Masato

2010-03-01

The electrical properties of axons critically influence the nature of communication between neurons. However, due to their small size, direct measurement of membrane potential dynamics in intact and complex mammalian axons has been a challenge. Furthermore, quantitative optical measurements of axonal membrane potential dynamics have not been available. To characterize the basic principles of somatic voltage signal propagation in intact axonal arbors, second-harmonic-generation (SHG) imaging is applied to cultured mouse hippocampal neurons. When FM4-64 is applied extracellularly to dissociated neurons, whole axonal arbors are visualized by SHG imaging. Upon action potential generation by somatic current injection, nonattenuating action potentials are recorded in intact axonal arbors. Interestingly, however, both current- and voltage-clamp recordings suggest that nonregenerative subthreshold somatic voltage changes at the soma are poorly conveyed to these axonal sites. These results reveal the nature of membrane potential dynamics of cultured hippocampal neurons, and further show the possibility of SHG imaging in physiological investigations of axons.

Optical filters for UV to near IR space applications

NASA Astrophysics Data System (ADS)

Begou, T.; Krol, H.; Hecquet, Christophe; Bondet, C.; Lumeau, J.; Grèzes-Besset, C.; Lequime, M.

2017-11-01

We present hereafter the results on the fabrication of complex optical filters within the Institut Fresnel in close collaboration with CILAS. Bandpass optical filters dedicated to astronomy and space applications, with central wavelengths ranging from ultraviolet to near infrared, were deposited on both sides of glass substrates with performances in very good congruence with theoretical designs. For these applications, the required functions are particularly complex as they must present a very narrow bandwidth as well as a high level of rejection over a broad spectral range. In addition to those severe optical performances, insensitivity to environmental conditions is necessary. For this purpose, robust solutions with particularly stable performances have to be proposed.

Preparation, linear and NLO properties of DNA-CTMA-SBE complexes

NASA Astrophysics Data System (ADS)

Manea, Ana-Maria; Rau, Ileana; Kajzar, Francois; Meghea, Aurelia

2013-10-01

Synthesis of deoxyribonucleic acid (DNA) - was cetyltrimethylammonium (CTMA) - sea buckthorn extract (SBE) at different concentrations is decribed. The complexes were processed into good optical quality thin films by spin coating on different substrates such as: glass, silica and ITO covered glass substrates. SBE contains many bioactive substances that can be used in the treatment of several diseases, such as cardiovascular disease, cancer, and acute mountain sickness. The obtained thin films were characterized for their spectroscopic, fluorescent, linear and nonlinear optical properties as function of SBE concentration. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength.

On the reduced-complexity of LDPC decoders for beyond 400 Gb/s serial optical transmission

NASA Astrophysics Data System (ADS)

Djordjevic, Ivan B.; Xu, Lei; Wang, Ting

2010-12-01

Two reduced-complexity (RC) LDPC decoders are proposed, which can be used in combination with large-girth LDPC codes to enable beyond 400 Gb/s serial optical transmission. We show that optimally attenuated RC min-sum sum algorithm performs only 0.45 dB worse than conventional sum-product algorithm, while having lower storage memory requirements and much lower latency. We further evaluate the proposed algorithms for use in beyond 400 Gb/s serial optical transmission in combination with PolMUX 32-IPQ-based signal constellation and show that low BERs can be achieved for medium optical SNRs, while achieving the net coding gain above 11.4 dB.

Three-dimensional scene encryption and display based on computer-generated holograms.

PubMed

Kong, Dezhao; Cao, Liangcai; Jin, Guofan; Javidi, Bahram

2016-10-10

An optical encryption and display method for a three-dimensional (3D) scene is proposed based on computer-generated holograms (CGHs) using a single phase-only spatial light modulator. The 3D scene is encoded as one complex Fourier CGH. The Fourier CGH is then decomposed into two phase-only CGHs with random distributions by the vector stochastic decomposition algorithm. Two CGHs are interleaved as one final phase-only CGH for optical encryption and reconstruction. The proposed method can support high-level nonlinear optical 3D scene security and complex amplitude modulation of the optical field. The exclusive phase key offers strong resistances of decryption attacks. Experimental results demonstrate the validity of the novel method.

Wavefront correction and high-resolution in vivo OCT imaging with an objective integrated multi-actuator adaptive lens

PubMed Central

Bonora, Stefano; Jian, Yifan; Zhang, Pengfei; Zam, Azhar; Pugh, Edward N.; Zawadzki, Robert J.; Sarunic, Marinko V.

2015-01-01

Adaptive optics is rapidly transforming microscopy and high-resolution ophthalmic imaging. The adaptive elements commonly used to control optical wavefronts are liquid crystal spatial light modulators and deformable mirrors. We introduce a novel Multi-actuator Adaptive Lens that can correct aberrations to high order, and which has the potential to increase the spread of adaptive optics to many new applications by simplifying its integration with existing systems. Our method combines an adaptive lens with an imaged-based optimization control that allows the correction of images to the diffraction limit, and provides a reduction of hardware complexity with respect to existing state-of-the-art adaptive optics systems. The Multi-actuator Adaptive Lens design that we present can correct wavefront aberrations up to the 4th order of the Zernike polynomial characterization. The performance of the Multi-actuator Adaptive Lens is demonstrated in a wide field microscope, using a Shack-Hartmann wavefront sensor for closed loop control. The Multi-actuator Adaptive Lens and image-based wavefront-sensorless control were also integrated into the objective of a Fourier Domain Optical Coherence Tomography system for in vivo imaging of mouse retinal structures. The experimental results demonstrate that the insertion of the Multi-actuator Objective Lens can generate arbitrary wavefronts to correct aberrations down to the diffraction limit, and can be easily integrated into optical systems to improve the quality of aberrated images. PMID:26368169

Electronic and optical properties of the LiCdX (X = N, P, As and Sb) filled-tetrahedral compounds with the Tran–Blaha modified Becke–Johnson density functional

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bouhemadou, A., E-mail: a_bouhemadou@yahoo.fr; Bin-Omran, S.; Department of Physics, Faculty of Science & Humanitarian Studies, Salman Bin Abdalaziz University, Alkharj 11942

Highlights: • Electronic and optical properties of the LiCdX compounds have been predicted. • Tran–Blaha-modified Becke–Johnson functional significantly improves the band gap. • We predict a direct band gap in all of the considered LiCdX compounds. • Origin of the peaks in the optical spectra is determined. - Abstract: The structural, electronic and optical properties of the LiCdN, LiCdP, LiCdAs and LiCdSb filled-tetrahedral compounds have been explored from first-principles. The calculated structural parameters are consistent with the available experimental results. Since DFT with the common LDA and GGA underestimates the band gap, we use a new developed functional able tomore » accurately describe the electronic structure of semiconductors, namely the Tran–Blaha-modified Becke–Johnson potential. The four investigated compounds demonstrate semiconducting behavior with direct band gap ranging from about 0.32 to 1.65 eV. The charge-carrier effective masses are evaluated at the topmost valence band and at the bottommost conduction band. The evolution of the value and nature of the energy band gap under pressure effect is also investigated. The frequency-dependent complex dielectric function and some macroscopic optical constants are estimated. The microscopic origins of the structures in the optical spectra are determined in terms of the calculated energy band structures.« less

Ultrahigh refractive index chalcogenide based copolymers for infrared optics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Anderson, Laura E.; Namnabat, Soha; Char, Kookheon; Glass, Richard; Norwood, Robert A.; Pyun, Jeffrey

2016-09-01

Current trends in technology development demand increased miniaturization and higher level integration of electronic and photonic components. Such needs arise in emerging imaging systems, optoelectronic devices, optical interconnects and photonic integrated circuits. Compact, integrated photonics requires high refractive index materials, which primarily comprise crystalline and amorphous semiconductors, as well as chalcogenide glasses, which can possess refractive indices higher than 4 and good infrared transparency. There is currently no high refractive index (n 2 or above) that has the low cost production and ease of processing available in optical polymers. Such polymers would potentially cover applications that are not convenient or possible with crystalline and vitreous semiconductors. Examples of such applications include micro lens arrays for image sensors, optical adhesives for bonding and antireflection coatings, and high contrast optical waveguides. While much of the focus has been in the telecommunications transparency regions, significant new opportunities exist for a polymer which is capable of transmitting efficiently in the MWIR region. While there are polymers that have been synthesized with refractive indices as high as 1.75, these polymers are generally conjugated and incorporate heteroatoms such as sulfur or metals, and generally have complex and expensive syntheses. Here we report on new chalcogenide based copolymers with very high refractive index (n 2) that also have good optical transmission properties in the near-, short- and mid-wave infrared up to 5µm. These polymers are rich in sulfur, have low hydrogen content and were made using inverse vulcanization.

Downstream DNA Tension Regulates the Stability of the T7 RNA Polymerase Initiation Complex

PubMed Central

Skinner, Gary M.; Kalafut, Bennett S.; Visscher, Koen

2011-01-01

Gene transcription by the enzyme RNA polymerase is tightly regulated. In many cases, such as in the lac operon in Escherichia coli, this regulation is achieved through the action of protein factors on DNA. Because DNA is an elastic polymer, its response to enzymatic processing can lead to mechanical perturbations (e.g., linear stretching and supercoiling) that can affect the operation of other DNA processing complexes acting elsewhere on the same substrate molecule. Using an optical-tweezers assay, we measured the binding kinetics between single molecules of bacteriophage T7 RNA polymerase and DNA, as a function of tension. We found that increasing DNA tension under conditions that favor formation of the open complex results in destabilization of the preinitiation complex. Furthermore, with zero ribonucleotides present, when the closed complex is favored, we find reduced tension sensitivity, implying that it is predominantly the open complex that is sensitive. This result strongly supports the “scrunching” model for T7 transcription initiation, as the applied tension acts against the movement of the DNA into the scrunched state, and introduces linear DNA tension as a potential regulatory quantity for transcription initiation. PMID:21320448

A novel all-fiber optic flow cytometer technology for Point-of Care and Remote Environments

NASA Astrophysics Data System (ADS)

Mermut, Ozzy

Traditional flow cytometry designs tend to be bulky systems with a complex optical-fluidic sub-system and often require trained personnel for operation. This makes them difficult to readily translate to remote site testing applications. A new compact and portable fiber-optic flow cell (FOFC) technology has been developed at INO. We designed and engineered a specialty optical fiber through which a square hole is transversally bored by laser micromachining. A capillary is fitted into that hole to flow analyte within the fiber square cross-section for detection and counting. With demonstrated performance benchmarks potentially comparable to commercial flow cytometers, our FOFC provides several advantages compared to classic free-space con-figurations, e.g., sheathless flow, low cost, reduced number of optical components, no need for alignment (occurring in the fabrication process only), ease-of-use, miniaturization, portability, and robustness. This sheathless configuration, based on a fiber optic flow module, renders this cytometer amenable to space-grade microgravity environments. We present our recent results for an all-fiber approach to achieve a miniature FOFC to translate flow cytometry from bench to a portable, point-of-care device for deployment in remote settings. Our unique fiber approach provides the capability to illuminate a large surface with a uniform intensity distri-bution, independently of the initial shape originating from the light source, and without loss of optical power. The CVs and sensitivities are measured and compared to industry benchmarks. Finally, integration of LEDs enable several advantages in cost, compactness, and wavelength availability.

Nonlinear Optical Properties of Carotenoid and Chlorophyll Harmonophores

NASA Astrophysics Data System (ADS)

Tokarz, Danielle Barbara

Information regarding the structure and function of living tissues and cells is instrumental to the advancement of cell biology and biophysics. Nonlinear optical microscopy can provide such information, but only certain biological structures generate nonlinear optical signals. Therefore, structural specificity can be achieved by introducing labels for nonlinear optical microscopy. Few studies exist in the literature about labels that facilitate harmonic generation, coined "harmonophores". This thesis consists of the first major investigation of harmonophores for third harmonic generation (THG) microscopy. Carotenoids and chlorophylls were investigated as potential harmonophores. Their nonlinear optical properties were studied by the THG ratio technique. In addition, a tunable refractometer was built in order to determine their second hyperpolarizability (gamma). At 830 nm excitation wavelength, carotenoids and chlorophylls were found to have large negative gamma values however, at 1028 nm, the sign of gamma reversed for carotenoids and remained negative for chlorophylls. Consequently, at 1028 nm wavelength, THG signal is canceled with mixtures of carotenoids and chlorophylls. Furthermore, when such molecules are covalently bonded as dyads or interact within photosynthetic pigment-protein complexes, it is found that additive effects with the gamma values still play a role, however, the overall gamma value is also influenced by the intra-pigment and inter-pigment interaction. The nonlinear optical properties of aggregates containing chlorophylls and carotenoids were the target of subsequent investigations. Carotenoid aggregates were imaged with polarization-dependent second harmonic generation and THG microscopy. Both techniques revealed crystallographic information pertaining to H and J aggregates and beta-carotene crystalline aggregates found in orange carrot. In order to demonstrate THG enhancement due to labeling, cultured cells were labeled with carotenoid incorporated liposomes. In addition, Drosophila melanogaster larvae muscle as well as keratin structures in the hair cortex were labeled with beta-carotene. Polarization-dependent THG studies may be particularly useful in understanding the structural organization that occurs within biological structures containing carotenoids and chlorophylls such as photosynthetic pigment-protein complexes and carotenoid aggregates in plants and alga. Further, artificial labeling with carotenoids and chlorophylls may be useful in clinical applications since they are nontoxic, nutritionally valuable, and they can aid in visualizing structural changes in cellular components.

[Representation and mathematical analysis of human crystalline lens].

PubMed

Tălu, Stefan; Giovanzana, Stefano; Tălu, Mihai

2011-01-01

The surface of human crystalline lens can be described and analyzed using mathematical models based on parametric representations, used in biomechanical studies and 3D solid modeling of the lens. The mathematical models used in lens biomechanics allow the study and the behavior of crystalline lens on variables and complex dynamic loads. Also, the lens biomechanics has the potential to improve the results in the development of intraocular lenses and cataract surgery. The paper presents the most representative mathematical models currently used for the modeling of human crystalline lens, both optically and biomechanically.

CONFERENCE NOTE: CETO—Centro de Ciências e Tecnologias Opticas, Trends in Optical Fibre Metrology and Standards

NASA Astrophysics Data System (ADS)

1994-01-01

Summer School, 27 June to 8 July 1994, Viana do Castelo, Hotel do Parque, Portugal Optical fibres, with their extremely low transmission loss, untapped bandwidth and controllable dispersion, dominate a broad range of technologies in which applications must respond to the increasing constraints of today's specifications as well as envisage future requirements. Optical fibres dominate communications systems. In the area of sensors, fibre optics will be fully exploited for their immunity to EMI, their high sensitivity and their large dynamic range. The maturity of single mode optical technology has led to intensive R&D of a range of components based on the advantages of transmission characteristics and signal processing. Specifications and intercompatibility requests for the new generation of both analogue and digital fibre optical components and systems has created a demand for sophisticated measuring techniques based on unique and complex instruments. In recent years there has been a signification evolution in response to the explosion of applications and the tightening of specifications. These developments justify a concerted effort to focus on trends in optical fibre metrology and standards. Objective The objective of this school is to provide a progressive and comprehensive presentation of current issues concerning passive and active optical fibre characterization and measurement techniques. Passive fibre components support a variety of developments in optical fibre systems and will be discussed in terms of relevance and standards. Particular attention will be paid to devices for metrological purposes such as reference fibres and calibration artefacts. The characterization and testing of optical fibre amplifiers, which have great potential in telecommunications, data distribution networks and as a system part in instrumentation, will be covered. Methods of measurement and means of calibration with traceability will be discussed, together with the characterization requirements of the new generation of analogue and digital fibre optical systems, which require sophisticated measurement techniques employing complex instruments unique to optical measurements. The school will foster and enhance the interaction between material, devices, systems, and standards-oriented R&D communities, as well as between engineers concerned with design and manufacturers of systems and instrumentation. Topics Review of optical fibre communication technology and systems Measurement techniques for fibre characterization: Reliability and traceability Reference fibres and calibration artefacts Ribbon fibres Mechanical and environmental testing Fibre reliability Polarimetric measurements Passive components characterization: Splices and connectors Couplers, splitters, taps and WDMs Optical fibres and isolators WDM technologies and applications: WDM technologies Tunable optical filters Fibre amplifiers and sources: Performances and characterization Design and standards Nonlinear effects Subsystem design and standards: Design and fabrication techniques Performance degradation and reliability Evaluation of costs/performance/technology Sensors IR - optical fibres Plastic fibres Instrumentation Registration Participation free of charge for postgraduate students, with some grants available for travel and lodging expenses. All correspondence should be addressed to: Secretariat, Trends in Optical Fibre Metrology and Standards, a/c Prof. Olivério D D Soares, Centro de Ciências e Tecnologias Opticas, Lab. Fisica - Faculdade de Ciências, Praça Gomes Teixeira, P-4000 Porto, Portugal. Tel: 351-2-310290, 351-2-2001648; Fax: 351-2-319267.

An autonomous vehicle approach for quantifying bioluminescence in ports and harbors

NASA Astrophysics Data System (ADS)

Moline, Mark; Bissett, Paul; Blackwell, Shelley; Mueller, James; Sevadjian, Jeff; Trees, Charles; Zaneveld, Ron

2005-05-01

Bioluminescence emitted from marine organisms upon mechanical stimulation is an obvious military interest, as it provides a low-tech method of identifying surface and subsurface vehicles and swimmer tracks. Clearly, the development of a passive method of identifying hostile ships, submarines, and swimmers, as well as the development of strategies to reduce the risk of detection by hostile forces is relevant to Naval operations and homeland security. The measurement of bioluminescence in coastal waters has only recently received attention as the platforms and sensors were not scaled for the inherent small-scale nature of nearshore environments. In addition to marine forcing, many ports and harbors are influenced by freshwater inputs, differential density layering and higher turbidity. The spatial and temporal fluctuations of these optical water types overlaid on changes in the bioluminescence potential make these areas uniquely complex. The development of an autonomous underwater vehicle with a bioluminescence capability allows measurements on sub-centimeter horizontal and vertical scales in shallow waters and provides the means to map the potential for detection of moving surface or subsurface objects. A deployment in San Diego Bay shows the influence of tides on the distribution of optical water types and the distribution of bioluminescent organisms. Here, these data are combined to comment on the potential for threat reduction in ports and harbors.

Fiber-Optic Strain Gauge With High Resolution And Update Rate

NASA Technical Reports Server (NTRS)

Figueroa, Fernando; Mahajan, Ajay; Sayeh, Mohammad; Regez, Bradley

2007-01-01

An improved fiber-optic strain gauge is capable of measuring strains in the approximate range of 0 to 50 microstrains with a resolution of 0.1 microstrain. (To some extent, the resolution of the strain gauge can be tailored and may be extensible to 0.01 microstrain.) The total cost of the hardware components of this strain gauge is less than $100 at 2006 prices. In comparison with prior strain gauges capable of measurement of such low strains, this strain gauge is more accurate, more economical, and more robust, and it operates at a higher update rate. Strain gauges like this one are useful mainly for measuring small strains (including those associated with vibrations) in such structures as rocket test stands, buildings, oilrigs, bridges, and dams. The technology was inspired by the need to measure very small strains on structures supporting liquid oxygen tanks, as a way to measure accurately mass of liquid oxygen during rocket engine testing. This improved fiber-optic strain gauge was developed to overcome some of the deficiencies of both traditional foil strain gauges and prior fiber-optic strain gauges. Traditional foil strain gages do not have adequate signal-to-noise ratios at such small strains. Fiber-optic strain gauges have been shown to be potentially useful for measuring such small strains, but heretofore, the use of fiberoptic strain gauges has been inhibited, variously, by complexity, cost, or low update rate.

Optical characterization and polarization calibration for rigid endoscopes

NASA Astrophysics Data System (ADS)

Garcia, Missael; Gruev, Viktor

2017-02-01

Polarization measurements give orthogonal information to spectral images making them a great tool in the characterization of environmental parameters in nature. Thus, polarization imagery has proven to be remarkably useful in a vast range of biomedical applications. One such application is the early diagnosis of flat cancerous lesions in murine colorectal tumor models, where polarization data complements NIR fluorescence analysis. Advances in nanotechnology have led to compact and precise bio-inspired imaging sensors capable of accurately co-registering multidimensional spectral and polarization information. As more applications emerge for these imagers, the optics used in these instruments get very complex and can potentially compromise the original polarization state of the incident light. Here we present a complete optical and polarization characterization of three rigid endoscopes of size 1.9mm x 10cm (Karl Storz, Germany), 5mm x 30cm, and 10mm x 33cm (Olympus, Germany), used in colonoscopy for the prevention of colitis-associated cancer. Characterization results show that the telescope optics act as retarders and effectively depolarize the linear component. These incorrect readings can cause false-positives or false-negatives leading to an improper diagnosis. In this paper, we offer a polarization calibration scheme for these endoscopes based on Mueller calculus. By modeling the optical properties from training data as real-valued Mueller matrices, we are able to successfully reconstruct the initial polarization state acquired by the imaging system.

Au nanoparticle monolayers covered with sol-gel oxide thin films: optical and morphological study.

PubMed

Della Gaspera, Enrico; Karg, Matthias; Baldauf, Julia; Jasieniak, Jacek; Maggioni, Gianluigi; Martucci, Alessandro

2011-11-15

In this work, we provide a detailed study of the influence of thermal annealing on submonolayer Au nanoparticle deposited on functionalized surfaces as standalone films and those that are coated with sol-gel NiO and TiO(2) thin films. The systems are characterized through the use of UV-vis absorption, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and spectroscopic ellipsometry. The surface plasmon resonance peak of the Au nanoparticles was found to red-shift and increase in intensity with increasing surface coverage, an observation that is directly correlated to the complex refractive index properties of Au nanoparticle layers. The standalone Au nanoparticles sinter at 200 °C, and a relationship between the optical properties and the annealing temperature is presented. When overcoated with sol-gel metal oxide films (NiO, TiO(2)), the optical properties of the Au nanoparticles are strongly affected by the metal oxide, resulting in an intense red shift and broadening of the plasmon band; moreover, the temperature-driven sintering is strongly limited by the metal oxide layer. Optical sensing tests for ethanol vapor are presented as one possible application, showing reversible sensing dynamics and confirming the effect of Au nanoparticles in increasing the sensitivity and in providing a wavelength dependent response, thus confirming the potential use of such materials as optical probes.

Compositionally Dependent Nonlinear Optical Bandgap Behavior of Mixed Anodic Oxides in Niobium-Titanium System.

PubMed

Bleckenwegner, Petra; Mardare, Cezarina Cela; Cobet, Christoph; Kollender, Jan Philipp; Hassel, Achim Walter; Mardare, Andrei Ionut

2017-02-13

Optical bandgap mapping of Nb-Ti mixed oxides anodically grown on a thin film parent metallic combinatorial library was performed via variable angle spectroscopic ellipsometry (VASE). A wide Nb-Ti compositional spread ranging from Nb-90 at.% Ti to Nb-15 at.% Ti deposited by cosputtering was used for this purpose. The Nb-Ti library was stepwise anodized at potentials up to 10 V SHE, and the anodic oxides optical properties were mapped along the Nb-Ti library with 2 at.% resolution. The surface dissimilarities along the Nb-Ti compositional gradient were minimized by tuning the deposition parameters, thus allowing a description of the mixed Nb-Ti oxides based on a single Tauc-Lorentz oscillator for data fitting. Mapping of the Nb-Ti oxides optical bandgap along the entire compositional spread showed a clear deviation from the linear model based on mixing individual Nb and Ti electronegativities proportional to their atomic fractions. This is attributed to the strong amorphization and an in-depth compositional gradient of the mixed oxides. A systematic optical bandgap decrease toward values as low as 2.0 eV was identified at approximately 50 at.% Nb. Mixing of Nb 2 O 5 and TiO 2 with both amorphous and crystalline phases is concluded, whereas the possibility of complex Nb a Ti b O y oxide formation during anodization is unlikely.

Preface to the special issue on ;Optical Communications Exploiting the Space Domain;

NASA Astrophysics Data System (ADS)

Wang, Jian; Yu, Siyuan; Li, Guifang

2018-02-01

The demand for high capacity optical communications will continue to be driven by the exponential growth of global internet traffic. Optical communications are about the exploitation of different physical dimensions of light waves, including complex amplitude, frequency (or wavelength), time, polarization, etc. Conventional techniques such as wavelength-division multiplexing (WDM), time-division multiplexing (TDM) and polarization-division multiplexing (PDM) have almost reached their scalability limits. Space domain is the only known physical dimension left and space-division multiplexing (SDM) seems the only option to further scale the transmission capacity and spectral efficiency of optical communications. In recent years, few-mode fiber (FMF), multi-mode fiber (MMF), multi-core fiber (MCF) and few-mode multi-core fiber (FM-MCF) have been widely explored as promising candidates for fiber-based SDM. The challenges for SDM include efficient (de)multiplexer, amplifiers, and multiple-input multiple-output (MIMO) digital signal processing (DSP) techniques. Photonic integration will also be a key technology to SDM. Meanwhile, free-space and underwater optical communications have also exploited the space domain to increase the transmission capacity and spectral efficiency. The challenges include long-distance transmission limited by propagation loss, divergence, scattering and turbulence. Very recently, helically phased light beams carrying orbital angular momentum (OAM) have also seen potential applications both in free-space, underwater and fiber-based optical communications. Actually, different mode bases such as linearly polarized (LP) modes and OAM modes can be employed for SDM. Additionally, SDM could be used in chip-scale photonic interconnects and data center optical interconnects. Quantum processing exploiting the space domain is of great interest. The information capacity limit and physical layer security in SDM optical communications systems are important issues to be addressed.

Graphene-Boron Nitride Heterostructure Based Optoelectronic Devices for On-Chip Optical Interconnects

NASA Astrophysics Data System (ADS)

Gao, Yuanda

Graphene has emerged as an appealing material for a variety of optoelectronic applications due to its unique electrical and optical characteristics. In this thesis, I will present recent advances in integrating graphene and graphene-boron nitride (BN) heterostructures with confined optical architectures, e.g. planar photonic crystal (PPC) nanocavities and silicon channel waveguides, to make this otherwise weakly absorbing material optically opaque. Based on these integrations, I will further demonstrate the resulting chip-integrated optoelectronic devices for optical interconnects. After transferring a layer of graphene onto PPC nanocavities, spectral selectivity at the resonance frequency and orders-of-magnitude enhancement of optical coupling with graphene have been observed in infrared spectrum. By applying electrostatic potential to graphene, electro-optic modulation of the cavity reflection is possible with contrast in excess of 10 dB. And furthermore, a novel and complex modulator device structure based on the cavity-coupled and BN-encapsulated dual-layer graphene capacitor is demonstrated to operate at a speed of 1.2 GHz. On the other hand, an enhanced broad-spectrum light-graphene interaction coupled with silicon channel waveguides is also demonstrated with ?0.1 dB/?m transmission attenuation due to graphene absorption. A waveguide-integrated graphene photodetector is fabricated and shown 0.1 A/W photoresponsivity and 20 GHz operation speed. An improved version of a similar photodetector using graphene-BN heterostructure exhibits 0.36 A/W photoresponsivity and 42 GHz response speed. The integration of graphene and graphene-BN heterostructures with nanophotonic architectures promises a new generation of compact, energy-efficient, high-speed optoelectronic device concepts for on-chip optical communications that are not yet feasible or very difficult to realize using traditional bulk semiconductors.

Seeing through Musculoskeletal Tissues: Improving In Situ Imaging of Bone and the Lacunar Canalicular System through Optical Clearing

PubMed Central

Berke, Ian M.; Miola, Joseph P.; David, Michael A.; Smith, Melanie K.; Price, Christopher

2016-01-01

In situ, cells of the musculoskeletal system reside within complex and often interconnected 3-D environments. Key to better understanding how 3-D tissue and cellular environments regulate musculoskeletal physiology, homeostasis, and health is the use of robust methodologies for directly visualizing cell-cell and cell-matrix architecture in situ. However, the use of standard optical imaging techniques is often of limited utility in deep imaging of intact musculoskeletal tissues due to the highly scattering nature of biological tissues. Drawing inspiration from recent developments in the deep-tissue imaging field, we describe the application of immersion based optical clearing techniques, which utilize the principle of refractive index (RI) matching between the clearing/mounting media and tissue under observation, to improve the deep, in situ imaging of musculoskeletal tissues. To date, few optical clearing techniques have been applied specifically to musculoskeletal tissues, and a systematic comparison of the clearing ability of optical clearing agents in musculoskeletal tissues has yet to be fully demonstrated. In this study we tested the ability of eight different aqueous and non-aqueous clearing agents, with RIs ranging from 1.45 to 1.56, to optically clear murine knee joints and cortical bone. We demonstrated and quantified the ability of these optical clearing agents to clear musculoskeletal tissues and improve both macro- and micro-scale imaging of musculoskeletal tissue across several imaging modalities (stereomicroscopy, spectroscopy, and one-, and two-photon confocal microscopy) and investigational techniques (dynamic bone labeling and en bloc tissue staining). Based upon these findings we believe that optical clearing, in combination with advanced imaging techniques, has the potential to complement classical musculoskeletal analysis techniques; opening the door for improved in situ investigation and quantification of musculoskeletal tissues. PMID:26930293

Seeing through Musculoskeletal Tissues: Improving In Situ Imaging of Bone and the Lacunar Canalicular System through Optical Clearing.

PubMed

Berke, Ian M; Miola, Joseph P; David, Michael A; Smith, Melanie K; Price, Christopher

2016-01-01

In situ, cells of the musculoskeletal system reside within complex and often interconnected 3-D environments. Key to better understanding how 3-D tissue and cellular environments regulate musculoskeletal physiology, homeostasis, and health is the use of robust methodologies for directly visualizing cell-cell and cell-matrix architecture in situ. However, the use of standard optical imaging techniques is often of limited utility in deep imaging of intact musculoskeletal tissues due to the highly scattering nature of biological tissues. Drawing inspiration from recent developments in the deep-tissue imaging field, we describe the application of immersion based optical clearing techniques, which utilize the principle of refractive index (RI) matching between the clearing/mounting media and tissue under observation, to improve the deep, in situ imaging of musculoskeletal tissues. To date, few optical clearing techniques have been applied specifically to musculoskeletal tissues, and a systematic comparison of the clearing ability of optical clearing agents in musculoskeletal tissues has yet to be fully demonstrated. In this study we tested the ability of eight different aqueous and non-aqueous clearing agents, with RIs ranging from 1.45 to 1.56, to optically clear murine knee joints and cortical bone. We demonstrated and quantified the ability of these optical clearing agents to clear musculoskeletal tissues and improve both macro- and micro-scale imaging of musculoskeletal tissue across several imaging modalities (stereomicroscopy, spectroscopy, and one-, and two-photon confocal microscopy) and investigational techniques (dynamic bone labeling and en bloc tissue staining). Based upon these findings we believe that optical clearing, in combination with advanced imaging techniques, has the potential to complement classical musculoskeletal analysis techniques; opening the door for improved in situ investigation and quantification of musculoskeletal tissues.

Hyperspectral Remote Sensing of the Coastal Ocean: Adaptive Sampling and Forecasting of In situ Optical Properties

DTIC Science & Technology

2002-09-30

integrated observation system that is being coupled to a data assimilative hydrodynamic bio-optical ecosystem model. The system was used adaptively to develop hyperspectral remote sensing techniques in optically complex nearshore coastal waters.

Nanomanipulation of Single RNA Molecules by Optical Tweezers

PubMed Central

Stephenson, William; Wan, Gorby; Tenenbaum, Scott A.; Li, Pan T. X.

2014-01-01

A large portion of the human genome is transcribed but not translated. In this post genomic era, regulatory functions of RNA have been shown to be increasingly important. As RNA function often depends on its ability to adopt alternative structures, it is difficult to predict RNA three-dimensional structures directly from sequence. Single-molecule approaches show potentials to solve the problem of RNA structural polymorphism by monitoring molecular structures one molecule at a time. This work presents a method to precisely manipulate the folding and structure of single RNA molecules using optical tweezers. First, methods to synthesize molecules suitable for single-molecule mechanical work are described. Next, various calibration procedures to ensure the proper operations of the optical tweezers are discussed. Next, various experiments are explained. To demonstrate the utility of the technique, results of mechanically unfolding RNA hairpins and a single RNA kissing complex are used as evidence. In these examples, the nanomanipulation technique was used to study folding of each structural domain, including secondary and tertiary, independently. Lastly, the limitations and future applications of the method are discussed. PMID:25177917

In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon

PubMed Central

Makey, Ghaith; Elahi, Parviz; Çolakoğlu, Tahir; Ergeçen, Emre; Yavuz, Özgün; Hübner, René; Borra, Mona Zolfaghari; Pavlov, Ihor; Bek, Alpan; Turan, Raşit; Kesim, Denizhan Koray; Tozburun, Serhat; Ilday, Serim; Ilday, F. Ömer

2017-01-01

Silicon is an excellent material for microelectronics and integrated photonics1–3 with untapped potential for mid-IR optics4. Despite broad recognition of the importance of the third dimension5,6, current lithography methods do not allow fabrication of photonic devices and functional microelements directly inside silicon chips. Even relatively simple curved geometries cannot be realised with techniques like reactive ion etching. Embedded optical elements, like in glass7, electronic devices, and better electronic-photonic integration are lacking8. Here, we demonstrate laser-based fabrication of complex 3D structures deep inside silicon using 1 µm-sized dots and rod-like structures of adjustable length as basic building blocks. The laser-modified Si has a different optical index than unmodified parts, which enables numerous photonic devices. Optionally, these parts are chemically etched to produce desired 3D shapes. We exemplify a plethora of subsurface, i.e., “in-chip” microstructures for microfluidic cooling of chips, vias, MEMS, photovoltaic applications and photonic devices that match or surpass the corresponding state-of-the-art device performances. PMID:28983323

Diamond-Based Magnetic Imaging with Fourier Optical Processing

NASA Astrophysics Data System (ADS)

Backlund, Mikael P.; Kehayias, Pauli; Walsworth, Ronald L.

2017-11-01

Diamond-based magnetic field sensors have attracted great interest in recent years. In particular, wide-field magnetic imaging using nitrogen-vacancy (NV) centers in diamond has been previously demonstrated in condensed matter, biological, and paleomagnetic applications. Vector magnetic imaging with NV ensembles typically requires a significant applied field (>10 G ) to resolve the contributions from four crystallographic orientations, hindering studies of magnetic samples that require measurement in low or independently specified bias fields. Here we model and measure the complex amplitude distribution of NV emission at the microscope's Fourier plane and show that by modulating this collected light at the Fourier plane, one can decompose the NV ensemble magnetic resonance spectrum into its constituent orientations by purely optical means. This decomposition effectively extends the dynamic range at a given bias field and enables wide-field vector magnetic imaging at arbitrarily low bias fields, thus broadening potential applications of NV imaging and sensing. Our results demonstrate that NV-based microscopy stands to benefit greatly from Fourier optical approaches, which have already found widespread utility in other branches of microscopy.

In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon

NASA Astrophysics Data System (ADS)

Tokel, Onur; Turnalı, Ahmet; Makey, Ghaith; Elahi, Parviz; ćolakoǧlu, Tahir; Ergeçen, Emre; Yavuz, Ã.-zgün; Hübner, René; Zolfaghari Borra, Mona; Pavlov, Ihor; Bek, Alpan; Turan, Raşit; Kesim, Denizhan Koray; Tozburun, Serhat; Ilday, Serim; Ilday, F. Ã.-mer

2017-10-01

Silicon is an excellent material for microelectronics and integrated photonics1-3, with untapped potential for mid-infrared optics4. Despite broad recognition of the importance of the third dimension5,6, current lithography methods do not allow the fabrication of photonic devices and functional microelements directly inside silicon chips. Even relatively simple curved geometries cannot be realized with techniques like reactive ion etching. Embedded optical elements7, electronic devices and better electronic-photonic integration are lacking8. Here, we demonstrate laser-based fabrication of complex 3D structures deep inside silicon using 1-µm-sized dots and rod-like structures of adjustable length as basic building blocks. The laser-modified Si has an optical index different to that in unmodified parts, enabling the creation of numerous photonic devices. Optionally, these parts can be chemically etched to produce desired 3D shapes. We exemplify a plethora of subsurface—that is, `in-chip'—microstructures for microfluidic cooling of chips, vias, micro-electro-mechanical systems, photovoltaic applications and photonic devices that match or surpass corresponding state-of-the-art device performances.

Iron Oxide and Gold Based Magneto-Plasmonic Nanostructures for Medical Applications: A Review

PubMed Central

Mammeri, Fayna; Ammar, Souad

2018-01-01

Iron oxide and gold-based magneto-plasmonic nanostructures exhibit remarkable optical and superparamagnetic properties originating from their two different components. As a consequence, they have improved and broadened the application potential of nanomaterials in medicine. They can be used as multifunctional nanoprobes for magneto-plasmonic heating as well as for magnetic and optical imaging. They can also be used for magnetically assisted optical biosensing, to detect extreme traces of targeted bioanalytes. This review introduces the previous work on magneto-plasmonic hetero-nanostructures including: (i) their synthesis from simple “one-step” to complex “multi-step” routes, including seed-mediated and non-seed-mediated methods; and (ii) the characterization of their multifunctional features, with a special emphasis on the relationships between their synthesis conditions, their structures and their properties. It also focuses on the most important progress made with regard to their use in nanomedicine, keeping in mind the same aim, the correlation between their morphology—namely spherical and non-spherical, core-satellite and core-shell, and the desired applications. PMID:29518969

Peptides and proteins in matter wave interferometry: Challenges and prospects

NASA Astrophysics Data System (ADS)

Sezer, Ugur; Geyer, Philipp; Mairhofer, Lukas; Brand, Christian; Doerre, Nadine; Rodewald, Jonas; Schaetti, Jonas; Koehler, Valentin; Mayor, Marcel; Arndt, Markus

2016-05-01

Recent developments in matter wave physics suggest that quantum interferometry with biologically relevant nanomaterials is becoming feasible for amino acids, peptides, proteins and RNA/DNA strands. Quantum interference of biomolecules is interesting as it can mimic Schrödinger's cat states with molecules of high mass, elevated temperature and biological functionality. Additionally, the high internal complexity can give rise to a rich variety of couplings to the environment and new handles for quantitative tests of quantum decoherence. Finally, matter wave interferometers are highly sensitive force sensors and pave the way for quantum-assisted measurements of biomolecular properties in interaction with tailored or biomimetic environments. Recent interferometer concepts such as the Kapitza-Dirac-Talbot-Lau interferometer (KDTLI) or the Optical Time-domain Matter Wave interferometer (OTIMA) have already proven their potential for quantum optics in the mass range beyond 10000 amu and for metrology. Here we show our advances in quantum interferometry with vitamins and peptides and discuss methods of realizing cold, intense and sufficiently slow beams of synthetically tailored or hydrated polypeptides with promising properties for a new generation of quantum optics.

A sensor system based on a luminescent protein complex in a biopolymer matrix for detecting small concentrations of hydrogen sulfide in aqueous solutions

NASA Astrophysics Data System (ADS)

Sergeev, A. A.; Leonov, A. A.; Kamenev, D. G.; Voznesenskii, S. S.; Kul'chin, Yu. M.

2017-09-01

We have studied the properties of luminescent protein complexes based on myoglobin with covalently bound CY3 luminophore, which were incorporated into polysaccharide agarose films, as potential elements sensitive to hydrogen sulfide (H2S) in aqueous solutions. The presence of this analyte changes the absorption spectrum of myoglobin, which influences the efficiency of luminophore excitation while having almost no effect on its emission spectrum. This effect shows that a luminescent sensor system with the optical response determined by analyte-induced changes in the efficiency of luminescence excitation in the sensitive element can be created. For the system studied, the limit of detection of H2S dissolved in water amounted to 100 pM.

Application of complex geometrical optics to determination of thermal, transport, and optical parameters of thin films by the photothermal beam deflection technique.

PubMed

Korte, Dorota; Franko, Mladen

2015-01-01

In this work, complex geometrical optics is, for what we believe is the first time, applied instead of geometrical or wave optics to describe the probe beam interaction with the field of the thermal wave in photothermal beam deflection (photothermal deflection spectroscopy) experiments on thin films. On the basis of this approach the thermal (thermal diffusivity and conductivity), optical (energy band gap), and transport (carrier lifetime) parameters of the semiconductor thin films (pure TiO2, N- and C-doped TiO2, or TiO2/SiO2 composites deposited on a glass or aluminum support) were determined with better accuracy and simultaneously during one measurement. The results are in good agreement with results obtained by the use of other methods and reported in the literature.

Precise determination of lattice phase shifts and mixing angles

DOE PAGES

Lu, Bing -Nan; Lähde, Timo A.; Lee, Dean; ...

2016-07-09

Here, we introduce a general and accurate method for determining lattice phase shifts and mixing angles, which is applicable to arbitrary, non-cubic lattices. Our method combines angular momentum projection, spherical wall boundaries and an adjustable auxiliary potential. This allows us to construct radial lattice wave functions and to determine phase shifts at arbitrary energies. For coupled partial waves, we use a complex-valued auxiliary potential that breaks time-reversal invariance. We benchmark our method using a system of two spin-1/2 particles interacting through a finite-range potential with a strong tensor component. We are able to extract phase shifts and mixing angles formore » all angular momenta and energies, with precision greater than that of extant methods. We discuss a wide range of applications from nuclear lattice simulations to optical lattice experiments.« less

Guiding Chiral Self-Propellers in a Periodic Potential

NASA Astrophysics Data System (ADS)

Nourhani, Amir; Crespi, Vincent H.; Lammert, Paul E.

2015-09-01

Ingenious suggestions continue to be made for separation of racemic mixtures according to the inert structural chirality of the constituents. Recently discovered self-motile micro- or nanoparticles express dynamical chirality, i.e., that which originates in motion, not structure. Here, we predict how dynamically chiral objects, with overdamped dynamics in a soft periodic two-dimensional potential, can display not only separation into well-defined dynamical subclasses defined by motility characteristics, but also the ability to be steered to arbitrary locations in the plane by simply changing the amplitude of the external potential. Orientational and translational diffusion produce new types of drift absent in the noise-free case. As practical implementation seems feasible with acoustic or optical fields, these phenomena can be useful for laboratory microscales manipulations, possibly including reconfigurable microfluidic circuits with complex networks of unidirectional channels.

Optical mapping of optogenetically shaped cardiac action potentials.

PubMed

Park, Sarah A; Lee, Shin-Rong; Tung, Leslie; Yue, David T

2014-08-19

Light-mediated silencing and stimulation of cardiac excitability, an important complement to electrical stimulation, promises important discoveries and therapies. To date, cardiac optogenetics has been studied with patch-clamp, multielectrode arrays, video microscopy, and an all-optical system measuring calcium transients. The future lies in achieving simultaneous optical acquisition of excitability signals and optogenetic control, both with high spatio-temporal resolution. Here, we make progress by combining optical mapping of action potentials with concurrent activation of channelrhodopsin-2 (ChR2) or halorhodopsin (eNpHR3.0), via an all-optical system applied to monolayers of neonatal rat ventricular myocytes (NRVM). Additionally, we explore the capability of ChR2 and eNpHR3.0 to shape action-potential waveforms, potentially aiding the study of short/long QT syndromes that result from abnormal changes in action potential duration (APD). These results show the promise of an all-optical system to acquire action potentials with precise temporal optogenetics control, achieving a long-sought flexibility beyond the means of conventional electrical stimulation.

Optical mapping of optogenetically shaped cardiac action potentials

PubMed Central

Park, Sarah A.; Lee, Shin-Rong; Tung, Leslie; Yue, David T.

2014-01-01

Light-mediated silencing and stimulation of cardiac excitability, an important complement to electrical stimulation, promises important discoveries and therapies. To date, cardiac optogenetics has been studied with patch-clamp, multielectrode arrays, video microscopy, and an all-optical system measuring calcium transients. The future lies in achieving simultaneous optical acquisition of excitability signals and optogenetic control, both with high spatio-temporal resolution. Here, we make progress by combining optical mapping of action potentials with concurrent activation of channelrhodopsin-2 (ChR2) or halorhodopsin (eNpHR3.0), via an all-optical system applied to monolayers of neonatal rat ventricular myocytes (NRVM). Additionally, we explore the capability of ChR2 and eNpHR3.0 to shape action-potential waveforms, potentially aiding the study of short/long QT syndromes that result from abnormal changes in action potential duration (APD). These results show the promise of an all-optical system to acquire action potentials with precise temporal optogenetics control, achieving a long-sought flexibility beyond the means of conventional electrical stimulation. PMID:25135113

Isotopologue-selective excitation studied via optical-optical double resonance using the E3 Σ1+(63S1) ←A3Π0+(53P1) ←X1Σ0+(51S0) transitions in CdAr and CdKr van der Waals complexes

NASA Astrophysics Data System (ADS)

Urbańczyk, T.; Dudek, J.; Koperski, J.

2018-06-01

A method of experimental selection of molecular isotopologues using optical-optical double resonance (OODR) scheme and supersonic beam source of van der Waals (vdW) complexes is presented. Due to an appropriately large isotopic shift, the proper choice of a wavenumber of a sufficiently narrowband laser in the first transition of OODR scheme can lead to a selective isotopologue excitation to the intermediate state. Thanks to this approach, it is possible to select some of the isotopologues which subsequently give a contribution to laser induced fluorescence (LIF) signal originated from the final state of OODR. In this article, results of tests of the proposed method that employs the E3 Σ1+ ←A3Π0+ ←X1Σ0+ transitions in two vdW complexes, CdKr and CdAr, are presented and analysed.

Drug-DNA interactions at single molecule level: A view with optical tweezers

NASA Astrophysics Data System (ADS)

Paramanathan, Thayaparan

Studies of small molecule--DNA interactions are essential for developing new drugs for challenging diseases like cancer and HIV. The main idea behind developing these molecules is to target and inhibit the reproduction of the tumor cells and infected cells. We mechanically manipulate single DNA molecule using optical tweezers to investigate two molecules that have complex and multiple binding modes. Mononuclear ruthenium complexes have been extensively studied as a test for rational drug design. Potential drug candidates should have high affinity to DNA and slow dissociation kinetics. To achieve this, motifs of the ruthenium complexes are altered. Our collaborators designed a dumb-bell shaped binuclear ruthenium complex that can only intercalate DNA by threading through its bases. Studying the binding properties of this complex in bulk studies took hours. By mechanically manipulating a single DNA molecule held with optical tweezers, we lower the barrier to thread and make it fast compared to the bulk experiments. Stretching single DNA molecules with different concentration of drug molecules and holding it at a constant force allows the binding to reach equilibrium. By this we can obtain the equilibrium fractional ligand binding and length of DNA at saturated binding. Fitting these results yields quantitative measurements of the binding thermodynamics and kinetics of this complex process. The second complex discussed in this study is Actinomycin D (ActD), a well studied anti-cancer agent that is used as a prototype for developing new generations of drugs. However, the biophysical basis of its activity is still unclear. Because ActD is known to intercalate double stranded DNA (dsDNA), it was assumed to block replication by stabilizing dsDNA in front of the replication fork. However, recent studies have shown that ActD binds with even higher affinity to imperfect duplexes and some sequences of single stranded DNA (ssDNA). We directly measure the on and off rates by stretching the DNA molecule to a certain force and holding it at constant force while adding the drug and then while washing off the drug. Our finding resolves the long lasting controversy of ActD binding modes, clearly showing that both the dsDNA binding and ssDNA binding converge to the same single mode. The result supports the hypothesis that the primary characteristic of ActD that contributes to its biological activity is its ability to inhibit cellular replication by binding to transcription bubbles and causing cell death.

Planar integrated optics, a new solution in optical instrumentation

NASA Astrophysics Data System (ADS)

Haguenauer, P.

2017-11-01

Planar integrated optics present an attractive solution for future instrumentation, both in ground and space based applications. The technologies used in the manufacturing of such components, supported by research laboratories as well as industries, are mature enough to provide complex devices.

Voltage-sensitive dye recording from networks of cultured neurons

NASA Astrophysics Data System (ADS)

Chien, Chi-Bin

This thesis describes the development and testing of a sensitive apparatus for recording electrical activity from microcultures of rat superior cervical ganglion (SCG) neurons by using voltage-sensitive fluorescent dyes.The apparatus comprises a feedback-regulated mercury arc light source, an inverted epifluorescence microscope, a novel fiber-optic camera with discrete photodiode detectors, and low-noise preamplifiers. Using an NA 0.75 objective and illuminating at 10 W/cm2 with the 546 nm mercury line, a typical SCG neuron stained with the styryl dye RH423 gives a detected photocurrent of 1 nA; the light source and optical detectors are quiet enough that the shot noise in this photocurrent--about.03% rms--dominates. The design, theory, and performance of this dye-recording apparatus are discussed in detail.Styryl dyes such as RH423 typically give signals of 1%/100 mV on these cells; the signals are linear in membrane potential, but do not appear to arise from a purely electrochromic mechanism. Given this voltage sensitivity and the noise level of the apparatus, it should be possible to detect both action potentials and subthreshold synaptic potentials from SCG cell bodies. In practice, dye recording can easily detect action potentials from every neuron in an SCG microculture, but small synaptic potentials are obscured by dye signals from the dense network of axons.In another microculture system that does not have such long and complex axons, this dye-recording apparatus should be able to detect synaptic potentials, making it possible to noninvasively map the synaptic connections in a microculture, and thus to study long-term synaptic plasticity.

Subsurface Optical Microscopy of Coarse Grain Spinels. Phase 1

DTIC Science & Technology

2013-12-01

A 456 nm LED line bar illuminated in figure 15 and a Xenon fiber optic bar illuminator is shown for figure 16. The optical in situ or subsurface ... imaging of coarse grain spinels and AlONs is optically more complex than expected. An overhead view of the side illumination field is shown in figure 20

Basic modelling of transport in 2D wave-mechanical nanodots and billiards with balanced gain and loss mediated by complex potentials

NASA Astrophysics Data System (ADS)

Berggren, Karl-Fredrik; Tellander, Felix; Yakimenko, Irina

2018-05-01

Non-Hermitian quantum mechanics with parity-time (PT) symmetry is presently gaining great interest, especially within the fields of photonics and optics. Here, we give a brief overview of low-dimensional semiconductor nanodevices using the example of a quantum dot with input and output leads, which are mimicked by imaginary potentials for gain and loss, and how wave functions, particle flow, coalescence of levels and associated breaking of PT symmetry may be analysed within such a framework. Special attention is given to the presence of exceptional points and symmetry breaking. Related features for musical string instruments and ‘wolf-notes’ are outlined briefly with suggestions for further experiments.

Gold and Iron-Gold Nanoparticles for Intracellular Tracking and in Vivo Medical Applicatons

NASA Astrophysics Data System (ADS)

Fu, Wei

2005-03-01

We have fabricated Au and Fe-Au nanoparticles for potential use in ex vivo experiments such as intracellular tracking, as well as a variety of in vivo medical applications. In order to improve their targeting potential, circulation time and flexibility, gold NPs were surface modified using a hetero-bifunctional poly(ethylene glycol) (PEG, MW 1,500) spacers. A coumarin-PEG-gold NP complex was formed and cell viability studies and optical fluorescence experiments were carried out demonstrating the use of these surface-modified gold NPs for drug delivery, gene therapy and cell trafficking experiments. Fe-Au nanoparticles were also fabricated and show significant contrast enhancement in MRI studies through a substantial reduction of the T2 relaxation time.

Noise-immune complex correlation for optical coherence angiography based on standard and Jones matrix optical coherence tomography

PubMed Central

Makita, Shuichi; Kurokawa, Kazuhiro; Hong, Young-Joo; Miura, Masahiro; Yasuno, Yoshiaki

2016-01-01

This paper describes a complex correlation mapping algorithm for optical coherence angiography (cmOCA). The proposed algorithm avoids the signal-to-noise ratio dependence and exhibits low noise in vasculature imaging. The complex correlation coefficient of the signals, rather than that of the measured data are estimated, and two-step averaging is introduced. Algorithms of motion artifact removal based on non perfusing tissue detection using correlation are developed. The algorithms are implemented with Jones-matrix OCT. Simultaneous imaging of pigmented tissue and vasculature is also achieved using degree of polarization uniformity imaging with cmOCA. An application of cmOCA to in vivo posterior human eyes is presented to demonstrate that high-contrast images of patients’ eyes can be obtained. PMID:27446673

Low complexity Reed-Solomon-based low-density parity-check design for software defined optical transmission system based on adaptive puncturing decoding algorithm

NASA Astrophysics Data System (ADS)

Pan, Xiaolong; Liu, Bo; Zheng, Jianglong; Tian, Qinghua

2016-08-01

We propose and demonstrate a low complexity Reed-Solomon-based low-density parity-check (RS-LDPC) code with adaptive puncturing decoding algorithm for elastic optical transmission system. Partial received codes and the relevant column in parity-check matrix can be punctured to reduce the calculation complexity by adaptive parity-check matrix during decoding process. The results show that the complexity of the proposed decoding algorithm is reduced by 30% compared with the regular RS-LDPC system. The optimized code rate of the RS-LDPC code can be obtained after five times iteration.

Page Oriented Holographic Memories And Optical Pattern Recognition

NASA Astrophysics Data System (ADS)

Caulfield, H. J.

1987-08-01

In the twenty-two years since VanderLugt's introduction of holographic matched filtering, the intensive research carried out throughout the world has led to no applications in complex environment. This leads one to the suspicion that the VanderLugt filter technique is insufficiently complex to handle truly complex problems. Therefore, it is of great interest to increase the complexity of the VanderLugt filtering operation. We introduce here an approach to the real time filter assembly: use of page oriented holographic memories and optically addressed SLMs to achieve intelligent and fast reprogramming of the filters using a 10 4 to 10 6 stored pattern base.

Dynamically reconfigurable complex emulsions via tunable interfacial tensions

PubMed Central

Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

2015-01-01

Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including multiple emulsions and Janus droplets which contain hemispheres of differing material, are of increasing importance1 in pharmaceuticals and medical diagnostics2, in the fabrication of microparticles and capsules3–5 for food6, in chemical separations7, in cosmetics8, and in dynamic optics9. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets’ physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes10, to small-volume but more precise microfluidic methods11,12. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have greatly increased utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials. PMID:25719669

Dynamically reconfigurable complex emulsions via tunable interfacial tensions.

PubMed

Zarzar, Lauren D; Sresht, Vishnu; Sletten, Ellen M; Kalow, Julia A; Blankschtein, Daniel; Swager, Timothy M

2015-02-26

Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including Janus droplets (that is, droplets with faces of differing chemistries) and multiple emulsions, are of increasing importance in pharmaceuticals and medical diagnostics, in the fabrication of microparticles and capsules for food, in chemical separations, in cosmetics, and in dynamic optics. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets' physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes, to small-volume but more precise microfluidic methods. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have great utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials.

Dynamically reconfigurable complex emulsions via tunable interfacial tensions

NASA Astrophysics Data System (ADS)

Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

2015-02-01

Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including Janus droplets (that is, droplets with faces of differing chemistries) and multiple emulsions, are of increasing importance in pharmaceuticals and medical diagnostics, in the fabrication of microparticles and capsules for food, in chemical separations, in cosmetics, and in dynamic optics. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets' physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes, to small-volume but more precise microfluidic methods. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have great utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with controllably reconfigurable morphologies and the potential to create a wide range of responsive materials.

Nonlinear and non-Hermitian optical systems applied to the development of filters and optical sensors

NASA Astrophysics Data System (ADS)

Amaro de Faria Júnior, A. C.

2015-09-01

In this work we present a method of investigation of nonlinear optical beams generated from non-Hermitian optical systems1 . This method can be applied in the development of optical filters and optical sensors to process, analyze and choose the passband of the propagation modes of an optical pulse from an non-Hermitian optical system. Non-Hermitian optical systems can be used to develop optical fiber sensors that suppress certain propagation modes of optical pulses that eventually behave as quantum noise. Such systems are described by the Nonlinear Schrödinger-like Equation with Parity-Time (PT) Symmetric Optical Potentials. There are optical fiber sensors that due to high laser intensity and frequency can produce quantum noise, such as Raman and Brillouin scattering. However, the optical fiber, for example, can be designed so that its geometry suppress certain propagation modes of the beam. We apply some results of non- Hermitian optical systems with PT symmetry to simulate optical lattice by a appropriate potential function, which among other applications, can naturally suppress certain propagation modes of an optical beam propagating through a waveguide. In other words, the optical system is modeled by a potential function in the Nonlinear Schrödinger-like Equation that one relates with the geometric aspects of the wave guides and with the optical beam interacting with the waveguide material. The paper is organized as follows: sections 1 and 2 present a brief description about nonlinear optical systems and non-Hermitian optical systems with PT symmetry. Section 3 presents a description of the dynamics of nonlinear optical pulses propagating through optical networks described by a optical potential non-Hermitian. Sections 4 and 5 present a general description of this non-Hermitian optical systems and how to get them from a more general model. Section 6 presents some conclusions and comment and the final section presents the references. Begin the abstract two lines below author names and addresses.

Lanthanides-clay nanocomposites: Synthesis, characterization and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Celedon, Salvador; Quiroz, Carolina; Gonzalez, Guillermo

2009-05-06

Complexes of Europium(III) and Terbium(III) with 2,2-bipyridine and 1,10-phenanthroline were inserted into Na-bentonite by ion exchange reactions at room temperature. The products display interlaminar distances and stoichiometries in agreement with the ion exchange capacity and the interlayer space available in the clay. The optical properties of the intercalates, being qualitatively similar to those of the free complexes, are additionally improved with respect to exchange processes with the medium, especially in a moist environment. The protection again hydrolysis, together with the intensity of the optical transition {sup 5}D{sub 0}-{sup 5}F{sub 2} observed in the nanocomposite, makes these products promising for themore » development of novel optical materials.« less

Synthesis, spectral, thermal and optical properties of Schiff-base complexes derived from 2(E)-2-((z)-4-hydroxypent-3-en-2-ylideneamino)-5-guanidinopentanoic acid and acetylacetone

NASA Astrophysics Data System (ADS)

Hosny, Nasser Mohammed; Hussien, Mostafa A.; Radwan, Fatima M.; Nawar, Nagwa

2017-09-01

New metal complexes derived from the in situ reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H2L) resulted from the condensation of 2-amino-5-guanidinopentanoic acid (arginine) and acetylacetone have been synthesized. The resulting complexes have been characterized by, elemental analyses, ES-MS, IR, Raman spectra, UV-Vis., 1HNMR, ESR, thermal analyses (TGA and DTG) and magnetic measurements. The results showed that, The Schiff-base ligand acts as bi-negative tridentate coordinating via azomethine nitrogen, enolic carbonyl oxygen and carboxylate oxygen after displacement of hydrogen. The thermodynamic parameters E∗, ΔH, ΔG and ΔS of the isolated complexes have been calculated. The optical band gap (Eg) values of Cu, Co, Ni and Zn were found to be 3.3, 3.4, 3.7 and 4.3 eV, respectively, arising from direct transitions. Optical band gap measurements indicate the semi-conductivity nature of these complexes.

On the functional anatomy of the nucleus of the optic tract-dorsal terminal nucleus commissural connection in the opossum (Didelphis marsupialis aurita).

PubMed

Vargas, C D; Volchan, E; Hokoç, J N; Pereira, A; Bernardes, R F; Rocha-Miranda, C E

1997-01-01

Immunocytochemical methods revealed the presence of GABA in cell bodies and terminals in the nucleus of the optic tract-dorsal terminal nucleus, the medial terminal nucleus, the lateral terminal nucleus and the interstitial nucleus of the superior fasciculus of the opossum (Didelphis marsupialis aurita). Moreover, after unilateral injections of rhodamine beads in the nucleus of the optic tract-dorsal terminal nucleus complex and processing for GABA, double-labelled cells were detected in the ipsilateral complex, up to 400 microns from the injected site, but not in the opposite. Analysis of the distributions of GABAergic and retrogradely-labelled cells throughout the contralateral nucleus of the optic tract-dorsal terminal nucleus showed that the highest density of GABAergic and rhodamine-labelled cells overlapped at the middle third of the complex. Previous electrophysiological data obtained in the opossum had suggested the existence, under certain conditions, of an inhibitory action between the nucleus of the optic tract-dorsal terminal nucleus of one side over the other. The absence of GABAergic commissural neurons may imply that this inhibition is mediated by an excitatory commissural pathway that activates GABAergic interneurons.

Synthesis, spectroscopic characterization, first order nonlinear optical properties and DFT calculations of novel Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with 1,3-diphenyl-4-phenylazo-5-pyrazolone ligand

NASA Astrophysics Data System (ADS)

Abdel-Latif, Samir A.; Mohamed, Adel A.

2018-02-01

Novel Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) metal ions with 1,3-diphenyl-4-phenylazo-5-pyrazolone (L) have been prepared and characterized using different analytical and spectroscopic techniques. 1:1 Complexes of Mn(II), Co(II) and Zn(II) are distorted octahedral whereas Ni(II) complex is square planar and Cu(II) is distorted trigonal bipyramid. 1:2 Complexes of Mn(II), Co(II), Cu(II) and Zn(II) are distorted trigonal bipyramid whereas Ni(II) complex is distorted tetrahedral. All complexes behave as non-ionic in dimethyl formamide (DMF). The electronic structure and nonlinear optical parameters (NLO) of the complexes were investigated theoretically at the B3LYP/GEN level of theory. Molecular stability and bond strengths have been investigated by applying natural bond orbital (NBO) analysis. The geometries of the studied complexes are non-planner. DFT calculations have been also carried out to calculate the global properties; hardness (η), global softness (S) and electronegativity (χ). The calculated small energy gap between HOMO and LUMO energies shows that the charge transfer occurs within the complexes. The total static dipole moment (μtot), the mean polarizability (<α>), the anisotropy of the polarizability (Δα) and the mean first-order hyperpolarizability (<β>) were calculated and compared with urea as a reference material. The complexes show implying optical properties.

Potential use of combining the diffusion equation with the free Shrödinger equation to improve the Optical Coherence Tomography image analysis

NASA Astrophysics Data System (ADS)

Cabrera Fernandez, Delia; Salinas, Harry M.; Somfai, Gabor; Puliafito, Carmen A.

2006-03-01

Optical coherence tomography (OCT) is a rapidly emerging medical imaging technology. In ophthalmology, OCT is a powerful tool because it enables visualization of the cross sectional structure of the retina and anterior eye with higher resolutions than any other non-invasive imaging modality. Furthermore, OCT image information can be quantitatively analyzed, enabling objective assessment of features such as macular edema and diabetes retinopathy. We present specific improvements in the quantitative analysis of the OCT system, by combining the diffusion equation with the free Shrödinger equation. In such formulation, important features of the image can be extracted by extending the analysis from the real axis to the complex domain. Experimental results indicate that our proposed novel approach has good performance in speckle noise removal, enhancement and segmentation of the various cellular layers of the retina using the OCT system.

Asymmetric optical image encryption using Kolmogorov phase screens and equal modulus decomposition

NASA Astrophysics Data System (ADS)

Kumar, Ravi; Bhaduri, Basanta; Quan, Chenggen

2017-11-01

An asymmetric technique for optical image encryption is proposed using Kolmogorov phase screens (KPSs) and equal modulus decomposition (EMD). The KPSs are generated using the power spectral density of Kolmogorov turbulence. The input image is first randomized and then Fresnel propagated with distance d. Further, the output in the Fresnel domain is modulated with a random phase mask, and the gyrator transform (GT) of the modulated image is obtained with an angle α. The EMD is operated on the GT spectrum to get the complex images, Z1 and Z2. Among these, Z2 is reserved as a private key for decryption and Z1 is propagated through a medium consisting of four KPSs, located at specified distances, to get the final encrypted image. The proposed technique provides a large set of security keys and is robust against various potential attacks. Numerical simulation results validate the effectiveness and security of the proposed technique.

Investigations of the Optical Properties of GaNAs Alloys by First-Principle.

PubMed

Borovac, Damir; Tan, Chee-Keong; Tansu, Nelson

2017-12-11

We present a Density Functional Theory (DFT) analysis of the optical properties of dilute-As GaN 1-x As x alloys with arsenic (As) content ranging from 0% up to 12.5%. The real and imaginary parts of the dielectric function are investigated, and the results are compared to experimental and theoretical values for GaN. The analysis extends to present the complex refractive index and the normal-incidence reflectivity. The refractive index difference between GaN and GaNAs alloys can be engineered to be up to ~0.35 in the visible regime by inserting relatively low amounts of As-content into the GaN system. Thus, the analysis elucidates on the birefringence of the dilute-As GaNAs alloys and comparison to other experimentally characterized III-nitride systems is drawn. Our findings indicate the potential of GaNAs alloys for III-nitride based waveguide and photonic circuit design applications.

Refractive-index measurement and inverse correction using optical coherence tomography.

PubMed

Stritzel, Jenny; Rahlves, Maik; Roth, Bernhard

2015-12-01

We describe a novel technique for determination of the refractive index of hard biological tissue as well as nonopaque technical samples based on optical coherence tomography (OCT). Our method relies on an inverse refractive-index correction (I-RIC), which matches a measured feature geometry distorted due to refractive-index boundaries to its real geometry. For known feature geometry, the refractive index can be determined with high precision from the best match between the distorted and corrected images. We provide experimental data for refractive-index measurements on a polymethylmethacrylate (PMMA) and on an ex vivo porcine cranial-bone, which are compared to reference measurements and previously published data. Our method is potentially capable of in vivo measurements on rigid biological tissue such as bone as, for example, is required to improve guidance in robot-aided surgical interventions and also for retrieving complex refractive-index profiles of compound materials.

Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

DOE PAGES

Kamaraju, N.; Pan, W.; Ekenberg, U.; ...

2015-01-21

Two-dimensional hole gases (2DHGs) have attracted recent attention for their unique quantum physics and potential applications in areas including spintronics and quantum computing. However, their properties remain relatively unexplored, motivating the use of different techniques to study them. We used terahertz magneto-optical spectroscopy to investigate the cyclotron resonance frequency in a high mobility 2DHG, revealing a nonlinear dependence on the applied magnetic field. This is also shown to be due to the complex non-parabolic valence band structure of the 2DHG, as verified by multiband Landau level calculations. We also find that impurity scattering dominates cyclotron resonance decay in the 2DHG,more » in contrast with the dominance of superradiant damping in two-dimensional electron gases. Furthermore, these results shed light on the properties of 2DHGs, motivating further studies of these unique 2D nanosystems.« less

Deep-tissue focal fluorescence imaging with digitally time-reversed ultrasound-encoded light

PubMed Central

Wang, Ying Min; Judkewitz, Benjamin; DiMarzio, Charles A.; Yang, Changhuei

2012-01-01

Fluorescence imaging is one of the most important research tools in biomedical sciences. However, scattering of light severely impedes imaging of thick biological samples beyond the ballistic regime. Here we directly show focusing and high-resolution fluorescence imaging deep inside biological tissues by digitally time-reversing ultrasound-tagged light with high optical gain (~5×105). We confirm the presence of a time-reversed optical focus along with a diffuse background—a corollary of partial phase conjugation—and develop an approach for dynamic background cancellation. To illustrate the potential of our method, we image complex fluorescent objects and tumour microtissues at an unprecedented depth of 2.5 mm in biological tissues at a lateral resolution of 36 μm×52 μm and an axial resolution of 657 μm. Our results set the stage for a range of deep-tissue imaging applications in biomedical research and medical diagnostics. PMID:22735456

Transient GaAs plasmonic metasurfaces at terahertz frequencies

DOE PAGES

Yang, Yuanmu; Kamaraju, N.; Campione, Salvatore; ...

2016-12-09

Here we demonstrate the ultrafast formation of terahertz (THz) metasurfaces through all-optical creation of spatially modulated carrier density profiles in a deep-subwavelength GaAs film. The switch-on of the transient plasmon mode, governed by the GaAs effective electron mass and electron–phonon interactions, is revealed by structured-optical pump THz probe spectroscopy, on a time scale of 500 fs. By modulating the carrier density using different pump fluences, we observe a wide tuning of the electric dipole resonance of the transient GaAs metasurface from 0.5 THz to 1.7 THz. Furthermore, we numerically demonstrate that the metasurface presented here can be generalized to moremore » complex architectures for realizing functionalities such as perfect absorption, leading to a 30 dB modulation depth. In conclusion, the platform also provides a pathway to achieve ultrafast manipulation of infrared beams in the linear and, potentially, nonlinear regime.« less

Binocular adaptive optics visual simulator.

PubMed

Fernández, Enrique J; Prieto, Pedro M; Artal, Pablo

2009-09-01

A binocular adaptive optics visual simulator is presented. The instrument allows for measuring and manipulating ocular aberrations of the two eyes simultaneously, while the subject performs visual testing under binocular vision. An important feature of the apparatus consists on the use of a single correcting device and wavefront sensor. Aberrations are controlled by means of a liquid-crystal-on-silicon spatial light modulator, where the two pupils of the subject are projected. Aberrations from the two eyes are measured with a single Hartmann-Shack sensor. As an example of the potential of the apparatus for the study of the impact of the eye's aberrations on binocular vision, results of contrast sensitivity after addition of spherical aberration are presented for one subject. Different binocular combinations of spherical aberration were explored. Results suggest complex binocular interactions in the presence of monochromatic aberrations. The technique and the instrument might contribute to the better understanding of binocular vision and to the search for optimized ophthalmic corrections.

Optical micromanipulation of nanoparticles and cells inside living zebrafish.

PubMed

Johansen, Patrick Lie; Fenaroli, Federico; Evensen, Lasse; Griffiths, Gareth; Koster, Gerbrand

2016-03-21

Regulation of biological processes is often based on physical interactions between cells and their microenvironment. To unravel how and where interactions occur, micromanipulation methods can be used that offer high-precision control over the duration, position and magnitude of interactions. However, lacking an in vivo system, micromanipulation has generally been done with cells in vitro, which may not reflect the complex in vivo situation inside multicellular organisms. Here using optical tweezers we demonstrate micromanipulation throughout the transparent zebrafish embryo. We show that different cells, as well as injected nanoparticles and bacteria can be trapped and that adhesion properties and membrane deformation of endothelium and macrophages can be analysed. This non-invasive micromanipulation inside a whole-organism gives direct insights into cell interactions that are not accessible using existing approaches. Potential applications include screening of nanoparticle-cell interactions for cancer therapy or tissue invasion studies in cancer and infection biology.

Photo Protection of Haematococcus pluvialis Algae by Astaxanthin: Unique Properties of Astaxanthin Deduced by EPR, Optical and Electrochemical Studies

PubMed Central

Focsan, A. Ligia; Polyakov, Nikolay E.; Kispert, Lowell D.

2017-01-01

The antioxidant astaxanthin is known to accumulate in Haematococcus pluvialis algae under unfavorable environmental conditions for normal cell growth. The accumulated astaxanthin functions as a protective agent against oxidative stress damage, and tolerance to excessive reactive oxygen species (ROS) is greater in astaxanthin-rich cells. The detailed mechanisms of protection have remained elusive, however, our Electron Paramagnetic Resonance (EPR), optical and electrochemical studies on carotenoids suggest that astaxanthin’s efficiency as a protective agent could be related to its ability to form chelate complexes with metals and to be esterified, its inability to aggregate in the ester form, its high oxidation potential and the ability to form proton loss neutral radicals under high illumination in the presence of metal ions. The neutral radical species formed by deprotonation of the radical cations can be very effective quenchers of the excited states of chlorophyll under high irradiation. PMID:29065482

Optical Control of Internal Conversion in Pyrazine

NASA Astrophysics Data System (ADS)

Barry, Grant; Singha, Sima; Hu, Zhan; Seideman, Tamar; Gordon, Robert

2014-03-01

We apply quantum control schemes previously reserved for atoms and small molecules to more complex polyatomic molecules. Pyrazine was chosen as a model polyatomic molecule for its well-studied conical intersection seam between the S1 and S2 potential energy surfaces (PESs). Using shaped ultraviolet femtosecond laser pulses, we demonstrate optical control of the excited state dynamics of this molecule under collisionless conditions. This was achieved in a pump-probe experiment by employing a genetic algorithm programmed to suppress ionization of the pyrazine molecules at a preselected time. Our findings indicate that the optimized pulses localize the wave packet for times up to 1.5 ps at a location on the coupled S1/S2 PESs where ionization is energetically forbidden. Our approach is general and does not require knowledge of the molecular Hamiltonian. Funding provided by National Science Foundation grant no. CHE-0848198.

Importance of Electronic Correlations and Unusual Excitonic Effects in Formamidinium Lead Halide Perovskites

NASA Astrophysics Data System (ADS)

Whitcher, T. J.; Zhu, J.-X.; Chi, X.; Hu, H.; Zhao, Daming; Asmara, T. C.; Yu, X.; Breese, M. B. H.; Castro Neto, A. H.; Lam, Y. M.; Wee, A. T. S.; Chia, Elbert E. M.; Rusydi, A.

2018-04-01

Hybrid inorganic-organic perovskites have recently attracted much interest because of both rich fundamental sciences and potential applications such as the primary energy-harvesting material in solar cells. However, an understanding of electronic and optical properties, particularly the complex dielectric function, of these materials is still lacking. Here, we report on the electronic and optical properties of selective perovskites using temperature-dependent spectroscopic ellipsometry, x-ray absorption spectroscopy supported by first-principles calculations. Surprisingly, the perovskite FA0.85Cs0.15PbI2.9Br0.1 has a very high density of low-energy excitons that increases with increasing temperature even at room temperature, which is not seen in any other material. This is found to be due to the strong, unscreened electron-electron and partially screened electron-hole interactions, which then tightly connect low- and high-energy bands caused by doping.

Compact Hyperspectral Mapper for Environmental Remote Sensing Applications (CHyMERA) End-of-phase Data Review Package

NASA Technical Reports Server (NTRS)

Janz, Scott J.; Hilsenrath, Ernest; Mount, George; Heath, Donald

2000-01-01

CHYMERA is an Instrument Incubator concept to design, build, and test an instrument that will reduce size, mass, and cost and increase science potential and flexibility for future atmospheric remote sensing missions within the focus of NASA's Earth Science Enterprise (ESE). The primary effort of the development plan will be on high spatial resolution ozone, N02, S02, aerosol, and cloud measurements, but it is hoped that the techniques developed will prove useful for other measurements as well. The core design will involve a high performance, wide field-of-view (FOV) front end telescope which will illuminate a filter/focal plane array (FFPA) package. The use of a non-dispersive optical configuration will reduce size, mass and complexity. The wide FOV optics will permit short duration global coverage (1-2 days) without the need for a scanner.

Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamaraju, N., E-mail: nkamaraju@lanl.gov; Taylor, A. J.; Prasankumar, R. P., E-mail: rpprasan@lanl.gov

2015-01-19

Two-dimensional hole gases (2DHGs) have attracted recent attention for their unique quantum physics and potential applications in areas including spintronics and quantum computing. However, their properties remain relatively unexplored, motivating the use of different techniques to study them. We used terahertz magneto-optical spectroscopy to investigate the cyclotron resonance frequency in a high mobility 2DHG, revealing a nonlinear dependence on the applied magnetic field. This is shown to be due to the complex non-parabolic valence band structure of the 2DHG, as verified by multiband Landau level calculations. We also find that impurity scattering dominates cyclotron resonance decay in the 2DHG, inmore » contrast with the dominance of superradiant damping in two-dimensional electron gases. Our results shed light on the properties of 2DHGs, motivating further studies of these unique 2D nanosystems.« less

Structural complexity and wide application of two-dimensional S/O type antimonene

NASA Astrophysics Data System (ADS)

Li, T. T.; He, C.; Zhang, W. X.

2018-05-01

Inspired by stable two-dimensional antimonene phases, two new allotropes (S/O and tricycle) antimonenes have been predicted by first-principles calculations in this paper. S/O type antimonene possesses remarkably thermodynamical and dynamical stability, which are comparable to that of buckled type antimonene. The results indicate that S/O type antimonene is a direct band gap semiconductor with a band gap of 2.314 eV and the electronic properties could be effectively tuned by the in-plane strain. In order to explore the potential application, the mechanical properties and optical properties of S/O type antimonene are also extensively studied. It is found the S/O type antimonene is an anisotropic material by the method of analyzing the linear Poisson's ratios and the phonon band structure. These systematical analyses show that S/O type antimonene is a new 2D material with tunable electronic properties, excellent mechanical and optical properties.

Multi-distance diffuse optical spectroscopy with a single optode via hypotrochoidal scanning.

PubMed

Applegate, Matthew B; Roblyer, Darren

2018-02-15

Frequency-domain diffuse optical spectroscopy (FD-DOS) is an established technique capable of determining optical properties and chromophore concentrations in biological tissue. Most FD-DOS systems use either manually positioned, handheld probes or complex arrays of source and detector fibers to acquire data from many tissue locations, allowing for the generation of 2D or 3D maps of tissue. Here, we present a new method to rapidly acquire a wide range of source-detector (SD) separations by mechanically scanning a single SD pair. The source and detector fibers are mounted on a scan head that traces a hypotrochoidal pattern over the sample that, when coupled with a high-speed FD-DOS system, enables the rapid collection of dozens of SD separations for depth-resolved imaging. We demonstrate that this system has an average error of 4±2.6% in absorption and 2±1.8% in scattering across all SD separations. Additionally, by linearly translating the device, the size and location of an absorbing inhomogeneity can be determined through the generation of B-scan images in a manner conceptually analogous to ultrasound imaging. This work demonstrates the potential of single optode diffuse optical scanning for depth resolved visualization of heterogeneous biological tissues at near real-time rates.

Development of a low-cost optical sensor for cupric reducing antioxidant capacity measurement of food extracts.

PubMed

Bener, Mustafa; Ozyürek, Mustafa; Güçlü, Kubilay; Apak, Reşat

2010-05-15

A low-cost optical sensor using an immobilized chromogenic redox reagent was devised for measuring the total antioxidant level in a liquid sample without requiring sample pretreatment. The reagent, copper(II)-neocuproine (Cu(II)-Nc) complex, was immobilized onto a cation-exchanger film of Nafion, and the absorbance changes associated with the formation of the highly colored Cu(I)-Nc chelate as a result of reaction with antioxidants was measured at 450 nm. The sensor gave a linear response over a wide concentration range of standard antioxidant compounds. The trolox equivalent antioxidant capacity (TEAC) values of various antioxidants reported in this work using the optical sensor-based "cupric reducing antioxidant capacity" (CUPRAC) assay were comparable to those of the standard solution-based CUPRAC assay, showing that the immobilized Cu(II)-Nc reagent retained its reactivity toward antioxidants. Common food ingredients like oxalate, citrate, fruit acids, and reducing sugars did not interfere with the proposed sensing method. This assay was validated through linearity, additivity, precision, and recovery, demonstrating that the assay is reliable and robust. The developed optical sensor was used to screen total antioxidant capacity (TAC) of some commercial fruit juices without preliminary treatment and showed a promising potential for the preparation of antioxidant inventories of a wide range of food plants.

Development of metrology for freeform optics in reflection mode

NASA Astrophysics Data System (ADS)

Burada, Dali R.; Pant, Kamal K.; Mishra, Vinod; Bichra, Mohamed; Khan, Gufran S.; Sinzinger, Stefan; Shakher, Chandra

2017-06-01

The increased range of manufacturable freeform surfaces offered by the new fabrication techniques is giving opportunities to incorporate them in the optical systems. However, the success of these fabrication techniques depends on the capabilities of metrology procedures and a feedback mechanism to CNC machines for optimizing the manufacturing process. Therefore, a precise and in-situ metrology technique for freeform optics is in demand. Though all the techniques available for aspheres have been extended for the freeform surfaces by the researchers, but none of the techniques has yet been incorporated into the manufacturing machine for in-situ measurement. The most obvious reason is the complexity involved in the optical setups to be integrated in the manufacturing platforms. The Shack-Hartmann sensor offers the potential to be incorporated into the machine environment due to its vibration insensitivity, compactness and 3D shape measurement capability from slope data. In the present work, a measurement scheme is reported in which a scanning Shack-Hartmann Sensor has been employed and used as a metrology tool for measurement of freeform surface in reflection mode. Simulation studies are conducted for analyzing the stitching accuracy in presence of various misalignment errors. The proposed scheme is experimentally verified on a freeform surface of cubic phase profile.

Tensor network states in time-bin quantum optics

NASA Astrophysics Data System (ADS)

Lubasch, Michael; Valido, Antonio A.; Renema, Jelmer J.; Kolthammer, W. Steven; Jaksch, Dieter; Kim, M. S.; Walmsley, Ian; García-Patrón, Raúl

2018-06-01

The current shift in the quantum optics community towards experiments with many modes and photons necessitates new classical simulation techniques that efficiently encode many-body quantum correlations and go beyond the usual phase-space formulation. To address this pressing demand we formulate linear quantum optics in the language of tensor network states. We extensively analyze the quantum and classical correlations of time-bin interference in a single fiber loop. We then generalize our results to more complex time-bin quantum setups and identify different classes of architectures for high-complexity and low-overhead boson sampling experiments.

Measurement of the complex transmittance of large optical elements with Ptychographical Iterative Engine.

PubMed

Wang, Hai-Yan; Liu, Cheng; Veetil, Suhas P; Pan, Xing-Chen; Zhu, Jian-Qiang

2014-01-27

Wavefront control is a significant parameter in inertial confinement fusion (ICF). The complex transmittance of large optical elements which are often used in ICF is obtained by computing the phase difference of the illuminating and transmitting fields using Ptychographical Iterative Engine (PIE). This can accurately and effectively measure the transmittance of large optical elements with irregular surface profiles, which are otherwise not measurable using commonly used interferometric techniques due to a lack of standard reference plate. Experiments are done with a Continue Phase Plate (CPP) to illustrate the feasibility of this method.

The double quasar 0957+561: a radio study at 6-centimeters wavelength.

PubMed

Roberts, D H; Greenfield, P E; Burke, B F

1979-08-31

The optical double quasar 0957+561 has been interpreted as the gravitational double image of a single object. A radio map made with the Very Large Array of the National Radio Astronomy Observatory shows unresolved sources coincident With the optical images as well as a complex of related extended emission. Although the results cannot rule out the gravitational lens hypothesis, the complex radio structure is more easily interpreted as two separate quasars. The optical and radio properties of the two quasars are so similar that the two must have been formed at the same time with similar initial conditions.

Optical techniques to feed and control GaAs MMIC modules for phased array antenna applications

NASA Astrophysics Data System (ADS)

Bhasin, K. B.; Anzic, G.; Kunath, R. R.; Connolly, D. J.

A complex signal distribution system is required to feed and control GaAs monolithic microwave integrated circuits (MMICs) for phased array antenna applications above 20 GHz. Each MMIC module will require one or more RF lines, one or more bias voltage lines, and digital lines to provide a minimum of 10 bits of combined phase and gain control information. In a closely spaced array, the routing of these multiple lines presents difficult topology problems as well as a high probability of signal interference. To overcome GaAs MMIC phased array signal distribution problems optical fibers interconnected to monolithically integrated optical components with GaAs MMIC array elements are proposed as a solution. System architecture considerations using optical fibers are described. The analog and digital optical links to respectively feed and control MMIC elements are analyzed. It is concluded that a fiber optic network will reduce weight and complexity, and increase reliability and performance, but higher power will be required.

Optical techniques to feed and control GaAs MMIC modules for phased array antenna applications

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Anzic, G.; Kunath, R. R.; Connolly, D. J.

1986-01-01

A complex signal distribution system is required to feed and control GaAs monolithic microwave integrated circuits (MMICs) for phased array antenna applications above 20 GHz. Each MMIC module will require one or more RF lines, one or more bias voltage lines, and digital lines to provide a minimum of 10 bits of combined phase and gain control information. In a closely spaced array, the routing of these multiple lines presents difficult topology problems as well as a high probability of signal interference. To overcome GaAs MMIC phased array signal distribution problems optical fibers interconnected to monolithically integrated optical components with GaAs MMIC array elements are proposed as a solution. System architecture considerations using optical fibers are described. The analog and digital optical links to respectively feed and control MMIC elements are analyzed. It is concluded that a fiber optic network will reduce weight and complexity, and increase reliability and performance, but higher power will be required.

A selective optical sensor based on [9]mercuracarborand-3, a new type of ionophore with a chloride complexing cavity

NASA Technical Reports Server (NTRS)

Badr, I. H.; Johnson, R. D.; Diaz, M.; Hawthorne, M. F.; Bachas, L. G.; Daunert, S. (Principal Investigator)

2000-01-01

A highly selective optical sensor for chloride, based on the multidentate Lewis acid ionophore [9]mercuracarborand-3, is described herein. This sensor is constructed by embedding the mercuracarborand ionophore, a suitable pH-sensitive lipophilic dye, and lipophilic cationic sites in a plasticized polymeric membrane. The multiple complementary interactions offered by the preorganized complexing cavity of [9]mercuracarborand-3 is shown to control the anion selectivity pattern of the optical film. The film exhibits a significantly enhanced selectivity for chloride over a variety of lipophilic anions such as perchlorate, nitrate, salicylate, and thiocyanate. Furthermore, the optical selectivity coefficients obtained for chloride over other biologically relevant anions are shown to meet the selectivity requirements for the determination of chloride in physiological fluids, unlike previously reported chloride optical sensors. In addition, the optical film responds to chloride reversibly over a wide dynamic range (16 microM-136 mM) with fast response and recovery times.

Organic light-emitting diodes from homoleptic square planar complexes

DOEpatents

Omary, Mohammad A

2013-11-12

Homoleptic square planar complexes [M(N.LAMBDA.N).sub.2], wherein two identical N.LAMBDA.N bidentate anionic ligands are coordinated to the M(II) metal center, including bidentate square planar complexes of triazolates, possess optical and electrical properties that make them useful for a wide variety of optical and electrical devices and applications. In particular, the complexes are useful for obtaining white or monochromatic organic light-emitting diodes ("OLEDs"). Improved white organic light emitting diode ("WOLED") designs have improved efficacy and/or color stability at high brightness in single- or two-emitter white or monochrome OLEDs that utilize homoleptic square planar complexes, including bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) ("Pt(ptp).sub.2").

Fiber optic-based biosensor

NASA Technical Reports Server (NTRS)

Ligler, Frances S.

1991-01-01

The NRL fiber optic biosensor is a device which measures the formation of a fluorescent complex at the surface of an optical fiber. Antibodies and DNA binding proteins provide the mechanism for recognizing an analyze and immobilizing a fluorescent complex on the fiber surface. The fiber optic biosensor is fast, sensitive, and permits analysis of hazardous materials remote from the instrumentation. The fiber optic biosensor is described in terms of the device configuration, chemistry for protein immobilization, and assay development. A lab version is being used for assay development and performance characterization while a portable device is under development. Antibodies coated on the fiber are stable for up to two years of storage prior to use. The fiber optic biosensor was used to measure concentration of toxins in the parts per billion (ng/ml) range in under a minute. Immunoassays for small molecules and whole bacteria are under development. Assays using DNA probes as the detection element can also be used with the fiber optic sensor, which is currently being developed to detect biological warfare agents, explosives, pathogens, and toxic materials which pollute the environment.

Complex topological structures of frustrated liquid crystals with potential for optics and photonics (Presentation Recording)

NASA Astrophysics Data System (ADS)

Žumer, Slobodan; Čančula, Miha; Čopar, Simon; Ravnik, Miha

2015-10-01

Geometrical constrains and intrinsic chirality in nematic mesophases enable formation of stable and metastable complex defect structures. Recently selected knotted and linked disclinations have been formed using laser manipulation of nematic braids entangling colloidal particles in nematic colloids [Tkalec et al., Science 2011; Copar et al., PNAS 2015]. In unwinded chiral nematic phases stable and metastable toron and hopfion defects have been implemented by laser tweezers [Smalyukh et al., Nature Materials 2010; Chen et al., PRL2013] and in chiral nematic colloids particles dressed by solitonic deformations [Porenta et al., Sci. Rep. 2014]. Modelling studies based on the numerical minimisation of the phenomenological free energy, supported with the adapted topological theory [Copar and Zumer, PRL 2011; Copar, Phys. Rep. 2014] allow describing the observed nematic defect structures and also predicting numerous structures in confined blue phases [Fukuda and Zumer, Nature Comms 2011 and PRL 2011] and stable knotted disclinations in cholesteric droplets with homeotropic boundary [Sec et al., Nature Comms 2014]. Coupling the modeling with finite difference time domain light field computation enables understanding of light propagation and light induced restructuring in these mesophases. The method was recently demonstrated for the description of low intensity light beam changes during the propagation along disclination lines [Brasselet et al., PRL 2009; Cancula et al., PRE 2014]. Allowing also high intensity light an order restructuring is induced [Porenta et al., Soft Matter 2012; Cancula et al., 2015]. These approaches help to uncover the potential of topological structures for beyond-display optical and photonic applications.

Towards a unifying theory for the first-, second-, and third-order molecular (non)linear optical response

NASA Astrophysics Data System (ADS)

Pérez-Moreno, Javier; Clays, Koen; Kuzyk, Mark G.

2010-05-01

We present a procedure for the modeling of the dispersion of the nonlinear optical response of complex molecular structures that is based strictly on the results from experimental characterization. We show how under some general conditions, the use of the Thomas-Kuhn sum-rules leads to a successful modeling of the nonlinear response of complex molecular structures.

Improved Algorithms for Accurate Retrieval of UV - Visible Diffuse Attenuation Coefficients in Optically Complex, Inshore Waters

NASA Technical Reports Server (NTRS)

Cao, Fang; Fichot, Cedric G.; Hooker, Stanford B.; Miller, William L.

2014-01-01

Photochemical processes driven by high-energy ultraviolet radiation (UVR) in inshore, estuarine, and coastal waters play an important role in global bio geochemical cycles and biological systems. A key to modeling photochemical processes in these optically complex waters is an accurate description of the vertical distribution of UVR in the water column which can be obtained using the diffuse attenuation coefficients of down welling irradiance (Kd()). The Sea UV Sea UVc algorithms (Fichot et al., 2008) can accurately retrieve Kd ( 320, 340, 380,412, 443 and 490 nm) in oceanic and coastal waters using multispectral remote sensing reflectances (Rrs(), Sea WiFS bands). However, SeaUVSeaUVc algorithms are currently not optimized for use in optically complex, inshore waters, where they tend to severely underestimate Kd(). Here, a new training data set of optical properties collected in optically complex, inshore waters was used to re-parameterize the published SeaUVSeaUVc algorithms, resulting in improved Kd() retrievals for turbid, estuarine waters. Although the updated SeaUVSeaUVc algorithms perform best in optically complex waters, the published SeaUVSeaUVc models still perform well in most coastal and oceanic waters. Therefore, we propose a composite set of SeaUVSeaUVc algorithms, optimized for Kd() retrieval in almost all marine systems, ranging from oceanic to inshore waters. The composite algorithm set can retrieve Kd from ocean color with good accuracy across this wide range of water types (e.g., within 13 mean relative error for Kd(340)). A validation step using three independent, in situ data sets indicates that the composite SeaUVSeaUVc can generate accurate Kd values from 320 490 nm using satellite imagery on a global scale. Taking advantage of the inherent benefits of our statistical methods, we pooled the validation data with the training set, obtaining an optimized composite model for estimating Kd() in UV wavelengths for almost all marine waters. This optimized composite set of SeaUVSeaUVc algorithms will provide the optical community with improved ability to quantify the role of solar UV radiation in photochemical and photobiological processes in the ocean.

Luminescent Properties of Eu(III) Chelates on Metal Nanorods

PubMed Central

Zhang, Jian; Fu, Yi; Ray, Krishanu; Wang, Yuan; Lakowicz, Joseph. R.

2013-01-01

In this article, we report the change of optical properties for europium chelates on silver nanorods by near-field interactions. The silver rods were fabricated in a seed-growth method followed by depositing thin layers of silica on the surfaces. The europium chelates were physically absorbed in the silica layers on the silver rods. The silver rods were observed to exhibit two plasmon absorption bands from longitudinal and transverse directions, respectively, centered at 394 and 675 nm, close to absorption and emission bands from the Eu(III) chelates. As a result, the immobilized Eu(III) chelates on the silver rods should have strong interactions with the silver nanorods and lead to greatly improved optical properties. The Eu–Ag rod complexes were observed to have enhanced emission intensity up to 240-fold in comparison with the Eu(III) chelates in the metal-free silica templates. This enhancement is much larger than the value for the Eu(III) chelates on the gold rods or silver spheres indicating the presence of stronger interactions for the Eu(III) chelates with the silver rods. The interactions of Eu(III) chelates with the silver rods were also proven by extremely reduced lifetime. Moreover, the Eu–Ag rod complexes exhibited a polarized emission, which was also due to strong interactions of the Eu(III) chelates with the silver rods. All of these features may promise that the Eu(III)–Ag rod complexes have great potential for use as fluorescence imaging agents in biological assays. PMID:24363816

Optical Imaging and Control of Neurons

NASA Astrophysics Data System (ADS)

Song, Yoon-Kyu

Although remarkable progress has been made in our understanding of the function, organization, and development of the brain by various approaches of modern science and technology, how the brain performs its marvelous function remains unsolved or incompletely understood. This is mainly attributed to the insufficient capability of currently available research tools and conceptual frameworks to deal with enormous complexity of the brain. Hence, in the last couple of decades, a significant effort has been made to crack the complexity of brain by utilizing research tools from diverse scientific areas. The research tools include the optical neurotechnology which incorporates the exquisite characteristics of optics, such as multi-parallel access and non-invasiveness, in sensing and stimulating the excitable membrane of a neuron, the basic functional unit of the brain. This chapter is aimed to serve as a short introduction to the optical neurotechnology for those who wish to use optical techniques as one of their brain research tools.

Optical vortex knots in tightly-focused light beams

NASA Astrophysics Data System (ADS)

Dennis, Mark; Sugic, Danica

Optical vortices, that is, zero lines of complex amplitude in a propagating light field, can be knotted or linked in a controlled way. This was demonstrated previously in experiments where a computer-controlled hologram determined the amplitude of paraxial laser light, meaning the longitudinal extent of the knot was several orders of magnitude larger than its width. We describe what happens to these optical knots when the transverse width of the beam, and hence the knot, is reduced. Outside the paraxial regime, the field's polarization becomes highly inhomogeneous, and knotted structures occur in a variety of polarization singularities. We propose experiments realising these knotted polarization structures in tightly-focused beams, which should yield optical knots of unit aspect ratio, of several optical wavelengths in size, which could be suitable for embedding knotted defect structures in liquid crystals, Bose-Einstein condensates and photopolymers. This work was supported by the Leverhulme Trust Programme Grant ''Scientific Properties of Complex Knots''.

Optically active single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Peng, Xiaobin; Komatsu, Naoki; Bhattacharya, Sumanta; Shimawaki, Takanori; Aonuma, Shuji; Kimura, Takahide; Osuka, Atsuhiro

2007-06-01

The optical, electrical and mechanical properties of single-walled carbon nanotubes (SWNTs) are largely determined by their structures, and bulk availability of uniform materials is vital for extending their technological applications. Since they were first prepared, much effort has been directed toward selective synthesis and separation of SWNTs with specific structures. As-prepared samples of chiral SWNTs contain equal amounts of left- and right-handed helical structures, but little attention has been paid to the separation of these non-superimposable mirror image forms, known as optical isomers. Here, we show that optically active SWNT samples can be obtained by preferentially extracting either right- or left-handed SWNTs from a commercial sample. Chiral `gable-type' diporphyrin molecules bind with different affinities to the left- and right-handed helical nanotube isomers to form complexes with unequal stabilities that can be readily separated. Significantly, the diporphyrins can be liberated from the complexes afterwards, to provide optically enriched SWNTs.

Duobinary pulse shaping for frequency chirp enabled complex modulation.

PubMed

Che, Di; Yuan, Feng; Khodakarami, Hamid; Shieh, William

2016-09-01

The frequency chirp of optical direct modulation (DM) used to be a performance barrier of optical transmission system, because it broadens the signal optical spectrum, which becomes more susceptible to chromatic dispersion induced inter-symbol interference (ISI). However, by considering the chirp as frequency modulation, the single DM simultaneously generates a 2-D signal containing the intensity and phase (namely, the time integral of frequency). This complex modulation concept significantly increases the optical signal to noise ratio (OSNR) sensitivity of DM systems. This Letter studies the duobinary pulse shaping (DB-PS) for chirp enabled DM and its impact on the optical bandwidth and system OSNR sensitivity. DB-PS relieves the bandwidth requirement, at the sacrifice of system OSNR sensitivity. As DB-PS induces a controlled ISI, the receiver requires one more tap for maximum likelihood sequence estimation (MLSE). We verify this modified MLSE with a 10-Gbaud duobinary PAM-4 transmission experiment.

The Determination of Molecular Quantities from Measurements on Macroscopic Systems.V. Existence and Properties of 1:1 and 2:1-Electron-Donor-Acceptor Complexes of Hexamethylbenzene with Tetracyanoethylene

NASA Astrophysics Data System (ADS)

Liptay, Wolfgang; Rehm, Torsten; Wehning, Detlev; Schanne, Lothar; Baumann, Wolfram; Lang, Werner

1982-12-01

The formation of electron-donor-acceptor complexes of hexamethylbenzene (HMB) with tetracyanoethylene (TCNE) was investigated by measurements of the optical absorptions, the densities, the permittivities and the electro-optical absorptions of solutions in CCl4. The careful evaluation of data based on some previously reported models, has shown that the assumption of the formation of the 1: 1 and the 2 : 1 complex agrees with all experimental data, but that the assumption of the formation of only the 1: 1 complex is contradictory to experimental facts even if the activity effects on the equilibrium constant and of the solvent dependences of observed molar quantities are taken into account. The evaluation leads to the molar optical absorption coefficients and the molar volumes of both complexes and to their electric dipole moments in the electronic ground state and the considered excited state. According to these results the complexes are of the sandwich type HMB-TCNE and HMB-TCNE-HMB. In spite of the fact that the 2: 1 complex owns a center of symmetry, at least approximately, there is a rather large electric dipole moment in its excited state. Furthermore, values for the equilibrium constants and for the standard reaction enthalpies of both complex formation reactions are estimated from experimental data.

Global optical model potential for A=3 projectiles

NASA Astrophysics Data System (ADS)

Pang, D. Y.; Roussel-Chomaz, P.; Savajols, H.; Varner, R. L.; Wolski, R.

2009-02-01

A global optical model potential (GDP08) for He3 projectiles has been obtained by simultaneously fitting the elastic scattering data of He3 from targets of 40⩽AT⩽209 at incident energies of 30⩽Einc⩽217 MeV. Uncertainties and correlation coefficients between the global potential parameters were obtained by using the bootstrap statistical method. GDP08 was found to satisfactorily account for the elastic scattering of H3 as well, which makes it a global optical potential for the A=3 nuclei. Optical model calculations using the GDP08 global potential are compared with the experimental angular distributions of differential cross sections for He3-nucleus and H3-nucleus scattering from different targets of 6⩽AT⩽232 at incident energies of 4⩽Einc⩽450 MeV. The optical potential for the doubly-magic nucleus Ca40, the low-energy correction to the real potential for nuclei with 58≲AT≲120 at Einc<30 MeV, the comparison with double-folding model calculations and the CH89 potential, and the spin-orbit potential parameters are discussed.

Brain plasticity and functionality explored by nonlinear optical microscopy

NASA Astrophysics Data System (ADS)

Sacconi, L.; Allegra, L.; Buffelli, M.; Cesare, P.; D'Angelo, E.; Gandolfi, D.; Grasselli, G.; Lotti, J.; Mapelli, J.; Strata, P.; Pavone, F. S.

2010-02-01

In combination with fluorescent protein (XFP) expression techniques, two-photon microscopy has become an indispensable tool to image cortical plasticity in living mice. In parallel to its application in imaging, multi-photon absorption has also been used as a tool for the dissection of single neurites with submicrometric precision without causing any visible collateral damage to the surrounding neuronal structures. In this work, multi-photon nanosurgery is applied to dissect single climbing fibers expressing GFP in the cerebellar cortex. The morphological consequences are then characterized with time lapse 3-dimensional two-photon imaging over a period of minutes to days after the procedure. Preliminary investigations show that the laser induced fiber dissection recalls a regenerative process in the fiber itself over a period of days. These results show the possibility of this innovative technique to investigate regenerative processes in adult brain. In parallel with imaging and manipulation technique, non-linear microscopy offers the opportunity to optically record electrical activity in intact neuronal networks. In this work, we combined the advantages of second-harmonic generation (SHG) with a random access (RA) excitation scheme to realize a new microscope (RASH) capable of optically recording fast membrane potential events occurring in a wide-field of view. The RASH microscope, in combination with bulk loading of tissue with FM4-64 dye, was used to simultaneously record electrical activity from clusters of Purkinje cells in acute cerebellar slices. Complex spikes, both synchronous and asynchronous, were optically recorded simultaneously across a given population of neurons. Spontaneous electrical activity was also monitored simultaneously in pairs of neurons, where action potentials were recorded without averaging across trials. These results show the strength of this technique in describing the temporal dynamics of neuronal assemblies, opening promising perspectives in understanding the computations of neuronal networks.

Optical Signature Analysis of Tumbling Rocket Bodies via Laboratory Measurements

NASA Technical Reports Server (NTRS)

Cowardin, H.; Lederer, S.; Liou, J.-C.

2012-01-01

The NASA Orbital Debris Program Office has acquired telescopic lightcurve data on massive intact objects, specifically spent rocket bodies, in order to ascertain tumble rates in support of the Active Debris Removal (ADR) task to help remediate the LEO environment. Rotation rates are needed to plan and develop proximity operations for potential future ADR operations. To better characterize and model optical data acquired from ground-based telescopes, the Optical Measurements Center (OMC) at NASA/JSC emulates illumination conditions in space using equipment and techniques that parallel telescopic observations and source-target-sensor orientations. The OMC employs a 75-watt Xenon arc lamp as a solar simulator, an SBIG CCD camera with standard Johnson/Bessel filters, and a robotic arm to simulate an object's position and rotation. The light source is mounted on a rotary arm, allowing access any phase angle between 0 -- 360 degrees. The OMC does not attempt to replicate the rotation rates, but focuses on how an object is rotating as seen from multiple phase angles. The two targets studied are scaled (1:48), SL-8 Cosmos 3M second stages. The first target is painted in the standard government "gray" scheme and the second target is primary white, as used for commercial missions. This paper summarizes results of the two scaled rocket bodies, each rotated about two primary axes: (a) a spin-stabilized rotation and (b) an end-over-end rotation. The two rotation states are being investigated as a basis for possible spin states of rocket bodies, beginning with simple spin states about the two primary axes. The data will be used to create a database of potential spin states for future works to convolve with more complex spin states. The optical signatures will be presented for specific phase angles for each rocket body and shown in conjunction with acquired optical data from multiple telescope sources.

CCKT Calculation of e-H Total Cross Sections

NASA Technical Reports Server (NTRS)

Bhatia, Aaron K.; Schneider, B. I.; Temkin, A.; Fisher, Richard R. (Technical Monitor)

2002-01-01

We are in the process of carrying out calculations of e-H total cross sections using the 'complex-correlation Kohn-T' (CCKT) method. In a later paper, we described the methodology more completely, but confined calculations to the elastic scattering region, with definitive, precision results for S-wave phase shifts. Here we extend the calculations to the (low) continuum (1 much less than k(exp 2) much less than 3) using a Green's function formulation. This avoids having to solve integro-differential equations; rather we evaluate indefinite integrals involving appropriate Green's functions and the (complex) optical potential to find the scattering function u(r). From the asymptotic form of u(r) we extract a T(sub L) which is a complex number. From T(sub L), elastic sigma(sub L)(elastic) = 4pi(2L+1)((absolute value of T(sub L))(exp 2)), and total sigma (sub L)(total) = 4pi/k(2L+1)Im(T(sub L)) cross sections follow.

Millimeter-wave interconnects for microwave-frequency quantum machines

NASA Astrophysics Data System (ADS)

Pechal, Marek; Safavi-Naeini, Amir H.

2017-10-01

Superconducting microwave circuits form a versatile platform for storing and manipulating quantum information. A major challenge to further scalability is to find approaches for connecting these systems over long distances and at high rates. One approach is to convert the quantum state of a microwave circuit to optical photons that can be transmitted over kilometers at room temperature with little loss. Many proposals for electro-optic conversion between microwave and optics use optical driving of a weak three-wave mixing nonlinearity to convert the frequency of an excitation. Residual absorption of this optical pump leads to heating, which is problematic at cryogenic temperatures. Here we propose an alternative approach where a nonlinear superconducting circuit is driven to interconvert between microwave-frequency (7 ×109 Hz) and millimeter-wave-frequency photons (3 ×1011 Hz). To understand the potential for quantum state conversion between microwave and millimeter-wave photons, we consider the driven four-wave mixing quantum dynamics of nonlinear circuits. In contrast to the linear dynamics of the driven three-wave mixing converters, the proposed four-wave mixing converter has nonlinear decoherence channels that lead to a more complex parameter space of couplings and pump powers that we map out. We consider physical realizations of such converter circuits by deriving theoretically the upper bound on the maximum obtainable nonlinear coupling between any two modes in a lossless circuit, and synthesizing an optimal circuit based on realistic materials that saturates this bound. Our proposed circuit dissipates less than 10-9 times the energy of current electro-optic converters per qubit. Finally, we outline the quantum link budget for optical, microwave, and millimeter-wave connections, showing that our approach is viable for realizing interconnected quantum processors for intracity or quantum data center environments.

The Individual Virtual Eye: a Computer Model for Advanced Intraocular Lens Calculation

PubMed Central

Einighammer, Jens; Oltrup, Theo; Bende, Thomas; Jean, Benedikt

2010-01-01

Purpose To describe the individual virtual eye, a computer model of a human eye with respect to its optical properties. It is based on measurements of an individual person and one of its major application is calculating intraocular lenses (IOLs) for cataract surgery. Methods The model is constructed from an eye's geometry, including axial length and topographic measurements of the anterior corneal surface. All optical components of a pseudophakic eye are modeled with computer scientific methods. A spline-based interpolation method efficiently includes data from corneal topographic measurements. The geometrical optical properties, such as the wavefront aberration, are simulated with real ray-tracing using Snell's law. Optical components can be calculated using computer scientific optimization procedures. The geometry of customized aspheric IOLs was calculated for 32 eyes and the resulting wavefront aberration was investigated. Results The more complex the calculated IOL is, the lower the residual wavefront error is. Spherical IOLs are only able to correct for the defocus, while toric IOLs also eliminate astigmatism. Spherical aberration is additionally reduced by aspheric and toric aspheric IOLs. The efficient implementation of time-critical numerical ray-tracing and optimization procedures allows for short calculation times, which may lead to a practicable method integrated in some device. Conclusions The individual virtual eye allows for simulations and calculations regarding geometrical optics for individual persons. This leads to clinical applications like IOL calculation, with the potential to overcome the limitations of those current calculation methods that are based on paraxial optics, exemplary shown by calculating customized aspheric IOLs.

In vivo determination of multiple indices of periodontal inflammation by optical spectroscopy

PubMed Central

Liu, KZ; Xiang, XM; Man, A; Sowa, MG; Cholakis, N; Ghiabi, E; Singer, DL; Scott, DA

2008-01-01

Background and Objective Visible – near infrared (optical) spectroscopy can be used to measure regional tissue hemodynamics and edema and, therefore, may represent an ideal tool with which to non-invasively study periodontal inflammation. The study objective was to evaluate the ability of optical spectroscopy to simultaneously determine multiple inflammatory indices (tissue oxygenation, total tissue hemoglobin, deoxyhemoglobin, oxygenated hemoglobin, and tissue edema) in periodontal tissues in vivo. Material and Methods Spectra were obtained, processed, and evaluated from healthy, gingivitis, and periodontitis sites (n = 133) using a portable optical – near infrared spectrometer. A modified Beer-Lambert unmixing model that incorporates a nonparametric scattering loss function was used to determine the relative contribution of each inflammatory component to the overall spectrum. Results Optical spectroscopy was harnessed to successfully generate complex inflammatory profiles in periodontal tissues. Tissue oxygenation at periodontitis sites was significantly decreased (p<0.05) compared to gingivitis and healthy controls. This is largely due to an increase in deoxyhemoglobin in the periodontitis sites compared to healthy (p<0.01) and gingivitis (p=0.05) sites. Tissue water content per se showed no significant difference between the sites but a water index associated with tissue electrolyte levels and temperature differed was significantly between periodontitis sites when compared to both healthy and gingivitis sites (p<0.03). Conclusion This study establishes that optical spectroscopy can simultaneously determine multiple inflammatory indices directly in the periodontal tissues in vivo. Visible - near infrared spectroscopy has the potential to be developed into a simple, reagent-free, user friendly, chair-side, site-specific, diagnostic and prognostic test for periodontitis. PMID:18973538

High-bandwidth and low-loss multimode polymer waveguides and waveguide components for high-speed board-level optical interconnects

NASA Astrophysics Data System (ADS)

Bamiedakis, N.; Chen, J.; Penty, R. V.; White, I. H.

2016-03-01

Multimode polymer waveguides are being increasingly considered for use in short-reach board-level optical interconnects as they exhibit favourable optical properties and allow direct integration onto standard PCBs with conventional methods of the electronics industry. Siloxane-based multimode waveguides have been demonstrated with excellent optical transmission performance, while a wide range of passive waveguide components that offer routing flexibility and enable the implementation of complex on-board interconnection architectures has been reported. In recent work, we have demonstrated that these polymer waveguides can exhibit very high bandwidth-length products in excess of 30 GHz×m despite their highly-multimoded nature, while it has been shown that even larger values of > 60 GHz×m can be achieved by adjusting their refractive index profile. Furthermore, the combination of refractive index engineering and launch conditioning schemes can ensure high bandwidth (> 100 GHz×m) and high coupling efficiency (<1 dB) with standard multimode fibre inputs with relatively large alignment tolerances (~17×15 μm2). In the work presented here, we investigate the effects of refractive index engineering on the performance of passive waveguide components (crossings, bends) and provide suitable design rules for their on-board use. It is shown that, depending on the interconnection layout and link requirements, appropriate choice of refractive index profile can provide enhanced component performance, ensuring low loss interconnection and adequate link bandwidth. The results highlight the strong potential of this versatile optical technology for the formation of high-performance board-level optical interconnects with high routing flexibility.

Optical and electronic structure description of metal-doped phthalocyanines.

PubMed

Leal, Luciano Almeida; da Cunha, Wiliam Ferreira; Ribeiro Junior, Luiz Antonio; Pereira, Tamires Lima; Blawid, Stefan Michael; de Sousa Junior, Rafael Timóteo; da Silva Filho, Demétrio Antonio

2017-05-01

Phthalocyanines represent a crucial class of organic compounds with high technological appeal. By doping the center of these systems with metals, one obtains the so-called metal-phthalocyanines, whose property of being an effective electron donor allows for potentially interesting uses in organic electronics. In this sense, investigating optical and electronic structure changes in the phthalocyanine profiles in the presence of different metals is of fundamental importance for evaluating the appropriateness of the resulting system as far as these uses are concerned. In the present work, we carry out this kind of effort for phthalocyanines doped with different metals, namely, copper, nickel, and magnesium. Density functional theory was applied to obtain the absorption spectra, and electronic and structural properties of the complexes. Our results suggest that depending on the dopant, a different level of change is achieved. Moreover, electrostatic potential energy mapping shows how the charge distribution can be affected by solar radiation. Our contribution is crucial in describing the best possible candidates for use in different organic photovoltaic applications. Graphical Abstract Representation of meta-phthalocyanine systems. All calculations of this work are based on varying metal position along z axis, considering the z-axis has its zero point matching with the center of phthalocyanine cavityconsidering.

3D near-infrared imaging based on a single-photon avalanche diode array sensor

NASA Astrophysics Data System (ADS)

Mata Pavia, Juan; Charbon, Edoardo; Wolf, Martin

2011-07-01

An imager for optical tomography was designed based on a detector with 128×128 single-photon pixels that included a bank of 32 time-to-digital converters. Due to the high spatial resolution and the possibility of performing time resolved measurements, a new contact-less setup has been conceived in which scanning of the object is not necessary. This enables one to perform high-resolution optical tomography with much higher acquisition rate, which is fundamental in clinical applications. The setup has a resolution of 97ps and operates with a laser source with an average power of 3mW. This new imaging system generated a high amount of data that could not be processed by established methods, therefore new concepts and algorithms were developed to take full advantage of it. Images were generated using a new reconstruction algorithm that combined general inverse problem methods with Fourier transforms in order to reduce the complexity of the problem. Simulations show that the potential resolution of the new setup is in the order of millimeters. Experiments have been performed to confirm this potential. Images derived from the measurements demonstrate that we have already reached a resolution of 5mm.

Detection of pointing errors with CMOS-based camera in intersatellite optical communications

NASA Astrophysics Data System (ADS)

Yu, Si-yuan; Ma, Jing; Tan, Li-ying

2005-01-01

For very high data rates, intersatellite optical communications hold a potential performance edge over microwave communications. Acquisition and Tracking problem is critical because of the narrow transmit beam. A single array detector in some systems performs both spatial acquisition and tracking functions to detect pointing errors, so both wide field of view and high update rate is required. The past systems tend to employ CCD-based camera with complex readout arrangements, but the additional complexity reduces the applicability of the array based tracking concept. With the development of CMOS array, CMOS-based cameras can employ the single array detector concept. The area of interest feature of the CMOS-based camera allows a PAT system to specify portion of the array. The maximum allowed frame rate increases as the size of the area of interest decreases under certain conditions. A commercially available CMOS camera with 105 fps @ 640×480 is employed in our PAT simulation system, in which only part pixels are used in fact. Beams angle varying in the field of view can be detected after getting across a Cassegrain telescope and an optical focus system. Spot pixel values (8 bits per pixel) reading out from CMOS are transmitted to a DSP subsystem via IEEE 1394 bus, and pointing errors can be computed by the centroid equation. It was shown in test that: (1) 500 fps @ 100×100 is available in acquisition when the field of view is 1mrad; (2)3k fps @ 10×10 is available in tracking when the field of view is 0.1mrad.

Designer Disordered Complex Media: Hyperuniform Photonic and Phononic Band Gap Materials

NASA Astrophysics Data System (ADS)

Amoah, Timothy

In this thesis we investigate designer disordered complex media for photonics and phononics applications. Initially we focus on the photonic properties and we analyse hyperuniform disordered structures (HUDS) using numerical simulations. Photonic HUDS are a new class of photonic solids, which display large, isotropic photonic band gaps (PBG) comparable in size to the ones found in photonic crystals (PC). We review their complex interference properties, including the origin of PBGs and potential applications. HUDS combine advantages of both isotropy due to disorder (absence of long-range order) and controlled scattering properties from uniform local topology due to hyperuniformity (constrained disorder). The existence of large band gaps in HUDS contradicts the longstanding intuition that Bragg scattering and long-range translational order is required in PBG formation, and demonstrates that interactions between Mie-like local resonances and multiple scattering can induce on their own PBGs. The discussion is extended to finite height effects of planar architectures such as pseudo-band-gaps in photonic slabs as well as the vertical confinement in the presence of disorder. The particular case of a silicon-on-insulator compatible hyperuniform disordered network structure is considered for TE polarised light. We address technologically realisable designs of HUDS including localisation of light in point-defect-like optical cavities and the guiding of light in freeform PC waveguide analogues. Using finite-difference time domain and band structure computer simulations, we show that it is possible to construct optical cavities in planar hyperuniform disordered solids with isotropic band gaps that effciently confine TE polarised radiation. We thus demonstrate that HUDS are a promising general-purpose design platform for integrated optical micro-circuitry. After analysing HUDS for photonic applications we investigate them in the context of elastic waves towards phononics applications. We demonstrate the first phononic band gaps (PnBG) for HUDS. We find that PnBGs in phononic HUDS can confine and guide elastic waves similar to photonic HUDS for EM radiation.

Uncooled Micro-Cantilever Infrared Imager Optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panagiotis, Datskos G.

2008-02-05

We report on the development, fabrication and characterization of microcantilever based uncooled focal plane array (FPA) for infrared imaging. By combining a streamlined design of microcantilever thermal transducers with a highly efficient optical readout, we minimized the fabrication complexity while achieving a competitive level of imaging performance. The microcantilever FPAs were fabricated using a straightforward fabrication process that involved only three photolithographic steps (i.e. three masks). A designed and constructed prototype of an IR imager employed a simple optical readout based on a noncoherent low-power light source. The main figures of merit of the IR imager were found to bemore » comparable to those of uncooled MEMS infrared detectors with substantially higher degree of fabrication complexity. In particular, the NETD and the response time of the implemented MEMS IR detector were measured to be as low as 0.5K and 6 ms, respectively. The potential of the implemented designs can also be concluded from the fact that the constructed prototype enabled IR imaging of close to room temperature objects without the use of any advanced data processing. The most unique and practically valuable feature of the implemented FPAs, however, is their scalability to high resolution formats, such as 2000 x 2000, without progressively growing device complexity and cost. The overall technical objective of the proposed work was to develop uncooled infrared arrays based on micromechanical sensors. Currently used miniature sensors use a number of different readout techniques to accomplish the sensing. The use of optical readout techniques sensing require the deposition of thin coatings on the surface of micromechanical thermal detectors. Oak Ridge National Laboratory (ORNL) is uniquely qualified to perform the required research and development (R&D) services that will assist our ongoing activities. Over the past decade ORNL has developed a number of unique methods and techniques that led to improved sensors using a number of different approaches.« less

Optical apparatus for laser scattering by objects having complex shapes

DOEpatents

Ellingson, William A.; Visher, Robert J.

2006-11-14

Apparatus for observing and measuring in realtime surface and subsurface characteristics of objects having complex shapes includes an optical fiber bundle having first and second opposed ends. The first end includes a linear array of fibers, where the ends of adjacent fibers are in contact and are aligned perpendicular to the surface of the object being studied. The second ends of some of the fibers are in the form of a polished ferrule forming a multi-fiber optical waveguide for receiving laser light. The second ends of the remaining fibers are formed into a linear array suitable for direct connection to a detector, such as a linear CMOS-based optical detector. The output data is analyzed using digital signal processing for the detection of anomalies such as cracks, voids, inclusions and other defects.

Optical, thermal and morphological study of ZnS doped PVA polymer nano composites

NASA Astrophysics Data System (ADS)

Guruswamy, B.; Ravindrachary, V.; Shruthi, C.; Sagar, Rohan N.; Hegde, Shreedatta

2018-05-01

The effect of ZnS nano particle doping on optical, thermal properties and morphological study of the PVA polymer has been investigated using FTIR, UV-Visible and TGA, FESEM techniques. Nano sized ZnS particles were synthesized by a simple wet chemical route. Pure and ZnS/PVA nano composites were prepared using solution casting technique. The FTIR study confirms that the ZnS nano particles interacts with the OH group of PVA polymer and forms the complex. The formation of these complexes affects the optical and thermal properties of the composite. The changes in optical properties were studied using UV-Vis absorption method. The variation in thermal property was analysed using TGA results. The modified surface morphology analysis was carried out using FESEM.

E.s.r., magnetic, optical and biological (SOD and antimicrobial) studies of imidazolate bridged Cu II-Zn II and Cu II-Ni II complexes with tris(2-amino ethyl)amine as capping ligand: a plausible model for superoxide dismutase

NASA Astrophysics Data System (ADS)

Singh, Nripendra; Shukla, K. K.; Patel, R. N.; Chauhan, U. K.; Shrivastava, R.

2003-11-01

X-band e.s.r. and optical absorption spectra of the imidazolate bridged heterobimetallic complexes [(tren)Cu-E-Im-Zn-(tren)](ClO 4) 3 and [(tren)Cu-E-Im-Ni-(tren)](ClO 4) 3, where trentris(2-aminoethyl)amine, E-Im=2-ethylimidazolate ion and the related mononuclear complexes [Cu(tren)](ClO 4) 2 and [(tren)Cu-E-ImH)](ClO 4) 2 have been described. Biological activities (superoxide dismutase and antimicrobial) have also been measured and compared with reported complexes.

Analysis of Multilayered Printed Circuit Boards using Computed Tomography

DTIC Science & Technology

2014-05-01

complex PCBs that present a challenge for any testing or fault analysis. Set-to- work testing and fault analysis of any electronic circuit require...Electronic Warfare and Radar Division in December 2010. He is currently in Electro- Optic Countermeasures Group. Samuel works on embedded system design...and software optimisation of complex electro-optical systems, including the set to work and characterisation of these systems. He has a Bachelor of

Preparation and characterization of nanocrystalline CuO powders with the different surfactants and complexing agent mediated precipitation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajendran, V.; Gajendiran, J., E-mail: gaja.nanotech@gmail.com

2014-08-15

Highlights: • CuO nanostructures by surfactants mediated method. • Structural and optical properties of CuO nanostructures changes under the effect of surface modifier. • Citric acid assisted is the best, in terms of size, morphology and optical properties than that of CTAB, SDS and PEG-400. - Abstract: Nanostructures of copper oxide (CuO) was synthesized into crystallite sized ranging from 20 to 50 nm in the presence of different surfactants, and complex agent such as cityl tri methyl ammonium bromide (CTAB), sodium do decyl sulfate (SDS), poly ethylene glycol (PEG-400) and citric acid via a precipitation route. Variations in several parametersmore » and their effects on the structural and optical properties of CuO nanostructures (crystallite size, morphology and band gap) were investigated by XRD, FTIR, SEM and UV analysis. The UV–visible absorption spectra of the different surfactants and complexing agent assisted CuO nanostructures indicates that the estimated optical band gap energy value (1.94–1.98 eV) is higher than that of the bulk CuO value (1.4 eV), which is attributed to the quantum confinement effect. The formation mechanism of different surfactants and complexing agent assisted CuO nanostructures is also proposed.« less

History of magnetorheological finishing

NASA Astrophysics Data System (ADS)

Harris, Daniel C.

2011-06-01

Magnetorheological finishing (MRF) is a deterministic method for producing complex optics with figure accuracy <50 nm and surface roughness <1 nm. MRF was invented at the Luikov Institute of Heat and Mass Transfer in Minsk, Belarus in the late 1980s by a team led by William Kordonski. When the Soviet Union opened up, New York businessman Lowell Mintz was invited to Minsk in 1990 to explore possibilities for technology transfer. Mintz was told of the potential for MRF, but did not understand whether it had value. Mintz was referred to Harvey Pollicove at the Center for Optics Manufacturing of the University of Rochester. As a result of their conversation, they sent Prof. Steve Jacobs to visit Minsk and evaluate MRF. From Jacobs' positive findings, and with support from Lowell Mintz, Kordonski and his colleagues were invited in 1993 to work at the Center for Optics Manufacturing with Jacobs and Don Golini to refine MRF technology. A "preprototype" finishing machine was operating by 1994. Prof. Greg Forbes and doctoral student Paul Dumas developed algorithms for deterministic control of MRF. In 1996, Golini recognized the commercial potential of MRF, secured investment capital from Lowell Mintz, and founded QED Technologies. The first commercial MRF machine was unveiled in 1998. It was followed by more advanced models and by groundbreaking subaperture stitching interferometers for metrology. In 2006, QED was acquired by and became a division of Cabot Microelectronics. This paper recounts the history of the development of MRF and the founding of QED Technologies.

Materials surface contamination analysis

NASA Technical Reports Server (NTRS)

Workman, Gary L.; Arendale, William F.

1992-01-01

The original research objective was to demonstrate the ability of optical fiber spectrometry to determine contamination levels on solid rocket motor cases in order to identify surface conditions which may result in poor bonds during production. The capability of using the spectral features to identify contaminants with other sensors which might only indicate a potential contamination level provides a real enhancement to current inspection systems such as Optical Stimulated Electron Emission (OSEE). The optical fiber probe can easily fit into the same scanning fixtures as the OSEE. The initial data obtained using the Guided Wave Model 260 spectrophotometer was primarily focused on determining spectra of potential contaminants such as HD2 grease, silicones, etc. However, once we began taking data and applying multivariate analysis techniques, using a program that can handle very large data sets, i.e., Unscrambler 2, it became apparent that the techniques also might provide a nice scientific tool for determining oxidation and chemisorption rates under controlled conditions. As the ultimate power of the technique became recognized, considering that the chemical system which was most frequently studied in this work is water + D6AC steel, we became very interested in trying the spectroscopic techniques to solve a broad range of problems. The complexity of the observed spectra for the D6AC + water system is due to overlaps between the water peaks, the resulting chemisorbed species, and products of reaction which also contain OH stretching bands. Unscrambling these spectral features, without knowledge of the specific species involved, has proven to be a formidable task.

Oxygen Diode Formed in Nickelate Heterostructures by Chemical Potential Mismatch

DOE PAGES

Guo, Erjia; Liu, Yaohua; Sohn, Changhee; ...

2018-03-07

Deliberate control of oxygen vacancy formation and migration in perovskite oxide thin films is important for developing novel electronic and iontronic devices. Here in this paper, it is found that the concentration of oxygen vacancies (V O) formed in LaNiO 3 (LNO) during pulsed laser deposition is strongly affected by the chemical potential mismatch between the LNO film and its proximal layers. Increasing the V O concentration in LNO significantly modifies the degree of orbital polarization and drives the metal–insulator transition. Changes in the nickel oxidization state and carrier concentration in the films are confirmed by soft X-ray absorption spectroscopymore » and optical spectroscopy. The ability to unidirectional-control the oxygen flow across the heterointerface, e.g., a so-called “oxygen diode”, by exploiting chemical potential mismatch at interfaces provides a new avenue to tune the physical and electrochemical properties of complex oxides.« less

Oxygen Diode Formed in Nickelate Heterostructures by Chemical Potential Mismatch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Erjia; Liu, Yaohua; Sohn, Changhee

Deliberate control of oxygen vacancy formation and migration in perovskite oxide thin films is important for developing novel electronic and iontronic devices. Here in this paper, it is found that the concentration of oxygen vacancies (V O) formed in LaNiO 3 (LNO) during pulsed laser deposition is strongly affected by the chemical potential mismatch between the LNO film and its proximal layers. Increasing the V O concentration in LNO significantly modifies the degree of orbital polarization and drives the metal–insulator transition. Changes in the nickel oxidization state and carrier concentration in the films are confirmed by soft X-ray absorption spectroscopymore » and optical spectroscopy. The ability to unidirectional-control the oxygen flow across the heterointerface, e.g., a so-called “oxygen diode”, by exploiting chemical potential mismatch at interfaces provides a new avenue to tune the physical and electrochemical properties of complex oxides.« less

Two-photon quantum walk in a multimode fiber

PubMed Central

Defienne, Hugo; Barbieri, Marco; Walmsley, Ian A.; Smith, Brian J.; Gigan, Sylvain

2016-01-01

Multiphoton propagation in connected structures—a quantum walk—offers the potential of simulating complex physical systems and provides a route to universal quantum computation. Increasing the complexity of quantum photonic networks where the walk occurs is essential for many applications. We implement a quantum walk of indistinguishable photon pairs in a multimode fiber supporting 380 modes. Using wavefront shaping, we control the propagation of the two-photon state through the fiber in which all modes are coupled. Excitation of arbitrary output modes of the system is realized by controlling classical and quantum interferences. This report demonstrates a highly multimode platform for multiphoton interference experiments and provides a powerful method to program a general high-dimensional multiport optical circuit. This work paves the way for the next generation of photonic devices for quantum simulation, computing, and communication. PMID:27152325

Computing with dynamical systems based on insulator-metal-transition oscillators

NASA Astrophysics Data System (ADS)

Parihar, Abhinav; Shukla, Nikhil; Jerry, Matthew; Datta, Suman; Raychowdhury, Arijit

2017-04-01

In this paper, we review recent work on novel computing paradigms using coupled oscillatory dynamical systems. We explore systems of relaxation oscillators based on linear state transitioning devices, which switch between two discrete states with hysteresis. By harnessing the dynamics of complex, connected systems, we embrace the philosophy of "let physics do the computing" and demonstrate how complex phase and frequency dynamics of such systems can be controlled, programmed, and observed to solve computationally hard problems. Although our discussion in this paper is limited to insulator-to-metallic state transition devices, the general philosophy of such computing paradigms can be translated to other mediums including optical systems. We present the necessary mathematical treatments necessary to understand the time evolution of these systems and demonstrate through recent experimental results the potential of such computational primitives.

Ultra-smooth finishing of aspheric surfaces using CAST technology

NASA Astrophysics Data System (ADS)

Kong, John; Young, Kevin

2014-06-01

Growing applications for astronomical ground-based adaptive systems and air-born telescope systems demand complex optical surface designs combined with ultra-smooth finishing. The use of more sophisticated and accurate optics, especially aspheric ones, allows for shorter optical trains with smaller sizes and a reduced number of components. This in turn reduces fabrication and alignment time and costs. These aspheric components include the following: steep surfaces with large aspheric departures; more complex surface feature designs like stand-alone off-axis-parabola (OAP) and free form optics that combine surface complexity with a requirement for ultra-high smoothness, as well as special optic materials such as lightweight silicon carbide (SiC) for air-born systems. Various fabrication technologies for finishing ultra-smooth aspheric surfaces are progressing to meet these growing and demanding challenges, especially Magnetorheological Finishing (MRF) and ion-milling. These methods have demonstrated some good success as well as a certain level of limitations. Amongst them, computer-controlled asphere surface-finishing technology (CAST), developed by Precision Asphere Inc. (PAI), plays an important role in a cost effective manufacturing environment and has successfully delivered numerous products for the applications mentioned above. One of the most recent successes is the Gemini Planet Imager (GPI), the world's most powerful planet-hunting instrument, with critical aspheric components (seven OAPs and free form optics) made using CAST technology. GPI showed off its first images in a press release on January 7, 2014 . This paper reviews features of today's technologies in handling the ultra-smooth aspheric optics, especially the capabilities of CAST on these challenging products. As examples, three groups of aspheres deployed in astronomical optics systems, both polished and finished using CAST, will be discussed in detail.

Intracellular distribution and stability of a luminescent rhenium(i) tricarbonyl tetrazolato complex using epifluorescence microscopy in conjunction with X-ray fluorescence imaging.

PubMed

Wedding, J L; Harris, H H; Bader, C A; Plush, S E; Mak, R; Massi, M; Brooks, D A; Lai, B; Vogt, S; Werrett, M V; Simpson, P V; Skelton, B W; Stagni, S

2017-04-19

Optical epifluorescence microscopy was used in conjunction with X-ray fluorescence imaging to monitor the stability and intracellular distribution of the luminescent rhenium(i) complex fac-[Re(CO) 3 (phen)L], where phen = 1,10-phenathroline and L = 5-(4-iodophenyl)tetrazolato, in 22Rv1 cells. The rhenium complex showed no signs of ancillary ligand dissociation, a conclusion based on data obtained via X-ray fluorescence imaging aligning iodine and rhenium distributions. A diffuse reticular localisation was detected for the complex in the nuclear/perinuclear region of cells, by either optical or X-ray fluorescence imaging techniques. X-ray fluorescence also showed that the rhenium complex disrupted the homeostasis of some biologically relevant elements, such as chlorine, potassium and zinc.

Plenoptic mapping for imaging and retrieval of the complex field amplitude of a laser beam.

PubMed

Wu, Chensheng; Ko, Jonathan; Davis, Christopher C

2016-12-26

The plenoptic sensor has been developed to sample complicated beam distortions produced by turbulence in the low atmosphere (deep turbulence or strong turbulence) with high density data samples. In contrast with the conventional Shack-Hartmann wavefront sensor, which utilizes all the pixels under each lenslet of a micro-lens array (MLA) to obtain one data sample indicating sub-aperture phase gradient and photon intensity, the plenoptic sensor uses each illuminated pixel (with significant pixel value) under each MLA lenslet as a data point for local phase gradient and intensity. To characterize the working principle of a plenoptic sensor, we propose the concept of plenoptic mapping and its inverse mapping to describe the imaging and reconstruction process respectively. As a result, we show that the plenoptic mapping is an efficient method to image and reconstruct the complex field amplitude of an incident beam with just one image. With a proof of concept experiment, we show that adaptive optics (AO) phase correction can be instantaneously achieved without going through a phase reconstruction process under the concept of plenoptic mapping. The plenoptic mapping technology has high potential for applications in imaging, free space optical (FSO) communication and directed energy (DE) where atmospheric turbulence distortion needs to be compensated.

Anterior Chamber Angle Shape Analysis and Classification of Glaucoma in SS-OCT Images.

PubMed

Ni Ni, Soe; Tian, J; Marziliano, Pina; Wong, Hong-Tym

2014-01-01

Optical coherence tomography is a high resolution, rapid, and noninvasive diagnostic tool for angle closure glaucoma. In this paper, we present a new strategy for the classification of the angle closure glaucoma using morphological shape analysis of the iridocorneal angle. The angle structure configuration is quantified by the following six features: (1) mean of the continuous measurement of the angle opening distance; (2) area of the trapezoidal profile of the iridocorneal angle centered at Schwalbe's line; (3) mean of the iris curvature from the extracted iris image; (4) complex shape descriptor, fractal dimension, to quantify the complexity, or changes of iridocorneal angle; (5) ellipticity moment shape descriptor; and (6) triangularity moment shape descriptor. Then, the fuzzy k nearest neighbor (fkNN) classifier is utilized for classification of angle closure glaucoma. Two hundred and sixty-four swept source optical coherence tomography (SS-OCT) images from 148 patients were analyzed in this study. From the experimental results, the fkNN reveals the best classification accuracy (99.11 ± 0.76%) and AUC (0.98 ± 0.012) with the combination of fractal dimension and biometric parameters. It showed that the proposed approach has promising potential to become a computer aided diagnostic tool for angle closure glaucoma (ACG) disease.

Simple, monolithic optical element for forward-viewing spectrally encoded endoscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Do, Dukho; Kang, Dongkyun; Ikuta, Mitsuhiro; Tearney, Guillermo J.

2016-03-01

Spectrally encoded endoscopy (SEE) is a miniature endoscopic technology that can acquire images of internal organs through a hair-thin probe. While most previously described SEE probes have been side viewing, forward-view (FV)-SEE is advantageous in certain clinical applications as it provides more natural navigation of the probe and has the potential to provide a wider field of view. Prior implementations of FV-SEE used multiple optical elements that increase fabrication complexity and may diminish the robustness of the device. In this paper, we present a new design that uses a monolithic optical element to realize FV-SEE imaging. The optical element is specially designed spacer, fabricated from a 500-μm-glass rod that has a mirror surface on one side and a grating stamped on its distal end. The mirror surface is used to change the incident angle on the grating to diffract the shortest wavelength of the spectrum so that it is parallel to the optical axis. Rotating the SEE optics creates a circular FV-SEE image. Custom-designed software processes FV-SEE images into circular images, which are displayed in real-time. In order to demonstrate this new design, we have constructed the FV-SEE optical element using a 1379 lines/mm diffraction grating. When illuminated with a source with a spectral bandwidth of 420-820 nm, the FV-SEE optical element provides 678 resolvable points per line. The imaging performance of the FV-SEE device was tested by imaging a USAF resolution target. SEE images showed that this new approach generates high quality images in the forward field with a field of view of 58°. Results from this preliminary study demonstrate that we can realize FV-SEE imaging with simple, monolithic, miniature optical element. The characteristics of this FV-SEE configuration will facilitate the development of robust miniature endoscopes for a variety of medical imaging applications.

Skin optical clearing potential of disaccharides

NASA Astrophysics Data System (ADS)

Feng, Wei; Shi, Rui; Ma, Ning; Tuchina, Daria K.; Tuchin, Valery V.; Zhu, Dan

2016-08-01

Skin optical clearing can significantly enhance the ability of biomedical optical imaging. Some alcohols and sugars have been selected to be optical clearing agents (OCAs). In this work, we paid attention to the optical clearing potential of disaccharides. Sucrose and maltose were chosen as typical disaccharides to compare with fructose, an excellent monosaccharide-OCA, by using molecular dynamics simulation and an ex vivo experiment. The experimental results indicated that the optical clearing efficacy of skin increases linearly with the concentration for each OCA. Both the theoretical predication and experimental results revealed that the two disaccharides exerted a better optical clearing potential than fructose at the same concentration, and sucrose is optimal. Since maltose has an extremely low saturation concentration, the other two OCAs with saturation concentrations were treated topically on rat skin in vivo, and optical coherence tomography imaging was applied to monitor the optical clearing process. The results demonstrated that sucrose could cause a more significant increase in imaging depth and signal intensity than fructose.

Label-Free Biosensing with High Selectivity in Complex Media using Microtoroidal Optical Resonators

NASA Astrophysics Data System (ADS)

Ozgur, Erol; Toren, Pelin; Aktas, Ozan; Huseyinoglu, Ersin; Bayindir, Mehmet

2015-08-01

Although label-free biosensors comprised of optical microcavities inherently possess the capability of resolving molecular interactions at individual level, this extreme sensitivity restricts their convenience for large scale applications by inducing vulnerability towards non-specific interactions that readily occur within complex media. Therefore, the use of optical microresonators for biosensing is mostly limited within strictly defined laboratory conditions, instead of field applications as early detection of cancer markers in blood, or identification of contamination in food. Here, we propose a novel surface modification strategy suitable for but not limited to optical microresonator based biosensors, enabling highly selective biosensing with considerable sensitivity as well. Using a robust, silane-based surface coating which is simultaneously protein resistant and bioconjugable, we demonstrate that it becomes possible to perform biosensing within complex media, without compromising the sensitivity or reliability of the measurement. Functionalized microtoroids are successfully shown to resist nonspecific interactions, while simultaneously being used as sensitive biological sensors. This strategy could pave the way for important applications in terms of extending the use of state-of-the-art biosensors for solving problems similar to the aforementioned.

Spatiotemporal chaos and two-dimensional dissipative rogue waves in Lugiato-Lefever model

NASA Astrophysics Data System (ADS)

Panajotov, Krassimir; Clerc, Marcel G.; Tlidi, Mustapha

2017-06-01

Driven nonlinear optical cavities can exhibit complex spatiotemporal dynamics. We consider the paradigmatic Lugiato-Lefever model describing driven nonlinear optical resonator. This model is one of the most-studied nonlinear equations in optics. It describes a large spectrum of nonlinear phenomena from bistability, to periodic patterns, localized structures, self-pulsating localized structures and to a complex spatiotemporal behavior. The model is considered also as prototype model to describe several optical nonlinear devices such as Kerr media, liquid crystals, left handed materials, nonlinear fiber cavity, and frequency comb generation. We focus our analysis on a spatiotemporal chaotic dynamics in one-dimension. We identify a route to spatiotemporal chaos through an extended quasiperiodicity. We have estimated the Kaplan-Yorke dimension that provides a measure of the strange attractor complexity. Likewise, we show that the Lugiato-Leferver equation supports rogues waves in two-dimensional settings. We characterize rogue-wave formation by computing the probability distribution of the pulse height. Contribution to the Topical Issue "Theory and Applications of the Lugiato-Lefever Equation", edited by Yanne K. Chembo, Damia Gomila, Mustapha Tlidi, Curtis R. Menyuk.

Phosphorescent binuclear iridium complexes based on terpyridine-carboxylate: an experimental and theoretical study.

PubMed

Andreiadis, Eugen S; Imbert, Daniel; Pécaut, Jacques; Calborean, Adrian; Ciofini, Ilaria; Adamo, Carlo; Demadrille, Renaud; Mazzanti, Marinella

2011-09-05

The phosphorescent binuclear iridium(III) complexes tetrakis(2-phenylpyridine)μ-(2,2':6',2''-terpyridine-6,6''-dicarboxylic acid)diiridium (Ir1) and tetrakis(2-(2,4-difluorophenyl) pyridine))μ-(2,2':6',2''-terpyridine-6,6''-dicarboxylic acid)diiridium (Ir2) were synthesized in a straightforward manner and characterized using X-ray diffraction, NMR, UV-vis absorption, and emission spectroscopy. The complexes have similar solution structures in which the two iridium centers are equivalent. This is further confirmed by the solid state structure of Ir2. The newly reported complexes display intense luminescence in dichloromethane solutions with maxima at 538 (Ir1) and 477 nm (Ir2) at 298 K (496 and 468 nm at 77 K, respectively) and emission quantum yields reaching ~18% for Ir1. The emission quantum yield for Ir1 is among the highest values reported for dinuclear iridium complexes. It shows only a 11% decrease with respect to the emission quantum yield reported for its mononuclear analogue, while the molar extinction coefficient is roughly doubled. This suggests that such architectures are of potential interest for the development of polymetallic assemblies showing improved optical properties. DFT and time-dependent-DFT calculations were performed on the ground and excited states of the complexes to provide insights into their structural, electronic, and photophysical properties.

Elucidation of two photon absorption of ethylenediaminium (2,4-dinitrophenolate) crystals

NASA Astrophysics Data System (ADS)

Indumathi, C.; Sabari Girisun, T. C.; Anitha, K.; Cecil Raj, S. Alfred

2016-10-01

Optical quality single crystals of ethylenediaminium (2,4-dinitrophenolate) [EDA(2,4)DNP] were grown by solvent evaporation method for optical limiting applications against intense ultrashot pulse lasers. Single crystal XRD showed that the material crystallizes in monoclinic system with centric space group P21/C. The crystal packing diagram was elucidated for the first time in literature and it revealed six hydrogen bonds played a very important role in stabilizing the structure. A bifurcated hydrogen bond was also observed between ethylenediamminium and dinitrophenolate ions. The formation of charge transfer complex during the reaction of ethylenediamine and 2,4-dinitrophenol was strongly evident through the vibrational spectroscopic studies. TG-DTA and DSC curves indicate that the material exhibited strong decomposition at 224 °C. Ground state absorption analysis showed that the grown crystals possess absorption maxima in UV region (270 nm, 346 nm) and wide optical transmittance window (480-1200 nm) in the entire visible and NIR region. Measurement of two photon absorption (2PA) and optical limiting response by Z-scan technique under nanosecond pulse excitation was reported. Hence EDA(2,4)DNP with high 2PA coefficient (0.79 ± 0.04 × 10-10 m/W) and low limiting threshold (2.40 ± 0.05 × 1012 W/m2) will be a potential candidate for optical limiting applications like eye and sensor protection against short pulse lasers that are well spread in human interactive sectors.

Measurement of aerosol optical properties by cw cavity enhanced spectroscopy

NASA Astrophysics Data System (ADS)

Jie, Guo; Ye, Shan-Shan; Yang, Xiao; Han, Ye-Xing; Tang, Huai-Wu; Yu, Zhi-Wei

2016-10-01

The CAPS (Cavity Attenuated Phase shift Spectroscopy) system, which detects the extinction coefficients within a 10 nm bandpass centered at 532 nm, comprises a green LED with center wavelength in 532nm, a resonant optical cavity (36 cm length), a Photo Multiplier Tube detector, and a lock in amplifier. The square wave modulated light from the LED passes through the optical cavity and is detected as a distorted waveform which is characterized by a phase shift with respect to the initial modulation. Extinction coefficients are determined from changes in the phase shift of the distorted waveform of the square wave modulated LED light that is transmitted through the optical cavity. The performance of the CAPS system was evaluated by using measurements of the stability and response of the system. The minima ( 0.1 Mm-1) in the Allan plots show the optimum average time ( 100s) for optimum detection performance of the CAPS system. In the paper, it illustrates that extinction coefficient was correlated with PM2.5 mass (0.91). These figures indicate that this method has the potential to become one of the most sensitive on-line analytical techniques for extinction coefficient detection. This work aims to provide an initial validation of the CAPS extinction monitor in laboratory and field environments. Our initial results presented in this paper show that the CAPS extinction monitor is capable of providing state-of-the-art performance while dramatically reducing the complexity of optical instrumentation for directly measuring the extinction coefficients.

Modulation of manganite nano-film properties mediated by strong influence of strontium titanate excitons.

PubMed

Yin, Xinmao; Tang, Chi Sin; Majidi, Muhammad Aziz; Ren, Peng; Wang, Le; Yang, Ping; Diao, Caozheng; Yu, Xiaojiang; Breese, Mark B H; Wee, Andrew Thye Shen; Wang, Junling; Rusydi, Andrivo

2017-12-06

Hole-doped perovskite manganites have attracted much attention because of their unique optical, electronic and magnetic properties induced by the interplay between spin, charge, orbital and lattice degrees of freedom. Here, a comprehensive investigation of the optical, electronic and magnetic properties of La0.7Sr0.3MnO3 thin-films on SrTiO3 (LSMO/STO) and other substrates is conducted using a combination of temperature-dependent transport, spectroscopic ellipsometry, X-ray absorption spectroscopy and X-ray magnetic circular dichroism. A significant difference in the optical property of LSMO/STO that occurs even in thick (87.2nm) LSMO/STO from that of LSMO on other substrates is discovered. Several excitonic features are observed in thin-film nanostructure LSMO/STO at ~4eV, which could be attributed to the formation of anomalous charged excitonic complexes. Based on spectral-weight transfer analysis, anomalous excitonic effects from STO strengthen the electronic-correlation in LSMO films. This results in the occurrence of optical spectral changes related to the intrinsic Mott-Hubbard properties in manganites. We find that while lattice strain from the substrate influences the optical properties of the LSMO thin-films, the coexistence of strong electron-electron (e-e) and electron-hole (e-h) interactions which leads to the resonant excitonic effects from the substrate play a much more significant role. Our result shows that the onset of anomalous excitonic dynamics in manganite oxides may potentially generate new approaches in manipulating exciton-based optoelectronic applications.

Analysis of form deviation in non-isothermal glass molding

NASA Astrophysics Data System (ADS)

Kreilkamp, H.; Grunwald, T.; Dambon, O.; Klocke, F.

2018-02-01

Especially in the market of sensors, LED lighting and medical technologies, there is a growing demand for precise yet low-cost glass optics. This demand poses a major challenge for glass manufacturers who are confronted with the challenge arising from the trend towards ever-higher levels of precision combined with immense pressure on market prices. Since current manufacturing technologies especially grinding and polishing as well as Precision Glass Molding (PGM) are not able to achieve the desired production costs, glass manufacturers are looking for alternative technologies. Non-isothermal Glass Molding (NGM) has been shown to have a big potential for low-cost mass manufacturing of complex glass optics. However, the biggest drawback of this technology at the moment is the limited accuracy of the manufactured glass optics. This research is addressing the specific challenges of non-isothermal glass molding with respect to form deviation of molded glass optics. Based on empirical models, the influencing factors on form deviation in particular form accuracy, waviness and surface roughness will be discussed. A comparison with traditional isothermal glass molding processes (PGM) will point out the specific challenges of non-isothermal process conditions. Furthermore, the underlying physical principle leading to the formation of form deviations will be analyzed in detail with the help of numerical simulation. In this way, this research contributes to a better understanding of form deviations in non-isothermal glass molding and is an important step towards new applications demanding precise yet low-cost glass optics.

Optical Trapping of Ion Coulomb Crystals

NASA Astrophysics Data System (ADS)

Schmidt, Julian; Lambrecht, Alexander; Weckesser, Pascal; Debatin, Markus; Karpa, Leon; Schaetz, Tobias

2018-04-01

The electronic and motional degrees of freedom of trapped ions can be controlled and coherently coupled on the level of individual quanta. Assembling complex quantum systems ion by ion while keeping this unique level of control remains a challenging task. For many applications, linear chains of ions in conventional traps are ideally suited to address this problem. However, driven motion due to the magnetic or radio-frequency electric trapping fields sometimes limits the performance in one dimension and severely affects the extension to higher-dimensional systems. Here, we report on the trapping of multiple barium ions in a single-beam optical dipole trap without radio-frequency or additional magnetic fields. We study the persistence of order in ensembles of up to six ions within the optical trap, measure their temperature, and conclude that the ions form a linear chain, commonly called a one-dimensional Coulomb crystal. As a proof-of-concept demonstration, we access the collective motion and perform spectrometry of the normal modes in the optical trap. Our system provides a platform that is free of driven motion and combines advantages of optical trapping, such as state-dependent confinement and nanoscale potentials, with the desirable properties of crystals of trapped ions, such as long-range interactions featuring collective motion. Starting with small numbers of ions, it has been proposed that these properties would allow the experimental study of many-body physics and the onset of structural quantum phase transitions between one- and two-dimensional crystals.

Optically activated switches for the generation of complex electrical waveforms with multigigahertz bandwidth

NASA Astrophysics Data System (ADS)

Skeldon, Mark D.; Okishev, Andrey V.; Letzring, Samuel A.; Donaldson, William R.; Green, Kenton; Seka, Wolf D.; Fuller, Lynn F.

1995-01-01

An electrical pulse-generation system using two optically activated Si photoconductive switches can generate shaped electrical pulses with multigigahertz bandwidth. The Si switches are activated by an optical pulse whose leading edge is steepened by stimulated Brillouin scattering (SBS) in CCl4. With the bandwidth generated by the SBS process, a laser having a 1- to 3-ns pulse width is used to generate electrical pulses with approximately 80-ps rise times (approximately 4-GHz bandwidth). Variable impedance microstrip lines are used to generate complex electrical waveforms that can be transferred to a matched load with minimal loss of bandwidth.

Coherent virtual absorption for discretized light

NASA Astrophysics Data System (ADS)

Longhi, S.

2018-05-01

Coherent virtual absorption (CVA) is a recently-introduced phenomenon for which exponentially growing waves incident onto a conservative optical medium are neither reflected nor transmitted, at least transiently. CVA has been associated to complex zeros of the scattering matrix and can be regarded as the time reversal of the decay process of a quasi-mode sustained by the optical medium. Here we consider CVA for discretized light transport in coupled resonator optical waveguides or waveguide arrays and show that a distinct kind of CVA, which is not related to complex zero excitation of quasi-modes, can be observed. This result suggests that scattering matrix analysis can not fully capture CVA phenomena.

Design and manufacturing methods for the integral field unit of the nirspec instrument on JWST

NASA Astrophysics Data System (ADS)

Lobb, Dan; Robertson, David

2017-11-01

An integral field unit, to be used with the near-IR spectrometer instrument of the James Webb Space Telescope (JWST), is currently under development by SSTL and CfAI. Special problems in design and manufacture of the optical system are outlined, and manufacturing methods for critical optical elements are discussed. The optical system is complex, requiring a total of 95 mirrors to produce 30 output channels. Emphasis is placed on the advantages of free-form machining in aluminium. These include: resistance to launch stress, insensitivity to temperature variations from ambient to cryogenic, and the possibility of relatively complex mirror surface shapes.

Analysis of corrections to the eikonal approximation

NASA Astrophysics Data System (ADS)

Hebborn, C.; Capel, P.

2017-11-01

Various corrections to the eikonal approximations are studied for two- and three-body nuclear collisions with the goal to extend the range of validity of this approximation to beam energies of 10 MeV/nucleon. Wallace's correction does not improve much the elastic-scattering cross sections obtained at the usual eikonal approximation. On the contrary, a semiclassical approximation that substitutes the impact parameter by a complex distance of closest approach computed with the projectile-target optical potential efficiently corrects the eikonal approximation. This opens the possibility to analyze data measured down to 10 MeV/nucleon within eikonal-like reaction models.

Ab initio method for calculating total cross sections

NASA Technical Reports Server (NTRS)

Bhatia, A. K.; Schneider, B. I.; Temkin, A.

1993-01-01

A method for calculating total cross sections without formally including nonelastic channels is presented. The idea is to use a one channel T-matrix variational principle with a complex correlation function. The derived T matrix is therefore not unitary. Elastic scattering is calculated from T-parallel-squared, but total scattering is derived from the imaginary part of T using the optical theorem. The method is applied to the spherically symmetric model of electron-hydrogen scattering. No spurious structure arises; results for sigma(el) and sigma(total) are in excellent agreement with calculations of Callaway and Oza (1984). The method has wide potential applicability.

Magnetic and optoelectronic properties of gold nanocluster-thiophene assembly.

PubMed

Qin, Wei; Lohrman, Jessica; Ren, Shenqiang

2014-07-07

Nanohybrids consisting of Au nanocluster and polythiophene nanowire assemblies exhibit unique thermal-responsive optical behaviors and charge-transfer controlled magnetic and optoelectronic properties. The ultrasmall Au nanocluster enhanced photoabsorption and conductivity effectively improves the photocurrent of nanohybrid based photovoltaics, leading to an increase of power conversion efficiency by 14 % under AM 1.5 illumination. In addition, nanohybrids exhibit electric field controlled spin resonance and magnetic field sensing behaviors, which open up the potential of charge-transfer complex system where the magnetism and optoelectronics interact. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photonics and application of dipyrrinates in the optical devices

NASA Astrophysics Data System (ADS)

Aksenova, Iu; Bashkirtsev, D.; Prokopenko, A.; Kuznetsova, R.; Dudina, N.; Berezin, M.

2016-08-01

In this paper spectral-luminescent, lasing, photochemical, and sensory characteristics of a number of Zn(II) and B(III) coordination complexes with dipyrrinates with different structures are presented. We have discussed relations of the structure of investigated compounds and formed solvates with their optical characteristics. The results showed that alkyl substituted dipyrrinates derivatives have excellent luminescent characteristics and demonstrated effective lasing upon excitation of Nd:YAG-laser. They can be used as active media for liquid tunable lasers. Zinc and boron fluoride complexes of dipyrrinates with heavy atoms in structure don't have fluorescence but have long-lived emission due to increased nonradiative intersystem processes in the excited state by the mechanism of a heavy atom. For solid samples based on halogenated complexes was found dependency of the long-lived emission intensity of the oxygen concentration in gas flow. The presence of line segment indicates the possibility of the use of these complexes as a basis for creation of optical sensors for oxygen. Moreover, results of a study of halogen-substituted aza-complexes under irradiation are presented. Such complexes are promising for the creating media for generation of singlet oxygen (1O2), which is important for photodynamic therapy in medicine and photocatalytic reactions in the industry.

Correction for frequency-dependent hydrophone response to nonlinear pressure waves using complex deconvolution and rarefactional filtering: application with fiber optic hydrophones.

PubMed

Wear, Keith; Liu, Yunbo; Gammell, Paul M; Maruvada, Subha; Harris, Gerald R

2015-01-01

Nonlinear acoustic signals contain significant energy at many harmonic frequencies. For many applications, the sensitivity (frequency response) of a hydrophone will not be uniform over such a broad spectrum. In a continuation of a previous investigation involving deconvolution methodology, deconvolution (implemented in the frequency domain as an inverse filter computed from frequency-dependent hydrophone sensitivity) was investigated for improvement of accuracy and precision of nonlinear acoustic output measurements. Timedelay spectrometry was used to measure complex sensitivities for 6 fiber-optic hydrophones. The hydrophones were then used to measure a pressure wave with rich harmonic content. Spectral asymmetry between compressional and rarefactional segments was exploited to design filters used in conjunction with deconvolution. Complex deconvolution reduced mean bias (for 6 fiber-optic hydrophones) from 163% to 24% for peak compressional pressure (p+), from 113% to 15% for peak rarefactional pressure (p-), and from 126% to 29% for pulse intensity integral (PII). Complex deconvolution reduced mean coefficient of variation (COV) (for 6 fiber optic hydrophones) from 18% to 11% (p+), 53% to 11% (p-), and 20% to 16% (PII). Deconvolution based on sensitivity magnitude or the minimum phase model also resulted in significant reductions in mean bias and COV of acoustic output parameters but was less effective than direct complex deconvolution for p+ and p-. Therefore, deconvolution with appropriate filtering facilitates reliable nonlinear acoustic output measurements using hydrophones with frequency-dependent sensitivity.

Soil Temperature Variability in Complex Terrain measured using Distributed a Fiber-Optic Distributed Temperature Sensing

NASA Astrophysics Data System (ADS)

Seyfried, M. S.; Link, T. E.

2013-12-01

Soil temperature (Ts) exerts critical environmental controls on hydrologic and biogeochemical processes. Rates of carbon cycling, mineral weathering, infiltration and snow melt are all influenced by Ts. Although broadly reflective of the climate, Ts is sensitive to local variations in cover (vegetative, litter, snow), topography (slope, aspect, position), and soil properties (texture, water content), resulting in a spatially and temporally complex distribution of Ts across the landscape. Understanding and quantifying the processes controlled by Ts requires an understanding of that distribution. Relatively few spatially distributed field Ts data exist, partly because traditional Ts data are point measurements. A relatively new technology, fiber optic distributed temperature system (FO-DTS), has the potential to provide such data but has not been rigorously evaluated in the context of remote, long term field research. We installed FO-DTS in a small experimental watershed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of SW Idaho. The watershed is characterized by complex terrain and a seasonal snow cover. Our objectives are to: (i) evaluate the applicability of fiber optic DTS to remote field environments and (ii) to describe the spatial and temporal variability of soil temperature in complex terrain influenced by a variable snow cover. We installed fiber optic cable at a depth of 10 cm in contrasting snow accumulation and topographic environments and monitored temperature along 750 m with DTS. We found that the DTS can provide accurate Ts data (+/- .4°C) that resolves Ts changes of about 0.03°C at a spatial scale of 1 m with occasional calibration under conditions with an ambient temperature range of 50°C. We note that there are site-specific limitations related cable installation and destruction by local fauna. The FO-DTS provide unique insight into the spatial and temporal variability of Ts in a landscape. We found strong seasonal trends in Ts variability controlled by snow cover and solar radiation as modified by topography. During periods of spatially continuous snow cover Ts was practically homogeneous throughout. In the absence of snow cover, Ts is highly variable, with most of the variability attributable to different topographic units defined by slope and aspect. During transition periods when snow melts out, Ts is highly variable within the watershed and within topographic units. The importance of accounting for these relatively small scale effects is underscored by the fact that the overall range of Ts in study area 600 m long is similar to that of the much large RCEW with 900 m elevation gradient.

Integrated optical dipole trap for cold neutral atoms with an optical waveguide coupler

NASA Astrophysics Data System (ADS)

Lee, J.; Park, D. H.; Mittal, S.; Dagenais, M.; Rolston, S. L.

2013-04-01

An integrated optical dipole trap uses two-color (red and blue-detuned) traveling evanescent wave fields for trapping cold neutral atoms. To achieve longitudinal confinement, we propose using an integrated optical waveguide coupler, which provides a potential gradient along the beam propagation direction sufficient to confine atoms. This integrated optical dipole trap can support an atomic ensemble with a large optical depth due to its small mode area. Its quasi-TE0 waveguide mode has an advantage over the HE11 mode of a nanofiber, with little inhomogeneous Zeeman broadening at the trapping region. The longitudinal confinement eliminates the need for a one dimensional optical lattice, reducing collisional blockaded atomic loading, potentially producing larger ensembles. The waveguide trap allows for scalability and integrability with nano-fabrication technology. We analyze the potential performance of such integrated atom traps.

Exploration on the matching between Optical Comprehensive Design Experiment and Washington Accord

NASA Astrophysics Data System (ADS)

Cao, Yiping; Chen, Wenjing; Zhang, Qican; Liu, Yuankun; Li, Dahai; Zhou, Xinzhi; Wei, Jun

2017-08-01

Common problems faced in optical comprehensive design experiment and going against the Washington Accord are pointed out. For resolving these problems, an instructional and innovative teaching scheme for Optics Comprehensive Design Experiment is proposed. We would like to understand the student that can improve the hands-on practical ability, theory knowledge understanding ability, complex problem solving ability, engineering application ability, cooperative ability after tracking and researching the student who have attended the class about Optical Comprehensive Design Experiment, We found that there are some problems on the course such as the experiment content vague, the student beginning less time, phase separation theory and engineering application, the experiment content lack of selectivity and so on. So we have made some improvements reference to the Washington Accord for the class teaching plan about Optical Comprehensive Design Experiment. This class must relevant to the engineering basic courses, professional foundation course and the major courses, so far as to the future study and work that which can play a role in inheriting and continuity to the students. The Optical Comprehensive Design Experiment teaching program requires students learning this course to have learnt basic courses like analog electronics technique, digital electronic technique, applied optics and computer and other related courses which students are required to comprehensively utilize. This teaching scheme contains six practical complex engineering problems which are respectively optical system design, light energy meter design, illuminometer design, material refractive index measuring system design, light intensity measuring system design and open design. Establishing the optional experiment and open experiment can provide students with a greater choice and enhance the students' creativity, vivid teaching experimental teachers and enriching contents of experiment can make the experiment more interesting, providing students with more opportunities to conduct experiment and improving students' practical ability with long learning time, putting emphasis on student's understanding of complex engineering problems and the cognitive of the process to solve complex engineering problems with actual engineering problems. Applying the scheme in other courses and improving accordingly will be able to ensure the quality of engineering education. Look forward to offering useful reference for the curriculum system construction in colleges and universities.

Optical Studies and Poling of DNA NLO Waveguides

NASA Astrophysics Data System (ADS)

Heckman, Emily; Grote, James

2005-04-01

Deoxyribonucleic acid (DNA), extracted from salmon sperm through an enzyme isolation process, is precipitated with a surfactant complex, cetyltrimethl-ammonium (CTMA), for application as a nonlinear optical material. Preliminary characterization studies suggest that DNA-CTMA may be suitable for use as the host material in the poled core layer of electro-optically-active waveguide devices. Poling results and techniques for poled chromophore-DNA-CTMA films will be discussed. Optical characterization studies of the DNA-CTMA films, including optical propagation losses and considerations in making DNA-CTMA an optical quality material, will be presented.

Two mode optical fiber in space optics communication

NASA Astrophysics Data System (ADS)

Hampl, Martin

2017-11-01

In our contribution we propose to use of a two-mode optical fiber as a primary source in a transmitting optical head instead of the laser diode. The distribution of the optical intensity and the complex degree of the coherence on the output aperture of the lens that is irradiated by a step-index weakly guiding optical fiber is investigated. In our treatment we take into account weakly guided modes with polarization corrections to the propagation constant and unified theory of second order coherence and polarization of electromagnetic beams.

Extraterrestrial applications of solar optics for interior illumination

NASA Technical Reports Server (NTRS)

Eijadi, David A.; Williams, Kyle D.

1992-01-01

Solar optics is a terrestrial technology that has potential extraterrestrial applications. Active solar optics (ASO) and passive solar optics (PSO) are two approaches to the transmission of sunlight to remote interior spaces. Active solar optics is most appropriate for task illumination, while PSO is most appropriate for general illumination. Research into solar optics, motivated by energy conservation, has produced lightweight and low-cost materials, products that have applications to NASA's Controlled Ecological Life Support System (CELSS) program and its lunar base studies. Specifically, prism light guides have great potential in these contexts. Several applications of solar optics to lunar base concepts are illustrated.

Whole-organ atlas imaged by label-free high-resolution photoacoustic microscopy assisted by a microtome

NASA Astrophysics Data System (ADS)

Wong, Terence T. W.; Zhang, Ruiying; Hsu, Hsun-Chia; Maslov, Konstantin I.; Shi, Junhui; Chen, Ruimin; Shung, K. Kirk; Zhou, Qifa; Wang, Lihong V.

2018-02-01

In biomedical imaging, all optical techniques face a fundamental trade-off between spatial resolution and tissue penetration. Therefore, obtaining an organelle-level resolution image of a whole organ has remained a challenging and yet appealing scientific pursuit. Over the past decade, optical microscopy assisted by mechanical sectioning or chemical clearing of tissue has been demonstrated as a powerful technique to overcome this dilemma, one of particular use in imaging the neural network. However, this type of techniques needs lengthy special preparation of the tissue specimen, which hinders broad application in life sciences. Here, we propose a new label-free three-dimensional imaging technique, named microtomy-assisted photoacoustic microscopy (mPAM), for potentially imaging all biomolecules with 100% endogenous natural staining in whole organs with high fidelity. We demonstrate the first label-free mPAM, using UV light for label-free histology-like imaging, in whole organs (e.g., mouse brains), most of them formalin-fixed and paraffin- or agarose-embedded for minimal morphological deformation. Furthermore, mPAM with dual wavelength illuminations is also employed to image a mouse brain slice, demonstrating the potential for imaging of multiple biomolecules without staining. With visible light illumination, mPAM also shows its deep tissue imaging capability, which enables less slicing and hence reduces sectioning artifacts. mPAM could potentially provide a new insight for understanding complex biological organs.

Spectrographs for astrophotonics.

PubMed

Blind, N; Le Coarer, E; Kern, P; Gousset, S

2017-10-30

The next generation of extremely large telescopes (ELT), with diameters up to 39 meters, is planned to begin operation in the next decade and promises new challenges in the development of instruments since the instrument size increases in proportion to the telescope diameter D, and the cost as D 2 or faster. The growing field of astrophotonics (the use of photonic technologies in astronomy) could solve this problem by allowing mass production of fully integrated and robust instruments combining various optical functions, with the potential to reduce the size, complexity and cost of instruments. Astrophotonics allows for a broad range of new optical functions, with applications ranging from sky background filtering, high spatial and spectral resolution imaging and spectroscopy. In this paper, we want to provide astronomers with valuable keys to understand how photonics solutions can be implemented (or not) according to the foreseen applications. The paper introduces first key concepts linked to the characteristics of photonics technologies, placed in the framework of astronomy and spectroscopy. We then describe a series of merit criteria that help us determine the potential of a given micro-spectrograph technology for astronomy applications, and then take an inventory of the recent developments in integrated micro-spectrographs with potential for astronomy. We finally compare their performance, to finally draw a map of typical science requirements and pin the identified integrated technologies on it. We finally emphasize the necessary developments that must support micro-spectrograph in the coming years.

A concept for a soft gamma-ray concentrator using thin-film multilayer structures

NASA Astrophysics Data System (ADS)

Bloser, Peter F.; Shirazi, Farzane; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Tsavalas, John G.; Wong, Emily N.; Aliotta, Paul H.

2016-07-01

We are investigating the use of thin-film, multilayer structures to form optics capable of concentrating soft gamma rays with energies greater than 100 keV, beyond the reach of current grazing-incidence hard X-ray mirrors. Alternating layers of low- and high-density materials (e.g., polymers and metals) will channel soft gamma-ray photons via total external reflection. A suitable arrangement of bent structures will then concentrate the incident radiation to a point. Gamma-ray optics made in this way offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments. Following initial investigations conducted at Los Alamos National Laboratory, we have constructed and tested a prototype structure using spin coating combined with magnetron sputtering. We are now investigating whether it is possible to grow such flexible multi-layer structures with the required thicknesses and smoothness more quickly by using magnetron sputter and pulsed laser deposition techniques. We present the latest results of our fabrication and gamma-ray channeling tests, and describe our modeling of the sensitivity of potential concentrator-based telescope designs. If successful, this technology offers the potential for transformational increases in sensitivity while dramatically improving the system-level performance of future high-energy astronomy missions through reduced mass and complexity.

Pulsed laser versus electrical energy for peripheral nerve stimulation

PubMed Central

Wells, Jonathon; Konrad, Peter; Kao, Chris; Jansen, E. Duco; Mahadevan-Jansen, Anita

2010-01-01

Transient optical neural stimulation has previously been shown to elicit highly controlled, artifact-free potentials within the nervous system in a non-contact fashion without resulting in damage to tissue. This paper presents the physiologic validity of elicited nerve and muscle potentials from pulsed laser induced stimulation of the peripheral nerve in a comparative study with the standard method of electrically evoked potentials. Herein, the fundamental physical properties underlying the two techniques are contrasted. Key laser parameters for efficient optical stimulation of the peripheral nerve are detailed. Strength response curves are shown to be linear for each stimulation modality, although fewer axons can be recruited with optically evoked potentials. Results compare the relative transient energy requirements for stimulation using each technique and demonstrate that optical methods can selectively excite functional nerve stimulation. Adjacent stimulation and recording of compound nerve potentials in their entirety from optical and electrical stimulation are presented, with optical responses shown to be free of any stimulation artifact. Thus, use of a pulsed laser exhibits some advantages when compared to standard electrical means for excitation of muscle potentials in the peripheral nerve in the research domain and possibly for clinical diagnostics in the future. PMID:17537515

Novel Image Quality Control Systems(Add-On). Innovative Computational Methods for Inverse Problems in Optical and SAR Imaging

DTIC Science & Technology

2007-02-28

Iterative Ultrasonic Signal and Image Deconvolution for Estimation of the Complex Medium Response, International Journal of Imaging Systems and...1767-1782, 2006. 31. Z. Mu, R. Plemmons, and P. Santago. Iterative Ultrasonic Signal and Image Deconvolution for Estimation of the Complex...rigorous mathematical and computational research on inverse problems in optical imaging of direct interest to the Army and also the intelligence agencies

Optical systems engineering - A tutorial

NASA Technical Reports Server (NTRS)

Wyman, C. L.

1979-01-01

The paper examines the use of the systems engineering approach in the design of optical systems, noting that the use of such an approach which involves an integrated interdisciplinary approach to the development of systems is most appropriate for optics. It is shown that the high precision character of optics leads to complex and subtle effects on optical system performance, resulting from structural, thermal dynamical, control system, and manufacturing and assembly considerations. Attention is given to communication problems that often occur among users and optical engineers due to the unique factors of optical systems. It is concluded that it is essential that the optics community provide leadership to resolve communication problems and fully formalize the field of optical systems engineering.

Local optical control of ferromagnetism and chemical potential in a topological insulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeats, Andrew L.; Mintun, Peter J.; Pan, Yu

Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate reconfigurable micron-scale optical control of both magnetization (which breaks time-reversal symmetry) and chemical potential in ferromagnetic thin films of Cr-(Bi,Sb) 2Te 3 grown on SrTiO 3. By optically modulating the coercivity of the films, we write and erase arbitrary patterns in their remanent magnetization, which we then image with Kerr microscopy. Additionally, by optically manipulating a space charge layer in the underlying SrTiO 3 substrates, we control the local chemical potential of the films. This optical gating effect allows us to writemore » and erase p-n junctions in the films, which we study with photocurrent microscopy. Both effects are persistent and may be patterned and imaged independently on a few-micron scale. As a result, dynamic optical control over both magnetization and chemical potential of a TI may be useful in efforts to understand and control the edge states predicted at magnetic domain walls in quantum anomalous Hall insulators.« less

Local optical control of ferromagnetism and chemical potential in a topological insulator

DOE PAGES

Yeats, Andrew L.; Mintun, Peter J.; Pan, Yu; ...

2017-09-12

Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate reconfigurable micron-scale optical control of both magnetization (which breaks time-reversal symmetry) and chemical potential in ferromagnetic thin films of Cr-(Bi,Sb) 2Te 3 grown on SrTiO 3. By optically modulating the coercivity of the films, we write and erase arbitrary patterns in their remanent magnetization, which we then image with Kerr microscopy. Additionally, by optically manipulating a space charge layer in the underlying SrTiO 3 substrates, we control the local chemical potential of the films. This optical gating effect allows us to writemore » and erase p-n junctions in the films, which we study with photocurrent microscopy. Both effects are persistent and may be patterned and imaged independently on a few-micron scale. As a result, dynamic optical control over both magnetization and chemical potential of a TI may be useful in efforts to understand and control the edge states predicted at magnetic domain walls in quantum anomalous Hall insulators.« less

Optical and relaxometric properties of monometallic (Eu(III), Tb(III), Gd(III)) and heterobimetallic (Re(I)/Gd(III)) systems based on a functionalized bipyridine-containing acyclic ligand.

PubMed

Leygue, Nadine; Boulay, Alexandre; Galaup, Chantal; Benoist, Eric; Laurent, Sophie; Vander Elst, Luce; Mestre-Voegtlé, Béatrice; Picard, Claude

2016-05-17

A series of lanthanide complexes of [LnL(H2O)](2-) composition where Ln = Eu(III), Tb(III) or Gd(III) has been studied for determining their photophysical and relaxometric properties in aqueous solution. The bifunctional ligand L (H5BPMNTA) is an acyclic chelator based on a central functionalized 2,2'-bipyridine core and two iminodiacetate coordinating arms. The mono-aqua Eu(III) and Tb(III) complexes display attractive spectroscopic properties with an excitation wavelength at 316 nm, similar excited state lifetimes and overall quantum yields (in the ranges 0.5-0.6 ms and 10-13%, respectively) in Tris buffer (pH 7.4). The proton longitudinal relaxivity, r1, of the Gd(III) complex is 4.4 mM(-1) s(-1) at 20 MHz and 310 K, which is comparable to that of the clinically used Gd-DTPA (Magnevist®). Interestingly, the water exchange rate between the coordination site and the bulk solvent is very fast (Kex = 2.6 × 10(8) s(-1) at 310 K). The ability of the complex to bind non-covalently to human serum albumin (HSA) was also examined by relaxometric measurements. We also report the synthesis and properties of a bimetallic complex based on Gd-BPMNTA and Re(I)(bpy)(CO)3 components. In this system, the Re core exhibits interesting photophysical properties (λem = 588 nm, Φ = 1.4%) and the Gd-BPMNTA core displays improved relaxivity (r1 = 6.6 mM(-1) s(-1) at 20 MHz and 310 K), due to an increase of the rotational correlation time. Besides these appealing optical and relaxometric properties, the presence of a reactive function on the structure proposes this potential dual imaging probe for conjugation to biomolecules or nanomaterials.

Speckle contrast diffuse correlation tomography of complex turbid medium flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Chong; Irwin, Daniel; Lin, Yu

2015-07-15

Purpose: Developed herein is a three-dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite-element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckle contrast diffuse correlation tomography (scDCT), enables incorporation of complex optical property heterogeneities and sample boundaries. When combined with a reflectance-based design, this system facilitates a rapid segue into flow contrast imaging of larger, in vivo applications such as humans. Methods: A highly sensitive CCD camera was integrated into a reflectance-based optical system. Four long-coherence laser source positions were coupledmore » to an optical switch for sequencing of tomographic data acquisition providing multiple projections through the sample. This system was investigated through incorporation of liquid and solid tissue-like phantoms exhibiting optical properties and flow characteristics typical of human tissues. Computer simulations were also performed for comparisons. A uniquely encountered smear correction algorithm was employed to correct point-source illumination contributions during image capture with the frame-transfer CCD and reflectance setup. Results: Measurements with scDCT on a homogeneous liquid phantom showed that speckle contrast-based deep flow indices were within 12% of those from standard DCT. Inclusion of a solid phantom submerged below the liquid phantom surface allowed for heterogeneity detection and validation. The heterogeneity was identified successfully by reconstructed 3D flow contrast tomography with scDCT. The heterogeneity center and dimensions and averaged relative flow (within 3%) and localization were in agreement with actuality and computer simulations, respectively. Conclusions: A custom cost-effective CCD-based reflectance 3D flow imaging system demonstrated rapid acquisition of dense boundary data and, with further studies, a high potential for translatability to real tissues with arbitrary boundaries. A requisite correction was also found for measurements in the fashion of scDCT to recover accurate speckle contrast of deep tissues.« less

Stereotactic radiotherapy for malignancies involving the trigeminal and facial nerves.

PubMed

Cuneo, K C; Zagar, T M; Brizel, D M; Yoo, D S; Hoang, J K; Chang, Z; Wang, Z; Yin, F F; Das, S K; Green, S; Ready, N; Bhatti, M T; Kaylie, D M; Becker, A; Sampson, J H; Kirkpatrick, J P

2012-06-01

Involvement of a cranial nerve caries a poor prognosis for many malignancies. Recurrent or residual disease in the trigeminal or facial nerve after primary therapy poses a challenge due to the location of the nerve in the skull base, the proximity to the brain, brainstem, cavernous sinus, and optic apparatus and the resulting complex geometry. Surgical resection caries a high risk of morbidity and is often not an option for these patients. Stereotactic radiosurgery and radiotherapy are potential treatment options for patients with cancer involving the trigeminal or facial nerve. These techniques can deliver high doses of radiation to complex volumes while sparing adjacent critical structures. In the current study, seven cases of cancer involving the trigeminal or facial nerve are presented. These patients had unresectable recurrent or residual disease after definitive local therapy. Each patient was treated with stereotactic radiation therapy using a linear accelerator based system. A multidisciplinary approach including neuroradiology and surgical oncology was used to delineate target volumes. Treatment was well tolerated with no acute grade 3 or higher toxicity. One patient who was reirradiated experienced cerebral radionecrosis with mild symptoms. Four of the seven patients treated had no evidence of disease after a median follow up of 12 months (range 2-24 months). A dosimetric analysis was performed to compare intensity modulated fractionated stereotactic radiation therapy (IM-FSRT) to a 3D conformal technique. The dose to 90% (D90) of the brainstem was lower with the IM-FSRT plan by a mean of 13.5 Gy. The D95 to the ipsilateral optic nerve was also reduced with IM-FSRT by 12.2 Gy and the D95 for the optic chiasm was lower with FSRT by 16.3 Gy. Treatment of malignancies involving a cranial nerve requires a multidisciplinary approach. Use of an IM-FSRT technique with a micro-multileaf collimator resulted in a lower dose to the brainstem, optic nerves and chiasm for each case examined.

Exploration of metastability and hidden phases in correlated electron crystals visualized by femtosecond optical doping and electron crystallography

PubMed Central

Han, Tzong-Ru T.; Zhou, Faran; Malliakas, Christos D.; Duxbury, Phillip M.; Mahanti, Subhendra D.; Kanatzidis, Mercouri G.; Ruan, Chong-Yu

2015-01-01

Characterizing and understanding the emergence of multiple macroscopically ordered electronic phases through subtle tuning of temperature, pressure, and chemical doping has been a long-standing central issue for complex materials research. We report the first comprehensive studies of optical doping–induced emergence of stable phases and metastable hidden phases visualized in situ by femtosecond electron crystallography. The electronic phase transitions are triggered by femtosecond infrared pulses, and a temperature–optical density phase diagram is constructed and substantiated with the dynamics of metastable states, highlighting the cooperation and competition through which the macroscopic quantum orders emerge. These results elucidate key pathways of femtosecond electronic switching phenomena and provide an important new avenue to comprehensively investigate optical doping–induced transition states and phase diagrams of complex materials with wide-ranging applications. PMID:26601190

Dispersive optical soliton solutions for the hyperbolic and cubic-quintic nonlinear Schrödinger equations via the extended sinh-Gordon equation expansion method

NASA Astrophysics Data System (ADS)

Seadawy, Aly R.; Kumar, Dipankar; Chakrabarty, Anuz Kumar

2018-05-01

The (2+1)-dimensional hyperbolic and cubic-quintic nonlinear Schrödinger equations describe the propagation of ultra-short pulses in optical fibers of nonlinear media. By using an extended sinh-Gordon equation expansion method, some new complex hyperbolic and trigonometric functions prototype solutions for two nonlinear Schrödinger equations were derived. The acquired new complex hyperbolic and trigonometric solutions are expressed by dark, bright, combined dark-bright, singular and combined singular solitons. The obtained results are more compatible than those of other applied methods. The extended sinh-Gordon equation expansion method is a more powerful and robust mathematical tool for generating new optical solitary wave solutions for many other nonlinear evolution equations arising in the propagation of optical pulses.