Science.gov

Sample records for optically realizable localized

  1. Super-diffusion in optical realizations of Anderson localization

    NASA Astrophysics Data System (ADS)

    Krivolapov, Yevgeny; Levi, Liad; Fishman, Shmuel; Segev, Mordechai; Wilkinson, Michael

    2012-04-01

    We discuss the dynamics of particles in one dimension in potentials that are random in both space and time. The results are applied to recent optics experiments on Anderson localization, in which the transverse spreading of a beam is suppressed by random fluctuations in the refractive index. If the refractive index fluctuates along the direction of the paraxial propagation of the beam, the localization is destroyed. We analyze this broken localization in terms of the spectral decomposition of the potential. When the potential has a discrete spectrum, the spread is controlled by the overlap of Chirikov resonances in phase space. As the number of Fourier components is increased, the resonances merge into a continuum, which is described by a Fokker-Planck equation. We express the diffusion coefficient in terms of the spectral intensity of the potential. For a general class of potentials that are commonly used in optics, the solutions to the Fokker-Planck equation exhibit anomalous diffusion in phase space, implying that when Anderson localization is broken by temporal fluctuations of the potential, the result is transport at a rate similar to a ballistic one or even faster. For a class of potentials which arise in some existing realizations of Anderson localization, atypical behavior is found.

  2. Bessel-Gauss pulse as an appropriate mathematical model for optically realizable localized waves.

    PubMed

    Reivelt, Kaido; Saari, Peeter

    2004-06-01

    We show that the field of the optically feasible luminal localized wave solutions of the scalar homogeneous wave equation can be modeled by means of Bessel-Gauss pulses. As the Bessel-Gauss pulses have a closed-form expression, this fact may be of great value in numerical simulations of various experimental situations.

  3. Realizing Parafermions in Optical Lattices

    NASA Astrophysics Data System (ADS)

    Liu, Fangli; Gorshkov, Alexey

    2016-05-01

    Parafermions, which are the fractional versions of Majorana fermions, possess more exotic braiding statistics than Majorana fermions and are therefore more powerful from the point of view of topological quantum computing. We propose a scheme to realize parafermionic zero modes in optical lattices, without the use of superconductive paring. With the help of laser assisted tunneling and on-site interactions, two layers of ultracold atoms in distinct hyperfine states can be engineered to host +/- 1 / m fractional quantum Hall states. We then introduce a finite-extent potential barrier that pierces both layers - this gives rise to two counter-propagating edge states that sit on top of each other. Finally, laser induced coupling is used to introduce backscattering between the two edge states and to gap them out. We show that the resulting defects give rise to the topological degeneracy associated with parafermions. We also discuss methods for preparation and detection.

  4. Nonlinear realization and hidden local symmetries

    NASA Astrophysics Data System (ADS)

    Bando, Masako; Kugo, Taichiro; Yamawaki, Koichi

    1988-07-01

    The idea of dynamical gauge bosons of hidden local symmetries in nonlinear sigma models is reviewed. Starting with a fresh look at the Goldstone theorem and low energy theorems, we present a modern review of the general theory of nonlinear realization both in nonsupersymmetric and supersymmetric cases. We then show that any nonlinear sigma model based on the manifold G/ H is gauge equivalent to a “linear” model possessing a Gglobal × Hlocal symmetry, Hlocal being a hidden local symmetry. The corresponding supersymmetric formulation is also presented. The above gauge equivalence can be extended to a model having a larger symmetry Gglobal × Glocal. Also reviewed are dynamical calculatio ns showing that in some two-, three- and four-dimensional models, the gauge bosons of the hidden local symmetries acquire the kinetic terms via quantum effects, thus becoming “dynamical”. We suggest that such a dynamical gauge boson may be a rather common phenomenon realized in Nature. As a realistic example, we examine the QCD case where we identify the vector mesons (ϱ,ω,ф,K ∗) with the dynamical gauge bosons of the hidden U(3) v local symmetry in the U(3) L × U(3) R/U(3) V nonlinear sigma model. The totality of the vector meson phenomenology seems to support our basic idea. The axial-vector mesons are also incorporated into our framework. Also given is a brief sketch of some applications of this formalism to unified models beyond the standard model, such as technicolor, composite W/Z boson and supergravity models.

  5. The Realization and Study of Optical Wings

    NASA Astrophysics Data System (ADS)

    Artusio-Glimpse, Alexandra Brae

    Consider the airfoil: a carefully designed structure capable of stable lift in a uniform air flow. It so happens that air pressure and radiation (light) pressure are similar phenomena because each transfer momentum to flow-disturbing objects. This, then, begs the question: does an optical analogue to the airfoil exist? Though an exceedingly small effect, scientists harness radiation pressure in a wide gamut of applications from micromanipulation of single biological particles to the propulsion of large spacecrafts called solar sails. We introduce a cambered, refractive rod that is subjected to optical forces analogous to those seen in aerodynamics, and I call this analogue the optical wing. Flight characteristics of optical wings are determined by wing shape and material in a uniform radiation field. Theory predicts the lift force and axial torque are functions of the wing's angle of attack with stable and unstable orientations. These structures can operate as intensity-dependent, parametrically driven oscillators. In two-dimensions, the wings exhibit bistability when analyzed in an accelerating frame. In three-dimensions, the motion of axially symmetric spinning hemispherical wings is analogous to a spinning top. Experiments on semi-buoyant wings in water found semicylindrically shaped, refractive microparticles traversed a laser beam and rotated to an illumination-dependent stable orientation. Preliminary tests aid in the development of a calibrated force measurement experiment to directly evaluate the optical forces and torque on these samples. A foundational study of the optical wing, this work contributes to future advancements of flight-by-light.

  6. Green photonics realized by optical complex systems

    NASA Astrophysics Data System (ADS)

    Nanri, Hiroto; Sasaki, Wakao

    2013-12-01

    We have experimentally demonstrated a new smart grid model which can control DC electric power flow autonomously among individual homes, by using an optical self-organized node with optical non-linear characteristics, and these homes are assumed to be installed by distributed power supplies, and electric power storage devices, and also supposed to be supplied partly by the commercial electric power grid utilities. An electric power network is composed of nodes and devises called Power Gate Unit (PGU). The nodes have optical nonlinearity for self-organizing informations about surplus or shortage of electric power as to individual homes. The PGU is a distributing unit of actual electric power based on above informations of power surplus or shortage at each home. The PGU at each home is electrically connected to both the onsite power supplies and household load such as a solar panel, a DC motor, and a storage battery as well as the commercial electric power grid utilities. In this work, we composed our experimental self-organized DC power grid with above components and supposed the supplied maximum power from the commercial electric power grid utilities to be limited to 5V-0.5A. In this network, information about surplus or shortage of electric power will propagate through the nodes. In the experiments, surplus electric current 0.4A at a particular node was distributed toward a PGU of another node suffering from shortage of electric current. We also confirmed in the experiments and simulations that even when signal propagation path was disconnected accidentally the network could recover an optimized path. The present smart grid system we have attained may be applied by optical fiber link in the near future because our essential components controlling PGU, i.e. the nodes are electro-optical hybrid which are easily applicable to fiber optical link so as to control electric power transmission line.

  7. Optical realization of two-boson tunneling dynamics

    SciTech Connect

    Longhi, Stefano

    2011-04-15

    An optical realization of the tunneling dynamics of two interacting bosons in a double-well potential, based on light transport in a four-core microstructured fiber, is proposed. The optical setting enables one to visualize, in a purely classical system, the entire crossover from Rabi oscillations to correlated pair tunneling and to tunneling of a fragmented pair in the fermionization limit.

  8. Design and realization of photoelectric instrument binocular optical axis parallelism calibration system

    NASA Astrophysics Data System (ADS)

    Ying, Jia-ju; Chen, Yu-dan; Liu, Jie; Wu, Dong-sheng; Lu, Jun

    2016-10-01

    The maladjustment of photoelectric instrument binocular optical axis parallelism will affect the observe effect directly. A binocular optical axis parallelism digital calibration system is designed. On the basis of the principle of optical axis binocular photoelectric instrument calibration, the scheme of system is designed, and the binocular optical axis parallelism digital calibration system is realized, which include four modules: multiband parallel light tube, optical axis translation, image acquisition system and software system. According to the different characteristics of thermal infrared imager and low-light-level night viewer, different algorithms is used to localize the center of the cross reticle. And the binocular optical axis parallelism calibration is realized for calibrating low-light-level night viewer and thermal infrared imager.

  9. Realization and characterization of fiber optic reflective sensor

    NASA Astrophysics Data System (ADS)

    Guzowski, B.; Łakomski, M.; Słapek, B.

    2016-11-01

    In almost all of non-invasive techniques, fiber optic sensors may be the most promising ones because of their inherent advantages such as very small size and hard environment tolerance. Proximity sensors based on optical fiber are highly required especially in the impact area of electromagnetic fields. In this paper three different types of fiber optic reflective sensors are presented. In all three types of the sensor four multimode optical fibers (MMF) illuminate the movable surface. The difference is in the number of collecting the reflected light MMF. In the first one, 12 MMF collect the light, in the second one 20 MMF, while in the third one the number of MMF collecting reflected light is 32. Moreover, all three types of fiber optic reflective sensors were realized in two configurations. In the first one, the cleaved MMF were used to collect reflected light, while in the second configuration - the ball-lensed optical fibers were chosen. In this paper an analysis of each type of realized sensor is presented. In the last part of this paper the obtained results and the detailed discussion are given.

  10. Realization of an all optical exciton-polariton router

    SciTech Connect

    Marsault, Félix; Nguyen, Hai Son; Tanese, Dimitrii; Lemaître, Aristide; Galopin, Elisabeth; Sagnes, Isabelle; Amo, Alberto

    2015-11-16

    We report on the experimental realization of an all optical router for exciton-polaritons. This device is based on the design proposed by Flayac and Savenko [Appl. Phys. Lett. 103, 201105 (2013)], in which a zero-dimensional island is connected through tunnel barriers to two periodically modulated wires of different periods. Selective transmission of polaritons injected in the island, into either of the two wires, is achieved by tuning the energy of the island state across the band structure of the modulated wires. We demonstrate routing of ps polariton pulses using an optical control beam which controls the energy of the island quantum states, thanks to polariton-exciton interactions.

  11. Experimental realization of an optical second with strontium lattice clocks.

    PubMed

    Le Targat, R; Lorini, L; Le Coq, Y; Zawada, M; Guéna, J; Abgrall, M; Gurov, M; Rosenbusch, P; Rovera, D G; Nagórny, B; Gartman, R; Westergaard, P G; Tobar, M E; Lours, M; Santarelli, G; Clairon, A; Bize, S; Laurent, P; Lemonde, P; Lodewyck, J

    2013-01-01

    Progress in realizing the SI second had multiple technological impacts and enabled further constraint of theoretical models in fundamental physics. Caesium microwave fountains, realizing best the second according to its current definition with a relative uncertainty of 2-4 × 10(-16), have already been overtaken by atomic clocks referenced to an optical transition, which are both more stable and more accurate. Here we present an important step in the direction of a possible new definition of the second. Our system of five clocks connects with an unprecedented consistency the optical and the microwave worlds. For the first time, two state-of-the-art strontium optical lattice clocks are proven to agree within their accuracy budget, with a total uncertainty of 1.5 × 10(-16). Their comparison with three independent caesium fountains shows a degree of accuracy now only limited by the best realizations of the microwave-defined second, at the level of 3.1 × 10(-16).

  12. Realizing type-II Weyl points in an optical lattice

    NASA Astrophysics Data System (ADS)

    Shastri, Kunal; Yang, Zhaoju; Zhang, Baile

    2017-01-01

    The recent discovery of the Lorentz symmetry-violating "type-II" Weyl semimetal phase has renewed interest in the study of Weyl physics in condensed-matter systems. However, tuning the exceptional properties of this novel state has remained a challenge. Optical lattices, created using standing laser beams, provide a convenient platform to tune tunneling parameters continuously in time. In this paper, we propose a generalized two level system exhibiting type-II Weyl points that can be realized using ultracold atoms in an optical lattice. The system is engineered using a three-dimensional lattice with complex π phase tunneling amplitudes. Various unique properties of the type-II Weyl semimetal such as open Fermi surface, anomalous chirality, and topological Fermi arcs can be probed using the proposed optical lattice scheme.

  13. Indoor Free Space Optic: a new prototype, realization and evaluation

    NASA Astrophysics Data System (ADS)

    Bouchet, Olivier; Besnard, Pascal; Mihaescu, Adrian

    2008-08-01

    The Free Space Optic (FSO) communication is a daily reality used by an increasing number of companies. For indoor environment, optical wireless communication becomes a good alternative with respect to radio proposals. For both technologies, the architecture is similar: emission/reception base station (Gateway or Bridge) are installed to cover zones, which are defined to ensure a quality of service. The customers may be connected to the Wireless Local Area Network (WLAN) with an adapter or module that emits and receives on this network. But due to its specific characteristics, wireless optical technology could present important advantages such as: Transmitted data security, medical immunity, high data rate, etc... Nevertheless, the optical system may have a limit on the network management aspect and link budget. The scope of this paper is to present a proposal at crossroads between optical fibre telecom system and data processing. In this document, we will present a prototype developed in Brittany during a regional collaborative project (Techim@ges). In order to answer to the management aspect and the link budget, this prototype uses an optical multiplexing technique in 1550 nm band: the Wavelength Division Multiple Access (WDMA). Moreover it also proposes a new class 1 high power emission solution. This full duplex system transmits these various wavelengths in free space, by using optical Multiplexer/Demultiplexer and optical modules. Each module has a defined and personal wavelength associated to the terminal identification (addresses MAC or IP). This approach permits a data rate at a minimum of a ten's Mbit/s per customer and potentially hundred Mbps for a line of sight system. The application field for the achieved and proposed prototype is potentially investigated from WLAN to WPAN.

  14. Recursive linear optical networks for realizing quantum algorithms

    NASA Astrophysics Data System (ADS)

    Tabia, Gelo Noel

    Linear optics has played a leading role in the development of practical quantum technologies. In recent years, advances in integrated quantum photonics have significantly improved the functionality and scalability of linear optical devices. In this talk, I present recursive schemes for implementing quantum Fourier transforms and inversion about the mean in Grover's algorithm with photonic integrated circuits. By recursive, I mean that two copies of a d-dimensional unitary operation is used to build the corresponding unitary operation on 2 d modes. The linear optical networks operate on path-encoded qudits and realize d-dimensional unitary operations using O (d2) elements. To demonstrate that the recursive circuits are viable in practice, I conducted simulations of proof-of-principle experiments using a fabrication model of realistic errors in silicon-based photonic integrated devices. The results indicate high-fidelity performance in the circuits for 2-qubit and 3-qubit quantum Fourier transforms, and for quantum search on 4-item and 8-item databases. This work was funded by institutional research grant IUT2-1 from the Estonian Research Council and by the European Union through the European Regional Development Fund.

  15. Experimental realization of a nondeterministic optical noiseless amplifier

    SciTech Connect

    Ferreyrol, Franck; Blandino, Remi; Barbieri, Marco; Tualle-Brouri, Rosa; Grangier, Philippe

    2011-06-15

    Linear amplifiers are necessarily affected by a minimal amount of noise, which is needed in order to preserve the linearity and the unitarity prescribed by quantum mechanics. Such a limitation might be partially overcome if the process is realized by conditioning its operation on a trigger event, for instance, the result of a measurement. Here we present a detailed analysis of a noiseless amplifier, implemented using linear optics, a down-conversion-based single-photon source, and single-photon detection. Our results demonstrate an amplification adding a level of noise lower than the minimum allowed by quantum mechanics for deterministic amplifiers. This is made possible by the nondeterministic character of our device, whose success rate is sufficiently low not to violate any fundamental limit. We compare our experimental data to a model taking into account the main imperfections of the setup and find a good agreement.

  16. Photonic processing and realization of an all-optical digital comparator based on semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Singh, Simranjit; Kaur, Ramandeep; Kaler, Rajinder Singh

    2015-01-01

    A module of an all-optical 2-bit comparator is analyzed and implemented using semiconductor optical amplifiers (SOAs). By employing SOA-based cross phase modulation, the optical XNOR logic is used to get an A=B output signal, where as AB¯ and A¯B> logics operations are used to realize A>B and Aoptical high speed networks and computing systems.

  17. Design principles and realization of electro-optical circuit boards

    NASA Astrophysics Data System (ADS)

    Betschon, Felix; Lamprecht, Tobias; Halter, Markus; Beyer, Stefan; Peterson, Harry

    2013-02-01

    The manufacturing of electro-optical circuit boards (EOCB) is based to a large extent on established technologies. First products with embedded polymer waveguides are currently produced in series. The range of applications within the sensor and data communication markets is growing with the increasing maturity level. EOCBs require design flows, processes and techniques similar to existing printed circuit board (PCB) manufacturing and appropriate for optical signal transmission. A key aspect is the precise and automated assembly of active and passive optical components to the optical waveguides which has to be supported by the technology. The design flow is described after a short introduction into the build-up of EOCBs and the motivation for the usage of this technology within the different application fields. Basis for the design of EOCBs are the required optical signal transmission properties. Thereafter, the devices for the electro-optical conversion are chosen and the optical coupling approach is defined. Then, the planar optical elements (waveguides, splitters, couplers) are designed and simulated. This phase already requires co-design of the optical and electrical domain using novel design flows. The actual integration of an optical system into a PCB is shown in the last part. The optical layer is thereby laminated to the purely electrical PCB using a conventional PCB-lamination process to form the EOCB. The precise alignment of the various electrical and optical layers is thereby essential. Electrical vias are then generated, penetrating also the optical layer, to connect the individual electrical layers. Finally, the board has to be tested electrically and optically.

  18. Non-local Optical Potentials

    NASA Astrophysics Data System (ADS)

    Thompson, Ian

    2010-11-01

    In all direct reactions to probe the structure of exotic nuclei at FRIB, optical potentials will be needed in the entrance and exit channels. At high energies Glauber approximations may be useful, but a low energies (5 to 20 MeV/nucleon) other approaches are required. Recent work of the UNEDF project [1] has shown that reaction cross sections at these energies can be accounted for by calculating all inelastic and transfer channels reachable by one particle-hole transitions from the elastic channel. In this model space, we may also calculate the two-step dynamic polarization potential (DPP) that adds to the bare folded potential to form the complex optical potential. Our calculations of the DPP, however, show that its non-localities are very significant, as well as the partial-wave dependence of both its real and imaginary components. The Perey factors (the wave function ratio to that from an equivalent local potential) are more than 20% different from unity, especially for partial waves inside grazing. These factors combine to suggest a reexamination of the validity of local and L-independent fitted optical potentials, especially for capture reactions that are dominated by low partial waves. Prepared by LLNL under Contract DE-AC52-07NA27344. [1] G.P.A. Nobre, F.S. Dietrich, J.E. Escher, I.J. Thompson, M. Dupuis, J. Terasaki and J. Engel, submitted to Phys. Rev. Letts., 2010.

  19. Realization of All-Optical Multistate Switching in an Atomic Coherent Medium

    NASA Astrophysics Data System (ADS)

    Sheng, Jiteng; Khadka, Utsab; Xiao, Min

    2012-11-01

    We have experimentally observed optical multistability (OM) in an optical ring cavity containing three-level Λ-type Doppler-broadened rubidium atoms. The shape of the OM curve can be significantly modified by changing the power of the control laser field. An all-optical multistate switching or coding element is realized and flexibly controlled by adding a pulse sequence to the input (probe) intensity.

  20. Optical interferometric logic gates based on metal slot waveguide network realizing whole fundamental logic operations.

    PubMed

    Pan, Deng; Wei, Hong; Xu, Hongxing

    2013-04-22

    Optical interferometric logic gates in metal slot waveguide network are designed and investigated by electromagnetic simulations. The designed logic gates can realize all fundamental logic operations. A single Y-shaped junction can work as logic gate for four logic functions: AND, NOT, OR and XOR. By cascading two Y-shaped junctions, NAND, NOR and XNOR can be realized. The working principle is analyzed in detail. In the simulations, these gates show large intensity contrast for the Boolean logic states of the output. These results can be useful for future integrated optical computing.

  1. Experimental Realization of Multipartite Entanglement of 60 Modes of a Quantum Optical Frequency Comb

    NASA Astrophysics Data System (ADS)

    Chen, Moran; Menicucci, Nicolas C.; Pfister, Olivier

    2014-03-01

    We report the experimental realization and characterization of one 60-mode copy and of two 30-mode copies of a dual-rail quantum-wire cluster state in the quantum optical frequency comb of a bimodally pumped optical parametric oscillator. This is the largest entangled system ever created whose subsystems are all available simultaneously. The entanglement proceeds from the coherent concatenation of a multitude of Einstein, Podolsky, and Rosen pairs by a single beam splitter, a procedure which is also a building block for the realization of hypercubic-lattice cluster states for universal quantum computing.

  2. Optical FFT/IFFT circuit realization using arrayed waveguide gratings and the applications in all-optical OFDM system.

    PubMed

    Wang, Zhenxing; Kravtsov, Konstantin S; Huang, Yue-Kai; Prucnal, Paul R

    2011-02-28

    Arrayed waveguide gratings (AWG) are widely used as wavelength division multiplexers (MUX) and demultiplexers (DEMUX) in optical networks. Here we propose and demonstrate that conventional AWGs can also be used as integrated spectral filters to realize a Fast Fourier transform (FFT) and its inverse form (IFFT). More specifically, we point out that the wavelength selection conditions of AWGs when used as wavelength MUX/DEMUX also enable them to perform FFT/IFFT functions. Therefore, previous research on AWGs can now be applied to optical FFT/IFFT circuit design. Compared with other FFT/IFFT optical circuits, AWGs have less structural complexity, especially for a large number of inputs and outputs. As an important application, AWGs can be used in optical OFDM systems. We propose an all-optical OFDM system with AWGs and demonstrate the simulation results. Overall, the AWG provides a feasible solution for all-optical OFDM systems, especially with a large number of optical subcarriers.

  3. Realization of preconditioned Lanczos and conjugate gradient algorithms on optical linear algebra processors.

    PubMed

    Ghosh, A

    1988-08-01

    Lanczos and conjugate gradient algorithms are important in computational linear algebra. In this paper, a parallel pipelined realization of these algorithms on a ring of optical linear algebra processors is described. The flow of data is designed to minimize the idle times of the optical multiprocessor and the redundancy of computations. The effects of optical round-off errors on the solutions obtained by the optical Lanczos and conjugate gradient algorithms are analyzed, and it is shown that optical preconditioning can improve the accuracy of these algorithms substantially. Algorithms for optical preconditioning and results of numerical experiments on solving linear systems of equations arising from partial differential equations are discussed. Since the Lanczos algorithm is used mostly with sparse matrices, a folded storage scheme to represent sparse matrices on spatial light modulators is also described.

  4. Accurate calculation and Matlab based fast realization of merit function's Hesse matrix for the design of multilayer optical coating

    NASA Astrophysics Data System (ADS)

    Wu, Su-Yong; Long, Xing-Wu; Yang, Kai-Yong

    2009-09-01

    To improve the current status of home multilayer optical coating design with low speed and poor efficiency when a large layer number occurs, the accurate calculation and fast realization of merit function’s gradient and Hesse matrix is pointed out. Based on the matrix method to calculate the spectral properties of multilayer optical coating, an analytic model is established theoretically. And the corresponding accurate and fast computation is successfully achieved by programming with Matlab. Theoretical and simulated results indicate that this model is mathematically strict and accurate, and its maximal precision can reach floating-point operations in the computer, with short time and fast speed. Thus it is very suitable to improve the optimal search speed and efficiency of local optimization methods based on the derivatives of merit function. It has outstanding performance in multilayer optical coating design with a large layer number.

  5. Local and long-range realizations of a spin-reorientation surface phase transition

    NASA Astrophysics Data System (ADS)

    He, G.; Winch, H.; Belanger, R.; Nguyen, P. H.; Venus, D.

    2017-03-01

    The spin-reorientation transition of an ultrathin film from perpendicular to in-plane magnetization is driven by a competition between dipole and anisotropy energies. In situ measurements of the magnetic susceptibility of Fe/2 monolayers (ML) Ni/W(110) films as a function of Fe coverage, made as the films are deposited at constant temperature, show two clear peaks that are described quantitatively as a long-range and a local realization of the transition. In the long-range realization, the susceptibility probes the striped domain pattern that is formed in response to the balance of energetics on a mesoscopic scale. Here the reorientation transition occurs at a noninteger layer thickness. In the local realization, the susceptibility probes the response of small islands with in-plane anisotropy in the third atomic Fe layer that are grown on the second atomic Fe layer, which has perpendicular anisotropy. It is a response to the local finite-size, metastable energetics due to discrete steps in thickness. An excellent quantitative description of the susceptibility data is obtained when both local and long-range aspects of the spin-reorientation transition are included.

  6. Ce:YIG/Silicon-on-Insulator waveguide optical isolator realized by adhesive bonding.

    PubMed

    Ghosh, S; Keyvavinia, S; Van Roy, W; Mizumoto, T; Roelkens, G; Baets, R

    2012-01-16

    A waveguide optical isolator realized by adhesive bonding of a garnet die, containing a Ce:YIG magneto-optic layer, on a silicon-on-insulator waveguide circuit is demonstrated. The die was bonded on top of an asymmetric Mach-Zehnder interferometer using a 100nm thick DVS-BCB adhesive bonding layer. A static magnetic field applied perpendicular to the light propagation direction results in a non-reciprocal phase shift for the fundamental quasi-TM mode in the hybrid waveguide geometry. A maximum optical isolation of 25 dB is obtained.

  7. Realization of a fiber optic sensor detecting the presence of a liquid

    NASA Astrophysics Data System (ADS)

    Guzowski, B.; Łakomski, M.; Nowogrodzki, K.

    2016-11-01

    Over the past thirty years, optical fibers have revolutionized the telecommunication market. Fiber optics play also important roles in other numerous applications. One of these applications is fiber sensing - very fast developing area. In this paper, realization of different configurations of a fiber optic sensor detecting the presence of liquid is presented. In the presented sensor, two multimode fibers (MMF) are placed opposite each other, where the first one transmits the light radiation, while the second one is a receiver. Due to the small size of the core (50 μm diameter), they had to be precisely positioned. Therefore the optical fibers were placed in the etched channels in the silicon substrate. In order to make sensors more sensitive, ball-lensed optical fibers were used. Four different diameters of lenses were examined. Sensitivity to the presence of liquids was compared in all realized sensors. Moreover, the influence of distance between the transmitting and receiving optical fiber on the received optical power is also described in this paper. All developed sensors were tested at 1300 nm wavelength. In the last part of this paper the detailed discussion is given.

  8. Two-photon absorption for the realization of optical waveguides on printed circuit boards

    NASA Astrophysics Data System (ADS)

    Langer, Gregor; Riester, Markus

    2007-02-01

    The integration of optical interconnections in printed circuit boards (PCBs) is an emerging field that arouses rapidly growing interest worldwide. At present the key issue is to identify a technical concept, which allows for the realization of optical interconnections that are compatible to existing PCB manufacturing processes. Above all, the material in which the optical interconnections are embedded has to withstand increased temperatures and lamination pressures as well as various wet chemistry processes. AT&S uses so-called two-photon absorption (TPA) laser structuring - a rather new and innovative technology - to realize optical circuits in a special polymer layer. In this case a near infrared laser is applied working in the femto-second regime. The high photon density that can be reached in the laser's focus results in a modification of the optical polymer, which is usually photosensitive in the UV-spectrum of light only. In our particular case, the refractive index of the optical polymer is increased. Choosing the right laser intensity and focus propagation speed one achieves a waveguide well embedded within the polymer layer, which has not been affected by the laser. In contrast to one-photon absorption, which only allows a two dimensional respectively lateral modification of a polymer, this technology allows a modification within the volume resulting in 3D-microstructures inside the polymer layer. Apart from the possibility to realize structures in three dimensions, this TPA-technique has additional advantages. First of all, it allows one step fabrication, which reduces costs and production time compared to etching procedures or conventional UV lithography processes. Moreover, this technique allows varying the waveguide's cross section geometry and diameter simply varying size and form of the structuring laser focus. Whereas the realization of optical waveguides is not challenging anymore the coupling of waveguides with optoelectronic components is rather

  9. Simple integration technique to realize parallel optical interconnects: implementation of a pluggable two-dimensional optical data link

    NASA Astrophysics Data System (ADS)

    Goulet, Alain; Naruse, Makoto; Ishikawa, Masatoshi

    2002-09-01

    An assembly technique is presented to realize pluggable or fully integrated optoelectronic systems based on image relays. A method to visually align and assemble optoelectronic chips or fiber bundles to half of a relay is explained. To validate this technique, two-dimensional arrays of vertical-cavity surface-emitting lasers and photodetectors and a fiber image guide have been integrated to gradient index lenses with simple optomechanical parts. Although the connection of these modules was realized with +/-0.5 mm lateral tolerances, parallel optical interconnects were successfully achieved at 10 MHz. The lateral misalignment between chips was on average 20 μm and at worst 60 μm.

  10. Orientation function of optical mouse realized by digital speckle correlation method

    NASA Astrophysics Data System (ADS)

    Zhen, ZhiQiang; Tang, ZhengXin; Yan, Haitao; Lai, Fangming

    2008-12-01

    Used digital speckle correlation method (DSCM) to realize orientation function of optical mouse is researched. The experiment is designed to obtain the dynamic speckle patterns which are shot by CCD, Then the DSCM is used to process the sequential images and also the experiment is simulated. The experimental results show the DSCM can confirm orientation function of the optical mouse, and have a good agreement with the simulation results, and the resolution we obtained is higher than the resolution of mouse on the market.

  11. Used digital speckle correlation method to realize orientation function of optical mouse

    NASA Astrophysics Data System (ADS)

    Yan, Haitao; Wang, Ming; Ge, Yixian; Zhou, Junping

    2008-09-01

    Used digital speckle correlation method (DSCM) to realize orientation function of optical mouse is researched. The experiment is designed to obtain the dynamic speckle patterns which are shot by CCD, then the DSCM is used to process the sequential images and also the experiment is simulated. The experimental results show the DSCM can confirm orientation function of the optical mouse, and have a good agreement with the simulation results, and the resolution we obtained is higher than the resolution of mouse on the market.

  12. Experimental realization of the quantum duel game using linear optical circuits

    NASA Astrophysics Data System (ADS)

    Balthazar, W. F.; Passos, M. H. M.; Schmidt, A. G. M.; Caetano, D. P.; Huguenin, J. A. O.

    2015-08-01

    We report on the experimental realization of the quantum duel game for two players, Alice and Bob. Using an all optical approach, we have encoded Alice and Bob states in transverse modes and polarization degrees of freedom of a laser beam, respectively. By setting Alice and Bob input states and considering the possibility of Alice performing two shots, we demonstrated the quantum features of the game as well as we recovered the classical version of the game.

  13. Optical Realization of Double-Continuum Fano Interference and Coherent Control in Plasmonic Metasurfaces.

    PubMed

    Arju, Nihal; Ma, Tzuhsuan; Khanikaev, Alexander; Purtseladze, David; Shvets, Gennady

    2015-06-12

    Classical realization of a ubiquitous quantum mechanical phenomenon of double-continuum Fano interference using metasurfaces is experimentally demonstrated by engineering the near-field interaction between two bright and one dark plasmonic modes. The competition between the bright modes, one of them effectively suppressing the Fano interference for the orthogonal light polarization, is discovered. Coherent control of optical energy concentration and light absorption by the ellipticity of the incident light is theoretically predicted.

  14. Optical Realization of Double-Continuum Fano Interference and Coherent Control in Plasmonic Metasurfaces

    NASA Astrophysics Data System (ADS)

    Arju, Nihal; Ma, Tzuhsuan; Khanikaev, Alexander; Purtseladze, David; Shvets, Gennady

    2015-06-01

    Classical realization of a ubiquitous quantum mechanical phenomenon of double-continuum Fano interference using metasurfaces is experimentally demonstrated by engineering the near-field interaction between two bright and one dark plasmonic modes. The competition between the bright modes, one of them effectively suppressing the Fano interference for the orthogonal light polarization, is discovered. Coherent control of optical energy concentration and light absorption by the ellipticity of the incident light is theoretically predicted.

  15. Optical communication with two-photon coherent states. III - Quantum measurements realizable with photoemissive detectors

    NASA Technical Reports Server (NTRS)

    Yuen, H. P.; Shapiro, J. H.

    1980-01-01

    Homodyne detection is shown to achieve the same signal-to-noise ratio as the quantum field quadrature measurement, thus providing a receiver which realizes linear modulation TCS performance gain. The full equivalence of homodyne detection and single-quadrature field measurement is established. A heterodyne configuration which uses a TCS image-band oscillator in addition to the usual coherent state local oscillator is studied. Results are obtained by means of a representation theorem which shows that photoemissive detection realizes the photon flux density measurement.

  16. Nonlinear optical localization in embedded chalcogenide waveguide arrays

    SciTech Connect

    Li, Mingshan; Huang, Sheng; Wang, Qingqing; Chen, Kevin P.; Petek, Hrvoje

    2014-05-15

    We report the nonlinear optical localization in an embedded waveguide array fabricated in chalcogenide glass. The array, which consists of seven waveguides with circularly symmetric cross sections, is realized by ultrafast laser writing. Light propagation in the chalcogenide waveguide array is studied with near infrared laser pulses centered at 1040 nm. The peak intensity required for nonlinear localization for the 1-cm long waveguide array was 35.1 GW/cm{sup 2}, using 10-nJ pulses with 300-fs pulse width, which is 70 times lower than that reported in fused silica waveguide arrays and with over 7 times shorter interaction distance. Results reported in this paper demonstrated that ultrafast laser writing is a viable tool to produce 3D all-optical switching waveguide circuits in chalcogenide glass.

  17. Optical Fibers Would Sense Local Strains

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1994-01-01

    Proposed fiber-optic transducers measure local strains. Includes lead-in and lead-out lengths producing no changes in phase shifts, plus short sensing length in which phase shift is sensitive to strain. Phase shifts in single-mode fibers vary with strains. In alternative version, multiple portions of optical fiber sensitive to strains characteristic of specific vibrational mode of object. Same principle also used with two-mode fiber.

  18. Realization of a video-rate distributed aperture millimeter-wave imaging system using optical upconversion

    NASA Astrophysics Data System (ADS)

    Schuetz, Christopher; Martin, Richard; Dillon, Thomas; Yao, Peng; Mackrides, Daniel; Harrity, Charles; Zablocki, Alicia; Shreve, Kevin; Bonnett, James; Curt, Petersen; Prather, Dennis

    2013-05-01

    Passive imaging using millimeter waves (mmWs) has many advantages and applications in the defense and security markets. All terrestrial bodies emit mmW radiation and these wavelengths are able to penetrate smoke, fog/clouds/marine layers, and even clothing. One primary obstacle to imaging in this spectrum is that longer wavelengths require larger apertures to achieve the resolutions desired for many applications. Accordingly, lens-based focal plane systems and scanning systems tend to require large aperture optics, which increase the achievable size and weight of such systems to beyond what can be supported by many applications. To overcome this limitation, a distributed aperture detection scheme is used in which the effective aperture size can be increased without the associated volumetric increase in imager size. This distributed aperture system is realized through conversion of the received mmW energy into sidebands on an optical carrier. This conversion serves, in essence, to scale the mmW sparse aperture array signals onto a complementary optical array. The side bands are subsequently stripped from the optical carrier and recombined to provide a real time snapshot of the mmW signal. Using this technique, we have constructed a real-time, video-rate imager operating at 75 GHz. A distributed aperture consisting of 220 upconversion channels is used to realize 2.5k pixels with passive sensitivity. Details of the construction and operation of this imager as well as field testing results will be presented herein.

  19. Optical Excision Program. Holographic Local Oscillator

    DTIC Science & Technology

    1979-07-01

    decade it has been known that an optical spectrum analyzer that has an acousto - optical input transducer can reconstruct the signal by coherently detecting...C)~ I,)) pcc F2- PSI-ER-5538-01 2.1 --Continued Figure 2 illustrates the use of the processed hologram to generate the optical local oscillator beam...below: 1) 7 minutes with gentle agitation in D -19 (400 mf of Kodak D -19 concentrate per 2 C of warm tap water. 2 ) 1 minute in 1.3% solution of acetic

  20. Realization of the Harper Hamiltonian with Artificial Gauge Fields in Optical Lattices

    NASA Astrophysics Data System (ADS)

    Miyake, Hirokazu; Siviloglou, Georgios; Kennedy, Colin; Burton, William Cody; Ketterle, Wolfgang

    2014-03-01

    Systems of charged particles in magnetic fields have led to many discoveries in science-such as the integer and fractional quantum Hall effects-and have become important paradigms of quantum many-body physics. We have proposed and implemented a scheme which realizes the Harper Hamiltonian, a lattice model for charged particles in magnetic fields, whose energy spectrum is the fractal Hofstadter butterfly. We experimentally realize this Hamiltonian for ultracold, charge neutral bosonic particles of 87Rb in a two-dimensional optical lattice by creating an artificial gauge field using laser-assisted tunneling and a potential energy gradient provided by gravity. Laser-assisted tunneling processes are characterized by studying the expansion of the atoms in the lattice. Furthermore, this scheme can be extended to realize spin-orbit coupling and the spin Hall effect for neutral atoms in optical lattices by modifying the motion of atoms in a spin-dependent way by laser recoil and Zeeman shifts created with a magnetic field gradient. Major advantages of our scheme are that it does not rely on near-resonant laser light to couple different spin states and should work even for fermionic particles. Our work is a step towards studying novel topological phenomena with ultracold atoms. Currently at the RAND Corporation.

  1. Teleportation-based realization of an optical quantum two-qubit entangling gate.

    PubMed

    Gao, Wei-Bo; Goebel, Alexander M; Lu, Chao-Yang; Dai, Han-Ning; Wagenknecht, Claudia; Zhang, Qiang; Zhao, Bo; Peng, Cheng-Zhi; Chen, Zeng-Bing; Chen, Yu-Ao; Pan, Jian-Wei

    2010-12-07

    In recent years, there has been heightened interest in quantum teleportation, which allows for the transfer of unknown quantum states over arbitrary distances. Quantum teleportation not only serves as an essential ingredient in long-distance quantum communication, but also provides enabling technologies for practical quantum computation. Of particular interest is the scheme proposed by D. Gottesman and I. L. Chuang [(1999) Nature 402:390-393], showing that quantum gates can be implemented by teleporting qubits with the help of some special entangled states. Therefore, the construction of a quantum computer can be simply based on some multiparticle entangled states, Bell-state measurements, and single-qubit operations. The feasibility of this scheme relaxes experimental constraints on realizing universal quantum computation. Using two different methods, we demonstrate the smallest nontrivial module in such a scheme--a teleportation-based quantum entangling gate for two different photonic qubits. One uses a high-fidelity six-photon interferometer to realize controlled-NOT gates, and the other uses four-photon hyperentanglement to realize controlled-Phase gates. The results clearly demonstrate the working principles and the entangling capability of the gates. Our experiment represents an important step toward the realization of practical quantum computers and could lead to many further applications in linear optics quantum information processing.

  2. Optical Fibers Would Sense Local Temperatures

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1994-01-01

    Proposed fiber-optic transducers measure local temperatures. Includes lead-in and lead-out lengths producing no changes in phase shifts, plus short sensing length in which phase shift sensitive to temperature. Phase shifts in two-mode fibers vary with temperatures.

  3. Transverse impedance localization using intensity dependent optics

    SciTech Connect

    Calaga,R.; Arduini, G.; Metral, E.; Papotti, G.; Quatraro, D.; Rumolo, G.; Salvant, B.; Tomas, R.

    2009-05-04

    Measurements of transverse impedance in the SPS to track the evolution over the last few years show discrepancies compared to the analytical estimates of the major contributors. Recent measurements to localize the major sources of the transverse impedance using intensity dependent optics are presented. Some simulations using HEADTAIL to understand the limitations of the reconstruction and related numerical aspects are also discussed.

  4. Trapped Fermi Gases in Rotating Optical Lattices: Realization and Detection of the Topological Hofstadter Insulator

    SciTech Connect

    Umucalilar, R. O.; Oktel, M. Oe.; Zhai Hui

    2008-02-22

    We consider a gas of noninteracting spinless fermions in a rotating optical lattice and calculate the density profile of the gas in an external confinement potential. The density profile exhibits distinct plateaus, which correspond to gaps in the single particle spectrum known as the Hofstadter butterfly. The plateaus result from insulating behavior whenever the Fermi energy lies within a gap. We discuss the necessary conditions to realize the Hofstadter insulator in a cold atom setup and show how the quantized Hall conductance can be measured from density profiles using the Streda formula.

  5. Plasmonic near-touching titanium oxide nanoparticles to realize solar energy harvesting and effective local heating.

    PubMed

    Yan, Jiahao; Liu, Pu; Ma, Churong; Lin, Zhaoyong; Yang, Guowei

    2016-04-28

    Through the excitation of plasmon resonance, the energy of plasmonic nanoparticles either reradiates through light scattering or decays into energetic electrons (absorption). The plasmon-induced absorption can greatly enhance the efficiency of solar energy harvesting, local heating, photodetection and photocatalysis. Here, we demonstrate that heavily self-doped titanium oxide nanoparticles (TiO1.67 analogue arising from oxygen vacancies in rutile TiO2) with the plasmon resonance dominated by an interband transition shows strong absorption to build a broadband perfect absorber in the wavelength range from 300 to 2000 nm covering the solar irradiation spectrum completely. The absorptivity of the fabricated array is greater than 90% in the whole spectral range. And the broadband and strong absorption is due to the plasmon hybridization and hot spot generation from near-touching TiO1.67 nanoparticles with different sizes. What is more, the local heating of a TiO1.67 nanoparticle layer is fast and effective. The temperature increases quickly from 30 °C to 80 °C within 200 seconds. This local heating can realize rapid solar-enabled evaporation which can find applications in large-scale distillation and seawater desalination. These findings actually open a pathway for applications of these newly developed plasmonic materials in the energy and environment fields.

  6. Classical realization of dispersion-canceled, artifact-free, and background-free optical coherence tomography.

    PubMed

    Ogawa, Kazuhisa; Kitano, Masao

    2016-04-18

    Quantum-optical coherence tomography (Q-OCT) provides a dispersion-canceled axial-imaging method, but its practical use is limited by the weakness of the light source and by artifacts in the images. A recent study using chirped-pulse interferometry (CPI) has demonstrated dispersion-canceled and artifact-free OCT with a classical system; however, unwanted background signals still remain after removing the artifacts. Here, we propose a classical optical method that realizes dispersion-canceled, artifact-free, and background-free OCT. We employ a time-reversed system for Q-OCT with transform-limited input laser pulses to achieve dispersion-canceled OCT with a classical system. We have also introduced a subtraction method to remove artifacts and background signals. With these methods, we experimentally demonstrated dispersion-canceled, artifact-free, and background-free axial imaging of a coverglass and cross-sectional imaging of the surface of a coin.

  7. Floquet Realization and Signatures of One-Dimensional Anyons in an Optical Lattice

    NASA Astrophysics Data System (ADS)

    Sträter, Christoph; Srivastava, Shashi C. L.; Eckardt, André

    2016-11-01

    We propose a simple scheme for mimicking the physics of one-dimensional anyons in an optical-lattice experiment. It relies on a bosonic representation of the anyonic Hubbard model to be realized via lattice-shaking-induced resonant tunneling against potential offsets, which are created by a combination of a lattice tilt and strong on-site interactions. No lasers additional to those used for the creation of the optical lattice are required. We also discuss experimental signatures of the continuous interpolation between bosons and fermions when the statistical angle θ is varied from 0 to π . Whereas the real-space density of the bosonic atoms corresponds directly to that of the simulated anyonic model, this is not the case for the momentum distribution. Therefore, we propose to use Friedel oscillations in the density as a probe for continuous fermionization of the bosonic atoms.

  8. Optofluidic realization and retaining of cell-cell contact using an abrupt tapered optical fibre

    NASA Astrophysics Data System (ADS)

    Xin, Hongbao; Zhang, Yao; Lei, Hongxiang; Li, Yayi; Zhang, Huixian; Li, Baojun

    2013-06-01

    Studies reveal that there exists much interaction and communication between bacterial cells, with parts of these social behaviors depending on cell-cell contacts. The cell-cell contact has proved to be crucial for determining various biochemical processes. However, for cell culture with relatively low cell concentration, it is difficult to precisely control and retain the contact of a small group of cells. Particularly, the retaining of cell-cell contact is difficult when flows occur in the medium. Here, we report an optofluidic method for realization and retaining of Escherichia coli cell-cell contact in a microfluidic channel using an abrupt tapered optical fibre. The contact process is based on launching a 980-nm wavelength laser into the fibre, E. coli cells were trapped onto the fibre tip one after another, retaining cell-cell contact and forming a highly organized cell chain. The formed chains further show the ability as bio-optical waveguides.

  9. Linear-optics realization of channels for single-photon multimode qudits

    SciTech Connect

    Piani, Marco; Pitkanen, David; Luetkenhaus, Norbert; Kaltenbaek, Rainer

    2011-09-15

    We propose and theoretically study a method for the stochastic realization of arbitrary quantum channels on multimode single-photon qudits. In order for our method to be undemanding in its implementation, we restrict our analysis to linear-optical techniques, vacuum ancillary states, and nonadaptive schemes, but we allow for random switching between different optical networks. With our method it is possible to deterministically implement random-unitary channels and to stochastically implement general channels. We provide an expression for the optimal probability of success of our scheme and calculate this quantity for specific examples such as the qubit amplitude-damping channel. The success probability is shown to be related to the entanglement properties of the Choi-Jamiolkowski state isomorphic to the channel.

  10. Realization of the scale of high fiber optic power at three national standards laboratories

    SciTech Connect

    Envall, Jouni; Andersson, Anne; Petersen, Jan C.; Kaerhae, Petri

    2005-08-20

    Nowadays the transmission powers in optical telecommunication networks are often hundreds of milliwatts. Such high power levels are known to cause several nonlinear effects, thus affecting data transfer. Therefore, accurate measurements of such high power levels are required. The general issues that are to be considered when one is realizing a scale for high fiber optic power are discussed. The scales of the national standards laboratories in Finland, Sweden, and Denmark are described, and the results of a trilateral comparison of these scales are presented. The power range of the comparison was 1-200 mW. The results show that the stated measurement uncertainties of the three laboratories (1.3%-2.9%,k=2) are applicable over this power range.

  11. Realization of optical OFDM using time lenses and its comparison with optical OFDM using FFT.

    PubMed

    Yang, Dong; Kumar, Shiva

    2009-09-28

    An optical orthogonal frequency division multiplexing (OFDM) scheme with Fourier transform in optical domain using time lenses both at the transmitter and at the receiver is analyzed. The comparison of performance between this scheme with the optical OFDM scheme that utilizes fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) in electrical domain is made. The nonlinear effects induced by Mach-Zehnder modulator (MZM) as well as by the fiber are investigated for both schemes. Results show that the coherent OFDM using time lenses has almost the same performance as that using FFT when the electrical driving message signal voltages are low so that MZM operates in the linear region. The nonlinearity of MZM deteriorates the conventional coherent OFDM based on FFT when the power of electrical driving signal increases significantly, but only has negligible impairment on the coherent OFDM using time lenses. Details of the time lens set up are provided and a novel scheme to implement the time lens without requiring the quadratic dependence of the driving voltage is presented.

  12. Ultralow bias power all-optical photonic crystal memory realized with systematically tuned L3 nanocavity

    SciTech Connect

    Kuramochi, Eiichi Nozaki, Kengo; Shinya, Akihiko; Taniyama, Hideaki; Notomi, Masaya; Takeda, Koji; Matsuo, Shinji; Sato, Tomonari

    2015-11-30

    An InP photonic crystal nanocavity with an embedded InGaAsP active region is a unique technology that has realized an all-optical memory with a sub-micro-watt operating power and limitless storage time. In this study, we employed an L3 design with systematic multi-hole tuning, which realized a higher loaded Q factor (>40 000) and a lower mode volume (0.9 μm{sup 3}) than a line-defect-based buried-heterostructure nanocavity (16 000 and 2.2 μm{sup 3}). Excluding the active region realized a record loaded Q factor (210 000) in all for InP-based nanocavities. The minimum bias power for bistable memory operation was reduced to 2.3 ± 0.3 nW, which is about 1/10 of the previous record of 30 nW. This work further established the capability of a bistable nanocavity memory for use in future ultralow-power-consumption on-chip integrated photonics.

  13. Fiber optic configurations for local area networks

    NASA Technical Reports Server (NTRS)

    Nassehi, M. M.; Tobagi, F. A.; Marhic, M. E.

    1985-01-01

    A number of fiber optic configurations for a new class of demand assignment multiple-access local area networks requiring a physical ordering among stations are proposed. In such networks, the data transmission and linear-ordering functions may be distinguished and be provided by separate data and control subnetworks. The configurations proposed for the data subnetwork are based on the linear, star, and tree topologies. To provide the linear-ordering function, the control subnetwork must always have a linear unidirectional bus structure. Due to the reciprocity and excess loss of optical couplers, the number of stations that can be accommodated on a linear fiber optic bus is severely limited. Two techniques are proposed to overcome this limitation. For each of the data and control subnetwork configurations, the maximum number of stations as a function of the power margin, for both reciprocal and nonreciprocal couplers, is computed.

  14. Plasmonic near-touching titanium oxide nanoparticles to realize solar energy harvesting and effective local heating

    NASA Astrophysics Data System (ADS)

    Yan, Jiahao; Liu, Pu; Ma, Churong; Lin, Zhaoyong; Yang, Guowei

    2016-04-01

    Through the excitation of plasmon resonance, the energy of plasmonic nanoparticles either reradiates through light scattering or decays into energetic electrons (absorption). The plasmon-induced absorption can greatly enhance the efficiency of solar energy harvesting, local heating, photodetection and photocatalysis. Here, we demonstrate that heavily self-doped titanium oxide nanoparticles (TiO1.67 analogue arising from oxygen vacancies in rutile TiO2) with the plasmon resonance dominated by an interband transition shows strong absorption to build a broadband perfect absorber in the wavelength range from 300 to 2000 nm covering the solar irradiation spectrum completely. The absorptivity of the fabricated array is greater than 90% in the whole spectral range. And the broadband and strong absorption is due to the plasmon hybridization and hot spot generation from near-touching TiO1.67 nanoparticles with different sizes. What is more, the local heating of a TiO1.67 nanoparticle layer is fast and effective. The temperature increases quickly from 30 °C to 80 °C within 200 seconds. This local heating can realize rapid solar-enabled evaporation which can find applications in large-scale distillation and seawater desalination. These findings actually open a pathway for applications of these newly developed plasmonic materials in the energy and environment fields.Through the excitation of plasmon resonance, the energy of plasmonic nanoparticles either reradiates through light scattering or decays into energetic electrons (absorption). The plasmon-induced absorption can greatly enhance the efficiency of solar energy harvesting, local heating, photodetection and photocatalysis. Here, we demonstrate that heavily self-doped titanium oxide nanoparticles (TiO1.67 analogue arising from oxygen vacancies in rutile TiO2) with the plasmon resonance dominated by an interband transition shows strong absorption to build a broadband perfect absorber in the wavelength range from 300 to

  15. Annular force based variable curvature mirror aiming to realize non-moving element optical zooming

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Xie, Xiaopeng; Wei, Jingxuan; Ren, Guorui; Pang, Zhihai; Xu, Liang

    2015-10-01

    Recently, a new kind of optical zooming technique in which no moving elements are involved has been paid much attention. The elimination of moving elements makes optical zooming suitable for applications which has exacting requirements in space, power cost and system stability. The mobile phone and the space-borne camera are two typical examples. The key to realize non-moving elements optical zooming lies in the introduction of variable curvature mirror (VCM) whose radius of curvature could be changed dynamically. When VCM is about to be used to implement optical zoom imaging, two characteristics should be ensured. First, VCM has to provide large enough saggitus variation in order to obtain a big magnification ratio. Second, after the radius of curvature has been changed, the corresponding surface figure accuracy should still be maintained superior to a threshold level to make the high quality imaging possible. In this manuscript, based on the elasticity theory, the physical model of the annular force based variable curvature mirror is established and numerically analyzed. The results demonstrate that when the annular force is applied at the half-the-aperture position, the actuation force is reduced and a smaller actuation force is required to generate the saggitus variation and thus the maintenance of surface figure accuracy becomes easier during the variation of radius of curvature. Besides that, a prototype VCM, whose diameter and thickness are 100mm and 3mm respectively, have been fabricated and the maximum saggitus variation that could be obtained approaches more than 30 wavelengths. At the same time, the degradation of surface figure accuracy is weakly correlated to the curvature radius variation. Keywords: optical zooming; variable curvature mirror; surface figure accuracy; saggitus;

  16. Seeing the unseen with localized optical contrast

    NASA Astrophysics Data System (ADS)

    Suran, Swathi; Bharadwaj, Krishna; Raghavan, Srinivasan; Varma, Manoj M.

    2016-03-01

    Optical wide-field imaging of sub-diffraction limit nanostructures is of interest in a wide array of applications. In applications where the nanostructures to be visualized are well isolated, a high enough optical contrast is sufficient to detect these. Here we demonstrate a technique to visualize nanoscale features, such as grain boundaries in Chemical Vapor Deposited (CVD) single layer graphene, which are just a few atom length defects, using regular bright field optical microscopy. This remarkably low lateral length scale was imaged using of a special thin film structure consisting of a water-soluble thin film layer deposited on a metal substrate, which produces a strong color change as a function of the film thickness. Small local water transport differences in the graphene layer result in thickness variation of the underlying thin film due to its solubility in water and produces color contrast readily observable under a normal brightfield optical microscope with the naked eye. We demonstrate the use of this technique for direct optical visualization of grain boundaries in graphene as wide as 2-5 nm and sub-100 nm photoresist lines. By using super-resolution image processing algorithms, we may be able to detect structure even smaller in size than currently achieved. We believe that this technique can be extended to single molecule detection.

  17. Realizing mode conversion and optical diode effect by coupling photonic crystal waveguides with cavity

    NASA Astrophysics Data System (ADS)

    Ye, Han; Zhang, Jin-Qian-Nan; Yu, Zhong-Yuan; Wang, Dong-Lin; Chen, Zhi-Hui

    2015-09-01

    We propose a novel two-dimensional photonic crystal structure consisting of two line defect waveguides and a cavity to realize mode conversion based on the coupling effect. The W1/cavity/W2 structure breaks the spatial symmetry and successfully converts the even (odd) mode to the odd (even) mode in the W2 waveguide during the forward (backward) transmission. When considering the incidence of only the even mode, the optical diode effect emerges and achieves approximate 35 dB unidirectionality at the resonant frequency. Moreover, owing to the narrow bandpass feature and the flexibility of the tuning cavity, utilization of the proposed structure as a wavelength filter is demonstrated in a device with a Y-branch splitter. Here, we provide a heuristic design for a mode converter, optical diode, and wavelength filter derived from the coupling effect between a cavity and adjacent waveguides, and expect that the proposed structure can be applied as a building block in future all-optical integrated circuits. Project supported by the National Natural Science Foundation of China (Grant Nos. 61372037 and 61307069), Beijing Excellent Ph. D. Thesis Guidance Foundation, China (Grant No. 20131001301), and the Natural Science Foundation of Shanxi Province, China (Grant No. 2013021017-3).

  18. Intrinsic Localized Modes in Optical Photonic Lattices and Arrays

    NASA Astrophysics Data System (ADS)

    Christodoulides, Demetrios

    Discretizing light behavior requires optical elements that can confine optical energy at distinct sites. One possible scenario in implementing such arrangements is to store energy within low loss high Q-microcavities and then allow photon exchange between such components in time. This scheme requires high-contrast dielectric elements that became available with the advent of photonic crystal technologies. Another possible avenue where such light discretization can be directly observed and studied is that based on evanescently coupled waveguide arrays. As indicated in several studies, discrete systems open up whole new directions in terms of modifying light transport properties. One such example is that of discrete solitons. By nature, discrete solitons represent self-trapped wavepackets in nonlinear periodic structures and result from the interplay between lattice diffraction (or dispersion) and material nonlinearity. In optics, this class of self-localized states has been successfully observed in both one- and two-dimensional nonlinear waveguide arrays. In recent years such photonic lattices have been implemented or induced in a variety of material systems, including those with cubic (Kerr), quadratic, photorefractive, and liquid-crystal nonlinearities. In all cases the underlying periodicity or discreteness can lead to new families of optical solitons that have no counterpart whatsoever in continuous systems. Interestingly, these results paved the way for observations in other physical systems obeying similar evolution equations like Bose-Einstein condensates. New developments in laser writing ultrashort femtosecond laser pulses, now allow the realization of all-optical switching networks in fully 3D environments using nonlinear discrete optics. Using this approach all-optical routing can be achieved using blocking operations. The spatio-temporal evolution of optical pulses in both normally and anomalously dispersive arrays can lead to novel schemes for mode

  19. Finite violations of a Bell inequality for high spin: An optical realization

    SciTech Connect

    Gerry, Christopher C.; Albert, Jaroslav

    2005-10-15

    Some years ago Peres [Phys. Rev. A 46, 4413 (1992)] described a gedanken experiment for a pair of spatially spin j particles in a singlet state and showed using with a dichotomic observable (essentially a parity operator) that Bell's theorem in the form of the Clauser-Home-Shimony-Holt (CHSH) inequality is violated by a constant amount (24%) in the limit j{yields}{infinity}. In this paper we present a scheme for an optical realization of a state that is very close to the spin-j singlet state using two traveling-wave modes of the quantized field using a 50:50 beam splitter with an input number state. A near-singlet states comes about because the binomial output state of the beam splitter can be written as a sum in terms of states in the form vertical bar j,m>{sub 1}x vertical bar j,-m>{sub 2}, each state being associated with a Holstein-Primakoff realization of the su(2) spin algebra in terms of the Bose operators of each of the field modes, where j=N/2, N being the number of photons passing through the beam splitter. The binomial state can violate the CHSH inequality to a greater degree than does the singlet state.

  20. Realization of a fiber-optic force-torque sensor with six degrees of freedom

    NASA Astrophysics Data System (ADS)

    Müller, M. S.; Hoffmann, L.; Buck, T. S.; Koch, A. W.

    2008-11-01

    Multi-axial force and torque sensing is of importance for robot control and many force-feedback applications. Minimal invasive robotic surgery (MIRS) is a possible field of application of force and torque sensors with up to six degrees of freedom. Although these sensors are not yet employed in current commercial MIRS systems, extensive work has been carried out on the development of these sensors. Some of their issues are related to their electric working principle: they are limited in performance by thermal noise, need electric power inside the patient and are not usable under influence of strong magnet fields (e. g. in MRI machines). One possible alternative is seen in fiber optic force torque sensors, since the signal demodulation may be located in some distance to the actual sensor and they also do not have to include any magnetic material. This article presents a fiber optic force and torque sensor with six degrees of freedom. The general setup resembles a Stewart Platform, whereas its connecting beams are formed by the fiber itself, and the element creating stiffness may be of arbitrary form. Only a single fiber is needed to extract all six parameters since they are measured on six multiplexed fiber Bragg grating sensors. We demonstrate how the sensor is realized and show results of torque measurements with variable load.

  1. Light-guided localization within tissue using biocompatible surgical suture fiber as an optical waveguide.

    PubMed

    Choi, Woo June; Park, Kwan Seob; Lee, Byeong Ha

    2014-09-01

    In breast-conserving surgery, an optical wire is a useful surgical guiding tool to optically locate small lesions within the breast tissue. However, the use of a long silica glass fiber as the optical wire can be burdensome to patients because of its stiffness and nonbiocompatibility. We investigate the use of a biocompatible fiber for light localization in tissue. A surgical suture with a diameter of 400 μm and a few centimeters long is employed as the biocompatible optical waveguide to transport the visible laser light to the inner tissue site. Optical location is confirmed with glow ball-like red laser illumination at the tip of the suture embedded within a fresh chicken breast tissue. Effective optical power coupling to the suture is made by using a double-cladding fiber coupler. From this preliminary result, we realize practical light localization with biopolymer waveguides.

  2. Direct optical nanoscopy with axially localized detection

    NASA Astrophysics Data System (ADS)

    Bourg, N.; Mayet, C.; Dupuis, G.; Barroca, T.; Bon, P.; Lécart, S.; Fort, E.; Lévêque-Fort, S.

    2015-09-01

    Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Here, we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called supercritical-angle fluorescence can be captured using a high-numerical-aperture objective and used to determine the axial position of the fluorophore with nanometre precision. We introduce a new technique for three-dimensional nanoscopy that combines direct stochastic optical reconstruction microscopy (dSTORM) with dedicated detection of supercritical-angle fluorescence emission. We demonstrate that our approach of direct optical nanoscopy with axially localized detection (DONALD) typically yields an isotropic three-dimensional localization precision of 20 nm within an axial range of ∼150 nm above the coverslip.

  3. Realizing A Mid-Infrared Optically Pumped Molecular Gas Laser Inside Hollow-Core Photonic Crystal Fiber

    DTIC Science & Technology

    2012-01-01

    REALIZING A MID-INFRARED OPTICALLY PUMPED MOLECULAR GAS LASER INSIDE HOLLOW-CORE PHOTONIC CRYSTAL FIBER by ANDREW MICHAEL JONES... Laser Inside Hollow-Core Photonic Crystal Fiber 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...optical fibers . These novel lasers are appealing for a variety of applications including frequency metrology in the midinfrared,free-space

  4. Realizing artificial spin ice states for magnetic colloids on optical trap arrays

    NASA Astrophysics Data System (ADS)

    Libál, A.; Reichhardt, C. M.; Olson Reichhardt, C. J.

    2016-10-01

    Colloids interacting with periodic substrates such as those created with optical traps are an ideal system in which to study various types of phase transitions such as commensurate to incommensurate states and melting behaviors, and they can also be used to create new types of ordering that can be mapped to spin systems. Here we numerically demonstrate how magnetic colloids interacting with an array of elongated two-state traps can be used to realize square artificial spin ice. By tuning the magnetic field, it is possible to precisely control the interaction strength between the colloids, making it possible to observe a transition from a disordered state to an ordered state that obeys the two-in/two-out ice rules. We also examine the dynamics of excitations of the ground state, including pairs of monopoles, and show that the monopoles have emergent attractive interactions. The strength of the interaction can be modified by the magnetic field, permitting the monopole velocity to be tuned.

  5. Localized Turing patterns in nonlinear optical cavities

    NASA Astrophysics Data System (ADS)

    Kozyreff, G.

    2012-05-01

    The subcritical Turing instability is studied in two classes of models for laser-driven nonlinear optical cavities. In the first class of models, the nonlinearity is purely absorptive, with arbitrary intensity-dependent losses. In the second class, the refractive index is real and is an arbitrary function of the intracavity intensity. Through a weakly nonlinear analysis, a Ginzburg-Landau equation with quintic nonlinearity is derived. Thus, the Maxwell curve, which marks the existence of localized patterns in parameter space, is determined. In the particular case of the Lugiato-Lefever model, the analysis is continued to seventh order, yielding a refined formula for the Maxwell curve and the theoretical curve is compared with recent numerical simulation by Gomila et al. [D. Gomila, A. Scroggie, W. Firth, Bifurcation structure of dissipative solitons, Physica D 227 (2007) 70-77.

  6. Fluorophores as optical sensors for local forces.

    PubMed

    Marawske, Stefan; Dörr, Denis; Schmitz, Daniel; Koslowski, Axel; Lu, You; Ritter, Helmut; Thiel, Walter; Seidel, Claus A M; Kühnemuth, Ralf

    2009-08-24

    The main aim of this study is to investigate correlations between the impact of an external mechanical force on the molecular framework of fluorophores and the resultant changes in their fluorescence properties. Taking into account previous theoretical studies, we designed a suitable custom-tailored oligoparaphenylenevinylene derivative (OPV5) with a twisted molecular backbone. Thin foils made of PVC doped with 100 nM OPV were prepared. By applying uniaxial force, the foils were stretched and three major optical effects were observed simultaneously. First, the fluorescence anisotropy increased, which indicates a reorientation of the fluorophores within the matrix. Second, the fluorescence lifetime decreased by approximately 2.5% (25 ps). Finally, we observed an increase in the emission energy of about 0.2% (corresponding to a blue-shift of 1.2 nm). In addition, analogous measurements with Rhodamine 123 as an inert reference dye showed only minor effects, which can be attributed to matrix effects due to refractive index changes. To relate the observed spectroscopic changes to the underlying changes in molecular properties, quantum-chemical calculations were also performed. Semiempirical methods had to be used because of the size of the OPV5 chromophore. Two conformers of OPV5 (C(2) and C(i) symmetry) were considered and both gave very similar results. Both the observed blue-shift of fluorescence and the reduced lifetime of OPV5 under tensile stress are consistent with the results of the semiempirical calculations. Our study proves the feasibility of fluorescence-based local force probes for polymers under tension. Improved optical sensors of this type should in principle be able to monitor local mechanical stress in transparent samples down to the single-molecule level, which harbors promising applications in polymer science and nanotechnology.

  7. Safety analysis and realization of safe information transmission optical LAN on high-speed railway

    NASA Astrophysics Data System (ADS)

    Tao, Ying; Wu, Chongqing; Li, Zuoyi

    2001-10-01

    High-speed railway that has been progressing very quickly is one of the greatest techniques in present time because of its high speed, economy, comfort, environment benefits and other advantages. And among all of these, safe is the backbone and lifeline, so the chief task in developing high-speed railway is to establish safety guarantee system. Also in this safety guarantee system, train control is one of the key techniques to guarantee safe train operation and to advance ability of transportation, so operation safe is located in the hardcore position. That is to say, it is imperative to set up a safe, real-time and reliable automatic train control system. And we can easily find out that this kind of system is now developed and applied in many countries. Important information related to train control, such as the received and transmitted information of track-sided equipment, is called safe information, because it deals with train operation's safe, reliability, and even directly with people's life and wealth. It is so important that if there were some kind of fault with its making, transmission, or processing, fatal accident would occur. So to some degree, it is impossible to transmit and process this information through present railway communication network because of the former's extreme importance and the latter's no safe capability. Therefore, a specific communication network that mainly considers about safe transmission and management should be established in order to realize the specific function for this specific information. High-speed railway safe information transmission optical LAN, which adopts optical fiber as transmission media and transmits safe information, is a kind of LAN designed for the request for safe, real-time and highly reliable automatic train control system in the process of our country's high-speed railway construction and commonly train speed. In this paper, after analyzing the characteristics of automatic train control system and the

  8. Experimental Realization of Strong Effective Magnetic Fields in an Optical Lattice

    SciTech Connect

    Aidelsburger, M.; Atala, M.; Trotzky, S.; Chen, Y.-A.; Bloch, I.; Nascimbene, S.

    2011-12-16

    We use Raman-assisted tunneling in an optical superlattice to generate large tunable effective magnetic fields for ultracold atoms. When hopping in the lattice, the accumulated phase shift by an atom is equivalent to the Aharonov-Bohm phase of a charged particle exposed to a staggered magnetic field of large magnitude, on the order of 1 flux quantum per plaquette. We study the ground state of this system and observe that the frustration induced by the magnetic field can lead to a degenerate ground state for noninteracting particles. We provide a measurement of the local phase acquired from Raman-induced tunneling, demonstrating time-reversal symmetry breaking of the underlying Hamiltonian. Furthermore, the quantum cyclotron orbit of single atoms in the lattice exposed to the magnetic field is directly revealed.

  9. Non-local classical optical correlation and implementing analogy of quantum teleportation.

    PubMed

    Sun, Yifan; Song, Xinbing; Qin, Hongwei; Zhang, Xiong; Yang, Zhenwei; Zhang, Xiangdong

    2015-03-17

    This study reports an experimental realization of non-local classical optical correlation from the Bell's measurement used in tests of quantum non-locality. Based on such a classical Einstein-Podolsky-Rosen optical correlation, a classical analogy has been implemented to the true meaning of quantum teleportation. In the experimental teleportation protocol, the initial teleported information can be unknown to anyone and the information transfer can happen over arbitrary distances. The obtained results give novel insight into quantum physics and may open a new field of applications in quantum information.

  10. Matter-wave localization in a weakly perturbed optical lattice

    SciTech Connect

    Cheng, Yongshan; Adhikari, S. K.

    2011-11-15

    By numerical solution and variational approximation of the Gross-Pitaevskii equation, we studied the localization of a noninteracting and weakly interacting Bose-Einstein condensate in a weakly perturbed optical lattice in one and three dimensions. The perturbation achieved through a weak delocalizing expulsive or a linear potential as well as a weak localizing harmonic potential removes the periodicity of the optical lattice and leads to localization. We also studied some dynamics of the localized state confirming its stability.

  11. Realization of rapid debugging for detection circuit of optical fiber gas sensor: Using an analog signal source

    NASA Astrophysics Data System (ADS)

    Tian, Changbin; Chang, Jun; Wang, Qiang; Wei, Wei; Zhu, Cunguang

    2015-03-01

    An optical fiber gas sensor mainly consists of two parts: optical part and detection circuit. In the debugging for the detection circuit, the optical part usually serves as a signal source. However, in the debugging condition, the optical part can be easily influenced by many factors, such as the fluctuation of ambient temperature or driving current resulting in instability of the wavelength and intensity for the laser; for dual-beam sensor, the different bends and stresses of the optical fiber will lead to the fluctuation of the intensity and phase; the intensity noise from the collimator, coupler, and other optical devices in the system will also result in the impurity of the optical part based signal source. In order to dramatically improve the debugging efficiency of the detection circuit and shorten the period of research and development, this paper describes an analog signal source, consisting of a single chip microcomputer (SCM), an amplifier circuit, and a voltage-to-current conversion circuit. It can be used to realize the rapid debugging detection circuit of the optical fiber gas sensor instead of optical part based signal source. This analog signal source performs well with many other advantages, such as the simple operation, small size, and light weight.

  12. Multi-Valued Neural Network Modified Model and Its Optical Realization,

    DTIC Science & Technology

    1995-03-07

    This paper presents a modified optical neural networK model, and the optical system, constructed with spatial light modulator PROM, can materialize...modified model improves cognitive ability of an optical neural network and also improves the storage capacity to a certain extent.

  13. Optical systems modeling and experimental realization of pump and probe technique: investigation of nonlinear absorption in colloidal quantum dots

    NASA Astrophysics Data System (ADS)

    Smirnov, A.; Golinskaya, A.; Ezhova, K.; Kozlova, M.; Dneprovskii, V.

    2016-04-01

    Two optical systems modeling of laser and broadband radiation focusing, that is necessary for realization of the pump and probe method, was carried out in this work. Modeling was utilized to construct experimental setup for transmission spectra measuring of studied sample by probe nanosecond broadband radiation (coumarin photoluminescence) depending on the intensity of the nanosecond laser pump pulses. The saturation effect of absorption and the induced charge Stark-effect coexistence and predominate issue of these effects are determined by power of optical excitation. In dependence of tuning of excitation radiation frequency from basic exciton transition frequency nonlinear effects in colloidal CdSe/ZnS quantum dots has been investigated.

  14. INTERNATIONAL REPORT: Practical realization of the definition of the metre, including recommended radiations of other optical frequency standards (2003)

    NASA Astrophysics Data System (ADS)

    Felder, R.

    2005-08-01

    In 2003, the International Committee for Weights and Measures (CIPM) recommended updated values of the frequency for certain optical frequency standards recommended for the practical realization of the definition of the metre. The text of this CIPM Recommendation and details of the updated radiations are given here. The complete updated set of recommended radiations, including frequencies, wavelengths, uncertainties and operating conditions where appropriate, is available on the BIPM website.

  15. Realization of the Haldane-Kane-Mele Model in a System of Localized Spins

    NASA Astrophysics Data System (ADS)

    Kim, Se Kwon; Ochoa, Héctor; Zarzuela, Ricardo; Tserkovnyak, Yaroslav

    2016-11-01

    We study a spin Hamiltonian for spin-orbit-coupled ferromagnets on the honeycomb lattice. At sufficiently low temperatures supporting the ordered phase, the effective Hamiltonian for magnons, the quanta of spin-wave excitations, is shown to be equivalent to the Haldane model for electrons, which indicates the nontrivial topology of the band and the existence of the associated edge state. At high temperatures comparable to the ferromagnetic-exchange strength, we take the Schwinger-boson representation of spins, in which the mean-field spinon band forms a bosonic counterpart of the Kane-Mele model. The nontrivial geometry of the spinon band can be inferred by detecting the spin Nernst effect. A feasible experimental realization of the spin Hamiltonian is proposed.

  16. Transformative Hispanic-Serving Institutions: Realizing Equity Praxis through Community Connections and Local Solutions

    ERIC Educational Resources Information Center

    Ruiz, Marisol; Valverde, Michelle

    2012-01-01

    Schools serve as antidemocratic spaces where teacher, parent, community member, and student voices are typically disregarded. Instead, philanthropists and businesses are allowed to drive school and district agendas. An exploration of 3 local efforts that connect a Hispanic-Serving Institution (HSI) with prekindergarten to Grade 12 students and…

  17. Realization of two-dimensional Aubry-André localization of light waves via electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Li, Hui-jun; Dou, Jian-peng; Huang, Guoxiang

    2014-03-01

    We propose a scheme to construct a two-dimensional Aubry-André (AA) model and realize two-dimensional AA localization of light waves via electromagnetically induced transparency (EIT). The system we suggest is a cold, resonant atomic gas with an N-type level configuration and interacting with probe, control, assisted, and far-detuned laser fields. We show that under EIT conditions the probe-field envelope obeys a modified nonlinear Schrödinger equation with a quasiperiodic potential, which becomes a two-dimensional nonlinear AA model when the system parameters are suitably chosen. The quasiperiodic potential is obtained by the cross-phase modulation of the assisted field and the Stark shift of the far-detuned laser field. In addition, the cubic nonlinearity term appearing in the model is contributed by the self-phase modulation of the probe field. We demonstrate that the system can be used to not only realize various two-dimensional AA localizations of light waves, but also to display nonlinearity and dimensionality effects on the AA localizations.

  18. Fiber Optic Tactical Local Network (FOTLAN)

    NASA Technical Reports Server (NTRS)

    Bergman, L. A.; Hartmayer, R.; Wu, W. H.; Cassell, P.; Edgar, G.; Lambert, J.; Mancini, R.; Jeng, J.; Pardo, C.

    1991-01-01

    A 100 Mbit/s FDDI (fiber distributed data interface) network interface unit is described that supports real-time data, voice and video. Its high-speed interrupt-driven hardware architecture efficiently manages stream and packet data transfer to the FDDI network. Other enhancements include modular single-mode laser-diode fiber optic links to maximize node spacing, optic bypass switches for increased fault tolerance, and a hardware performance monitor to gather real-time network diagnostics.

  19. Realization of optical bistability and multistability in Landau-quantized graphene

    NASA Astrophysics Data System (ADS)

    Hamedi, H. R.; Asadpour, S. H.

    2015-05-01

    The solution of input-output curves in an optical ring cavity containing Landau-quantized graphene is theoretically investigated taking the advantage of density-matrix method. It is found that under the action of strong magnetic and infrared laser fields, one can efficiently reduce the threshold of the onset of optical bistability (OB) at resonance condition. At non-resonance condition, we observed that graphene metamaterial can support the possibility to obtain optical multistability (OM), which is more practical in all-optical switching or coding elements. We present an analytical approach to elucidate our simulations. Due to very high infrared optical nonlinearity of graphene stemming from very unique and unusual properties of quantized Landau levels near the Dirac point, such controllability on OB and OM may provide new technological possibilities in solid state quantum information science.

  20. Realization of optical bistability and multistability in Landau-quantized graphene

    SciTech Connect

    Hamedi, H. R.; Asadpour, S. H.

    2015-05-14

    The solution of input-output curves in an optical ring cavity containing Landau-quantized graphene is theoretically investigated taking the advantage of density-matrix method. It is found that under the action of strong magnetic and infrared laser fields, one can efficiently reduce the threshold of the onset of optical bistability (OB) at resonance condition. At non-resonance condition, we observed that graphene metamaterial can support the possibility to obtain optical multistability (OM), which is more practical in all-optical switching or coding elements. We present an analytical approach to elucidate our simulations. Due to very high infrared optical nonlinearity of graphene stemming from very unique and unusual properties of quantized Landau levels near the Dirac point, such controllability on OB and OM may provide new technological possibilities in solid state quantum information science.

  1. Protein phosphorylation: Localization in regenerating optic axons

    SciTech Connect

    Larrivee, D. )

    1990-09-01

    A number of axonal proteins display changes in phosphorylation during goldfish optic nerve regeneration. (1) To determine whether the phosphorylation of these proteins was closely linked to their synthesis in the retinal ganglion cell body, cycloheximide was injected intraocularly into goldfish whose optic nerves had been regenerating for 3 weeks. Cycloheximide reduced the incorporation of (3H)proline and 32P orthophosphate into total nerve protein by 84% and 46%, respectively. Of the 20 individual proteins examined, 17 contained less than 15% of the (3H)proline label measured in corresponding controls, whereas 18 proteins contained 50% or more of the 32P label, suggesting that phosphorylation was largely independent of synthesis. (2) To determine whether the proteins were phosphorylated in the ganglion cell axons, axonal transport of proteins was blocked by intraocular injection of vincristine. Vincristine reduced (3H)proline labeling of total protein by 88% and 32P labeling by 49%. Among the individual proteins (3H)proline labeling was reduced by 90% or more in 18 cases but 32P labeling was reduced only by 50% or less. (3) When 32P was injected into the cranial cavity near the ends of the optic axons, all of the phosphoproteins were labeled more intensely in the optic tract than in the optic nerve. These results suggest that most of the major phosphoproteins that undergo changes in phosphorylation in the course of regeneration are phosphorylated in the optic axons.

  2. Realization of all-optical switch and diode via Raman gain process using a Kerr field

    NASA Astrophysics Data System (ADS)

    Abbas, Muqaddar; Qamar, Sajid; Qamar, Shahid

    2016-08-01

    The idea of optical photonic crystal, which is generated using two counter-propagating fields, is revisited to study gain-assisted all-optical switch and diode using Kerr field. Two counter-propagating fields with relative detuning Δ ν generate standing-wave field pattern which interacts with a four-level atomic system. The standing-wave field pattern acts like a static photonic crystal for Δ ν =0 , however, it behaves as a moving photonic crystal for Δ ν \

  3. Optical integration of laterally modified multiple quantum well structures by implantation enhanced intermixing to realize gain coupled DFB lasers

    NASA Astrophysics Data System (ADS)

    Hofsäß, V.; Kuhn, J.; Kaden, C.; Härle, V.; Bolay, H.; Scholz, F.; Schweizer, H.; Hillmer, H.; Lösch, R.; Schlapp, W.

    1995-12-01

    We report on the realization of gain coupled distributed feedback (GC-DFB) lasers using masked implantation enhanced intermixing (MIEI) in a full planar technology. The process requires only planar epitaxy steps to minimize ion straggling. We present a detailed investigation on the integration processing steps as implantation, subsequent annealing and regrowth with InP (MOCVD). We also discuss critical technology steps. Surface morphology depends very sensitive on implantation and annealing. Nonradiative recombination caused by defects leads to high losses in optical devices. We achieve good results for an AsH 3 stabilized annealing step in a MOCVD equipment, compared to rapid thermal annealing (RTA), which proceeds as the second epitaxial step. Photoluminescence (PL) studies show the excellent interface quality. High homogeneity and small linewidth after the integration process indicate sufficient quality to realize electrical gain coupled DFB-laser devices by IEI.

  4. Realizing the Harper Hamiltonian and Spin-Orbit Coupling with Laser-Assisted Tunneling in an Optical Lattice

    NASA Astrophysics Data System (ADS)

    Kennedy, Colin; Miyake, Hiro; Burton, Cody; Chung, Woo Chang; Siviloglou, Georgios; Ketterle, Wolfgang

    2014-05-01

    The study of charged particles in a magnetic field has led to paradigm shifts in condensed matter physics including the discovery of topologically ordered states like the quantum Hall and fractional quantum Hall states. Quantum simulation of such systems using neutral atoms has drawn much interest recently in the atomic physics community due to the versatility and defect-free nature of such systems. We discuss our recent experimental realization of the Harper Hamiltonian and strong, uniform effective magnetic fields for neutral particles in an optical lattice. Additionally, our scheme represents a promising system to realize spin-orbit coupling and the quantum spin Hall states without flipping atomic spin states and thus without the intrinsic heating that comes with near-resonant Raman lasers. We point out that our scheme can be implemented all optically through the use of a period-tripling superlattice, offering faster switching times and more precise control than with magnetic field gradients. Finally, we show that this method is very general for engineering novel single particle spectra in an optical lattice and can be used to map out Hofstadter's butterfly.

  5. Optical study of a polymeric LED with a nano-sized electrode realized by a modified SNOM setup

    NASA Astrophysics Data System (ADS)

    Micheletto, Ruggero; Yoshimatsu, Nobuki; Yokokawa, Masatoshi; An, Taekyung; Lee, Haiwon; Okazaki, Satoshi

    2001-09-01

    Semiconductive polythiophene derivate polymers show electroluminescence (EL) properties if excited under opportune conditions and can be used as active element in novel efficient light-emitting diodes (LEDs) or in photovoltaic applications as detectors or solar cells. These intriguing and innovative materials are so far studied in bulk condition, under the excitation of two macroscopic electrodes, averaging the optical phenomena over a large region. To realize a better understanding of the spatial distribution of the EL on the films and its optical properties, we modified a scanning near-field optical microscope (SNOM) setup in order to measure the EL signal of poly-3-(2-(5-chlorobenzotriazolo)ethyl)thiophene. The film were deposited over a macroscopic electrode substrate (a transparent indium tin oxide (ITO) treated glass), while a sharp aluminum coated glass probe worked as a nano-sized Al electrode, realizing an Al/polymer/ITO light emitting device in a highly confined region. We describe in detail the methodology we used for the novel EL measurements and we will show the first resulting high-resolution EL emission mapping, as well as other spectroscopic and morphological characterization of the film used.

  6. Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators

    PubMed Central

    Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun

    2016-01-01

    The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface. PMID:27405356

  7. Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators

    NASA Astrophysics Data System (ADS)

    Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun

    2016-07-01

    The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface.

  8. Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators.

    PubMed

    Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun

    2016-07-13

    The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface.

  9. Improved high order grating method to realize wide angle beam steering on liquid crystal optical phased array

    NASA Astrophysics Data System (ADS)

    Wu, Liang; Wang, Xiangru; Xiong, Caidong; Huang, Ziqiang; Du, Jing; Tan, Qinggui; Li, Man; Wu, Shuanghong; Qiu, Qi

    2015-11-01

    To achieve a wider scanning range of liquid crystal optical phased array (LC-OPA), in this paper, a novel method of improved high order grating (i-HOG) is proposed in one device without introducing any other devices. The method of i-HOG breaks through the traditional ideas of modulo 𝟐𝛑 phase and takes the fringe effect into account to have a multi order extension. Subsequently, the method is verified by numerical simulation showing that it realizes a scanning range of wider than 20 degrees and even wider.

  10. Fano resonant Ge2Sb2Te5 nanoparticles realize switchable lateral optical force

    NASA Astrophysics Data System (ADS)

    Cao, Tun; Mao, Libang; Gao, Dongliang; Ding, Weiqiang; Qiu, Cheng-Wei

    2016-03-01

    Sophisticated optical micromanipulation of small biomolecules usually relies on complex light, e.g., structured light, highly non-paraxial light, or chiral light. One emerging technique is to employ chiral light to drive the chiral nanoparticle along the direction perpendicular to the propagation of the light, i.e., the lateral optical force. Here, we theoretically study the lateral optical force exerted by a entirely Gaussian beam. For the very first time we demonstrate that the Fano resonances (FRs) of the Ge2Sb2Te5 (GST) phase-change nanoparticles encapsulated with Au shells could enable a conventional Gaussian laser to exert a lateral force on such a dielectric GST nanoparticle, attributed to the strongly asymmetric energy flow around the sphere in the dipole-quadrupole FRs. More interestingly, the direction of this lateral force could be reversible during the state transition (i.e., from amorphous to crystalline). By bonding small biomolecules to the outer surface of the phase-change nanoparticle, the particle behaves as a direction-selective vehicle to transport biomolecules along opposite directions, at pre-assessed states of the Ge2Sb2Te5 core correspondingly. Importantly, the origin of the reversal of the lateral optical force is further unveiled by the optical singularity of the Poynting vector. Our mechanism of tailoring the FRs of phase-change nanoparticles, not just limited to GST, may bring a new twist to optical micromanipulation and biomedical applications.Sophisticated optical micromanipulation of small biomolecules usually relies on complex light, e.g., structured light, highly non-paraxial light, or chiral light. One emerging technique is to employ chiral light to drive the chiral nanoparticle along the direction perpendicular to the propagation of the light, i.e., the lateral optical force. Here, we theoretically study the lateral optical force exerted by a entirely Gaussian beam. For the very first time we demonstrate that the Fano resonances

  11. Optical localization in quasi-periodic multilayers

    NASA Astrophysics Data System (ADS)

    Vasconcelos, M. S.; Albuquerque, E. L.; Mariz, A. M.

    1998-07-01

    We investigate the optical transmission spectra of quasi-periodic dielectric multilayer slabs arranged in a fashion that exhibits what has been called deterministic disorders. They can be of the so-called substitutional sequences type, and are characterized by the nature of their Fourier spectrum, which can be dense pure point (e.g. a Fibonacci sequence) or singular continuous (e.g. Thue-Morse and double-period sequences). The transmission coefficients are conveniently derived by using a theoretical model based on the transfer-matrix approach. A comparison between the oblique-incidence optical transmission spectrum and the normal-incidence one shows quite a different transmission behaviours over a particular range of frequency.

  12. The research and realization of digital management platform for ultra-precision optical elements within life-cycle

    NASA Astrophysics Data System (ADS)

    Wang, Juan; Wang, Jian; Li, Lijuan; Zhou, Kun

    2014-08-01

    In order to solve the information fusion, process integration, collaborative design and manufacturing for ultra-precision optical elements within life-cycle management, this paper presents a digital management platform which is based on product data and business processes by adopting the modern manufacturing technique, information technique and modern management technique. The architecture and system integration of the digital management platform are discussed in this paper. The digital management platform can realize information sharing and interaction for information-flow, control-flow and value-stream from user's needs to offline in life-cycle, and it can also enhance process control, collaborative research and service ability of ultra-precision optical elements.

  13. Localized structures in dissipative media: from optics to plant ecology

    PubMed Central

    Tlidi, M.; Staliunas, K.; Panajotov, K.; Vladimirov, A. G.; Clerc, M. G.

    2014-01-01

    Localized structures (LSs) in dissipative media appear in various fields of natural science such as biology, chemistry, plant ecology, optics and laser physics. The proposal for this Theme Issue was to gather specialists from various fields of nonlinear science towards a cross-fertilization among active areas of research. This is a cross-disciplinary area of research dominated by nonlinear optics due to potential applications for all-optical control of light, optical storage and information processing. This Theme Issue contains contributions from 18 active groups involved in the LS field and have all made significant contributions in recent years. PMID:25246688

  14. Realization of non-PT -symmetric optical potentials with all-real spectra in a coherent atomic system

    NASA Astrophysics Data System (ADS)

    Hang, Chao; Gabadadze, Gregory; Huang, Guoxiang

    2017-02-01

    We present a physical setup for realizing all-real-spectrum optical potentials with arbitrary gain-and-loss distributions in a coherent medium consisting of a cold three-level atomic gas driven by control and probe laser fields. We show that by the interference of Raman resonances and the Stark shift induced by a far-detuned laser field, tunable, non-parity-time (non-PT )-symmetric optical potentials with all-real spectra proposed recently by Nixon and Yang [Phys. Rev. A 93, 031802(R) (2016), 10.1103/PhysRevA.93.031802] can be actualized physically. We also show that when the real parts of the non-PT -symmetric optical potentials are tuned cross certain thresholds, phase transitions—where the eigenspectrum of the system changes from all real to complex—may occur and hence the stability of the probe-field propagation is altered. Our scheme can also be extended to high dimensions and to a nonlinear propagation regime, where stable optical solitons with power of the order of nano-Watts may be generated in the system.

  15. The Spitzer Local Volume Legacy (LVL) global optical photometry

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Johnson, Benjamin D.; Van Zee, Liese; Lee, Janice C.; Kennicutt, Robert C.; Calzetti, Daniela; Staudaher, Shawn M.; Engelbracht, Charles W.

    2014-11-01

    We present the global optical photometry of 246 galaxies in the Local Volume Legacy (LVL) survey. The full volume-limited sample consists of 258 nearby (D < 11 Mpc) galaxies whose absolute B-band magnitude span a range of -9.6 < MB < -20.7 mag. A composite optical (UBVR) data set is constructed from observed UBVR and Sloan Digital Sky Survey ugriz imaging, where the ugriz magnitudes are transformed into UBVR. We present photometry within three galaxy apertures defined at UV, optical, and IR wavelengths. Flux comparisons between these apertures reveal that the traditional optical R25 galaxy apertures do not fully encompass extended sources. Using the larger IR apertures, we find colour-colour relationships where later type spiral and irregular galaxies tend to be bluer than earlier type galaxies. These data provide the missing optical emission from which future LVL studies can construct the full panchromatic (UV-optical-IR) spectral energy distributions.

  16. Fibre optic sensor with disturbance localization in one optical fibre

    NASA Astrophysics Data System (ADS)

    Zyczkowski, M.; Ciurapinski, W.

    2007-05-01

    Ordinary perimeter security systems consist of many individual sensors with detection range 200-300 meters. These limitations are connected with physical phenomena that are used in microwave and infrared barriers as well as in ground and fence cable sensors. On the contrary, fiber optic perimeter sensors can be applied in the range of many kilometers and zone length 200-300 meters is degradation of their possibilities. This paper presents investigation results of a new generation of the fiber optic perimeter sensor in a two Sagnac and Sagna'c interferometers configuration. This system can detect a potential intruder and determine its position along a protected zone. We propose a method that makes use of the inherent properties of both interferometers. After demodulation of signals from both interferometers, obtained amplitude characteristic of the Sagnac interferometer depends on position of a disturbance along the both interferometer. So, quotient of both demodulated characteristics is proportional to the position of the disturbance. Arrangement of a laboratory model of the sensor and its signal processing scheme is presented. During research of a laboratory model, it was possible to detect the position of the disturbance with resolution of about 50m along a 10-km long sensor.

  17. Super-resolution optical telescopes with local light diffraction shrinkage

    PubMed Central

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-01-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems. PMID:26677820

  18. Super-resolution optical telescopes with local light diffraction shrinkage.

    PubMed

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-12-18

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems.

  19. Super-resolution optical telescopes with local light diffraction shrinkage

    NASA Astrophysics Data System (ADS)

    Wang, Changtao; Tang, Dongliang; Wang, Yanqin; Zhao, Zeyu; Wang, Jiong; Pu, Mingbo; Zhang, Yudong; Yan, Wei; Gao, Ping; Luo, Xiangang

    2015-12-01

    Suffering from giant size of objective lenses and infeasible manipulations of distant targets, telescopes could not seek helps from present super-resolution imaging, such as scanning near-field optical microscopy, perfect lens and stimulated emission depletion microscopy. In this paper, local light diffraction shrinkage associated with optical super-oscillatory phenomenon is proposed for real-time and optically restoring super-resolution imaging information in a telescope system. It is found that fine target features concealed in diffraction-limited optical images of a telescope could be observed in a small local field of view, benefiting from a relayed metasurface-based super-oscillatory imaging optics in which some local Fourier components beyond the cut-off frequency of telescope could be restored. As experimental examples, a minimal resolution to 0.55 of Rayleigh criterion is obtained, and imaging complex targets and large targets by superimposing multiple local fields of views are demonstrated as well. This investigation provides an access for real-time, incoherent and super-resolution telescopes without the manipulation of distant targets. More importantly, it gives counterintuitive evidence to the common knowledge that relayed optics could not deliver more imaging details than objective systems.

  20. All-optical devices realized by the post-growth processing of multiquantum-well structures

    NASA Astrophysics Data System (ADS)

    LiKamWa, Patrick; Kan'an, Ayman M.; Dutta, Mitra; Pamulapati, Jagadeesh

    1997-01-01

    An inexpensive and reliable process for the area-selective disordering of MQW structures is reported. The method relies on the diffusion, by rapid thermal annealing, of surface vacancies into the quantum wells thereby intermixing the Ga and Al atoms between the wells and barriers. A silicon oxide cap that is formed by curing a spun-on solution of glass forming compound acts as porous layer that enhances the formation of surface vacancies by allowing out-diffusion of Ga and Al atoms. This technique has been applied to the fabrication of two integrated optical devices. One is the nonlinear zero-gap directional coupler with disordered input and output branching waveguides, and the other is the symmetric nonlinear integrated Mach-Zehnder interferometer with one arm containing a non-intermixed MQW section. In both devices, the mechanism for the switching is the nonlinear refractive index that is caused by photo-generated carriers. Since this mechanism entails absorption of some of the pump beam, it is hence very important that the optical absorption be confined to the active sections only. Selective area disordering is shown to be very effective at defining regions of different bandgap energies. Hence it can be ensured that the energy of the pump laser beam is too low in comparison to the bandgap energy of the passive regions to be absorbed and the free carriers are only created in the non-intermixed active sections. The devices investigated using a pump-probe setup, exhibited strong all-optical switching behavior with a contrast ratio of better than 7:1. The controlled selective area intermixing of MQW structures will potentially play a significant role in the advancement of photonic integrated circuits.

  1. Fiber optic vibration sensor for high-power electric machines realized using 3D printing technology

    NASA Astrophysics Data System (ADS)

    Igrec, Bojan; Bosiljevac, Marko; Sipus, Zvonimir; Babic, Dubravko; Rudan, Smiljko

    2016-03-01

    The objective of this work was to demonstrate a lightweight and inexpensive fiber-optic vibration sensor, built using 3D printing technology, for high-power electric machines and similar applications. The working principle is based on modulating the light intensity using a blade attached to a bendable membrane. The sensor prototype was manufactured using PolyJet Matrix technology with DM 8515 Grey 35 Polymer. The sensor shows linear response, expected bandwidth (< 150 Hz), and from our measurements we estimated the damping ratio for used polymer to be ζ ≍ 0.019. The developed prototype is simple to assemble, adjust, calibrate and repair.

  2. Magnetic domains and defects in ferromagnetic liquid crystal colloids realized with optical patterning

    NASA Astrophysics Data System (ADS)

    Hess, Andrew; Liu, Qingkun; Smalyukh, Ivan

    A promising approach in designing composite materials with unusual physical behavior combines solid nanostructures and orientationally ordered soft matter at the mesoscale. Such composites not only inherit properties of their constituents but also can exhibit emergent behavior, such as ferromagnetic ordering of colloidal metal nanoparticles forming mesoscopic magnetization domains when dispersed in a nematic liquid crystal. Here we demonstrate the optical patterning of domain structures and topological defects in such ferromagnetic liquid crystal colloids which allows for altering their response to magnetic fields. Our findings reveal the nature of the defects in this soft matter system which is different as compared to non-polar nematic and ferromagnetic systems alike. This research was supported by the NSF Grant DMR-1420736.

  3. Single-step optical realization of bio-inspired dual-periodic motheye and gradient-index-array photonic structures.

    PubMed

    Behera, Saraswati; Joseph, Joby

    2016-08-01

    This Letter demonstrates a single-step optical realization method for hexagonal and square lattice-based dual periodic motheye and gradient-index-array photonic structures over large areas. Computed phase mask of gradient interference patterns are used as inputs to a phase-only spatial light modulator (SLM), and the first-order diffracting beams are coherently superposed with the help of a 2f-2f Fourier filtering setup to avoid complex optical geometry for generation and control of individual beams. The simulated interference patterns are verified experimentally through a CMOS camera. The fabricated micro-structures on a positive photoresist are shown to have a major periodicity of 638 μm and minor periodicity of 25.2 μm, with the air hole diameter varying from 22.7 to 6.9 μm along the X and Y axes. The depth of the fabricated structure gradually varies from 4.203 μm at the center to 1.818 μm at the corner. These structures may be scaled down to submicron features that can show improved anti-reflection properties for solar energy harvesting and GRIN lens for optical wavelength region.

  4. The realization of the dipole (γ, γ) method and its application to determine the absolute optical oscillator strengths of helium

    PubMed Central

    Xu, Long-Quan; Liu, Ya-Wei; Kang, Xu; Ni, Dong-Dong; Yang, Ke; Hiraoka, Nozomu; Tsuei, Ku-Ding; Zhu, Lin-Fan

    2015-01-01

    The dipole (γ, γ) method, which is the inelastic x-ray scattering operated at a negligibly small momentum transfer, is proposed and realized to determine the absolute optical oscillator strengths of the vanlence-shell excitations of atoms and molecules. Compared with the conventionally used photoabsorption method, this new method is free from the line saturation effect, which can seriously limit the accuracies of the measured photoabsorption cross sections for discrete transitions with narrow natural linewidths. Furthermore, the Bethe-Born conversion factor of the dipole (γ, γ) method varies much more slowly with the excitation energy than does that of the dipole (e, e) method. Absolute optical oscillator strengths for the excitations of 1s2 → 1 snp(n = 3 − 7) of atomic helium have been determined using the high-resolution dipole (γ, γ) method, and the excellent agreement of the present measurements with both those measured by the dipole (e, e) method and the previous theoretical calculations indicates that the dipole (γ, γ) method is a powerful tool to measure the absolute optical oscillator strengths of the valence-shell excitations of atoms and molecules. PMID:26678298

  5. Localized biosensing with Topas microstructured polymer optical fiber.

    PubMed

    Emiliyanov, Grigoriy; Jensen, Jesper B; Bang, Ole; Hoiby, Poul E; Pedersen, Lars H; Kjaer, Erik M; Lindvold, Lars

    2007-03-01

    We present what is believed to be the first microstructured polymer optical fiber (mPOF) fabricated from Topas cyclic olefin copolymer, which has attractive material and biochemical properties. This polymer allows for a novel type of fiber-optic biosensor, where localized sensor layers may be activated on the inner side of the air holes in a predetermined section of the mPOF. The concept is demonstrated using a fluorescence-based method for selective detection of fluorophore-labeled antibodies.

  6. The optical Anderson localization in three-dimensional percolation system

    NASA Astrophysics Data System (ADS)

    Burlak, G.; Martinez-Sánchez, E.

    2017-03-01

    We study the optical Anderson localization associated with the properties of three-dimensional (3D) disordered percolation system, where the percolating clusters are filled by active media composed by light noncoherent emitters. In such a non-uniformly spatial structure the radiating and scattering of field occur by incoherent way. We numerically study 3D field structures where the wave localization takes place and propose the criterion of field localization based on conception of a mean photon free path in such system. The analysis of a mean free path and the Inverse participation ratio (IPR) shows that the localization arises closely to the threshold of 3D percolation phase transition.

  7. Spread spectrum fiber-optic local area network using optical processing

    NASA Technical Reports Server (NTRS)

    Prucnal, P. R.; Santoro, M. A.; Fan, T. R.

    1986-01-01

    Spread spectrum code division multiple access (CDMA) allows asynchronous multiple access to a local area network (LAN) with no waiting. The additional bandwidth required by spread spectrum can be accommodated by using a fiber-optic channel and incoherent optical signal processing. New CDMA sequences are designed specifically for optical processing. It is shown that increasing the number of chips per bit, by using optical processing, allows an increase in capacity of a CDMA LAN. An experiment is performed demonstrating the performance of an optical CDMA LAN, operating at 100 Mbd with three users.

  8. Vortex emission accompanies the advection of optical localized structures.

    PubMed

    Haudin, F; Rojas, R G; Bortolozzo, U; Clerc, M G; Residori, S

    2011-02-11

    We show that the advection of optical localized structures is accompanied by the emission of vortices, with phase singularities appearing in the wake of the drifting structure. Localized structures are obtained in a light-valve experiment and made to drift by a mirror tilt in the feedback loop. Pairs of oppositely charged vortices are detected for small drifts, whereas for large drifts a vortex array develops. Observations are supported by numerical simulations and linear stability analysis of the system equations and are expected to be generic for a large class of translated optical patterns.

  9. Gateway design specification for fiber optic local area networks

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This is a Design Specification for a gateway to interconnect fiber optic local area networks (LAN's). The internetworking protocols for a gateway device that will interconnect multiple local area networks are defined. This specification serves as input for preparation of detailed design specifications for the hardware and software of a gateway device. General characteristics to be incorporated in the gateway such as node address mapping, packet fragmentation, and gateway routing features are described.

  10. Optical superheterodyne receiver uses laser for local oscillator

    NASA Technical Reports Server (NTRS)

    Lucy, R. F.

    1966-01-01

    Optical superheterodyne receiver uses a laser coupled to a frequency translator to supply both the incident signal and local oscillator signal and thus permit reception of amplitude modulated video bandwidth signals through the atmosphere. This receiver is useful in scientific propagation experiments, tracking experiments, and communication experiments.

  11. Fibre Optics In A Multi-Star Wideband Local Network

    NASA Astrophysics Data System (ADS)

    Fox, J. R.

    1983-08-01

    Early experience has been gained with the switched-star type of network in the Fibrevision cable TV trial at Milton Keynes, and British Telecom are progressing towards a full-scale multi-star wideband local network. This paper discusses both the present and future use of fibre optics in this type of network.

  12. Optical fingerprint recognition based on local minutiae structure coding.

    PubMed

    Yi, Yao; Cao, Liangcai; Guo, Wei; Luo, Yaping; Feng, Jianjiang; He, Qingsheng; Jin, Guofan

    2013-07-15

    A parallel volume holographic optical fingerprint recognition system robust to fingerprint translation, rotation and nonlinear distortion is proposed. The optical fingerprint recognition measures the similarity by using the optical filters of multiplexed holograms recorded in the holographic media. A fingerprint is encoded into multiple template data pages based on the local minutiae structure coding method after it is adapted for the optical data channel. An improved filter recording time schedule and a post-filtering calibration technology are combined to suppress the calculating error from the large variations in data page filling ratio. Experimental results tested on FVC2002 DB1 and a forensic database comprising 270,216 fingerprints demonstrate the robustness and feasibility of the system.

  13. Automated localization of the optic disc and the fovea.

    PubMed

    Niemeijer, M; Abramoff, M D; van Ginneken, B

    2008-01-01

    The detection of the position of the normal anatomy in color fundus photographs is an important step in the automated analysis of retinal images. An automatic system for the detection of the position of the optic disc and the fovea is presented. The method integrates the use of local vessel geometry and image intensity features to find the correct positions in the image. A kNN regressor is used to accomplish the integration. Evaluation was performed on a set of 250 digital color fundus photographs and the detection performance for the optic disc and the fovea were 99.2% and 96.4% respectively.

  14. Local probing and stimulation of neuronal cells by optical manipulation

    NASA Astrophysics Data System (ADS)

    Cojoc, Dan

    2014-09-01

    During development and in the adult brain, neurons continuously explore the environment searching for guidance cues, leading to the appropriate connections. Elucidating these mechanisms represents a gold goal in neurobiology. Here, I discuss our recent achievements developing new approaches to locally probe the growth cones and stimulate neuronal cell compartments with high spatial and temporal resolution. Optical tweezers force spectroscopy applied in conjunction with metabolic inhibitors reveals new properties of the cytoskeleton dynamics. On the other hand, using optically manipulated microvectors as functionalized beads or filled liposomes, we demonstrate focal stimulation of neurons by small number of signaling molecules.

  15. Optical Excitation of Carbon Nanotubes Drives Localized Diazonium Reactions.

    PubMed

    Powell, Lyndsey R; Piao, Yanmei; Wang, YuHuang

    2016-09-15

    Covalent chemistries have been widely used to modify carbon nanomaterials; however, they typically lack the precision and efficiency required to directly engineer their optical and electronic properties. Here, we show, for the first time, that visible light which is tuned into resonance with carbon nanotubes can be used to drive their functionalization by aryldiazonium salts. The optical excitation accelerates the reaction rate 154-fold (±13) and makes it possible to significantly improve the efficiency of covalent bonding to the sp(2) carbon lattice. Control experiments suggest that the reaction is dominated by a localized photothermal effect. This light-driven reaction paves the way for precise nanochemistry that can directly tailor carbon nanomaterials at the optical and electronic levels.

  16. Deploying Monitoring Trails for Fault Localization in All- Optical Networks and Radio-over-Fiber Passive Optical Networks

    NASA Astrophysics Data System (ADS)

    Maamoun, Khaled Mohamed

    Fault localization is the process of realizing the true source of a failure from a set of collected failure notifications. Isolating failure recovery within the network optical domain is necessary to resolve alarm storm problems. The introduction of the monitoring trail (m-trail) has been proven to deliver better performance by employing monitoring resources in a form of optical trails - a monitoring framework that generalizes all the previously reported counterparts. In this dissertation, the m-trail design is explored and a focus is given to the analysis on using m-trails with established lightpaths to achieve fault localization. This process saves network resources by reducing the number of the m-trails required for fault localization and therefore the number of wavelengths used in the network. A novel approach based on Geographic Midpoint Technique, an adapted version of the Chinese Postman's Problem (CPP) solution and an adapted version of the Traveling Salesman's Problem (TSP) solution algorithms is introduced. The desirable features of network architectures and the enabling of innovative technologies for delivering future millimeter-waveband (mm-WB) Radio-over-Fiber (RoF) systems for wireless services integrated in a Dense Wavelength Division Multiplexing (DWDM) is proposed in this dissertation. For the conceptual illustration, a DWDM RoF system with channel spacing of 12.5 GHz is considered. The mm-WB Radio Frequency (RF) signal is obtained at each Optical Network Unit (ONU) by simultaneously using optical heterodyning photo detection between two optical carriers. The generated RF modulated signal has a frequency of 12.5 GHz. This RoF system is easy, cost-effective, resistant to laser phase noise and also reduces maintenance needs, in principle. A revision of related RoF network proposals and experiments is also included. A number of models for Passive Optical Networks (PON)/ RoF-PON that combine both innovative and existing ideas along with a number of

  17. Local and nonlocal optically induced transparency effects in graphene-silicon hybrid nanophotonic integrated circuits.

    PubMed

    Yu, Longhai; Zheng, Jiajiu; Xu, Yang; Dai, Daoxin; He, Sailing

    2014-11-25

    Graphene is well-known as a two-dimensional sheet of carbon atoms arrayed in a honeycomb structure. It has some unique and fascinating properties, which are useful for realizing many optoelectronic devices and applications, including transistors, photodetectors, solar cells, and modulators. To enhance light-graphene interactions and take advantage of its properties, a promising approach is to combine a graphene sheet with optical waveguides, such as silicon nanophotonic wires considered in this paper. Here we report local and nonlocal optically induced transparency (OIT) effects in graphene-silicon hybrid nanophotonic integrated circuits. A low-power, continuous-wave laser is used as the pump light, and the power required for producing the OIT effect is as low as ∼0.1 mW. The corresponding power density is several orders lower than that needed for the previously reported saturated absorption effect in graphene, which implies a mechanism involving light absorption by the silicon and photocarrier transport through the silicon-graphene junction. The present OIT effect enables low power, all-optical, broadband control and sensing, modulation and switching locally and nonlocally.

  18. Localization of collisionally inhomogeneous condensates in a bichromatic optical lattice

    SciTech Connect

    Cheng Yongshan; Adhikari, S. K.

    2011-02-15

    By direct numerical simulation and variational solution of the Gross-Pitaevskii equation, we studied the stationary and dynamic characteristics of a cigar-shaped, localized, collisionally inhomogeneous Bose-Einstein condensate trapped in a one-dimensional bichromatic quasiperiodic optical-lattice potential, as used in a recent experiment on the localization of a Bose-Einstein condensate [Roati et al., Nature (London) 453, 895 (2008)]. The effective potential characterizing the spatially modulated nonlinearity is obtained. It is found that the collisional inhomogeneity has influence not only on the central region but also on the tail of the Bose-Einstein condensate. The influence depends on the sign and value of the spatially modulated nonlinearity coefficient. We also demonstrate the stability of the stationary localized state by performing a standard linear stability analysis. Where possible, the numerical results are shown to be in good agreement with the variational results.

  19. Correction of localized shape errors on optical surfaces by altering the localized density of surface or near-surface layers

    SciTech Connect

    Taylor, John S.; Folta, James A.; Montcalm, Claude

    2005-01-18

    Figure errors are corrected on optical or other precision surfaces by changing the local density of material in a zone at or near the surface. Optical surface height is correlated with the localized density of the material within the same region. A change in the height of the optical surface can then be caused by a change in the localized density of the material at or near the surface.

  20. Optic disk localization by a robust fusion method

    NASA Astrophysics Data System (ADS)

    Zhang, Jielin; Yin, Fengshou; Wong, Damon W. K.; Liu, Jiang; Baskaran, Mani; Cheng, Ching-Yu; Wong, Tien Yin

    2013-02-01

    The optic disk localization plays an important role in developing computer-aided diagnosis (CAD) systems for ocular diseases such as glaucoma, diabetic retinopathy and age-related macula degeneration. In this paper, we propose an intelligent fusion of methods for the localization of the optic disk in retinal fundus images. Three different approaches are developed to detect the location of the optic disk separately. The first method is the maximum vessel crossing method, which finds the region with the most number of blood vessel crossing points. The second one is the multichannel thresholding method, targeting the area with the highest intensity. The final method searches the vertical and horizontal region-of-interest separately on the basis of blood vessel structure and neighborhood entropy profile. Finally, these three methods are combined using an intelligent fusion method to improve the overall accuracy. The proposed algorithm was tested on the STARE database and the ORIGAlight database, each consisting of images with various pathologies. The preliminary result on the STARE database can achieve 81.5%, while a higher result of 99% can be obtained for the ORIGAlight database. The proposed method outperforms each individual approach and state-of-the-art method which utilizes an intensity-based approach. The result demonstrates a high potential for this method to be used in retinal CAD systems.

  1. Optical Photometry of the Local Volume Legacy (LVL) Survey

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, D. A.; van Zee, L.; Johnson, B. D.; Lee, J. C.; Cales, S.; LVL Team

    2014-01-01

    We present new optical (UBVR) imaging of 258 nearby (D < 11 Mpc) galaxies in the Local Volume Legacy (LVL) survey. The volume limited sample is dominated by dwarf galaxies, however, the sample as a whole probes many global galaxy environments. This photometry completes the panchromatic data set which spans a wide wavelength range (1500 Å - 160 μm). This study focuses on GALEX (FUV & NUV), optical (UBVR), 2MASS (JHK), and Spitzer (3.6 μm, 4.5 μm, 5 um, 8 μm, & 24 μm) data. Photometry was performed with three separate apertures (defined from the FUV, 3.6 μm, and optical) to allow direct photometric comparisons between galaxies with consistent apertures. The wide wavelength coverage with uniform apertures across many environments will facilitate studying the effect of secular galaxy evolution and environment on galaxy-wide properties. Furthermore, the proximity of these galaxies will yield a wealth information on sub-kpc scales since individual star-forming regions can be identified and studied with the same wide wavelength coverage. We present the basic optical properties and SEDs of these galaxies and their relationships to the full panchromatic data set to evince underlying physical processes.

  2. Analysis of Optical Imaging from the Local Volume Legacy Survey

    NASA Astrophysics Data System (ADS)

    Friberg, Sarah; Snyder, E.; van Zee, L.; Croxall, K. V.; Funes, J. G.; Warren, S. R.; Lee, H.; Lee, J. C.; LVL Team

    2010-01-01

    We report the results of Halpha and broadband optical imaging of 96 galaxies in the Local Volume Legacy Survey (LVL). The majority of galaxies in the volume limited (D < 11 Mpc) parent sample are low luminosity dwarf galaxies. We examine optical colors, star formation rates, and Halpha equivalent widths both as global values and as a function of radius. As expected, the majority of galaxies in this sample have blue colors and modest star formation activity. While the majority of galaxies have negligible color gradients in their stellar disks, a handful of galaxies have strong red color gradients (greater than 0.4 mag/kpc in U-B). These galaxies tend to be smaller and more compact than other galaxies in the sample with comparable luminosities and are likely starbursting or post-burst systems.

  3. [Local involvement of the optic nerve by acute lymphoblastic leukemia].

    PubMed

    Bernardczyk-Meller, Jadwiga; Stefańska, Katarzyna

    2005-01-01

    The leucemias quite commonly involve the eyes and adnexa. In some cases it causes visual complants. Both, the anterior chamber of the eye and the posterior portion of the globe may sites of acute or chronic leukemia and leucemic relapse. We report an unique case of a 14 years old leucemic patient who suffered visual loss and papilloedema, due to a unilateral local involvement within optic nerve, during second relapse of acute lymphocytic leuemia. In spite of typical treatment of main disease, the boy had died. The authors present typical ophthalmic features of the leucemia, too.

  4. Initiatory concept of localized CO2 laser-based tapering rig for realization of in-fiber devices

    NASA Astrophysics Data System (ADS)

    Aharoni, Ran; Bidani, Liron; Sinvani, Moshe; Zalevsky, Zeev

    2012-07-01

    We present the development procedure as well as preliminary fabrication results for a CO2 laser-based tapering rig allowing one stage tapering of optical fibers. Our aim is to develop in-fiber devices constructed from fibers filled with various materials, which can be drawn from thick preforms using the presented procedure. The constructed tapering rig consists of a CO2 laser as the heating source, ellipsoid-based mirror optics, and computer-controlled high-precision motors.

  5. Localized modes in optics of photonic liquid crystals with local anisotropy of absorption

    NASA Astrophysics Data System (ADS)

    Belyakov, V. A.; Semenov, S. V.

    2016-05-01

    The localized optical modes in spiral photonic liquid crystals are theoretically studied for the certainty at the example of chiral liquid crystals (CLCs) for the case of CLC with an anisotropic local absorption. The model adopted here (absence of dielectric interfaces in the structures under investigation) makes it possible to get rid of mixing of polarizations on the surfaces of the CLC layer and of the defect structure and to reduce the corresponding equations to only the equations for light with polarization diffracting in the CLC. The dispersion equations determining connection of the edge mode (EM) and defect mode (DM) frequencies with the CLC layer parameters (anisotropy of local absorption, CLC order parameter) and other parameters of the DMS are obtained. Analytic expressions for the transmission and reflection coefficients of CLC layer and DMS for the case of CLC with an anisotropic local absorption are presented and analyzed. It is shown that the CLC layers with locally anisotropic absorption reduce the EM and DM lifetimes (and increase the lasing threshold) in the way different from the case of CLC with an isotropic local absorption. Due to the Borrmann effect revealing of which is different at the opposite stop-band edges in the case of CLC layers with an anisotropic local absorption the EM life-times for the EM frequencies at the opposite stop-bands edges may be significantly different. The options of experimental observations of the theoretically revealed phenomena are briefly discussed.

  6. Depth-resolved photothermal optical coherence tomography by local optical path length change measurement (Conference Presentation)

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Photothermal OCT has been emerged to contrast absorbers in biological tissues. The tissues response to photothermal excitation as change of thermal strain and refractive index. To resolve the depth of absorption agents, the measurements of the local thermal strain change and local refractive index change due to photothermal effect is required. In this study, we developed photothermal OCT for depth-resolved absorption contrast imaging. The phase-resolved OCT can measure the axial strain change and local refractive index change as local optical path length change. A swept-source OCT system is used with a wavelength swept laser at 1310 nm with a scanning rate of 50 kHz. The sensitivity of 110 dB is achieved. At the sample arm, the excitation beam from a fiber-coupled laser diode of 406 nm wavelength is combined with the OCT probe beam co-linearly. The slowly modulated excitation beam around 300 Hz illuminate biological tissues. M-mode scan is applied during one-period modulation duration. The local optical path length change is measured by temporal and axial phase difference. The theoretical prediction of the photothermal response is derived and in good agreement with experimental results. In the case of slow modulation, the delay of photothermal response can be neglected. The local path length changes are averaged over the half period of the excitation modulation, and then demodulated. This method exhibits 3-dB gain in the sensitivity of the local optical path length change measurement over the direct Fourier transform method. In vivo human skin imaging of endogenous absorption agent will be demonstrated.

  7. Light Localization by Defects in Optically Induced Photonic Structures

    NASA Astrophysics Data System (ADS)

    Yang, Jianke; Wang, Xiaosheng; Wang, Jiandong; Chen, Zhigang

    In the past ten years, there has blossomed an interest in the study of collective behavior of wave propagation in periodic waveguide arrays and photonic lattices [1-3]. The unique bandgap structures of these periodic media, coupled with nonlinear effects, give rise to many types of novel soliton structures [1- 26]. On the other hand, it is well known that one of the unique and most interesting features of photonic band-gap structures is a fundamentally different way of waveguiding by defects in otherwise uniformly periodic structures. Such waveguiding has been demonstrated with an "air-hole" in photonic crystal fibers (PCF) for optical waves [27, 28], in an isolated defect in two-dimensional arrays of dielectric cylinders for microwaves [29-31], and recently in all-solid PCF with a lower-index core [32, 33]. In addition, laser emission based on photonic defect modes has been realized in a number of experiments [34-38]. In one-dimensional (1D) fabricated semiconductor waveguide arrays, previous experiments have investigated nonlinearity-induced escape from a defect state [39] and interactions of discrete solitons with structural defects [40] (see also [41]). Despite the above efforts, theoretical understanding on defect guiding was still limited, and experimental demonstrations of defect guiding was still scarce. In addition, when nonlinear effects are significant, how defect guiding is affected by nonlinearity is largely an open issue. Recently, in a series of theoretical and experimental studies, we optically induced 1D, 2D and ringlike photonic lattices with single-site negative defects in photorefractive crystals, and investigated their linear and nonlinear light guiding properties [42-48]. This work will be reviewed in this Chapter. In addition, we present the first experimental demonstration of nonlinear defect modes which undergoes nonlinear propagation through the defects. Our work not only has a direct link to technologically important systems of periodic

  8. Analysis of localized fringes in the holographic optical Schlieren system

    NASA Technical Reports Server (NTRS)

    Kurtz, R. L.

    1980-01-01

    The relation between localization of interference fringes in classical and holographic interferometry is reviewed and an application of holographic interferometry is considered for which the object is a transparent medium with nonhomogeneous refractive index. The technique is based on the analysis of the optical path length change of the object wave as it propagates through a transparent medium. Phase shifts due to variations of the speed of light within the medium give rise to an interference pattern. The resulting interferogram can be used to determine the physical properties of the medium or transparent object. Such properties include the mass density of fluids, electron densities of plasmas, the temperature of fluids, the chemical species concentration of fluids, and the state of stress in solids. The optical wave used can be either a simple plane or spherical wave, or it may be a complicated spatial wave scattered by a diffusing screen. The mathematical theory on the formation and analysis of localized fringes, the general theoretical concepts used, and a computer code for analysis are included along with the inversion of fringe order data.

  9. Creating and Probing Graphene Electron Optics with Local Scanning Probes

    NASA Astrophysics Data System (ADS)

    Stroscio, Joseph

    Ballistic propagation and the light-like dispersion of graphene charge carriers make graphene an attractive platform for optics-inspired graphene electronics where gate tunable potentials can control electron refraction and transmission. In analogy to optical wave propagation in lenses, mirrors and metamaterials, gate potentials can be used to create a negative index of refraction for Veselago lensing and Fabry-Pérot interferometers. In circular geometries, gate potentials can induce whispering gallery modes (WGM), similar to optical and acoustic whispering galleries albeit on a much smaller length scale. Klein scattering of Dirac carriers plays a central role in determining the coherent propagation of electron waves in these resonators. In this talk, I examine the probing of electron resonators in graphene confined by linear and circular gate potentials with the scanning tunneling microscope (STM). The tip in the STM tunnel junction serves both as a tunable local gate potential, and as a probe of the graphene states through tunneling spectroscopy. A combination of a back gate potential, Vg, and tip potential, Vb, creates and controls a circular pn junction that confines the WGM graphene states. The resonances are observed in two separate channels in the tunneling spectroscopy experiment: first, by directly tunneling into the state at the bias energy eVb, and, second, by tunneling from the resonance at the Fermi level as the state is gated by the tip potential. The second channel produces a fan-like set of WGM peaks, reminiscent of the fringes seen in planar geometries by transport measurements. The WGM resonances split in a small applied magnetic field, with a large energy splitting approaching the WGM spacing at 0.5 T. These results agree well with recent theory on Klein scattering in graphene electron resonators. This work is done in collaboration with Y. Zhao, J. Wyrick, F.D. Natterer, J. F. Rodriquez-Nieva, C. Lewandoswski, K. Watanabe, T. Taniguchi, N. B

  10. Localizer with high occlusion immunity using diffraction optics

    NASA Astrophysics Data System (ADS)

    Ditto, Thomas D.; Farges, Jacques

    2004-10-01

    The chromatic method of diffraction range finding can be exploited to construct a 3D localizer that tracks the position of a pointer, a 3-D scanner or a robotic end-effecter. A spectrogram is made using a diffraction grating as the primary objective of an optical system that tracks a broad band emitter such as a tungsten filament or white L.E.D. Image processing on the resulting spectra transforms the spectrogram at the input to distance and displacement at the output. The behavior conforms to geometric optics following the Diffraction Equation. This novel technique has unique features. For example, the number of samples increases with target distance, reversing the loss of resolution as a function of distance that is endemic to triangulation. The plurality of samples also can overcome occlusion liability common to time-of-flight range finders, since multiple paths exist between emitter and sensor. The grating can be made from inexpensive embossed plastic, and a wave length sensor can be constructed from garden variety color cameras. The method is robust at a grazing exodus angles that allow for a compact configuration of the receiver. In this paper we disclose the theory of operation including a mathematical model, and we demonstrate the method empirically.

  11. Novel localized surface plasmon resonance based optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Muri, Harald Ian D. I.; Hjelme, Dag R.

    2016-03-01

    Over the last decade various optical fiber sensing schemes have been proposed based on local surface plasmon resonance (LSPR). LSPR are interacting with the evanescent field from light propagating in the fiber core or by interacting with the light at the fiber end face. Sensor designs utilizing the fiber end face is strongly preferred from a manufacturing point of view. However, the different techniques available to immobilize metallic nanostructures on the fiber end face for LSPR sensing is limited to essentially a monolayer, either by photolithographic structuring of metal film, thermal nucleation of metal film, or by random immobilization of nanoparticles (NP). In this paper, we report on a novel LSPR based optical fiber sensor architecture. The sensor is prepared by immobilizing gold NP's in a hydrogel droplet polymerized on the fiber end face. This design has several advantages over earlier designs. It dramatically increase the number of NP's available for sensing, it offers precise control over the NP density, and the NPs are position in a true 3D aqueous environment. The sensor design is also compatible with low cost manufacturing. The sensor design can measure volumetric changes in a stimuli-responsive hydrogel or measure binding to receptors on the NP surface. It can also be used as a two-parameter sensor by utilizing both effects. We present results from proof-of-concept experiments demonstrating a pH sensor based on LSPR sensing in a poly(acrylamide-co-acrylic acid) hydrogel embedding gold nanoparticles.

  12. Optical Sensing and Trapping Based on Localized Surface Plasmons

    NASA Astrophysics Data System (ADS)

    Kang, Zhiwen

    This project involves the study of novel plasmonic nanodevices that provide unique functionality in optical sensing, surface-enhanced Raman scattering (SERS), and optical trapping. The first design is based on a coupling system involving double-layered metal nano-strips arrays. This system has the advantages of simple geometry and direct integration with microfluidic chips. The intense optical localization due to field coupling within the system can enhance detection sensitivity of target molecules, especially by virtue of the optical trapping of plasmonic nanoparticles. The optical resonant condition is obtained theoretically through analyzing the SPs modes. Numerical modeling based on two-dimensional (2D) finite-difference time-domain (FDTD) is consistent with the theoretical analysis and demonstrates the feasibility of using this system for optical sensing and trapping. In the second design, a gold nano-ring structure is demonstrated to be an effective approach for plasmonic nano-optical tweezers (PNOTs) for trapping metallic nanoparticles. In our demonstration example, we have optimized a device for SERS operation at the wavelength of 785 nm. Three-dimensional (3D) FDTD techniques have been employed to calculate the optical response, and the optical force distribution have been derived using the Maxwell stress tensor (MST) method. Simulation results indicate that the nano-ring produces a maximum trapping potential well of ~32 kBT on a 20 nm gold nanoparticle. The existence of multiple potential well results in a very large active trapping volume of ~106 nm3 for the target particles. Furthermore, the trapped gold nanoparticles further lead to the formation of nano-gaps that offer a near-field enhancement of ~160 times, resulting in an achievable EF of 108 for SERS. In the third design, we propose a concept of all-optical nano-manipulation. We show that target molecules, after being trapped, can be transferred between the trapping sites within a linear array of

  13. Localized Spoof Surface Plasmons based on Closed Subwavelength High Contrast Gratings: Concept and Microwave-Regime Realizations

    NASA Astrophysics Data System (ADS)

    Li, Zhuo; Xu, Bingzheng; Liu, Liangliang; Xu, Jia; Chen, Chen; Gu, Changqing; Zhou, Yongjin

    2016-06-01

    In this work, we report the existence of spoof localized surface plasmons (spoof-LSPs) arising with closed high contrast gratings (HCGs) at deep subwavelength scales, another platform for field localization at microwave frequencies. The HCGs are in the form of a periodic array of radial dielectric blocks with high permittivity around a metal core supporting spoof-LSPs of transverse magnetic (TM) form. Simulation results validate the phenomenon and a metamaterial approach is also given to capture all the resonant features of this kind of spoof-LSPs. In addition, experimental verification of the existence of spoof-LSPs supported by a three dimensional (3D) HCGs resonance structure in the microwave regime is presented. This work expands the original spoof-LSPs theory and opens up a new avenue for obtaining resonance devices in the microwave frequencies.

  14. Localized Spoof Surface Plasmons based on Closed Subwavelength High Contrast Gratings: Concept and Microwave-Regime Realizations

    PubMed Central

    Li, Zhuo; Xu, Bingzheng; Liu, Liangliang; Xu, Jia; Chen, Chen; Gu, Changqing; Zhou, Yongjin

    2016-01-01

    In this work, we report the existence of spoof localized surface plasmons (spoof-LSPs) arising with closed high contrast gratings (HCGs) at deep subwavelength scales, another platform for field localization at microwave frequencies. The HCGs are in the form of a periodic array of radial dielectric blocks with high permittivity around a metal core supporting spoof-LSPs of transverse magnetic (TM) form. Simulation results validate the phenomenon and a metamaterial approach is also given to capture all the resonant features of this kind of spoof-LSPs. In addition, experimental verification of the existence of spoof-LSPs supported by a three dimensional (3D) HCGs resonance structure in the microwave regime is presented. This work expands the original spoof-LSPs theory and opens up a new avenue for obtaining resonance devices in the microwave frequencies. PMID:27251026

  15. Fast left ventricle tracking using localized anatomical affine optical flow.

    PubMed

    Queirós, Sandro; Vilaça, João L; Morais, Pedro; Fonseca, Jaime C; D'hooge, Jan; Barbosa, Daniel

    2017-02-16

    In daily clinical cardiology practice, left ventricle (LV) global and regional function assessment is crucial for disease diagnosis, therapy selection and patient follow-up. Currently, this is still a time-consuming task, spending valuable human resources. In this work, a novel fast methodology for automatic LV tracking is proposed based on localized anatomically constrained affine optical flow. This novel method can be combined to previously proposed segmentation frameworks or manually delineated surfaces at an initial frame to obtain fully delineated datasets and, thus, assess both global and regional myocardial function. Its feasibility and accuracy was investigated in three distinct public databases, namely in realistically simulated 3D ultrasound (US), clinical 3D echocardiography and clinical cine cardiac magnetic resonance (CMR) images. The method showed accurate tracking results in all databases, proving its applicability and accuracy for myocardial function assessment. Moreover, when combined to previous state-of-the-art segmentation frameworks, it outperformed previous tracking strategies in both 3D US and CMR data, automatically computing relevant cardiac indices with smaller biases and narrower limits of agreement compared to reference indices. Simultaneously, the proposed localized tracking method showed to be suitable for online processing, even for 3D motion assessment. Importantly, although here evaluated for LV tracking only, this novel methodology is applicable for tracking of other target structures with minimal adaptations. This article is protected by copyright. All rights reserved.

  16. Nonlinear optical methods for cellular imaging and localization.

    PubMed

    McVey, A; Crain, J

    2014-07-01

    Of all the ways in which complex materials (including many biological systems) can be explored, imaging is perhaps the most powerful because delivering high information content directly. This is particular relevant in aspects of cellular localization where the physical proximity of molecules is crucial in biochemical processes. A great deal of effort in imaging has been spent on enabling chemically selective imaging so that only specific features are revealed. This is almost always achieved by adding fluorescent chemical labels to specific molecules. Under appropriate illumination conditions only the molecules (via their labels) will be visible. The technique is simple and elegant but does suffer from fundamental limitations: (1) the fluorescent labels may fade when illuminated (a phenomenon called photobleaching) thereby constantly decreasing signal contrast over the course of image acquisition. To combat photobleaching one must reduce observation times or apply unfavourably low excitation levels all of which reduce the information content of images; (2) the fluorescent species may be deactivated by various environmental factors (the general term is fluorescence quenching); (3) the presence of fluorescent labels may introduce unexpected complications or may interfere with processes of interest (4) Some molecules of interest cannot be labelled. In these circumstances we require a fundamentally different strategy. One of the most promising alternative is based on a technique called Coherent Anti-Stokes Raman scattering (CARS). CARS is a fundamentally more complex process than is fluorescence and the experimental procedures and optical systems required to deliver high quality CARS images are intricate. However, the rewards are correspondingly very high: CARS probes the chemically distinct vibrations of the constituent molecules in a complex system and is therefore also chemically selective as are fluorescence-based methods. Moreover,the potentially severe problems of

  17. The realization of optical switching generated from the combination of Ag/a-Si/p-Si memristor and silicon waveguide

    NASA Astrophysics Data System (ADS)

    Li, Dongyang; Guo, Anran; Song, Qinjian; Guo, Guohui; Jiang, Yadong; Li, Wei

    2016-10-01

    Much attention has been attracted by applications of memristor in data storage, unconventional computing and logic circuit since 2008, but very few have been focused on applications in optical switches and optical modulators. Here, by combining a silicon waveguide with a memristor of Ag/a-Si/p-Si structure, a novel optical switch (OS) for use at 1.55μm has been set up. The device consists of a bottom p-Si waveguide, an upper a-Si layer and a top Ag electrode, i.e. a sandwich structure named as Ag/a-Si/p-Si. The light transmitting through the silicon waveguide can be modulated by changing optical parameters of a-Si dielectric layer in which the formation and annihilation of Ag filament can be adjusted by an alternately electrical field between Ag and p-Si electrodes. The distribution of optical power dependence on the thicknesses of a-Si layer and Ag layer as well as the geometric size of waveguide have been studied by numerical analysis. Finally, based on Ag/a-Si/p-Si sandwich structure and the simulated results, we have proposed a new and improved OS.

  18. A highly stable mm-wave synthesizer realized by mixing two lasers locked to an optical frequency comb generator

    NASA Astrophysics Data System (ADS)

    Musha, Mitsuru; Ueda, Akitoshi; Horikoshi, Munekazu; Nakagawa, Ken'ichi; Ishiguro, Masato; Ueda, Ken-ichi; Ito, Hiroshi

    2004-10-01

    Millimeter signal generation with high spectral purity and low phase fluctuations up to 100 GHz were demonstrated with an optical method in which two external-cavity laser diodes were phase-locked to an electro-optic modulator (EOM)-based optical frequency comb generator (OFCG). The additional phase noise caused from the cavity fluctuation in OFCG was completely canceled, and the phase noise of the heterodyne beat note of two LDs was determined only by that of the signal generator below offset frequency of 10 kHz. The detailed investigation of such a high frequency signal had never been done before, and the measured frequency of 100 GHz was limited only by the bandwidth of the phase noise detection system, and can be expanded up to more than 1 THz.

  19. Realization of tellurium-based all dielectric optical metamaterials using a multi-cycle deposition-etch process

    NASA Astrophysics Data System (ADS)

    Liu, Sheng; Ihlefeld, Jon F.; Dominguez, Jason; Gonzales, Edward F.; Eric Bower, John; Bruce Burckel, D.; Sinclair, Michael B.; Brener, Igal

    2013-04-01

    Tellurium (Te) dielectric resonator metamaterials for thermal infrared applications were fabricated using a multi-cycle deposition-etch process that circumvents pinch-off issues during deposition. Deposition and etching of Te were studied in detail. Metamaterial samples with varying resonator dimensions were fabricated using this technique. All the samples showed two transmission minima corresponding to magnetic and electric dipole resonances. Longer resonant wavelengths were observed as the resonator dimension was increased. Observation of spectral overlap between magnetic and electric resonances gives us the potential opportunity to realize a negative refractive index material.

  20. Blu-ray-sensitive localized surface plasmon resonance for high-density optical memory

    NASA Astrophysics Data System (ADS)

    Fu, Shencheng; Zhang, Xintong; Han, Qiang; Liu, Shuangyan; Han, Xiuxiu; Liu, Yichun

    2016-11-01

    Tunable spectrum-response is desired for efficient photo-energy transformation. Blu-ray (~405 nm) and polarization sensitive Ag/TiO2 nanocomposite films are thus fascinating in application of fast-response and high-density optical memory device. The Ag/TiO2 film has the ability of replicating hologram based on optical coherence by laser-stimulated dissolution of Ag nanoparticles (NPs). The rate and efficiency of the dissolution are supposed to be enhanced by introducing uniform and small-sized Ag NPs in TiO2 nanoporous films. However, no effective methods have been proposed to resolve this issue by now. Here, we develop a simple method of thermal-reduction to obtain high-density, space-dispersed and extremely small-sized Ag NPs in TiO2 nanoporous films pretreated with tannic acid. The film shows both high and narrow absorbance band centered at ~405 nm. Diffraction efficiency of the blu-ray holographic storage in the Ag/TiO2 film is improved by one order of magnitude compared to the traditional UV-reduced sample. Based on such properties, polarization-multiplexing holograms are able to be written at 405 nm and readout with little crosstalk. This work provides effective solutions for sensitizing localized surface plasmon resonance at near-UV region, extending the growth range of Ag NPs in the volume of TiO2, and resultantly, realizing high-density optical memory.

  1. Blu-ray-sensitive localized surface plasmon resonance for high-density optical memory

    PubMed Central

    Fu, Shencheng; Zhang, Xintong; Han, Qiang; Liu, Shuangyan; Han, Xiuxiu; Liu, Yichun

    2016-01-01

    Tunable spectrum-response is desired for efficient photo-energy transformation. Blu-ray (~405 nm) and polarization sensitive Ag/TiO2 nanocomposite films are thus fascinating in application of fast-response and high-density optical memory device. The Ag/TiO2 film has the ability of replicating hologram based on optical coherence by laser-stimulated dissolution of Ag nanoparticles (NPs). The rate and efficiency of the dissolution are supposed to be enhanced by introducing uniform and small-sized Ag NPs in TiO2 nanoporous films. However, no effective methods have been proposed to resolve this issue by now. Here, we develop a simple method of thermal-reduction to obtain high-density, space-dispersed and extremely small-sized Ag NPs in TiO2 nanoporous films pretreated with tannic acid. The film shows both high and narrow absorbance band centered at ~405 nm. Diffraction efficiency of the blu-ray holographic storage in the Ag/TiO2 film is improved by one order of magnitude compared to the traditional UV-reduced sample. Based on such properties, polarization-multiplexing holograms are able to be written at 405 nm and readout with little crosstalk. This work provides effective solutions for sensitizing localized surface plasmon resonance at near-UV region, extending the growth range of Ag NPs in the volume of TiO2, and resultantly, realizing high-density optical memory. PMID:27819328

  2. Realization of all-optical three-person voting function based on self-collimation with the two-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Jiang, Yu-Chi; Liu, Shao-Bin

    2016-01-01

    In the paper, a simple structure of three-person voting circuit is proposed and based on self-collimation effect with the two-dimensional photonic crystals. The electric field intensity of the proposed structure is deduced according to optical interference theory. The results show that the simple structure with two-dimensional photonic crystals can realize the three-person voting either from the optical interference theory or simulation, meanwhile, the light contrast ratio between the output logic signal "1" and "0" can reach as high as 19 dB. When compared with three-person voting designed with digital electronic technology, the size of the proposed design in this paper is more smaller, which is valuable in photonic device integration and compactness.

  3. Analysis of the Localization of Michelson Interferometer Fringes Using Fourier Optics and Temporal Coherence

    ERIC Educational Resources Information Center

    Narayanamurthy, C. S.

    2009-01-01

    Fringes formed in a Michelson interferometer never localize in any plane, in the detector plane and in the localization plane. Instead, the fringes are assumed to localize at infinity. Except for some explanation in "Principles of Optics" by Born and Wolf (1964 (New York: Macmillan)), the fringe localization phenomena of Michelson's interferometer…

  4. Local-field effects and nanostructuring for controlling optical properties and enabling novel optical phenomena

    NASA Astrophysics Data System (ADS)

    Dolgaleva, Ksenia

    My Ph. D. thesis is devoted to the investigation of the methods of controlling and improving the linear and nonlinear optical properties of materials. Within my studies, two approaches are considered: nanostructuring and invoking local-field effects. These broad topics involve various projects that I have undertaken during my Ph. D. research. The first project is on composite laser gain media. It involves both nanostructuring and using local-field effects to control the basic laser parameters, such as the radiative lifetime, small-signal gain and absorption, and the saturation intensity. While being involved in this project, I have performed both theoretical and experimental studies of laser characteristics of composite materials. In particular, I have developed simple theoretical models for calculating the effective linear susceptibilities of layered and Maxwell Garnett composite materials with a gain resonance in one of their components. The analysis of the results given by the models suggests that local-field effects provide considerable freedom in controlling the optical properties of composite laser gain media. I have also experimentally measured the radiative lifetime of Nd:YAG nanopowder suspended in different liquids to extract information regarding local-field effects. The second project is devoted to the investigation of a not-well-known phenomenon that local-field effects can induce, which is microscopic cascading in nonlinear optics. This project involves the theoretical prediction of local-field-induced microscopic cascading effect in the fifth-order nonlinear response and its first experimental observation. This effect has been mostly overlooked or underestimated, but could prove useful in quantum optics. I have shown that, under certain conditions, the microscopic cascaded contribution can be a dominant effect in high-order nonlinearities. The third project is about characterization of laser performance of a new dye, oligofluorene, embedded into

  5. Localized immunoassay in flow-through optical microbubble resonator (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Berneschi, Simone; Baldini, Francesco; Cosci, Alessandro; Cosi, Franco; Farnesi, Daniele; Nunzi Conti, Gualtiero; Tombelli, Sara; Trono, Cosimo; Pelli, Stefano; Giannetti, Ambra

    2016-05-01

    The integration of the Whispering Gallery Modes (WGMs) resonators in a microfluidics platform represents an important feature towards the realization of a compact high performance label-free biosensor. These hollow resonant microstructures present the advantage to combine the WGM resonator properties with the intrinsic capability of integrated microfluidics. In this sense, optical microbubble resonators (OMBRs), intended as a hollow core spherical bulge realized in a glass microcapillary by a suitable fabrication process, with their high Q factors (< 107 in air) well satisfy this requirement. Their operation is based on the fact that, given a small enough wall thickness of the bubble, the WGM optical field extends on both sides of the wall, so that it is possible to couple light into the resonator from an outer waveguide, and at the same time to have interaction of the WGM field with the inner fluid and analyte. The biosensing mechanism of these devices is based on the WGMs morphological dependence: any change on the OMBR inner surface, due to some chemical and/or biochemical binding, causes a shift of the resonance position and reduces the Q factor of the OMBR. By measuring these changes, important information about the sensing capability of the device can be obtained. In order to develop an OMBR based biosensor and optimize its performance, a crucial step is represented by its chemical/biochemical functionalization. Here we present a novel technique able to guarantee that the chemical interaction occurs in the OMBR inner wall, leaving the other microfluidic parts completely inert from a biochemical point of view. The method is based on UV photoactivation, which allows to localize the biolayers only in correspondence of the OMBR inner wall. As a proof of concept, an immunoassay based on rabbit IgG/anti rabbit-IgG interaction was performed and. The anti rabbit-IgG antibody was labelled with Alexa Fluor 488 to verify, by a fluorescence characterization, the goodness

  6. Local electronic, sensing and optical properties of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Staii, Cristian

    The work presented in this thesis is focused on the electronic and optical properties of single wall carbon nanotubes (swCNs). In a first set of experiments we investigate the local electronic properties of swCNs using novel scanning probe microscopies. We use Scanning Gate Microscopy (SGM) to measure the energy of the resonant scattering centers in metallic swCNs, and to show the local nature of the memory effect observed in swCN field effect transistors (swCN-FETs). We also combine Impedance Spectroscopy and SGM to measure the high frequency properties of swCN-FETs. These experiments provide the first observations concerning the role of individual defects at high frequencies. The results are consistent with a simple parallel R-C circuit model for the swCN-FET. Furthermore, we present a quantitative model for the phase shifts observed in Scanning Conductance Microscopy (SCM) and demonstrate that this can be used to investigate the electronic properties of nanoscale samples without requiring electrical contacts. We provide a general method based on SCM that can be used to measure the dielectric constant of nanoscale objects. In a second set of experiments we demonstrate that swCN-FETs functionalized with single stranded DNA (ss-DNA) act as highly sensitive chemical sensors. The ss-DNA decorated swCN-FETs are sensitive to chemical species (odors) that do not cause a detectable response in non-functionalized swCN-FETs. Moreover, odor responses of these devices are different in sign and magnitude for different odors, and the odor response characteristics are dependent on the base sequence of the ss-DNA used to decorate the swCN. These results suggest that swCN-FET functionalized with ss-DNA and related molecules (RNA, aptamers, etc) are extremely promising candidates for sensing applications. Finally, we present photoluminescence measurements on individual swCNs, freely suspended across open apertures. These experiments show asymmetric peak line shapes, with line

  7. Nano-composite magnetic material embedded on TiO2 pillars to realize magneto-optical resonant guided mode gratings

    NASA Astrophysics Data System (ADS)

    Varghese, B.; Gamet, E.; Jamon, D.; Neveu, S.; Berthod, L.; Shavdina, O.; Reynaud, S.; Verrier, I.; Veillas, C.; Royer, F.

    2016-02-01

    Periodic structuration of magnetic material is a way to enhance the magneto-optical behavior of optical devices like isolators. It is useful to reduce the footprint of such integrated devices or to improve their features. However, the structuration and/or integration of efficient magnetic materials on photonic platforms is still a difficult problem, because classical magneto-optical materials require an annealing temperature as high as 700°C. A novel wafer-scale approach is to incorporate that material into an already structured template through a single step deposition at low temperature. Using the dip-coating method, a magneto-optical thin film (~300nm) of CoFe2O4 nanoparticles in silica matrix prepared by sol-gel technique was coated on a 1D and 2D TiO2 subwavelength gratings. Such gratings were realized by the patterning of TiO2 films obtained by a sol-gel process. It was confirmed by Scanning Electron Microscope images that the magneto-optical composite completely occupies the voids of the 2D structuration showing a good compatibility between both materials. This composite shows a specific Faraday rotation of about 200°cm-1 at 1,5μm for 1% of volume fraction of nanoparticles. Spectral studies of the transmission and the reflection of a 1D TiO2 grating filled with the MO composite have evidenced the presence of a guided-mode optical resonance at 1,55μm. The position of this resonance was confirmed by numerical simulations, as well as its quite low efficiency. Based on simulations results, one can conclude that an increase of the grating depth is required to improve the efficiency of the resonance.

  8. A design of panoramic lens system to realize the projection from the local annular object field to rectangular image field by using freeform surfaces

    NASA Astrophysics Data System (ADS)

    Bian, Xuqi; Ma, Tao; Zhang, Jun

    2016-10-01

    Nowadays, panoramic annular lens (PAL) applies in aerospace, robotics vision, industrial pipeline endoscope and corporate video conferencing. A cylinder-to-plane projection which called the Flat Cylinder Perspective (FCP) is adopted in PAL. The FCP projected the three-dimensional cylindrical field object onto a two-dimensional annular image plane. The optical system has fade zone in the center of detector. Based on the structure of the PAL system, this paper shows that a panoramic lens is designed with free-form surfaces. In the designed optical system, the local annular object field of view is projected onto a rectangular image plane. The free-form panoramic lens has a wide field of view of 140°in horizontal direction and a field of view of 40°in vertical direction. The design of the panoramic lens can maximize the use of area and have no fade zone in rectangular detector.

  9. Optical Activity Governed by Local Chiral Structures in Two-Dimensional Curved Metallic Nanostructures.

    PubMed

    Narushima, Tetsuya; Hashiyada, Shun; Okamoto, Hiromi

    2016-07-01

    Chiral nanostructures show macroscopic optical activity. Local optical activity and its handedness are not uniform in the nanostructure, and are spatially distributed depending on the shape of the nanostructure. In this study we fabricated curved chain nanostructures made of gold by connecting linearly two or more arc structures in a two-dimensional plane. Spatial features of local optical activity in the chain structures were evaluated with near-field circular dichroism (CD) imaging, and analyzed with the aid of classical electromagnetic simulation. The electromagnetic simulation predicted that local optical activity appears at inflection points where arc structures are connected. The handedness of the local optical activity was dependent on the handedness of the local chirality at the inflection point. Chiral chain structures have odd inflection points and the local optical activity distributed symmetrically with respect to structural centers. In contrast, achiral chain structures have even inflection points and showed antisymmetric distribution. In the near-field CD images of fabricated chain nanostructures, the symmetric and antisymmetric distributions of local CD were observed for chiral and achiral chain structures, respectively, consistent with the simulated results. The handedness of the local optical activity was found to be determined by the handedness of the inflection point, for the fabricated chain structures having two or more inflection points. The local optical activity was thus governed primarily by the local chirality of the inflection points for the gold chain structures. The total effect of all the inflection points in the chain structure is considered to be a predominant factor that determines the macroscopic optical activity. Chirality 28:540-544, 2016. © 2016 Wiley Periodicals, Inc.

  10. Topology, localization, and quantum information in atomic, molecular and optical systems

    NASA Astrophysics Data System (ADS)

    Yao, Norman Ying

    The scientific interface between atomic, molecular and optical (AMO) physics, condensed matter, and quantum information science has recently led to the development of new insights and tools that bridge the gap between macroscopic quantum behavior and detailed microscopic intuition. While the dialogue between these fields has sharpened our understanding of quantum theory, it has also raised a bevy of new questions regarding the out-of-equilibrium dynamics and control of many-body systems. This thesis is motivated by experimental advances that make it possible to produce and probe isolated, strongly interacting ensembles of disordered particles, as found in systems ranging from trapped ions and Rydberg atoms to ultracold polar molecules and spin defects in the solid state. The presence of strong interactions in these systems underlies their potential for exploring correlated many-body physics and this thesis presents recent results on realizing fractionalization and localization. From a complementary perspective, the controlled manipulation of individual quanta can also enable the bottom-up construction of quantum devices. To this end, this thesis also describes blueprints for a room-temperature quantum computer, quantum credit cards and nanoscale quantum thermometry.

  11. Topological defect formation in 1D and 2D spin chains realized by network of optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Hamerly, Ryan; Inaba, Kensuke; Inagaki, Takahiro; Takesue, Hiroki; Yamamoto, Yoshihisa; Mabuchi, Hideo

    2016-09-01

    A network of optical parametric oscillators (OPOs) is used to simulate classical Ising and XY spin chains. The collective nonlinear dynamics of this network, driven by quantum noise rather than thermal fluctuations, seeks out the Ising/XY ground state as the system transitions from below to above the lasing threshold. We study the behavior of this “Ising machine” for three canonical problems: a 1D ferromagnetic spin chain, a 2D square lattice and problems where next-nearest-neighbor couplings give rise to frustration. If the pump turn-on time is finite, topological defects form (domain walls for the Ising model, winding number and vortices for XY) and their density can be predicted from a numerical model involving a linear “growth stage” and a nonlinear “saturation stage”. These predictions are compared against recent data for a 10,000-spin 1D Ising machine.

  12. Investigation of local and nonlocal nonlinear optical refraction effect in IZO thin films

    NASA Astrophysics Data System (ADS)

    Htwe, Zin Maung; Zhang, Yun-Dong; Yao, Cheng-Bao; Li, Hui; Yuan, Ping

    2016-10-01

    We report the local and nonlocal nonlinear optical refraction properties of indium doped zinc oxide (IZO) thin films using closed aperture Z-scan technique. The Z-scan results show the films have positive nonlinear optical refraction properties. The nonlocal parameter m of samples is increased with indium. In both of local and nonlocal studies, the nonlinear optical refractions of thin films were increased with In contents and laser energy. This relation reveals the role of In composition in IZO affects on the nonlinear optical responses of the films. These results make the IZO thin films as the promising application in optoelectronics devices.

  13. Lightfast optical current in dielectric by plasmonically induced local field

    NASA Astrophysics Data System (ADS)

    Kim, Seungchul; Kwon, Ojoon; Lee, Tae-Woo

    2014-08-01

    Recently, ultrafast strong field induced optical current in SiO2 dielectric medium has demonstrated. By foaming laser intensity more than 1013 W•cm-2 in the dielectric material, the optical current was generated in a dielectric gap without any DC bias. This phenomenon is affected by the strength electric field of incident laser field and the generated electrons follow the speed of optical frequency enabling lightfast electronics in the future. In this study, we especially adopted nanoplasmonic field to trigger and control current flow in a nanometer spatial resolution. Nanoplasmonic field enables to manipulate light field in nanoscale domain. By using nanoplasmonic field, optically induced current flow can be selectively controlled by characteristic of nanoplasmonic nanostructure. For the first demonstration, saw tooth like 2-D nano Au pattern was numerically and experimentally investigated to boost up the laser intensity of incident 4.5 fs laser pulse with minimum field distortion and broadening. The intensity enhancement factor of plasmonic field at the saw tooth tip was ~40, enabling Wannier-Stark effect with incidence intensity level of only 1011W•cm-2 in the TiO2 substrate. The carrier envelope phase of laser pulse is controlled to measure ultrafast optical current generation in dielectric medium by plasmonically induced strong near-field. This will be the basis for developing practical lightfast optical electronics in the future.

  14. Design and realization of a side-polished single-mode fiber optic high-sensitive temperature sensor

    NASA Astrophysics Data System (ADS)

    Nagaraju, B.; Varshney, R. K.; Pal, B. P.; Singh, A.; Monnom, G.; Dussardier, B.

    2008-11-01

    A high sensitive temperature sensor based on evanescent field coupling between a side-polished fiber half-coupler (SPFHC) and a thermo-optic multimode overlay waveguide (MMOW) is designed and demonstrated. Such a structure essentially functions as an asymmetric directional coupler with a band-stop characteristic attributable to the wavelengthdependent resonant coupling between the mode of the SPFHC and one or more modes of the MMOW. A slight change in temperature leads to a significant shift in the phase resonance-coupling wavelength ( λr ) between the MMOW and SPFHC λr, which is easily measurable. The wavelength sensitivity of the device is measured to be ~ 5.3 nm/°C within the measurement range of 26-70°C this sensitivity is more than 5 times higher compared to earlier reported temperature sensors of this kind. The SPFHC was fabricated by selective polishing of the cladding from one side of a bent telecommunication standard single-mode fiber and the MMOW was formed on top of the SPFHC through spin coating. A semi- numerical rigorous normal mode analysis was employed at the design stage by including the curvature effect of the fiber lay in the half-coupler block and the resultant z-dependent evanescent coupling mechanism. An excellent agreement between theoretical and experimental results is found.

  15. Local Optical Spectroscopies for Subnanometer Spatial Resolution Chemical Imaging

    SciTech Connect

    Weiss, Paul

    2014-01-20

    The evanescently coupled photon scanning tunneling microscopes (STMs) have special requirements in terms of stability and optical access. We have made substantial improvements to the stability, resolution, and noise floor of our custom-built visible-photon STM, and will translate these advances to our infrared instrument. Double vibration isolation of the STM base with a damping system achieved increased rigidity, giving high tunneling junction stability for long-duration and high-power illumination. Light frequency modulation with an optical chopper and phase-sensitive detection now enhance the signal-to-noise ratio of the tunneling junction during irradiation.

  16. Optical fiber sensor based on localized surface plasmon resonance using silver nanoparticles photodeposited on the optical fiber end.

    PubMed

    Ortega-Mendoza, J Gabriel; Padilla-Vivanco, Alfonso; Toxqui-Quitl, Carina; Zaca-Morán, Placido; Villegas-Hernández, David; Chávez, Fernando

    2014-10-09

    This paper reports the implementation of an optical fiber sensor to measure the refractive index in aqueous media based on localized surface plasmon resonance (LSPR). We have used a novel technique known as photodeposition to immobilize silver nanoparticles on the optical fiber end. This technique has a simple instrumentation, involves laser light via an optical fiber and silver nanoparticles suspended in an aqueous medium. The optical sensor was assembled using a tungsten lamp as white light, a spectrometer, and an optical fiber with silver nanoparticles. The response of this sensor is such that the LSPR peak wavelength is linearly shifted to longer wavelengths as the refractive index is increased, showing a sensitivity of 67.6 nm/RIU. Experimental results are presented.

  17. Spatiotemporal localized modes in PT-symmetric optical media

    NASA Astrophysics Data System (ADS)

    Wang, Yue-Yue; Dai, Chao-Qing; Wang, Xiao-Gang

    2014-09-01

    We firstly obtain spatiotemporal localized mode solutions of a (3+1)-dimensional nonlinear Schrödinger equation in PT-symmetric potentials, and then discuss the linear stability of LMs, which are also tested by means of direct simulations. Moreover, phase switches and transverse power-flow density associated with these localized modes have also been examined. At last, we investigate the dynamical behaviors of spatiotemporal LMs in three kinds of inhomogeneous media.

  18. New compact and efficient local oscillator optic system for the KSTAR electron cyclotron emission imaging system

    NASA Astrophysics Data System (ADS)

    Nam, Y. B.; Lee, D. J.; Lee, J.; Kim, C.; Yun, G. S.; Lee, W.; Park, H. K.

    2016-11-01

    Electron cyclotron emission imaging (ECEI) diagnostic on Korean Superconducting Tokamak Advanced Research utilizes quasi-optical heterodyne-detection method to measure 2D (vertical and radial) Te fluctuations from two toroidally separated poloidal cross section of the plasma. A cylindrical lens local oscillator (LO) optics with optical path length (OPL) 2-2.5 m has been used in the current ECEI system to couple the LO source to the 24 vertically aligned array of ECE detectors. For efficient and compact LO optics employing the Powell lens is proposed so that the OPL of the LO source is significantly reduced from ˜2.0 m to 0.4 m with new optics. The coupling efficiency of the LO source is expected to be improved especially at the edge channels. Results from the optical simulation together with the laboratory test of the prototype optics will be discussed in this paper.

  19. Local density of optical states of an asymmetric waveguide grating at photonic band gap resonant wavelength

    NASA Astrophysics Data System (ADS)

    Alatas, Husin; Sumaryada, Tony I.; Ahmad, Faozan

    2015-01-01

    We have investigated the characteristics of local density of optical states (LDOS) at photonic band gap resonant wavelength of an asymmetric waveguide grating based on Green's function formulation. It is found that the LDOS of the considered structure exhibits different characteristics in its localization between the upper and lower resonant wavelengths of the corresponding photonic band gap edges.

  20. Research in high speed fiber optics local area networks

    NASA Technical Reports Server (NTRS)

    Tobagi, F. A.

    1986-01-01

    The design of high speed local area networks (HSLAN) for communication among distributed devices requires solving problems in three areas: the network medium and its topology, the medium access control, and the network interface. Considerable progress was already made in the first two areas. Accomplishments are divided into two groups according to their theoretical or experimental nature. A brief summary is given.

  1. Fire Source Localization Based on Distributed Temperature Sensing by a Dual-Line Optical Fiber System

    PubMed Central

    Sun, Miao; Tang, Yuquan; Yang, Shuang; Li, Jun; Sigrist, Markus W.; Dong, Fengzhong

    2016-01-01

    We propose a method for localizing a fire source using an optical fiber distributed temperature sensor system. A section of two parallel optical fibers employed as the sensing element is installed near the ceiling of a closed room in which the fire source is located. By measuring the temperature of hot air flows, the problem of three-dimensional fire source localization is transformed to two dimensions. The method of the source location is verified with experiments using burning alcohol as fire source, and it is demonstrated that the method represents a robust and reliable technique for localizing a fire source also for long sensing ranges. PMID:27275822

  2. Fire Source Localization Based on Distributed Temperature Sensing by a Dual-Line Optical Fiber System.

    PubMed

    Sun, Miao; Tang, Yuquan; Yang, Shuang; Li, Jun; Sigrist, Markus W; Dong, Fengzhong

    2016-06-06

    We propose a method for localizing a fire source using an optical fiber distributed temperature sensor system. A section of two parallel optical fibers employed as the sensing element is installed near the ceiling of a closed room in which the fire source is located. By measuring the temperature of hot air flows, the problem of three-dimensional fire source localization is transformed to two dimensions. The method of the source location is verified with experiments using burning alcohol as fire source, and it is demonstrated that the method represents a robust and reliable technique for localizing a fire source also for long sensing ranges.

  3. Improved passive optical network architectures to support local area network emulation and protection

    NASA Astrophysics Data System (ADS)

    Wong, Elaine; Nadarajah, Nishaanthan; Chae, Chang-Joon; Nirmalathas, Ampalavanapillai; Attygalle, Sanjeewa M.

    2006-01-01

    We describe two optical layer schemes which simultaneously facilitate local area network emulation and automatic protection switching against distribution fiber breaks in passive optical networks. One scheme employs a narrowband fiber Bragg grating placed close to the star coupler in the feeder fiber of the passive optical network, while the other uses an additional short length distribution fiber from the star coupler to each customer for the redirection of the customer traffic. Both schemes use RF subcarrier multiplexed transmission for intercommunication between customers in conjunction with upstream access to the central office at baseband. Failure detection and automatic protection switching are performed independently by each optical network unit that is located at the customer premises in a distributed manner. The restoration of traffic transported between the central office and an optical network unit in the event of the distribution fiber break is performed by interconnecting adjacent optical network units and carrying out signal transmissions via an independent but interconnected optical network unit. Such a protection mechanism enables multiple adjacent optical network units to be simultaneously protected by a single optical network unit utilizing its maximum available bandwidth. We experimentally verify the feasibility of both schemes with 1.25 Gb/s upstream baseband transmission to the central office and 155 Mb/s local area network data transmission on a RF subcarrier frequency. The experimental results obtained from both schemes are compared, and the power budgets are calculated to analyze the scalability of each scheme.

  4. Delivery of video-on-demand services using local storages within passive optical networks.

    PubMed

    Abeywickrama, Sandu; Wong, Elaine

    2013-01-28

    At present, distributed storage systems have been widely studied to alleviate Internet traffic build-up caused by high-bandwidth, on-demand applications. Distributed storage arrays located locally within the passive optical network were previously proposed to deliver Video-on-Demand services. As an added feature, a popularity-aware caching algorithm was also proposed to dynamically maintain the most popular videos in the storage arrays of such local storages. In this paper, we present a new dynamic bandwidth allocation algorithm to improve Video-on-Demand services over passive optical networks using local storages. The algorithm exploits the use of standard control packets to reduce the time taken for the initial request communication between the customer and the central office, and to maintain the set of popular movies in the local storage. We conduct packet level simulations to perform a comparative analysis of the Quality-of-Service attributes between two passive optical networks, namely the conventional passive optical network and one that is equipped with a local storage. Results from our analysis highlight that strategic placement of a local storage inside the network enables the services to be delivered with improved Quality-of-Service to the customer. We further formulate power consumption models of both architectures to examine the trade-off between enhanced Quality-of-Service performance versus the increased power requirement from implementing a local storage within the network.

  5. Development of all-solid-state coherent 589 nm light source: toward the realization of sodium lidar and laser guide star adaptive optics

    NASA Astrophysics Data System (ADS)

    Saito, Norihito; Akagawa, Kazuyuki; Kato, Mayumi; Takazawa, Akira; Hayano, Yutaka; Saito, Yoshihiko; Ito, Meguru; Takami, Hideki; Iye, Masanori; Wada, Satoshi

    2006-12-01

    We report an all-solid-state coherent 589 nm light source in single-pass sum-frequency generation (SFG) with actively mode-locked Nd:YAG lasers for the realization of sodium lidar and laser guide star adaptive optics. The Nd:YAG lasers are constructed as a LD-side-pumped configuration and are operated at 1064 and 1319 nm for 589 nm light generation in SFG. Output powers of 16.5 and 5.3 W at 1064 and 1319 nm are obtained with two pumping chambers. Each chamber consisted of three 80-W-LD arrays. Single transverse mode TEM 00; M2 ~1.1 is achieved with adjustment of cavity length considering thermal lens effect with increase of input LD power. The cavity length is set to approximately 1 m. Accordingly the mode-locked lasers are operated at a repetition rate of approximately 150 MHz. Synchronization of two pulse trains at 1064 and 1319 nm is accomplished by control of phase difference between two radio frequencies input in acousto-optic mode-lockers. Then temporal delay is controlled with a resolution of 37 ps/degree. Pump beams are mixed in periodically poled stoichiometric lithium tantalate (PPSLT) without an antireflection coating. The effective aperture and length of the crystal are 0.5 × 2 mm2 and 15 mm. When input intensity is set at 5.6 MW/cm , an average output power of 4.6 W is obtained at 589.159 nm. Precise tuning to the sodium D II line is accomplished by thermal control of etalons set in the Nd:YAG lasers. The output power at 589.159 nm is stably maintained within +/-1.2% for 8 hours.

  6. Understanding AGNs in the Local Universe through Optical Reverberation Mapping

    NASA Astrophysics Data System (ADS)

    Pei, Liuyi

    2016-01-01

    I present the results of observational projects aimed at measuring the mass of the black hole at the center of active galactic nuclei (AGNs) and understanding the structure and kinematics of the broad-line emitting gas within the black hole's sphere of influence.The first project aims to measure the black hole mass in the Kepler-field AGN KA1858. We obtained simultaneous spectroscopic data from the Lick Observatory 3-m telescope using the Kast Double Spectrograph and photometry data from five ground-based telescopes, and used reverberation mapping (RM) techniques to measure the emission-line light curves' lags relative to continuum variations. We obtained lags for H-beta, H-gamma, H-delta, and He II, and obtained the first black hole mass measurement for this object. Our results will serve as a reference point for future studies on relations between black hole mass and continuum variability characteristics using Kepler AGN light curves.The second project, in collaboration with the AGN STORM team, aims to understand the structure and dynamics of the broad line region (BLR) in NGC 5548 in both UV and optical wavelengths. To supplement 6 months of HST UV observations, we obtained simultaneous optical spectroscopic data from six ground-based observatories. We obtained emission-line lags for the optical H-beta and He II lines as well as velocity-resolved lag measurements for H-beta. We also compared the velocity-resolved lags for H-beta to the UV emission lines C IV and Ly-alpha and found similar lag profiles for all three lines.Finally, I will discuss my contributions to two other collaborations in AGN RM. A key component in RM is monitoring continuum variability, which is often done through ground-based photometry. I will present a pipeline that performs aperture photometry on any number of images of an AGN with WCS coordinates and immediately produces relative light curves. This pipeline enables quick looks of AGN variability in real time and has been used in the

  7. Intraoperative localization using a three-dimensional optical digitizer

    NASA Astrophysics Data System (ADS)

    Bucholz, Richard D.; Smith, Kurt R.; Henderson, Jaimie M.; McDurmont, Lee L.; Schulze, Dean W.

    1993-09-01

    Frame based stereotactic surgery allows the surgeon to precisely approach a predetermined target. Although useful for diagnostic and functional procedures, mechanical instruments fail to indicate position quickly during open craniotomy. We have developed a system employing an infrared optical digitizer to indicate position on either CT, MRI, or PET scans. The system consists of a base ring attached to the patient's head during surgery, hand held instruments of any type, a camera array, and a computer display. Light emitting diodes on the instruments and head ring are tracked by three linear CCDs suspended over the surgical field. The position of the surgical instrument relative to the patient's head is computed by a personal computer. Surgical position is indicated on an individual CT, MRI, or PET slice. A graphics workstation provides three dimensional display of position.

  8. High speed fiber optics local area networks: Design and implementation

    NASA Technical Reports Server (NTRS)

    Tobagi, Fouad A.

    1988-01-01

    The design of high speed local area networks (HSLAN) for communication among distributed devices requires solving problems in three areas: (1) the network medium and its topology; (2) the medium access control; and (3) the network interface. Considerable progress has been made in all areas. Accomplishments are divided into two groups according to their theoretical or experimental nature. A brief summary is given in Section 2, including references to papers which appeared in the literature, as well as to Ph.D. dissertations and technical reports published at Stanford University.

  9. The local density of optical states of a metasurface

    PubMed Central

    Lunnemann, Per; Koenderink, A. Femius

    2016-01-01

    While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers, i.e., the response to near field excitation by a point source. Based on a pointdipole theory using Ewald summation and an array scanning method, we can swiftly and semi-analytically evaluate the local density of states (LDOS) for magnetoelectric point sources in front of an infinite two-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expected for reflection off homogeneous magnetic respectively electric mirrors. Furthermore, we identify in which source-surface separation regimes the metasurface may be treated as a homogeneous interface, and in which homogenization fails. A strong frequency and in-plane position dependence of the LDOS close to the lattice reveals coupling to guided modes supported by the lattice. PMID:26868601

  10. Electro-optically modulated localized surface plasmon resonance biosensors with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Tzyy-Jiann; Lin, Wen-Shao

    2006-10-01

    An integrated-optic biosensor based on electro-optically modulated localized surface plasmon resonance (LSPR) is demonstrated. This biosensor utilizes the electro-optic effect to modulate the wave vector of incident lightwave used to excite localized surface plasmons. Electro-optically modulated LSPR results in the analyte-dependent variation of output intensity with the applied voltage. The linear regression slope of this relation is used to determine the analyte concentration. On the sensing region of LSPR biosensor, human serum albumin is self-assembled on gold nanoparticles in order to sense the beta-blocker concentration. The use of the presented biosensor has the features of no intensity drift problem, no absorption diversity problem in different sample media, and noise reduction by linear regression analysis.

  11. Non-invasive optical modulation of local vascular permeability

    NASA Astrophysics Data System (ADS)

    Choi, Myunghwan; Choi, Chulhee

    2011-03-01

    For a systemically administered drug to act, it first needs to cross the vascular wall. This step represents a bottleneck for drug development, especially in the brain or retina, where tight junctions between endothelial cells form physiological barriers. Here, we demonstrate that femtosecond pulsed laser irradiation focused on the blood vessel wall induces transient permeabilization of plasma. Nonlinear absorption of the pulsed laser enabled the noninvasive modulation of vascular permeability with high spatial selectivity in three dimensions. By combining this method with systemic injection, we could locally deliver molecular probes in various tissues, such as brain cortex, meninges, ear, striated muscle, and bone. We suggest this method as a novel delivery tool for molecular probes or drugs.

  12. Influence of localized surface plasmons on Pauli blocking and optical limiting in graphene under femtosecond pumping

    NASA Astrophysics Data System (ADS)

    Bongu, Sudhakara Reddy; Bisht, Prem B.; Namboodiri, Raman C. K.; Nayak, Pranati; Ramaprabhu, Sundara; Kelly, Thomas J.; Fallon, Colm; Costello, John T.

    2014-08-01

    The Pauli blocking limit and optical limiting threshold have been found to be modified following silver-nanoparticle decoration of functionalized hydrogen induced exfoliated graphene. Femtosecond Z-scan experiments have been used to measure the Pauli blocking range, optical limiting threshold, and the third order nonlinear susceptibility (χ(3)) values. The observed results have been explained by modified band structure of graphene in the presence of silver nanoparticles and their localized surface plasmon resonances.

  13. Observations of regional and local variability in the optical properties of maritime clouds

    SciTech Connect

    White, A.B.

    1996-04-01

    White and Fairall (1995) calculated the optical properties of the marine boundary layer (MBL) clouds observed during the Atlantic Stratocumulus Transition Experiment (ASTEX) and compared their results with the results obtained by Fairall et al. for the MBL clouds observed during the First International Satellite Climatology Program (ISSCP) Regional Experiment (FIRE). They found a factor of two difference in the optical depth versus liquid water relationship that applies to the clouds observed in each case. In the present study, we present evidence to support this difference. We also investigate the local variability exhibited in the ASTEX optical properties using measurements of the boundary layer aerosol concentration.

  14. All-optical diode with photonic multilayers based on asymmetric light localization

    NASA Astrophysics Data System (ADS)

    Jin, Li; Zhou, Jun; Yang, Mingyang; Xue, Chunhua; He, Miao

    2011-03-01

    An all-optical diode (AOD) with structure (AB)m(BA)n(BBAA)k is proposed based on asymmetric light localization, and its optical bistability are numerically investigated by the nonlinear transfer matrix method. Research results show that the behavior of the AOD strongly depends on the period number m, n, and k, the transmission direction of the AOD is related to the values of m and n, while k affects the transmission contrast of the AOD. It is a significant reference for the design of all-optical signal processing devices.

  15. Enhancement of Optical Nonlinearities in Composite Media and Structures via Local Fields and Electromagnetic Coupling Effects

    NASA Technical Reports Server (NTRS)

    Smith, David D.

    2002-01-01

    This talk will review the linear and nonlinear optical properties of metal nanoparticles and dielectric microparticles, with an emphasis on local field effects, and whispering gallery modes (WGMs), as well as the conjunction of these two effects for enhanced Raman. In particular, enhanced optical properties that result from electromagnetic coupling effects will be discussed in the context of Mie scattering from concentric spheres and bispheres. Predictions of mode splitting and photonic bandgaps in micro-spheres will be presented and will be shown to be analogous to effects that occur in coupled resonator optical waveguides (CROW). Slow and fast light in SCISSOR / CROW configurations will also be discussed.

  16. Non-local Optical Topological Transitions and Critical States in Electromagnetic Metamaterials

    PubMed Central

    Ishii, Satoshi; Narimanov, Evgenii

    2015-01-01

    Just as the topology of the Fermi surface defines the properties of the free electrons in metals and semiconductors, the geometry of the iso-frequency surface in the phase space of the propagating electromagnetic waves, determines the optical properties of the corresponding optical materials. Furthermore, in the direct analog to the Lifshitz transition in condensed matter physics, a change in the topology of iso-frequency surface has a dramatic effect on the emission, propagation and scattering of the electromagnetic waves. Here, we uncover a new class of such optical topological transitions in metamaterials, induced by the non-locality of the electromagnetic response inherent to these composites. PMID:26670600

  17. Cryogenic optical localization provides 3D protein structure data with Angstrom resolution.

    PubMed

    Weisenburger, Siegfried; Boening, Daniel; Schomburg, Benjamin; Giller, Karin; Becker, Stefan; Griesinger, Christian; Sandoghdar, Vahid

    2017-02-01

    We introduce Cryogenic Optical Localization in 3D (COLD), a method to localize multiple fluorescent sites within a single small protein with Angstrom resolution. We demonstrate COLD by determining the conformational state of the cytosolic Per-ARNT-Sim domain from the histidine kinase CitA of Geobacillus thermodenitrificans and resolving the four biotin sites of streptavidin. COLD provides quantitative 3D information about small- to medium-sized biomolecules on the Angstrom scale and complements other techniques in structural biology.

  18. Self-localization of Bose–Einstein condensates in optical lattices

    NASA Astrophysics Data System (ADS)

    Kruse, Johannes; Fleischmann, Ragnar

    2017-03-01

    Mean field and beyond mean field model calculations of Bose–Einstein condensates trapped in optical lattices have shown that initially homogeneous condensates can evolve into self-trapped, strongly localized states in the presence of weak boundary dissipation, a phenomenon called self-localization. A dynamical phase transition from extended to localized states can be observed when the effective nonlinearity exceeds a critical threshold {{{Λ }}}{eff}{{c}}. We investigate this phase transition to self-localization in the mean field approximation of the discrete nonlinear Schrödinger equation. We quantitatively characterize the properties of the discrete breathers, i.e. the nonlinear localized solutions, at the phase transition. This leads us to propose and numerically verify an analytical lower bound {{{Λ }}}{eff}{{L}} for the critical nonlinearity based on the idea of self-induced Anderson localization.

  19. Photonic nanojets as a versatile optical tool for wave super-localization

    NASA Astrophysics Data System (ADS)

    Geints, Yu. E.; Zemlyanov, A. A.; Panina, E. K.

    2016-08-01

    The dimensional parameters and intensity of localized light structures (area "photonic nanojet"—PNJ) formed in the near field scattering of the optical wave by dielectric micron particles are studied. The difference between the PNJ characteristics of homogeneous quartz microparticles of different spatial shape and orientation are shown.

  20. Resolving phase information of the optical local density of state with scattering near-field probes

    NASA Astrophysics Data System (ADS)

    Prasad, R.; Vincent, R.

    2016-10-01

    We theoretically discuss the link between the phase measured using a scattering optical scanning near-field microscopy (s-SNOM) and the local density of optical states (LDOS). A remarkable result is that the LDOS information is directly included in the phase of the probe. Therefore by monitoring the spatial variation of the trans-scattering phase, we locally measure the phase modulation associated with the probe and the optical paths. We demonstrate numerically that a technique involving two-phase imaging of a sample with two different sized tips should allow to obtain the image the pLDOS. For this imaging method, numerical comparison with extinction probe measurement shows crucial qualitative and quantitative improvement.

  1. Goos-Hänchen shift and localization of optical modes in deformed microcavities.

    PubMed

    Unterhinninghofen, Julia; Wiersig, Jan; Hentschel, Martina

    2008-07-01

    Recently, an interesting phenomenon of spatial localization of optical modes along periodic ray trajectories near avoided resonance crossings has been observed [Wiersig, Phys. Rev. Lett. 97, 253901 (2006)]. For the case of a microdisk cavity with elliptical cross section, we use the Husimi function to analyze this localization in phase space. Moreover, we present a semiclassical explanation of this phenomenon in terms of the Goos-Hänchen shift, which works very well even deep in the wave regime. This semiclassical correction to the ray dynamics modifies the phase-space structure such that modes can localize either on stable islands or along unstable periodic ray trajectories.

  2. Optical Generation and Detection of Local Nonequilibrium Phonons in Suspended Graphene

    NASA Astrophysics Data System (ADS)

    Sullivan, Sean; Vallabhaneni, Ajit; Kholmanov, Iskandar; Ruan, Xiulin; Murthy, Jayathi; Shi, Li

    2017-03-01

    The measured frequencies and intensities of different first- and second- order Raman peaks of suspended graphene are used to show that optical phonons and different acoustic phonon polarizations are driven out of local equilibrium inside a sub-micron laser spot. The experimental results are correlated with a first principles-based multiple temperature model to suggest a considerably lower equivalent local temperature of the flexural phonons than those of other phonon polarizations. The finding reveals weak coupling between the flexural modes with hot electrons and optical phonons. Since the ultrahigh intrinsic thermal conductivity of graphene has been largely attributed to contributions from the flexural phonons, the observed local non-equilibrium phenomena have important implications for understanding energy dissipation processes in graphene-based electronic and optoelectronic devices, as well as in Raman measurements of thermal transport in graphene and other two-dimensional materials.

  3. Si dielectric function in a local basis representation: Optical properties, local field effects, excitons, and stopping power

    NASA Astrophysics Data System (ADS)

    Gómez, M.; González, P.; Ortega, J.; Flores, F.

    2014-11-01

    An atomiclike basis representation is used to analyze the dielectric function ɛ (q ⃗+G ⃗,q ⃗+G⃗';ω ) of Si. First, we show that a s p3d5 local basis set yields good results for the electronic band structure of this crystal and, then, we analyze the Si optical properties including local field and excitonic effects. In our formulation, we follow Hanke and Sham [W. Hanke and L. J. Sham, Phys. Rev. B 12, 4501 (1975), 10.1103/PhysRevB.12.4501; Phys. Rev. B 21, 4656 (1980), 10.1103/PhysRevB.21.4656], and introduce excitonic effects using a many-body formulation that incorporates a static screened electron-hole interaction. Dynamical effects in this interaction are also analyzed and shown to introduce non-negligible corrections in the optical spectrum. Our results are found in reasonable agreement with the experimental evidence and with other theoretical results calculated with the computationally more demanding plane-wave representation. Finally, calculations for the stopping power of Si are also presented.

  4. Localization of a Bose-Fermi mixture in a bichromatic optical lattice

    SciTech Connect

    Cheng Yongshan; Adhikari, S. K.

    2011-08-15

    We study the localization of a cigar-shaped superfluid Bose-Fermi mixture in a quasiperiodic bichromatic optical lattice (OL) for interspecies attraction and intraspecies repulsion. The mixture is described by the Gross-Pitaevskii equation for the bosons, coupled to a hydrodynamic mean-field equation for fermions at unitarity. We confirm the existence of the symbiotic localized states in the Bose-Fermi mixture and Anderson localization of the Bose component in the interacting Bose-Fermi mixture on a bichromatic OL. The phase diagram in boson and fermion numbers showing the regions of the symbiotic and Anderson localization of the Bose component is presented. Finally, the stability of symbiotic and Anderson localized states is established under small perturbations.

  5. Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes

    NASA Astrophysics Data System (ADS)

    Mor, Flavio M.; Sienkiewicz, Andrzej; Magrez, Arnaud; Forró, László; Jeney, Sylvia

    2016-03-01

    Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal fluctuations and optical forces of singly-trapped KNbO3 particles within the optical trapping volume of a PFM microscope. We also show that, under near-infrared (NIR) excitation of the highly focused laser beam of the PFM microscope, a single optically-trapped KNbO3 particle reveals a strong SHG signal manifested by a narrow peak (λem = 532 nm) at half the excitation wavelength (λex = 1064 nm). Moreover, we demonstrate that the thus induced SHG emission can be used as a local light source that is capable of optically exciting molecules of an organic dye, Rose Bengal (RB), which adhere to the particle surface, through the mechanism of luminescence energy transfer (LET).Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal

  6. Optically Thick H I Dominant in the Local Interstellar Medium: An Alternative Interpretation to "Dark Gas"

    NASA Astrophysics Data System (ADS)

    Fukui, Y.; Torii, K.; Onishi, T.; Yamamoto, H.; Okamoto, R.; Hayakawa, T.; Tachihara, K.; Sano, H.

    2015-01-01

    Dark gas in the interstellar medium (ISM) is believed to not be detectable either in CO or H I radio emission, but it is detectable by other means including γ rays, dust emission, and extinction traced outside the Galactic plane at |b| > 5°. In these analyses, the 21 cm H I emission is usually assumed to be completely optically thin. We have reanalyzed the H I emission from the whole sky at |b| > 15° by considering temperature stratification in the ISM inferred from the Planck/IRAS analysis of the dust properties. The results indicate that the H I emission is saturated with an optical depth ranging from 0.5 to 3 for 85% of the local H I gas. This optically thick H I is characterized by spin temperature in the range 10 K-60 K, significantly lower than previously postulated in the literature, whereas such low temperature is consistent with emission/absorption measurements of the cool H I toward radio continuum sources. The distribution and the column density of the H I are consistent with those of the dark gas suggested by γ rays, and it is possible that the dark gas in the Galaxy is dominated by optically thick cold H I gas. This result implies that the average density of H I is 2-2.5 times higher than that derived on the optically thin assumption in the local ISM. ), an ESA science mission with instruments and contributions directly funded by ESA Member States, NASA, and Canada.

  7. Broadband local service offerings using free-space optical links: a network business perspective

    NASA Astrophysics Data System (ADS)

    Britz, David M.; Dodley, J. P.; Barnickel, D. J.

    2001-02-01

    12 This paper describes a promising optical wireless broadband technology that will provide low cost broadband services to the local access `last mile' market. This paper examines the application, advantages and limitations of utilizing Free Space Optical Communications (FSOC) systems for broadband access markets. The service markets that would fully utilize FSOC technologies include metropolitan areas, BLECs (multi- tenant dwellings/business apartments), campuses, industrial parks and `pole-to-hole' neighborhood deployments. This paper will identify weather dependent link availability as being the primary consideration in defining and selecting suitable locations for FSOC-based systems. Link availability in turn determines link range, type of service, and the need for transmission diversity. This paper will describe the implications of telecom `five nines' last-mile access availability and its effect on the transparent integration of FSOC technologies into the existing fiber optic networks. This paper will also describe propagation losses and link budget requirements for broadband FSOC-based local service. During adverse weather conditions, stand-alone, FSOC-based optical wireless links typically offer path lengths of less than 200 meters while still meeting the `five nines' availability criteria. This paper will also consider `availability limited' services. These services may prove to be attractive to customers who are willing to accept broadband service on an `as available basis'. The use of availability-enhancing transmission diversity and the use of intelligent `roof-top' routing and optical wireless cross connects between buildings will also be discussed.

  8. OPTICALLY THICK H I DOMINANT IN THE LOCAL INTERSTELLAR MEDIUM: AN ALTERNATIVE INTERPRETATION TO ''DARK GAS''

    SciTech Connect

    Fukui, Y.; Torii, K.; Yamamoto, H.; Okamoto, R.; Hayakawa, T.; Tachihara, K.; Sano, H.; Onishi, T.

    2015-01-01

    Dark gas in the interstellar medium (ISM) is believed to not be detectable either in CO or H I radio emission, but it is detectable by other means including γ rays, dust emission, and extinction traced outside the Galactic plane at |b| > 5°. In these analyses, the 21 cm H I emission is usually assumed to be completely optically thin. We have reanalyzed the H I emission from the whole sky at |b| > 15° by considering temperature stratification in the ISM inferred from the Planck/IRAS analysis of the dust properties. The results indicate that the H I emission is saturated with an optical depth ranging from 0.5 to 3 for 85% of the local H I gas. This optically thick H I is characterized by spin temperature in the range 10 K-60 K, significantly lower than previously postulated in the literature, whereas such low temperature is consistent with emission/absorption measurements of the cool H I toward radio continuum sources. The distribution and the column density of the H I are consistent with those of the dark gas suggested by γ rays, and it is possible that the dark gas in the Galaxy is dominated by optically thick cold H I gas. This result implies that the average density of H I is 2-2.5 times higher than that derived on the optically thin assumption in the local ISM.

  9. Nonlinear localized modes in PT-symmetric optical media with competing gain and loss

    SciTech Connect

    Midya, Bikashkali; Roychoudhury, Rajkumar

    2014-02-15

    The existence and stability of the nonlinear spatial localized modes are investigated in parity-time symmetric optical media characterized by a generic complex hyperbolic refractive index distribution with competing gain and loss profile. The exact analytical expression of the localized modes are found for all values of the competing parameter and in the presence of both the self-focusing and self-defocusing Kerr nonlinearity. The effects of competing gain/loss profile on the stability structure of these localized modes are discussed with the help of linear stability analysis followed by the direct numerical simulation of the governing equation. The spatial localized modes in two-dimensional geometry as well as the transverse power-flow density associated with these localized modes are also examined. -- Highlights: • Existence of localized modes is investigated in PT-symmetric complex potentials. • Exact analytical expression of the localized modes is obtained. • Effect of gain/loss profile on the stability of these localized modes is discussed. • Localized modes in 2D and associated transverse power-flow density are also examined.

  10. Influence of Injection Molding Process on the Local Fluctuations of Magneto-Optical Signals

    NASA Astrophysics Data System (ADS)

    Umezawa, Tomokazu; Horiguchi, Toru; Tomie, Takashi

    2001-01-01

    The local fluctuations of magneto-optical (MO) signals were investigated in the vicinity of the preformat pits of polycarbonate (PC) substrates fabricated under different injection molding conditions and also using stampers which had different shapes of grooves and preformat pits. A strong correlation was observed between the substrate birefringence and the fluctuation of the MO signal. The rate-of-change of the fluctuations, as the phase shift of the optical head was varied, was attributed to the shapes of preformat pits and grooves. The fluctuation of the MO signal could be controlled by varying the injection molding conditions and the shapes of preformat pits and grooves.

  11. The optical theorem for local source excitation of a particle near a plane interface

    NASA Astrophysics Data System (ADS)

    Eremin, Yuri; Wriedt, Thomas

    2015-11-01

    Based on classic Maxwell's theory and the Gauss Theorem we extended the Optical Theorem to the case of a penetrable particle excited by a local source deposited near a plane interface. We demonstrate that the derived Extinction Cross-Section involves the total point source radiating cross-section and some definite integrals responsible for the scattering by the interface. The derived extinction cross-section can be employed to estimate the quantum yield and the optical antenna efficiency without computation of the absorption cross-section.

  12. Gold nanoparticle-assisted all optical localized stimulation and monitoring of Ca2+ signaling in neurons

    PubMed Central

    Lavoie-Cardinal, Flavie; Salesse, Charleen; Bergeron, Éric; Meunier, Michel; De Koninck, Paul

    2016-01-01

    Light-assisted manipulation of cells to control membrane activity or intracellular signaling has become a major avenue in life sciences. However, the ability to perform subcellular light stimulation to investigate localized signaling has been limited. Here, we introduce an all optical method for the stimulation and the monitoring of localized Ca2+ signaling in neurons that takes advantage of plasmonic excitation of gold nanoparticles (AuNPs). We show with confocal microscopy that 800 nm laser pulse application onto a neuron decorated with a few AuNPs triggers a transient increase in free Ca2+, measured optically with GCaMP6s. We show that action potentials, measured electrophysiologically, can be induced with this approach. We demonstrate activation of local Ca2+ transients and Ca2+ signaling via CaMKII in dendritic domains, by illuminating a single or few functionalized AuNPs specifically targeting genetically-modified neurons. This NP-Assisted Localized Optical Stimulation (NALOS) provides a new complement to light-dependent methods for controlling neuronal activity and cell signaling. PMID:26857748

  13. Preparation and characterization WDM technique for linear disturbance localization in fibre optical sensor

    NASA Astrophysics Data System (ADS)

    Życzkowski, M.; Ciurapinski, W.; Szustakowski, M.

    2007-10-01

    Ordinary perimeter security systems consist of many individual sensors with detection range 200-300 meters. These limitations are connected with physical phenomena that are used in microwave and infrared barriers as well as in ground and fence cable sensors. On the contrary, fiber optic perimeter sensors can be applied in the range of many kilometers and zone length 200-300 meters is degradation of their possibilities. This paper presents investigation results of a new generation of the fiber optic perimeter sensor using WDM technique. These systems can detect a potential intruder and determine its position along a protected zone. The work presents a method of linear localization of disturbance point in the two-interferometer and modalmertic fiber optic sensors in one optical fiber. These sensors are in one fiber optic cable with two- interferometers (Sagnac) and in transmissive configuration. Using WDM technique makes it possible to obtain new technical properties that can broaden effectiveness and scope of application. Arrangement of a laboratory model of the sensors and its signal processing scheme is presented. During research of a laboratory model, it was possible to detect the position of the disturbance in one optical fiber with resolution of about 50m along a 10-km long sensor.

  14. Optical Storage Systems for Records and Information Management: Overview, Recommendations and Guidelines for Local Governments. Local Government Records Technical Information Series. Number 45.

    ERIC Educational Resources Information Center

    Schwartz, Stanley F.

    This publication discusses optical storage, a term encompassing technologies that use laser-produced light to record and store information in digital form. The booklet also discusses how optical storage systems relate to records management, in particular to the management of local government records in New York State. It describes components of…

  15. Localization of a spin-orbit-coupled Bose-Einstein condensate in a bichromatic optical lattice

    NASA Astrophysics Data System (ADS)

    Cheng, Yongshan; Tang, Gaohui; Adhikari, S. K.

    2014-06-01

    We study the localization of a noninteracting and weakly interacting Bose-Einstein condensate (BEC) with spin-orbit coupling loaded in a quasiperiodic bichromatic optical lattice potential using the numerical solution and variational approximation of a binary mean-field Gross-Pitaevskii equation with two pseudospin components. We confirm the existence of the stationary localized states in the presence of the spin-orbit and Rabi couplings for an equal distribution of atoms in the two components. We find that the interaction between the spin-orbit and Rabi couplings favors the localization or delocalization of the BEC depending on the phase difference between the components. We also studied the oscillation dynamics of the localized states for an initial population imbalance between the two components.

  16. Dynamics of localization phenomena for hard-core bosons in optical lattices

    SciTech Connect

    Horstmann, Birger; Cirac, J. Ignacio; Roscilde, Tommaso

    2007-10-15

    We investigate the behavior of ultracold bosons in optical lattices with a disorder potential generated via a secondary species frozen in random configurations. The statistics of disorder is associated with the physical state in which the secondary species is prepared. The resulting random potential, albeit displaying algebraic correlations, is found to lead to localization of all single-particle states. We then investigate the real-time dynamics of localization for a hardcore gas of mobile bosons which are brought into sudden interaction with the random potential. Regardless of their initial state and for any disorder strength, the mobile particles are found to reach a steady state characterized by exponentially decaying off-diagonal correlations and by the absence of quasicondensation; when the mobile particles are initially confined in a tight trap and then released in the disorder potential, their expansion is stopped and the steady state is exponentially localized in real space, clearly revealing Anderson localization.

  17. Partially Strong Transparency Conditions and a Singular Localization Method In Geometric Optics

    NASA Astrophysics Data System (ADS)

    Lu, Yong; Zhang, Zhifei

    2016-10-01

    This paper focuses on the stability analysis of WKB approximate solutions in geometric optics with the absence of strong transparency conditions under the terminology of Joly, Métivier and Rauch. We introduce a compatible condition and a singular localization method which allows us to prove the stability of WKB solutions over long time intervals. This compatible condition is weaker than the strong transparency condition. The singular localization method allows us to do delicate analysis near resonances. As an application, we show the long time approximation of Klein-Gordon equations by Schrödinger equations in the non-relativistic limit regime.

  18. Measurement of biofilm growth and local hydrodynamics using optical coherence tomography

    PubMed Central

    Weiss, Nicolás; Obied, Khalid El Tayeb El; Kalkman, Jeroen; Lammertink, Rob G.H.; van Leeuwen, Ton G.

    2016-01-01

    We report on localized and simultaneous measurement of biofilm growth and local hydrodynamics in a microfluidic channel using optical coherence tomography. We measure independently with high spatio-temporal resolution the longitudinal flow velocity component parallel to the imaging beam and the transverse flow velocity component perpendicular to the imaging beam. Based on the measured velocities we calculate the shear-rates in the flow channel. We show the relation between the measured biofilm structure and flow velocities as biofilm growth progresses over the course of 48 hours. PMID:27699116

  19. Non-linear non-local molecular electrodynamics with nano-optical fields.

    PubMed

    Chernyak, Vladimir Y; Saurabh, Prasoon; Mukamel, Shaul

    2015-10-28

    The interaction of optical fields sculpted on the nano-scale with matter may not be described by the dipole approximation since the fields may vary appreciably across the molecular length scale. Rather than incrementally adding higher multipoles, it is advantageous and more physically transparent to describe the optical process using non-local response functions that intrinsically include all multipoles. We present a semi-classical approach for calculating non-local response functions based on the minimal coupling Hamiltonian. The first, second, and third order response functions are expressed in terms of correlation functions of the charge and the current densities. This approach is based on the gauge invariant current rather than the polarization, and on the vector potential rather than the electric and magnetic fields.

  20. Star Formation and Integrated Optical Colors from the Local Volume Legacy Survey

    NASA Astrophysics Data System (ADS)

    Minns, Cody; Shackleford, B. R.; van Zee, L.; Friberg, S.; Barnes, K. L.; Sakai, S.; LVL Team

    2011-01-01

    We present results of an optical imaging study of 73 galaxies from the Spitzer Local Volume Legacy (LVL) survey. The broadband and narrowband optical images were analyzed in order to determine information about global star formation rates, histories, and evolution of these nearby galaxies. The observed UBVR colors are consistent with the expected colors of star forming galaxies, with B-R colors ranging from 0.4 to 1.4. The blue, low mass galaxies appear to have a wider dispersion of current-to-past star formation rates than the more massive spiral galaxies in the sample. These results are discussed in the context of possible star formation histories for galaxies in the Local Volume.

  1. Localization and fractal spectra of optical phonon modes in quasiperiodic structures

    NASA Astrophysics Data System (ADS)

    Anselmo, D. H. A. L.; Dantas, A. L.; Medeiros, S. K.; Albuquerque, E. L.; Freire, V. N.

    2005-04-01

    The dispersion relation and localization profile of confined optical phonon modes in quasiperiodic structures, made up of nitride semiconductor materials, are analyzed through a transfer-matrix approach. The quasiperiodic structures are characterized by the nature of their Fourier spectrum, which can be dense pure point (Fibonacci sequences) or singular continuous (Thue-Morse and Double-period sequences). These substitutional sequences are described in terms of a series of generations that obey peculiar recursion relations and/or inflation rules. We present a quantitative analysis of the localization and magnitude of the allowed band widths in the optical phonons spectra of these quasiperiodic structures, as well as how they scale as a function of the number of generations of the sequences.

  2. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    DOE PAGES

    Caselli, Niccolò; La China, Federico; Bao, Wei; ...

    2015-06-05

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magneticmore » intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. In conclusion, by exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.« less

  3. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    SciTech Connect

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H.; Pagliano, Francesco; Fiore, Andrea; Schuck, P. James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-06-05

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. In conclusion, by exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.

  4. Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

    PubMed Central

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H.; Pagliano, Francesco; Fiore, Andrea; Schuck, P. James; Cabrini, Stefano; Weber-Bargioni, Alexander; Gurioli, Massimo; Intonti, Francesca

    2015-01-01

    Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magnetic intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. By exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions. PMID:26045401

  5. Fault localization and analysis in semiconductor devices with optical-feedback infrared confocal microscopy

    SciTech Connect

    Sarmiento, Raymund; Cemine, Vernon Julius; Tagaca, Imee Rose; Salvador, Arnel; Mar Blanca, Carlo; Saloma, Caesar

    2007-11-01

    We report on a cost-effective optical setup for characterizing light-emitting semiconductor devices with optical-feedback confocal infrared microscopy and optical beam-induced resistance change.We utilize the focused beam from an infrared laser diode to induce local thermal resistance changes across the surface of a biased integrated circuit (IC) sample. Variations in the multiple current paths are mapped by scanning the IC across the focused beam. The high-contrast current maps allow accurate differentiation of the functional and defective sites, or the isolation of the surface-emittingp-i-n devices in the IC. Optical beam-induced current (OBIC) is not generated since the incident beam energy is lower than the bandgap energy of the p-i-n device. Inhomogeneous current distributions in the IC become apparent without the strong OBIC background. They are located at a diffraction-limited resolution by referencing the current maps against the confocal reflectance image that is simultaneously acquired via optical-feedback detection. Our technique permits the accurate identification of metal and semiconductor sites as well as the classification of different metallic structures according to thickness, composition, or spatial inhomogeneity.

  6. Signal attenuation and localization in optical coherence tomography studied by Monte Carlo simulation.

    PubMed

    Smithies, D J; Lindmo, T; Chen, Z; Nelson, J S; Milner, T E

    1998-10-01

    A Monte Carlo model has been developed for optical coherence tomography (OCT). A geometrical optics implementation of the OCT probe with low-coherence interferometric detection was combined with three-dimensional stochastic Monte Carlo modelling of photon propagation in the homogeneous sample medium. Optical properties of the sample were selected to simulate intralipid and blood, representing moderately (g = 0.7) and highly (g = 0.99) anisotropic scattering respectively. For shallow optical depths in simulated intralipid (<3 scattering mean free path (mfp) units), the number of detected backscattered photons followed the extinction-single-backscatter model, and OCT was found to detect only minimally scattered photons. Within this depth range the backscatter positions of detected photons corresponded well with the nominal focus position of the probe. For propagation to deeper positions in intralipid, localization of backscattering was quickly lost due to detection of stray photons, and the number of detected photons remained constant with increasing depth in the non-absorbing medium. For strongly forward-directed scattering in simulated blood, the number of detected photons approached the extinction-single-backscatter model only for very shallow depths (<2 mfp units). However, backscattering positions for detected photons correlated well with the nominal focus position of the probe even for optical depths greater than 40 mfp units.

  7. Local field-induced optical properties of Ag-coated CdS quantum dots.

    PubMed

    Je, Koo-Chul; Ju, Honglyoul; Treguer, Mona; Cardinal, Thierry; Park, Seung-Han

    2006-08-21

    Local field-induced optical properties of Ag-coated CdS quantum dot structures are investigated. We experimentally observe a clear exciton peak due to the quantum confinement effect in uncoated CdS quantum dots, and surface plasmon resonance and red-shifted exciton peak in Ag-coated CdS composite quantum dot structures. We have calculated the Stark shift of the exciton peak as a function of the local field for different silver thicknesses and various sizes of quantum dots based on the effective-mass Hamiltonian using the numerical-matrix-diagonalization method. Our theoretical calculations strongly indicate that the exciton peak is red-shifted in the metal-semiconductor composite quantum dots due to a strong local field, i.e., the quantum confined Stark effect.

  8. Magnons and Phonons Optically Driven out of Local Equilibrium in a Magnetic Insulator

    NASA Astrophysics Data System (ADS)

    An, Kyongmo; Olsson, Kevin S.; Weathers, Annie; Sullivan, Sean; Chen, Xi; Li, Xiang; Marshall, Luke G.; Ma, Xin; Klimovich, Nikita; Zhou, Jianshi; Shi, Li; Li, Xiaoqin

    2016-09-01

    The coupling and possible nonequilibrium between magnons and other energy carriers have been used to explain several recently discovered thermally driven spin transport and energy conversion phenomena. Here, we report experiments in which local nonequilibrium between magnons and phonons in a single crystalline bulk magnetic insulator, Y3Fe5O12 , has been created optically within a focused laser spot and probed directly via micro-Brillouin light scattering. Through analyzing the deviation in the magnon number density from the local equilibrium value, we obtain the diffusion length of thermal magnons. By explicitly establishing and observing local nonequilibrium between magnons and phonons, our studies represent an important step toward a quantitative understanding of various spin-heat coupling phenomena.

  9. Glaucoma detection using novel optic disc localization, hybrid feature set and classification techniques.

    PubMed

    Akram, M Usman; Tariq, Anam; Khalid, Shehzad; Javed, M Younus; Abbas, Sarmad; Yasin, Ubaid Ullah

    2015-12-01

    Glaucoma is a chronic and irreversible neuro-degenerative disease in which the neuro-retinal nerve that connects the eye to the brain (optic nerve) is progressively damaged and patients suffer from vision loss and blindness. The timely detection and treatment of glaucoma is very crucial to save patient's vision. Computer aided diagnostic systems are used for automated detection of glaucoma that calculate cup to disc ratio from colored retinal images. In this article, we present a novel method for early and accurate detection of glaucoma. The proposed system consists of preprocessing, optic disc segmentation, extraction of features from optic disc region of interest and classification for detection of glaucoma. The main novelty of the proposed method lies in the formation of a feature vector which consists of spatial and spectral features along with cup to disc ratio, rim to disc ratio and modeling of a novel mediods based classier for accurate detection of glaucoma. The performance of the proposed system is tested using publicly available fundus image databases along with one locally gathered database. Experimental results using a variety of publicly available and local databases demonstrate the superiority of the proposed approach as compared to the competitors.

  10. Advances in cables and outside plant for cable television and optical fibre local networks

    NASA Astrophysics Data System (ADS)

    Bridle, Peter

    1986-11-01

    During 1985 Bristish Telecom commenced the installation of a number of cable television systems in the United Kingdom. One of these systems, in Westminster, London, is of the Switched Star type, developed by the British Telecom Research Laboratories. The network comprises optical fiber cable between the head-end and the cabinet-mounted switch, and coaxial cable between the switch and the customer. A number of new outside plant products have been developed to meet the special requirements of the Westminister installation. This earlier work, together with the experience gained from the installation of optical fibers in the British Telecom trunk and junction networks, formed an ideal basis for evolving the line plant necessary to enable BT to introduce singlemode optical fiber into the local network. A range of cables is being developed by UK companies, suitable for installing in the harsh environment of the local network. Joint organizers and flexibility nodes are being introduced, both for underground application and for within the exchange and customer's premises. In addition blown-fiber techniques are being used to introduce fiber into these networks.

  11. Narrowing of the linewidth of an optical parametric oscillator by an acousto-optic modulator for the realization of mid-IR noise-immune cavity-enhanced optical heterodyne molecular spectrometry down to 10⁻¹⁰ cm⁻¹ Hz⁻¹/².

    PubMed

    Hausmaninger, Thomas; Silander, Isak; Axner, Ove

    2015-12-28

    The linewidth of a singly resonant optical parametric oscillator (OPO) has been narrowed with respect to an external cavity by the use of an acousto-optic modulator (AOM). This made possible an improvement of the sensitivity of a previously realized OPO-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry instrument for the 3.2 - 3.9 µm mid-infrared region by one order of magnitude. The resulting system shows a detection sensitivity for methane of 2.4 × 10(-10) cm(-1) Hz(-1∕2) and 1.3 × 10(-10) cm(-1) at 20 s, which allows for detection of both the environmentally important (13)CH(4) and CH(3)D isotopologues in atmospheric samples.

  12. Visualizing the local optical response to extreme-ultraviolet radiation with a resolution of λ/380

    NASA Astrophysics Data System (ADS)

    Tamasaku, Kenji; Sawada, Kei; Nishibori, Eiji; Ishikawa, Tetsuya

    2011-09-01

    Scientists have continually tried to improve the spatial resolution of imaging ever since the invention of the optical microscope in around 1610 by Galileo. Recently, a spatial resolution near λ/10 was achieved in a near-field scheme by using surface plasmon polaritons. However, further improvement in this direction is hindered by the size of metallic nanostructures. Here we show that atom-scale resolution is achievable in the extreme-ultraviolet region by using X-ray parametric down-conversion, which detaches the achievable resolution from the wavelength of the probe light. We visualize three-dimensionally the local optical response of diamond at wavelengths between 103 and 206Å with a resolution as fine as 0.54Å. This corresponds to a resolution from λ/190 to λ/380, an order of magnitude better than ever achieved. Although the present study focuses on the relatively high-energy optical regions, our method could be extended into the visible region using advanced X-ray sources, and would open a new window into the optical properties of solids.

  13. Local-field enhancement of optical nonlinearities in the AGZO nano-triangle array

    NASA Astrophysics Data System (ADS)

    Long, Hua; Bao, Lijiao; Wang, Kai; Liu, Shuhui; Wang, Bing

    2016-10-01

    Enhancement of the third order optical nonlinearities in Ga and Al co-doped ZnO (AGZO) nano-triangle array was investigated by performing a Z-scan method with a femtosecond laser (800 nm, 40 fs). The AGZO nano-triangle array was fabricated on silica substrates by nanosphere lithography (NSL) method, showing a surface plasmon resonance (SPR) peak around 3 μm. The two photon absorption (TPA) coefficient and nonlinear refractive index of the AGZO nano-triangle array were determined to be 340 cm/GW and 3.22 × 10-2 cm2/GW under an excitation intensity of 26 GW/cm2. It shows a 3.4-fold enhancement of the nonlinear refraction in the AGZO array with respect to that in the AGZO film, which attributes to the local field enhancement effect. The finite-difference time-domain (FDTD) simulation was in agreement with the experimental results. It indicates that the AGZO nano-triangle arrays have potential applications for nonlinear optical devices like all-optical switching, optical limiting and other types of signal processing.

  14. The viscoelastic properties of the vitreous humor measured using an optically trapped local probe

    NASA Astrophysics Data System (ADS)

    Watts, Fiona; Tan, Lay Ean; Tassieri, Manlio; McAlinden, Niall; Wilson, Clive G.; Girkin, John M.; Wright, Amanda J.

    2011-10-01

    We present results demonstrating for the first time that an optically trapped bead can be used as a local probe to measure the variation in the viscoelastic properties of the vitreous humor of a rabbit eye. The Brownian motion of the optically trapped bead was monitored on a fast CCD camera on the millisecond timescale. Analysis of the bead trajectory provides local information about the viscoelastic properties of the medium surrounding the particle. Previous, bulk, methods for measuring the viscoelastic properties of the vitreous destroy the sample and allow only a single averaged measurement to be taken per eye. Whereas, with our approach, we were able to observe local behaviour typical of non-Newtonian and gel-like materials, along with the homogenous and in-homogeneous nature of different regions of the dissected vitreous humor. The motivation behind these measurements is to gain a better understanding of the structure of the vitreous humor in order to design effective drug delivery techniques. In particular, we are interested in methods for delivering drug to the retina of the eye in order to treat sight threatening diseases such as age related macular degeneration.

  15. Method for the three-dimensional localization of intramyocardial excitation centers using optical imaging.

    PubMed

    Khait, Vadim D; Bernus, Olivier; Mironov, Sergey F; Pertsov, Arkady M

    2006-01-01

    This study explores the possibility of localizing the excitation centers of electrical waves inside the heart wall using voltage-sensitive dyes (fluorescent or absorptive). In the present study, we propose a method for the 3-D localization of excitation centers from pairs of 2-D images obtained in two modes of observation: reflection and transillumination. Such images can be obtained using high-speed charge-coupled device (CCD) cameras and photodiode arrays with time resolution up to 0.5 ms. To test the method, we simulate optical signals produced by point sources and propagating ellipsoidal waves in 1-cm-thick slabs of myocardial tissue. Solutions of the optical diffusion equation are constructed by employing the method of images with Robin boundary conditions. The coordinates of point sources as well as of the centers of expanding waves can be accurately determined using the proposed algorithm. The method can be extended to depth estimations of the outer boundaries of the expanding wave. The depth estimates are based on ratios of spatially integrated images. The method shows high tolerance to noise and can give accurate results even at relatively low signal-to-noise ratios. In conclusion, we propose a novel and efficient algorithm for the localization of excitation centers in 3-D cardiac tissue.

  16. H(alpha) and Optical Imaging of Local Volume Galaxies in the Northern Hemisphere

    NASA Astrophysics Data System (ADS)

    Sakai, Shoko; van Zee, Liese; Lee, Janice C.; Kennicutt, Robert C.; Funes, Jose G.

    2010-02-01

    We propose H(alpha) and B,R imaging observations of 33 galaxies in the Local Volume Legacy (LVL) survey to measure current star formation activity and derive emission-line corrected optical colors throughout the stellar disk. The proposed imaging observations will be combined with existing UV and IR observations, and will serve to nearly complete the optical imaging coverage of the full LVL sample of 258 galaxies. The observed surface photometry and radial trace of the star formation activity will allow us to study the photometric properties, the morphology, and spatial distributions of different stellar populations in these nearby galaxies. These images will also form the basis for a definitive multiwavelength dataset for studies of star formation in nearby galaxies.

  17. Cavity solitons and localized patterns in a finite-size optical cavity

    NASA Astrophysics Data System (ADS)

    Kozyreff, G.; Gelens, L.

    2011-08-01

    In appropriate ranges of parameters, laser-driven nonlinear optical cavities can support a wide variety of optical patterns, which could be used to carry information. The intensity peaks appearing in these patterns are called cavity solitons and are individually addressable. Using the Lugiato-Lefever equation to model a perfectly homogeneous cavity, we show that cavity solitons can only be located at discrete points and at a minimal distance from the edges. Other localized states which are attached to the edges are identified. By interpreting these patterns in an information coding frame, the information capacity of this dynamical system is evaluated. The results are explained analytically in terms of the the tail characteristics of the cavity solitons. Finally, the influence of boundaries and of cavity imperfections on cavity solitons are compared.

  18. AIS wavefront sensor: a robust optical test of exposure tools using localized wavefront curvature

    NASA Astrophysics Data System (ADS)

    Miyakawa, Ryan; Zhou, Xibin; Goldstein, Michael; Ashworth, Dominic; Cummings, Kevin; Fan, Yu-Jen; Shroff, Yashesh; Denbeaux, Greg; Kandel, Yudhi; Naulleau, Patrick

    2014-04-01

    We present an update of the AIS wavefront sensor, a diagnostic sensor set for insertion in the upgraded 0.5 NA SEMATECH Albany and Berkeley METs. AIS works by using offset monopole illumination to probe localized regions of the test optic pupil. Variations in curvature manifest as focus shifts, which are measured using a photodiode- based grating-on- grating contrast monitor, and the wavefront aberrations are reconstructed using a least-squares approach. We present results from an optical prototype of AIS demonstrating an accuracy of better than λ/30 rms for Zernike polynomials Z4 through Z10. We also discuss integration strategies and requirements as well as specifications on system alignment.

  19. Tissue motion tracking at the edges of a radiation treatment field using local optical flow analysis

    NASA Astrophysics Data System (ADS)

    Teo, P. T.; Pistorius, S.

    2014-03-01

    This paper investigates the feasibility and accuracy of tracking the motion of an intruding organ-at-risk (OAR) at the edges of a treatment field using a local optical flow analysis of electronic portal images. An intruding OAR was simulated by modifying the portal images obtained by irradiating a programmable phantom's lung tumour. A rectangular treatment aperture was assumed and the edges of the beam's eye view (BEV) were partitioned into clusters/grids according to the width of the multi-leaf collimators (MLC). The optical flow velocities were calculated and the motion accuracy in these clusters was analysed. A velocity error of 0.4 ± 1.4 mm/s with a linearity of 1.04 for tracking an object intruding at 10mm/s (max) was obtained.

  20. Characterization of the optical properties of hydrophobic coatings and realization of high performance AR coatings with dust- and water-repellent properties

    NASA Astrophysics Data System (ADS)

    Bruynooghe, S.; Spinzig, S.; Fliedner, M.; Hsu, G. J.

    2008-09-01

    Hydrophobic coatings enable the manufacture of easy-to-clean surfaces having dust- and water-repellent properties. In this work, a hydrophobic coating is deposited as a top layer on an antireflective (AR) multilayer system comprising a MgF2 upper layer to produce low reflectance optical surfaces at a normal incident angle in the visible spectrum with dust- and water-repellent properties for applications in precision optics. We report on the preparation and characterization of the optical properties of hydrophobic coatings deposited using a vacuum evaporation process and a commercially available water repellent substance. By means of a grazing incidence X-ray reflectometer it is shown that the hydrophobic coating can be considered, from an optical point of view, as two adjacent thin layers having specific thicknesses and densities. In fact, the hydrophobic layer is one monolayer comprising molecular chains with anchoring groups responsible for the chemical bond with the substrate material and functional groups responsible for the water- and oil-repellent properties. Optical constants are determined using a spectroscopic ellipsometer and are taken into account in the final multilayer system design. High performance AR coatings having an average reflectance of 0.14% at 7° incident angle in the 400-680nm spectral range together with a pleasing purple-red reflex color are produced. Coated lenses exhibit an excellent abrasion resistance, environmental stability, resistance to cleaning agents, homogeneity and water repellence with contact angles against water higher than 110°.

  1. Local surface plasmon mediated extraordinary optical transmission of multi-spatial-mode quantum noise reduction

    SciTech Connect

    Lawrie, Benjamin J; Evans, Philip G; Pooser, Raphael C

    2013-01-01

    We demonstrate the coherent transduction of quantum noise reduction, or squeezed light, by Ag localized surface plasmons (LSPs). Squeezed light, generated through four-wave-mixing in Rb vapor, is coupled to a Ag nanohole array designed to exhibit LSP mediated extraordinary-optical transmission (EOT) spectrally coincident with the squeezed light source at 795 nm. We demonstrate that quantum noise reduction as a function of transmission is found to match closely with linear attenuation models, thus demonstrating that the photon-LSP-photon transduction process is coherent near the LSP resonance.

  2. Localization and delocalization of ultracold bosonic atoms in finite optical lattices

    SciTech Connect

    Luehmann, Dirk-Soeren; Pfannkuche, Daniela; Bongs, Kai; Sengstock, Klaus

    2008-02-15

    We study bosonic atoms in small optical lattices by exact diagonalization and observe a striking similarity to the superfluid to Mott insulator transition in macroscopic systems. The momentum distribution, the formation of an energy gap, and the pair correlation function show only a weak size dependence. For noncommensurate filling we reveal in deep lattices a mixture of localized and delocalized particles, which is sensitive to lattice imperfections. Breaking the lattice symmetry causes a Bose-glass-like behavior. We discuss the nature of excited states and orbital effects by using an exact diagonalization technique that includes higher bands.

  3. Defect modes of a Bose-Einstein condensate in an optical lattice with a localized impurity

    SciTech Connect

    Brazhnyi, Valeriy A.; Konotop, Vladimir V.; Perez-Garcia, Victor M.

    2006-08-15

    We study defect modes of a Bose-Einstein condensate in an optical lattice with a localized defect within the framework of the one-dimensional Gross-Pitaevskii equation. It is shown that for a significant range of parameters the defect modes can be accurately described by an expansion over Wannier functions, whose envelope is governed by the coupled nonlinear Schroedinger equations with a {delta} impurity. The stability of the defect modes is verified by direct numerical simulations of the underlying Gross-Pitaevskii equation with a periodic and defect potentials. We also discuss possibilities of driving defect modes through the lattice and suggest ideas for their experimental generation.

  4. A photonic-crystal optical antenna for extremely large local-field enhancement.

    PubMed

    Chang, Hyun-Joo; Kim, Se-Heon; Lee, Yong-Hee; Kartalov, Emil P; Scherer, Axel

    2010-11-08

    We propose a novel design of an all-dielectric optical antenna based on photonic-band-gap confinement. Specifically, we have engineered the photonic-crystal dipole mode to have broad spectral response (Q~70) and well-directed vertical-radiation by introducing a plane mirror below the cavity. Considerably large local electric-field intensity enhancement~4,500 is expected from the proposed design for a normally incident planewave. Furthermore, an analytic model developed based on coupled-mode theory predicts that the electric-field intensity enhancement can easily be over 100,000 by employing reasonably high-Q (~10,000) resonators.

  5. Narrow linewidth comb realized with a mode-locked fiber laser using an intra-cavity waveguide electro-optic modulator for high-speed control.

    PubMed

    Iwakuni, Kana; Inaba, Hajime; Nakajima, Yoshiaki; Kobayashi, Takumi; Hosaka, Kazumoto; Onae, Atsushi; Hong, Feng-Lei

    2012-06-18

    We have developed an optical frequency comb using a mode-locked fiber ring laser with an intra-cavity waveguide electro-optic modulator controlling the optical length in the laser cavity. The mode-locking is achieved with a simple ring configuration and a nonlinear polarization rotation mechanism. The beat note between the laser and a reference laser and the carrier envelope offset frequency of the comb were simultaneously phase locked with servo bandwidths of 1.3 MHz and 900 kHz, respectively. We observed an out-of-loop beat between two identical combs, and obtained a coherent δ-function peak with a signal to noise ratio of 70 dB/Hz.

  6. Stationary and traveling solitons via local dissipation in Bose-Einstein condensates in ring optical lattices

    NASA Astrophysics Data System (ADS)

    Campbell, Russell; Oppo, Gian-Luca

    2016-10-01

    A model of a Bose-Einstein condensate in a ring optical lattice with atomic dissipations applied at a stationary or at a moving location on the ring is presented. The localized dissipation is shown to generate and stabilize both stationary and traveling lattice solitons. Among many localized solutions, we have generated spatially stationary quasiperiodic lattice solitons and a family of traveling lattice solitons with two intensity peaks per potential well with no counterpart in the discrete case. Collisions between traveling and stationary lattice solitons as well as between two traveling lattice solitons display a critical dependence from the lattice depth. Stable counterpropagating solitons in ring lattices can find applications in gyroscope interferometers with ultracold gases.

  7. Itinerant-localized dual character of a strongly correlated superfluid Bose gas in an optical lattice

    SciTech Connect

    Ohashi, Y.; Kitaura, M.; Matsumoto, H.

    2006-03-15

    We investigate a strongly correlated Bose gas in an optical lattice. Extending the standard-basis operator method developed by Haley and Erdoes to a boson Hubbard model, we calculate excitation spectra in the superfluid phase, as well as in the Mott insulating phase, at T=0. In the Mott phase, the excitation spectrum has a finite energy gap, reflecting the localized character of atoms. In the superfluid phase, the excitation spectrum is shown to have an itinerant-localized dual structure, where the gapless Bogoliubov mode (which describes the itinerant character of superfluid atoms) and a band with a finite energy gap coexist. We also show that the rf-tunneling current measurement would give useful information about the duality of a strongly correlated superfluid Bose gas near the superfluid-insulator transition.

  8. Optical Switching of Nematic Liquid Crystal Film based on Localized Surface Plasmon Resonance

    NASA Astrophysics Data System (ADS)

    Quint, Makiko; Delgado, Silverio; Nuno, Zachary; Hirst, Linda; Ghosh, Sayantani

    2015-03-01

    We have demonstrated an all-optical technique to reversibly switch the spatial orientation of nematic liquid crystal molecules from homeotropic to planar in a few micron thick films. Our method leverages the highly localized electric fields that are generated in the near-field of a densely packed gold nanoparticle layer when the samples are excited by light resonant with the localized surface plasmon absorption. We present simulations and control measurements for off-resonance excitation, where the switching behavior is not observed. Using polarized microscopy and transmission measurements, we observe this switching over a temperature range starting several degrees below and up to the isotropic transition, and at on-resonance excitation power less than 10 μW. In addition, we controllably vary the in-plane directionality of the liquid crystal molecules in the planar state by altering the linear polarization of the incident excitation. This work is supported by NSF Grant No. DMR-1056860 and ECC-1227034.

  9. A fiber optic strain measurement and quench localization system for use in superconducting accelerator dipole magnets

    SciTech Connect

    van Oort, J.M.; Scanlan, R.M.; ten Kate, H.H.J.

    1994-10-17

    A novel fiber-optic measurement system for superconducting accelerator magnets is described. The principal component is an extrinsic Fabry-Perot Interferometer to determine localized strain and stress in coil windings. The system can be used either as a sensitive relative strain measurement system or as an absolute strain detector. Combined, one can monitor the mechanical behaviour of the magnet system over time during construction, long time storage and operation. The sensing mechanism is described, together with various tests in laboratory environments. The test results of a multichannel test matrix to be incorporated first in the dummy coils and then in the final version of a 13T Nb{sub 3}Sn accelerator dipole magnet are presented. Finally, the possible use of this system as a quench localization system is proposed.

  10. A synchronous fiber optic ring local area network for multigigabit/s mixed-traffic communication

    NASA Technical Reports Server (NTRS)

    Bergman, L. A.; Eng, S. T.

    1985-01-01

    A synchronous-ring fiber optic local area network is reported that facilitates the simultaneous transmission of packet and real-time traffic at gigabit/s rates, minimizes the amount of high-speed logic, and simplifies the user interface to the network. The novelty of the technique is based on (1) suspending in transit around the ring's circumference an integral number of data frames and (2) achieving this condition by skewing the frame clock rate a small amount. Rather than use the whole data frame as one packet destined to a specific user, many individual channels are instead time-multiplexed into the data frame. This technique only becomes feasible for local networks as data rates approach the Gbit/s range. This departure from other synchronous rings results in several advantages both in terms of system performance and hardware simplicity.

  11. A Sagnac-Michelson fibre optic interferometer: Signal processing for disturbance localization

    NASA Astrophysics Data System (ADS)

    Kondrat, M.; Szustakowski, M.; Pałka, N.; Ciurapiński, W.; Życzkowski, M.

    2007-09-01

    We present numerical and experimental results on a new generation fibre optic perimeter sensor based on a Sagnac and Michelson interferometers configuration. In particular, an original signal processing scheme is presented. The sensor can detect a potential intruder and determine its position along a protected zone. We propose a localization method that offers the inherent properties of both interferometers. After demodulation of the signals from both interferometers, the obtained amplitude characteristic of the Sagnac interferometer depends on a position of a disturbance along the interferometer, while amplitude characteristic of the Michelson interferometer does not depend on this position. So, quotient of both demodulated characteristics makes it possible to localize the disturbance. During investigations of a laboratory model of the sensor, it was possible to detect the position of the disturbance with a resolution of about 40 m along the 6-km-long sensor.

  12. Enhanced-locality fiber-optic two-photon-fluorescence live-brain interrogation

    SciTech Connect

    Fedotov, I. V.; Doronina-Amitonova, L. V.; Sidorov-Biryukov, D. A.; Fedotov, A. B.; Anokhin, K. V.; Kilin, S. Ya.; Sakoda, K.; Zheltikov, A. M.

    2014-02-24

    Two-photon excitation is shown to substantially enhance the locality of fiber-based optical interrogation of strongly scattering biotissues. In our experiments, a high-numerical-aperture, large-core-are fiber probe is used to deliver the 200-fs output of a 100-MHz mode-locked ytterbium fiber laser to samples of live mouse brain, induce two-photon fluorescence of nitrogen–vacancy centers in diamond markers in brain sample. Fiber probes with a high numerical aperture and a large core area are shown to enable locality enhancement in fiber-laser–fiber-probe two-photon brain excitation and interrogation without sacrificing the efficiency of fluorescence response collection.

  13. Technique of fiber optics used to localize epidural space in piglets.

    PubMed

    Ting, Chien-Kun; Chang, Yin

    2010-05-24

    Technique of loss-of-resistance in epidural block is commonly used for epidural anesthesia in humans with approximately 90% successful rate. However, it may be one of the most difficult procedures to learn for anesthesia residents in hospital. A two-wavelength (650 nm and 532 nm) fiber-optical method has been developed according to the characteristic reflectance spectra of ex-vivo porcine tissues, which are associated with the needle insertion to localize the epidural space (ES). In an in-vivo study in piglets showed that the reflected lights from ES and its surrounding tissue ligamentum flavum (LF) are highly distinguishable. This indicates that this technique has potential to localize the ES on the spot without the help of additional guiding assistance.

  14. Taking local optics outreach abroad for IYL 2015: administrative and logistical challenges and strategies

    NASA Astrophysics Data System (ADS)

    Wong, Nicholas H. L.; Posner, Matthew T.; Mittal, Vinita; Gray, David R.; John, Pearl V.

    2016-09-01

    The Lightwave Roadshow is an outreach program run by research students at the University of Southampton, UK, that seeks to educate and inspire young students with optics, through conducting workshops in local schools and exhibiting at local and regional educational fairs. Adopting a hands-on philosophy enabled by an extensive collection of experimental optical demonstrations, Lightwave aims to promote scientific interest and indirectly address the global STEM skills shortage. While Lightwave has become a well-established program in local schools since its inception in 1998, 2015 included an unprecedented number of overseas activities. Inspired by the In- ternational Year of Light and Light-based Technologies (IYL 2015), Lightwave organized a school workshop in a foreign country (Singapore) as well as exhibited at major events, including the IYL 2015 opening ceremony in France, which marked the first time that the roadshow used UK school students to deliver outreach activities beyond the UK. These recent successful overseas projects have encouraged the outreach team to continue expand- ing the reach of the roadshow internationally. Of particular note is the involvement of Lightwave at academic conferences, where experiences and best practices can be shared among outreach ambassadors from different programs, student chapters, universities, and organizations. This paper provides a review of these activities, and identifies the administrative and practical challenges of bringing a local outreach program abroad and some strategies to overcome them. We also outline our travel suite of experimental demonstration kit, a portable selection from our main equipment inventory. This won the recent OSA `IYL-To-Go' student competition.

  15. Fast localization of the optic disc using projection of image features.

    PubMed

    Mahfouz, Ahmed E; Fahmy, Ahmed S

    2010-12-01

    Optic Disc (OD) localization is an important pre-processing step that significantly simplifies subsequent segmentation of the OD and other retinal structures. Current OD localization techniques suffer from impractically-high computation times (few minutes per image). In this work, we present a fast technique that requires less than a second to localize the OD. The technique is based upon obtaining two projections of certain image features that encode the x- and y- coordinates of the OD. The resulting 1-D projections are then searched to determine the location of the OD. This avoids searching the 2-D image space and, thus, enhances the speed of the OD localization process. Image features such as retinal vessels orientation and the OD brightness are used in the current method. Four publicly-available databases, including STARE and DRIVE, are used to evaluate the proposed technique. The OD was successfully located in 330 images out of 340 images (97%) with an average computation time of 0.65 s.

  16. Design of a Base Station for MEMS CCR Localization in an Optical Sensor Network

    PubMed Central

    Park, Chan Gook; Jeon, Hyun Cheol; Kim, Hyoun Jin; Kim, Jae Yoon

    2014-01-01

    This paper introduces a design and implementation of a base station, capable of positioning sensor nodes using an optical scheme. The base station consists of a pulse laser module, optical detectors and beam splitter, which are mounted on a rotation-stage, and a Time to Digital Converter (TDC). The optical pulse signal transmitted to the sensor node with a Corner Cube Retro-reflector (CCR) is reflected to the base station, and the Time of Flight (ToF) data can be obtained from the two detectors. With the angle and flight time data, the position of the sensor node can be calculated. The performance of the system is evaluated by using a commercial CCR. The sensor nodes are placed at different angles from the base station and scanned using the laser. We analyze the node position error caused by the rotation and propose error compensation methods, namely the outlier sample exception and decreasing the confidence factor steadily using the recursive least square (RLS) methods. Based on the commercial CCR results, the MEMS CCR is also tested to demonstrate the compatibility between the base station and the proposed methods. The result shows that the localization performance of the system can be enhanced with the proposed compensation method using the MEMS CCR. PMID:24815681

  17. Design of a base station for MEMS CCR localization in an optical sensor network.

    PubMed

    Park, Chan Gook; Jeon, Hyun Cheol; Kim, Hyoun Jin; Kim, Jae Yoon

    2014-05-08

    This paper introduces a design and implementation of a base station, capable of positioning sensor nodes using an optical scheme. The base station consists of a pulse laser module, optical detectors and beam splitter, which are mounted on a rotation-stage, and a Time to Digital Converter (TDC). The optical pulse signal transmitted to the sensor node with a Corner Cube Retro-reflector (CCR) is reflected to the base station, and the Time of Flight (ToF) data can be obtained from the two detectors. With the angle and flight time data, the position of the sensor node can be calculated. The performance of the system is evaluated by using a commercial CCR. The sensor nodes are placed at different angles from the base station and scanned using the laser. We analyze the node position error caused by the rotation and propose error compensation methods, namely the outlier sample exception and decreasing the confidence factor steadily using the recursive least square (RLS) methods. Based on the commercial CCR results, the MEMS CCR is also tested to demonstrate the compatibility between the base station and the proposed methods. The result shows that the localization performance of the system can be enhanced with the proposed compensation method using the MEMS CCR.

  18. A study of topologies and protocols for fiber optic local area network

    NASA Technical Reports Server (NTRS)

    Yeh, C.; Gerla, M.; Rodrigues, P.

    1985-01-01

    The emergence of new applications requiring high data traffic necessitates the development of high speed local area networks. Optical fiber is selected as the transmission medium due to its inherent advantages over other possible media and the dual optical bus architecture is shown to be the most suitable topology. Asynchronous access protocols, including token, random, hybrid random/token, and virtual token schemes, are developed and analyzed. Exact expressions for insertion delay and utilization at light and heavy load are derived, and intermediate load behavior is investigated by simulation. A new tokenless adaptive scheme whose control depends only on the detection of activity on the channel is shown to outperform round-robin schemes under uneven loads and multipacket traffic and to perform optimally at light load. An approximate solution to the queueing delay for an oscillating polling scheme under chaining is obtained and results are compared with simulation. Solutions to the problem of building systems with a large number of stations are presented, including maximization of the number of optical couplers, and the use of passive star/bus topologies, bridges and gateways.

  19. Interaction of electrons with optical phonons localized in a quantum well

    SciTech Connect

    Pozela, J. Pozela, K.; Juciene, V.; Suziedelis, A.; Shkolnik, A. S.; Mikhrin, S. S.; Mikhrin, V. S.

    2009-12-15

    The scattering rate of electrons in a quantum well by localized polar optical and interface phonons is considered. The dependence of the force of the electron-phonon interaction on the frequency of optical phonons in materials of the heterostructure forming the electron and phonon quantum wells is determined. It is shown that, by varying the composition of semiconductors forming the quantum well and its barriers, it is possible to vary the scattering rates of electrons by a factor of several times. The scattering rates of electrons by polar optical phonons are calculated depending on the fractions In{sub x} and In{sub y} in the composition of semiconductors forming the In{sub x}Al{sub 1-x}As/In{sub y}Ga{sub 1-y}As quantum wells. Dependences of the mobility and saturated drift velocity of electrons in high electric fields and quantum wells In{sub y}Ga{sub 1-y}As on the composition of the In{sub x}Al{sub 1-x}As barriers introduced into quantum wells are determined experimentally. The electron mobility increases, while the saturated drift velocity decreases as the fraction of In{sub x} in the composition of barriers is increased.

  20. 1 Hz linewidth Ti:sapphire laser as local oscillator for (40)Ca(+) optical clocks.

    PubMed

    Bian, Wu; Huang, Yao; Guan, Hua; Liu, Peiliang; Ma, Longsheng; Gao, Kelin

    2016-06-01

    A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10(-15) frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled (40)Ca(+) ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10(-14)) is observed. This laser is also used as the local oscillator for the comparison experiment of two (40)Ca(+) ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results.

  1. 1 Hz linewidth Ti:sapphire laser as local oscillator for 40Ca+ optical clocks

    NASA Astrophysics Data System (ADS)

    Bian, Wu; Huang, Yao; Guan, Hua; Liu, Peiliang; Ma, Longsheng; Gao, Kelin

    2016-06-01

    A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10-15 frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled 40Ca+ ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10-14) is observed. This laser is also used as the local oscillator for the comparison experiment of two 40Ca+ ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results.

  2. Broadband optical mammography instrument for depth-resolved imaging and local dynamic measurements

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, Nishanth; Kainerstorfer, Jana M.; Sassaroli, Angelo; Anderson, Pamela G.; Fantini, Sergio

    2016-02-01

    We present a continuous-wave instrument for non-invasive diffuse optical imaging of the breast in a parallel-plate transmission geometry. The instrument measures continuous spectra in the wavelength range 650-1000 nm, with an intensity noise level <1.5% and a spatial sampling rate of 5 points/cm in the x- and y-directions. We collect the optical transmission at four locations, one collinear and three offset with respect to the illumination optical fiber, to recover the depth of optical inhomogeneities in the tissue. We imaged a tissue-like, breast shaped, silicone phantom (6 cm thick) with two embedded absorbing structures: a black circle (1.7 cm in diameter) and a black stripe (3 mm wide), designed to mimic a tumor and a blood vessel, respectively. The use of a spatially multiplexed detection scheme allows for the generation of on-axis and off-axis projection images simultaneously, as opposed to requiring multiple scans, thus decreasing scan-time and motion artifacts. This technique localizes detected inhomogeneities in 3D and accurately assigns their depth to within 1 mm in the ideal conditions of otherwise homogeneous tissue-like phantoms. We also measured induced hemodynamic changes in the breast of a healthy human subject at a selected location (no scanning). We applied a cyclic, arterial blood pressure perturbation by alternating inflation (to a pressure of 200 mmHg) and deflation of a pneumatic cuff around the subject's thigh at a frequency of 0.05 Hz, and measured oscillations with amplitudes up to 1 μM and 0.2 μM in the tissue concentrations of oxyhemoglobin and deoxyhemoglobin, respectively. These hemodynamic oscillations provide information about the vascular structure and functional integrity in tissue, and may be used to assess healthy or abnormal perfusion in a clinical setting.

  3. Fast left ventricle tracking in CMR images using localized anatomical affine optical flow

    NASA Astrophysics Data System (ADS)

    Queirós, Sandro; Vilaça, João. L.; Morais, Pedro; Fonseca, Jaime C.; D'hooge, Jan; Barbosa, Daniel

    2015-03-01

    In daily cardiology practice, assessment of left ventricular (LV) global function using non-invasive imaging remains central for the diagnosis and follow-up of patients with cardiovascular diseases. Despite the different methodologies currently accessible for LV segmentation in cardiac magnetic resonance (CMR) images, a fast and complete LV delineation is still limitedly available for routine use. In this study, a localized anatomically constrained affine optical flow method is proposed for fast and automatic LV tracking throughout the full cardiac cycle in short-axis CMR images. Starting from an automatically delineated LV in the end-diastolic frame, the endocardial and epicardial boundaries are propagated by estimating the motion between adjacent cardiac phases using optical flow. In order to reduce the computational burden, the motion is only estimated in an anatomical region of interest around the tracked boundaries and subsequently integrated into a local affine motion model. Such localized estimation enables to capture complex motion patterns, while still being spatially consistent. The method was validated on 45 CMR datasets taken from the 2009 MICCAI LV segmentation challenge. The proposed approach proved to be robust and efficient, with an average distance error of 2.1 mm and a correlation with reference ejection fraction of 0.98 (1.9 +/- 4.5%). Moreover, it showed to be fast, taking 5 seconds for the tracking of a full 4D dataset (30 ms per image). Overall, a novel fast, robust and accurate LV tracking methodology was proposed, enabling accurate assessment of relevant global function cardiac indices, such as volumes and ejection fraction

  4. Dynamic localization in optical and Zeeman lattices in the presence of spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Kartashov, Yaroslav V.; Konotop, Vladimir V.; Zezyulin, Dmitry A.; Torner, Lluis

    2016-12-01

    The dynamic localization of a two-level atom in a periodic potential under the action of spin-orbit coupling and a weak harmonically varying linear force is studied. We consider optical and Zeeman potentials that are either in phase or out of phase in two spinor components, respectively. The expectation value for the position of the atom after one oscillation period of the linear force is recovered in authentic resonances or in pseudoresonances. The frequencies of the linear force corresponding to authentic resonances are determined by the band structure of the periodic potential and are affected by the spin-orbit coupling. The width or dispersion of the wave packet in authentic resonances is usually minimal. The frequencies corresponding to pseudoresonances do not depend on the type of potential and on the strength of the spin-orbit coupling, while the evolution of excitations at the corresponding frequencies is usually accompanied by significant dispersion. Pseudoresonances are determined by the initial phase of the linear force and by the quasimomentum of the wave packet. Due to the spinor nature of the system, the motion of the atom is accompanied by periodic, but not harmonic, spin oscillations. Under the action of spin-orbit coupling the oscillations of the wave packet can be nearly completely suppressed in optical lattices. Dynamic localization in Zeeman lattices is characterized by doubling of the resonant oscillation periods due to band crossing at the boundary of the Brillouin zone. We also show that higher harmonics in the Fourier expansion of the energy band lead to effective dispersion, which can be strong enough to prevent dynamic localization of the Bloch wave packet.

  5. Experimental demonstration of a novel indoor optical wireless localization system for high-speed personal area networks.

    PubMed

    Wang, Ke; Nirmalathas, Ampalavanapillai; Lim, Christina; Skafidas, Efstratios

    2015-04-01

    In this Letter, we propose a novel indoor localization system based on optical wireless technology. By using the same architecture as the high-speed full-duplex indoor optical wireless communication system, the "search and scan" process, and the added transmission power and beam footprint information in the "search and scan" message, indoor localization functionality is achieved. Proof-of-concept experiments are carried out, and results show that an average error of <15  cm is achieved with a localization beam size of 1 m. In addition, the major localization-accuracy-limiting factors are analyzed both theoretically and experimentally. When incorporated with the optical wireless communication system, high-speed indoor wireless personal area networks can be achieved.

  6. Local delivery of fluorescent dye for fiber-optics confocal microscopy of the living heart

    PubMed Central

    Huang, Chao; Kaza, Aditya K.; Hitchcock, Robert W.; Sachse, Frank B.

    2014-01-01

    Fiber-optics confocal microscopy (FCM) is an emerging imaging technology with various applications in basic research and clinical diagnosis. FCM allows for real-time in situ microscopy of tissue at sub-cellular scale. Recently FCM has been investigated for cardiac imaging, in particular, for discrimination of cardiac tissue during pediatric open-heart surgery. FCM relies on fluorescent dyes. The current clinical approach of dye delivery is based on systemic injection, which is associated with high dye consumption, and adverse clinical events. In this study, we investigated approaches for local dye delivery during FCM imaging based on dye carriers attached to the imaging probe. Using three-dimensional confocal microscopy, automated bench tests, and FCM imaging we quantitatively characterized dye release of carriers composed of open-pore foam only and foam loaded with agarose hydrogel. In addition, we compared local dye delivery with a model of systemic dye delivery in the isolated perfused rodent heart. We measured the signal-to-noise ratio (SNR) of images acquired in various regions of the heart. Our evaluations showed that foam-agarose dye carriers exhibited a prolonged dye release vs. foam-only carriers. Foam-agarose dye carriers allowed reliable imaging of 5–9 lines, which is comparable to 4–8 min of continuous dye release. Our study in the living heart revealed that the SNR of FCM images using local and systemic dye delivery is not different. However, we observed differences in the imaged tissue microstructure with the two approaches. Structural features characteristic of microvasculature were solely observed for systemic dye delivery. Our findings suggest that local dye delivery approach for FCM imaging constitutes an important alternative to systemic dye delivery. We suggest that the approach for local dye delivery will facilitate clinical translation of FCM, for instance, for FCM imaging during pediatric heart surgery. PMID:25309455

  7. Local delivery of fluorescent dye for fiber-optics confocal microscopy of the living heart.

    PubMed

    Huang, Chao; Kaza, Aditya K; Hitchcock, Robert W; Sachse, Frank B

    2014-01-01

    Fiber-optics confocal microscopy (FCM) is an emerging imaging technology with various applications in basic research and clinical diagnosis. FCM allows for real-time in situ microscopy of tissue at sub-cellular scale. Recently FCM has been investigated for cardiac imaging, in particular, for discrimination of cardiac tissue during pediatric open-heart surgery. FCM relies on fluorescent dyes. The current clinical approach of dye delivery is based on systemic injection, which is associated with high dye consumption, and adverse clinical events. In this study, we investigated approaches for local dye delivery during FCM imaging based on dye carriers attached to the imaging probe. Using three-dimensional confocal microscopy, automated bench tests, and FCM imaging we quantitatively characterized dye release of carriers composed of open-pore foam only and foam loaded with agarose hydrogel. In addition, we compared local dye delivery with a model of systemic dye delivery in the isolated perfused rodent heart. We measured the signal-to-noise ratio (SNR) of images acquired in various regions of the heart. Our evaluations showed that foam-agarose dye carriers exhibited a prolonged dye release vs. foam-only carriers. Foam-agarose dye carriers allowed reliable imaging of 5-9 lines, which is comparable to 4-8 min of continuous dye release. Our study in the living heart revealed that the SNR of FCM images using local and systemic dye delivery is not different. However, we observed differences in the imaged tissue microstructure with the two approaches. Structural features characteristic of microvasculature were solely observed for systemic dye delivery. Our findings suggest that local dye delivery approach for FCM imaging constitutes an important alternative to systemic dye delivery. We suggest that the approach for local dye delivery will facilitate clinical translation of FCM, for instance, for FCM imaging during pediatric heart surgery.

  8. Doppler optical coherence tomography imaging of local fluid flow and shear stress within microporous scaffolds

    NASA Astrophysics Data System (ADS)

    Jia, Yali; Bagnaninchi, Pierre O.; Yang, Ying; Haj, Alicia El; Hinds, Monica T.; Kirkpatrick, Sean J.; Wang, Ruikang K.

    2009-05-01

    Establishing a relationship between perfusion rate and fluid shear stress in a 3D cell culture environment is an ongoing and challenging task faced by tissue engineers. We explore Doppler optical coherence tomography (DOCT) as a potential imaging tool for in situ monitoring of local fluid flow profiles inside porous chitosan scaffolds. From the measured fluid flow profiles, the fluid shear stresses are evaluated. We examine the localized fluid flow and shear stress within low- and high-porosity chitosan scaffolds, which are subjected to a constant input flow rate of 0.5 ml.min-1. The DOCT results show that the behavior of the fluid flow and shear stress in micropores is strongly dependent on the micropore interconnectivity, porosity, and size of pores within the scaffold. For low-porosity and high-porosity chitosan scaffolds examined, the measured local fluid flow and shear stress varied from micropore to micropore, with a mean shear stress of 0.49+/-0.3 dyn.cm-2 and 0.38+/-0.2 dyn.cm-2, respectively. In addition, we show that the scaffold's porosity and interconnectivity can be quantified by combining analyses of the 3D structural and flow images obtained from DOCT.

  9. Nonlinear localized modes in dipolar Bose-Einstein condensates in optical lattices

    SciTech Connect

    Rojas-Rojas, S.; Vicencio, R. A.; Molina, M. I.; Abdullaev, F. Kh.

    2011-09-15

    Modulational instability and discrete matter wave solitons in dipolar BECs, loaded into a deep optical lattice, are investigated analytically and numerically. The process of modulational instability of nonlinear plane matter waves in a dipolar nonlinear lattice is studied and the regions of instability are established. The existence and stability of bulk discrete solitons are analyzed analytically and confirmed by numerical simulations. In marked contrast with the usual discrete nonlinear Schroedinger behavior (no dipolar interactions), we found a region where the two fundamental modes are simultaneously unstable, allowing enhanced mobility across the lattice for large norm values. To study the existence and properties of surface discrete solitons, an analysis of the dimer configuration is performed. The properties of symmetric and antisymmetric modes including stability diagrams and bifurcations are investigated in closed form. For the case of a bulk medium, properties of fundamental on-site and intersite localized modes are analyzed. On-site and intersite surface localized modes are studied, and we find that they do not exist when nonlocal interactions predominate with respect to local ones.

  10. Non-local effects in dual-probe-sideband Brillouin optical time domain analysis.

    PubMed

    Dominguez-Lopez, Alejandro; Angulo-Vinuesa, Xabier; Lopez-Gil, Alexia; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

    2015-04-20

    According to recent models, non-local effects in dual-probe-sideband Brillouin Optical Time Domain Analysis (BOTDA) systems should be essentially negligible whenever the probe power is below the Stimulated Brillouin Scattering (SBS) threshold. This paper shows that actually there appear non-local effects in this type of systems before the SBS threshold. To explain these effects it is necessary to take into account a full spectral description of the SBS process. The pump pulse experiences a frequency-dependent spectral deformation that affects the readout process differently in the gain and loss configurations. This paper provides a simple analytical model of this phenomenon, which is validated against compelling experimental data, showing good agreement. The main conclusion of our study is that the measurements in gain configuration are more robust to this non-local effect than the loss configuration. Experimental and theoretical results show that, for a total probe wave power of ~1 mW (500 μW on each sideband), there is an up-shifting of ~1 MHz in the Brillouin Frequency Shift (BFS) retrieved from the Brillouin Loss Spectrum, whereas the BFS extracted from the measured Brillouin Gain Spectrum is up-shifted only ~0.6 MHz. These results are of particular interest for manufacturers of long-range BOTDA systems.

  11. Manipulation of the coherent spatial and angular shifts of Goos-Hänchen effect to realize the digital optical switch in silicon-on-insulator waveguide corner

    NASA Astrophysics Data System (ADS)

    Sun, DeGui

    2016-11-01

    In this work, based on the quantum process of the Goos-Hänchen (GH) spatial shift, a quantum process of the GH angular shift is also theoretically investigated. Then, the coherence between spatial and angular shifts in the GH effect is discovered and developed to manipulate the final total displacement for a digital optical switch. It is found that a waveguide corner structure always makes the reflected guide-mode have a GH angular shift in the minus direction when the incident beam is in the Brewster angle vicinity, while it always makes the spatial shift in the plus direction. Meanwhile, the coherence of these two GH shifts has an interesting distribution with the incident angle, and only in the common linear response area to the incident angle, the two GH shifts are mutually enhancing, and then a mini refractive index modulation of the guided-mode at the reflecting interface can create a great stable jump of reflected beam displacement at an eigenstate under the GH effect. As a result, on the 220 nm CMOS-compatible silicon-on-insulator waveguide platform, with a tapered multimode interference (MMI) waveguide, a 5 × 1018cm-3 concentration variation of free carriers can create an absolute digital total displacement of 8-25 μm of the reflected beam on the MMI waveguide output end, leading to a 1 × 5 scale digital optical switching function.

  12. Itinerant vs local moment approaches to Fe-pnictides: insight from optical spectroscopy study

    NASA Astrophysics Data System (ADS)

    Wang, Nan Lin

    2010-03-01

    I present optical spectroscopy investigations on single crystal samples of 4 different Fe-based systems: 1111, 122, 111, and 11. For all FeAs-based parent compounds we observed common spectral features: partial energy-gaps formation along with a removal of a large part of free-carrier spectral weight and a steep reduction of the carrier scattering rate in the magnetic ordered state. However, the 11-type FeTe behaves very differently. No energy gap opens in the magnetic ordered state. We proposed that both the itinerancy and local moment interactions of Fe 3d electrons are present, but they contribute differently to the magnetic instabilities in different systems. Work done with W. Z. Hu, G. Li, Z. G. Chen, J. Dong, P. Zheng, G. F. Chen, and J. L. Luo.

  13. Decoherence dynamics of interacting qubits coupled to a bath of local optical phonons

    NASA Astrophysics Data System (ADS)

    Lone, Muzaffar Qadir; Yarlagadda, S.

    2016-04-01

    We study decoherence in an interacting qubit system described by infinite range Heisenberg model (IRHM) in a situation where the system is coupled to a bath of local optical phonons. Using perturbation theory in polaron frame of reference, we derive an effective Hamiltonian that is valid in the regime of strong spin-phonon coupling under nonadiabatic conditions. It is shown that the effective Hamiltonian commutes with the IRHM upto leading orders of perturbation and thus has the same eigenstates as the IRHM. Using a quantum master equation with Markovian approximation of dynamical evolution, we show that the off-diagonal elements of the density matrix do not decay in the energy eigen basis of IRHM.

  14. Full optical characterization of autostereoscopic 3D displays using local viewing angle and imaging measurements

    NASA Astrophysics Data System (ADS)

    Boher, Pierre; Leroux, Thierry; Bignon, Thibault; Collomb-Patton, Véronique

    2012-03-01

    Two commercial auto-stereoscopic 3D displays are characterized a using Fourier optics viewing angle system and an imaging video-luminance-meter. One display has a fixed emissive configuration and the other adapts its emission to the observer position using head tracking. For a fixed emissive condition, three viewing angle measurements are performed at three positions (center, right and left). Qualified monocular and binocular viewing spaces in front of the display are deduced as well as the best working distance. The imaging system is then positioned at this working distance and crosstalk homogeneity on the entire surface of the display is measured. We show that the crosstalk is generally not optimized on all the surface of the display. Display aspect simulation using viewing angle measurements allows understanding better the origin of those crosstalk variations. Local imperfections like scratches and marks generally increase drastically the crosstalk, demonstrating that cleanliness requirements for this type of display are quite critical.

  15. Local aerosol concentrations and optical characteristics influenced by the Indonesian forest fire

    NASA Astrophysics Data System (ADS)

    Ru, Jianfei; Minomura, Mitsuo; Kuze, Hiroaki; Takeuchi, Nobuo

    1998-08-01

    Indonesian forest fire took place on Kalimantan and Sumatera islands in 1997 and continuously influenced the atmospheric conditions of South-East Asia nearly throughout the last half of that year. The color composed images of visible, near IR and IR channels from NOAA AVHRR daily data, arbitrarily assigned to red, green and blue respectively, were synthesized for distinguishing the smoke area. The data of three periods, the beginning, mid, and ending parts of the fire, were collected and analyzed in order to show the variation of atmosphere with the development of fire. A retrieval algorithm was established by use of Mie theory calculation and the radiative transfer codes. Local aerosol concentrations and properties over ocean parts between the two islands were derived. It is found that the aerosol optical thickness increased in accordance with the exacerbation of the fires. The changes of angstrom exponents show that smaller particle amounts were raised by the effects of burning.

  16. Multi-wavelength coherent transmission using an optical frequency comb as a local oscillator.

    PubMed

    Kemal, Juned N; Pfeifle, Joerg; Marin-Palomo, Pablo; Pascual, M Deseada Gutierrez; Wolf, Stefan; Smyth, Frank; Freude, Wolfgang; Koos, Christian

    2016-10-31

    Steadily increasing data rates of optical interfaces require spectrally efficient coherent transmission using higher-order modulation formats in combination with scalable wavelength-division multiplexing (WDM) schemes. At the transmitter, optical frequency combs (OFC) lend themselves to particularly precise multi-wavelength sources for WDM transmission. In this work we demonstrate that these advantages can also be leveraged at the receiver by using an OFC as a highly scalable multi-wavelength local oscillator (LO) for coherent detection. In our experiments, we use a pair of OFC that rely on gain switching of injection-locked semiconductor lasers both for WDM transmission and intradyne reception. We synchronize the center frequency and the free spectral range of the receiver comb to the transmitter, keeping the intradyne frequencies for all data channels below 15 MHz. Using 13 WDM channels, we transmit an aggregate line rate (net data rate) of 1.104 Tbit/s (1.032 Tbit/s) over a 10 km long standard single mode fiber at a spectral efficiency of 5.16 bit/s/Hz. To the best of our knowledge, this is the first demonstration of coherent WDM transmission using synchronized frequency combs as light source at the transmitter and as multi-wavelength LO at the receiver.

  17. A Fibrous Localized Drug Delivery Platform with NIR-Triggered and Optically Monitored Drug Release.

    PubMed

    Liu, Heng; Fu, Yike; Li, Yangyang; Ren, Zhaohui; Li, Xiang; Han, Gaorong; Mao, Chuanbin

    2016-09-06

    Implantable localized drug delivery systems (LDDSs) with intelligent functionalities have emerged as a powerful chemotherapeutic platform in curing cancer. Developing LDDSs with rationally controlled drug release and real-time monitoring functionalities holds promise for personalized therapeutic protocols but suffers daunting challenges. To overcome such challenges, a series of porous Yb(3+)/Er(3+) codoped CaTiO3 (CTO:Yb,Er) nanofibers, with specifically designed surface functionalization, were synthesized for doxorubicin (DOX) delivery. The content of DOX released could be optically monitored by increase in the intensity ratio of green to red emission (I550/I660) of upconversion photoluminescent nanofibers under 980 nm near-infrared (NIR) excitation owing to the fluorescence resonance energy transfer (FRET) effect between DOX molecules and the nanofibers. More importantly, the 808 nm NIR irradiation enabled markedly accelerated DOX release, confirming representative NIR-triggered drug release properties. In consequence, such CTO:Yb,Er nanofibers presented significantly enhanced in vitro anticancer efficacy under NIR irradiation. This study has thus inspired another promising fibrous LDDS platform with NIR-triggered and optics-monitored DOX releasing for personalized tumor chemotherapy.

  18. A Fibrous Localized Drug Delivery Platform with NIR-Triggered and Optically Monitored Drug Release

    PubMed Central

    Liu, Heng; Fu, Yike; Li, Yangyang; Ren, Zhaohui; Li, Xiang; Han, Gaorong; Mao, Chuanbin

    2016-01-01

    Implantable localized drug delivery systems (LDDSs) with intelligent functionalities have emerged as a powerful chemotherapeutic platform in curing cancer. Developing LDDSs with rationally controlled drug release and real-time monitoring functionalities holds promise for personalized therapeutic protocols but suffers daunting challenges. To overcome such challenges, a series of porous Yb3+/Er3+ codoped CaTiO3 (CTO:Yb,Er) nanofibers, with specifically designed surface functionalization, were synthesized for doxorubicin (DOX) delivery. The content of DOX released could be optically monitored by increase in the intensity ratio of green to red emission (I550/I660) of upconversion photoluminescent nanofibers under 980 nm near-infrared (NIR) excitation owing to the fluorescence resonance energy transfer (FRET) effect between DOX molecules and the nanofibers. More importantly, the 808 nm NIR irradiation enabled markedly accelerated DOX release, confirming representative NIR-triggered drug release properties. In consequence, such CTO:Yb,Er nanofibers presented significantly enhanced in vitro anticancer efficacy under NIR irradiation. This study has thus inspired another promising fibrous LDDS platform with NIR-triggered and optics-monitored DOX releasing for personalized tumor chemotherapy. PMID:27557281

  19. Local structure and optical absorption characteristic investigation on Fe doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Tian-Xing; Feng, Ya-Juan; Huang, Jun-Heng; He, Jin-Fu; Liu, Qing-Hua; Pan, Zhi-Yun; Wu, Zi-Yu

    2015-02-01

    The local structures and optical absorption characteristics of Fe doped TiO2 nanoparticles synthesized by the sol-gel method were characterized by X-ray diffraction (XRD), X-ray absorption fine structure spectroscopy (XAFS) and ultraviolet-visible absorption spectroscopy (UV-Vis). XRD patterns show that all Fe-doped TiO2 samples have the characteristic anatase structure. Accurate Fe and Ti K-edge EXAFS analysis further reveal that all Fe atoms replace Ti atoms in the anatase lattice. The analysis of UV-Vis data shows a red shift to the visible range. According to the above results, we claim that substitutional Fe atoms lead to the formation of structural defects and new intermediate energy levels appear, narrowing the band gap and extending the optical absorption edge towards the visible region. Supported by National Basic Research Program of China (2012CB825801), Science Fund for Creative Research Groups of NSFC (11321503), National Natural Science Foundation of China (11321503, 11179004) and Guangdong Natural Science Foundation (S2011040003985)

  20. Protection Switching and Local Area Network Emulation in Passive Optical Networks

    NASA Astrophysics Data System (ADS)

    Nadarajah, Nishaanthan; Wong, Elaine; Attygalle, Manik; Nirmalathas, Ampalavanapillai Thas

    2006-05-01

    This paper proposes and experimentally demonstrates an automatic-protection-switching (APS) mechanism against distribution fiber breaks in passive optical networks (PONs). The protection of optical-network units (ONUs) that are located at the customer premises is carried out by monitoring the distribution fiber using the traffic that is transported among the customers in the PON. This configuration emulates a local area network (LAN) over the existing PON while facilitating the switching of signal transmissions to a predetermined protection path in an event of a distribution fiber break. As failure detection and APS are performed independently by each ONU in a distributed manner, the processing complexities and delays are reduced at the central office (CO). The restoration of the traffic transported between the CO and an ONU in the event of the distribution fiber break is performed by interconnecting adjacent ONUs and carrying out signal transmissions via an independent but interconnected ONU. Such a protection mechanism enables multiple adjacent ONUs to be simultaneously protected by a single ONU utilizing its maximum available bandwidth. This paper experimentally verifies the feasibility of the proposed protection mechanism in conjunction with two different LAN-emulation schemes with a 1.25-Gb/s upstream baseband transmission to the CO and a 155-Mb/s LAN data transmission on a radio-frequency carrier. The experimental results obtained from both schemes are compared, and the power budgets are calculated to analyze the scalability of each scheme.

  1. Improved optical limiting performance of laser-ablation-generated metal nanoparticles due to silica-microsphere-induced local field enhancement.

    PubMed

    Du, Zheren; Chen, Lianwei; Kao, Tsung-Sheng; Wu, Mengxue; Hong, Minghui

    2015-01-01

    For practical application, optical limiting materials must exhibit a fast response and a low threshold in order to be used for the protection of the human eye and electro-optical sensors against intense light. Many nanomaterials have been found to exhibit optical limiting properties. Laser ablation offers the possibility of fabricating nanoparticles from a wide range of target materials. For practical use of these materials, their optical limiting performance, including optical limiting threshold and the ability to efficiently attenuate high intensity light, needs to be improved. In this paper, we fabricate nanoparticles of different metals by laser ablation in liquid. We study the optical nonlinear properties of the laser-generated nanoparticle dispersion. Silica microspheres are used to enhance the optical limiting performance of the nanoparticle dispersion. The change in the optical nonlinear properties of the laser-generated nanoparticle dispersion caused by silica microspheres is studied. It is found that the incident laser beam is locally focused by the microspheres, leading to an increased optical nonlinearity of the nanoparticle dispersion.

  2. Improving the light quantification of near infrared (NIR) diffused light optical tomography with ultrasound localization

    NASA Astrophysics Data System (ADS)

    Ardeshirpour, Yasaman

    According to the statistics published by the American Cancer Society, currently breast cancer is the second most common cancer after skin cancer and the second cause of cancer death after lung cancer in the female population. Diffuse optical tomography (DOT) using near-infrared (NIR) light, guided by ultrasound localization, has shown great promise in distinguishing benign from malignant breast tumors and in assessing the response of breast cancer to chemotherapy. Our ultrasound-guided DOT system is based on reflection geometry, with patients scanned in supine position using a hand-held probe. For patients with chest-wall located at a depth shallower than 1 to 2cm, as in about 10% of our clinical cases, the semi-infinite imaging medium is not a valid assumption and the chest-wall effect needs to be considered in the imaging reconstruction procedure. In this dissertation, co-registered ultrasound images were used to model the breast-tissue and chest-wall as a two-layer medium. The effect of the chest wall on breast lesion reconstruction was systematically investigated. The performance of the two-layer model-based reconstruction, using the Finite Element Method, was evaluated by simulation, phantom experiments and clinical studies. The results show that the two-layer model can improve the accuracy of estimated background optical properties, the reconstructed absorption map and the total hemoglobin concentration of the lesion. For patients' data affected by chest wall, the perturbation, which is the difference between measurements obtained at lesion and normal reference sites, may include the information of background mismatch between these two sites. Because the imaging reconstruction is based on the perturbation approach, the effect of this mismatch between the optical properties at the two sites on reconstructed optical absorption was studied and a guideline for imaging procedure was developed to reduce these effects during data capturing. To reduce the artifacts

  3. Bulk and Local Electron Transport and Optical Properties of Aluminum-doped Zinc Oxide

    NASA Astrophysics Data System (ADS)

    Likovich, Edward Michael

    ZnO is a promising transparent conducting oxide (TCO) because its components are naturally abundant and inexpensive; and ZnO can be synthesized by several methods as thin films and nanostructures. Doping ZnO with Al (to form what is called AZO) significantly increases electrical conductivity while retaining high optical transparency, making AZO ideal for use as transparent electrodes in optoelectronic devices. However, the electrical conductivity of AZO has not exceeded that of indium tin oxide (ITO), the most widely-utilized TCO. A systematic study of bulk and local electrical and optical properties of AZO is needed to improve conductivity while maintaining transparency. To this end, we conducted bulk magnetotransport measurements on AZO, which indicated that its electron mobility was significantly lower than that of single-crystal ZnO, primarily due to electron scattering at AZO grain boundaries. To further understand this detrimental effect, we directly probed these grain boundaries with a scanning tunneling microscope. These measurements are the first investigation of a broad spectrum of grain boundary traps in AZO, which include shallow states near the conduction band edge that may limit electron mobility, and deeper states that may deplete carriers. Because optical properties can affect transparency in devices, we characterized AZO through a combination of photoluminescence and scanning tunneling microscope cathodoluminescence (STM-CL). STM-CL, which probes only the surface, shows a dramatic narrowing of emission lines compared to bulk photoluminescence. We attribute this to different charge states of oxygen vacancies preferentially located near the surface. This observed difference is especially of interest in understanding transport across interfaces. Finally, we present one application of AZO: a monolayer quantum dot (QD) light-emitting device with AZO electrodes that uses atomic layer deposited insulating oxide to fill the interstices among QDs. This

  4. Theoretical evaluation of Brillouin dynamic grating length localized by optical correlation domain technique through reflection spectrum simulation

    NASA Astrophysics Data System (ADS)

    Kendy Yamashita, Rodrigo; Kishi, Masato; Hotate, Kazuo

    2017-04-01

    We derive formulae based on Fourier transformation to calculate the reflection spectrum of a Brillouin dynamic grating (BDG), which is localized along an optical fiber by an optical correlation domain technique. First, we calculate the typical reflection spectra of the BDG localized by the technique and confirm the validity of the formulae by showing coincidence with previous theoretical or experimental works. Next, we evaluate theoretically the spatial resolution in the BDG distributed measurement by the technique, through simulations considering different strained fiber lengths. It is confirmed theoretically, for the first time, that the resolution in the BDG measurement is worse than that for the Brillouin gain spectrum.

  5. Optical antenna of comb-shaped split ring architecture for increased field localization in NIR and MIR.

    PubMed

    Kilic, Veli Tayfun; Erturk, Vakur B; Demir, Hilmi Volkan

    2013-12-02

    We propose and demonstrate novel designs of optical antennas based on comb-shaped split ring architecture that display multi resonance field intensity enhancement spectrum. These nanoantennas achieve substantially increased field localization at longer wavelengths than that of a single or an array of dipoles with the same side length. With these optical antennas, localizing near infrared (NIR) and mid infrared (MIR) lights within a region of tens of nanometers at an intensity enhancement level of the order of thousands of magnitude can be accomplished.

  6. Successful product realization strategies

    NASA Technical Reports Server (NTRS)

    Peeples, John; Boulton, William R.

    1995-01-01

    Product realization is the process of defining, designing, developing, and delivering products to the market. While the main thrust of this JTEC panel was to conduct a complete investigation of the state of Japanese low-cost electronic packaging technologies, it is very difficult to totally separate the development of technology and products from the product realization process. Japan's electronics firms adhere to a product realization strategy based on a strong customer focus, a consistent commitment to excellence in design, and a cost-effective approach to technology commercialization. The Japanese product-pull strategy has been a successful driver and influencing factor in every aspect of the product development cycle.

  7. A first principle approach using Maximally Localized Wannier Functions for computing and understanding elasto-optic reponse

    NASA Astrophysics Data System (ADS)

    Liang, Xin; Ismail-Beigi, Sohrab

    Strain-induced changes of optical properties are of use in the design and functioning of devices that couple photons and phonons. The elasto-optic (or photo-elastic) effect describes a general materials property where strain induces a change in the dielectric tensor. Despite a number of experimental and computational works, it is fair to say that a basic physical understanding of the effect and its materials dependence is lacking: e.g., we know of no materials design rule for enhancing or suppressing elasto-optic response. Based on our previous work, we find that a real space representation, as opposed to a k-space description, is a promising way to understand this effect. We have finished the development of a method of computing the dielectric and elasto-optic tensors using Maximally Localized Wannier Functions (MLWFs). By analyzing responses to uniaxial strain, we find that both tensors respond in a localized manner to the perturbation: the dominant optical transitions are between local electronic states on nearby bonds. We describe the method, the resulting physical picture and computed results for semiconductors. This work is supported by the National Science Foundation through Grant NSF DMR-1104974.

  8. A 250-Mbit/s ring local computer network using 1.3-microns single-mode optical fibers

    NASA Technical Reports Server (NTRS)

    Eng, S. T.; Tell, R.; Andersson, T.; Eng, B.

    1985-01-01

    A 250-Mbit/s three-station fiber-optic ring local computer network was built and successfully demonstrated. A conventional token protocol was employed for bus arbitration to maximize the bus efficiency under high loading conditions, and a non-return-to-zero (NRS) data encoding format was selected for simplicity and maximum utilization of the ECL-circuit bandwidth.

  9. Anomalous Above-Gap Photoexcitations and Optical Signatures of Localized Charge Puddles in Monolayer Molybdenum Disulfide.

    PubMed

    Borys, Nicholas J; Barnard, Edward S; Gao, Shiyuan; Yao, Kaiyuan; Bao, Wei; Buyanin, Alexander; Zhang, Yingjie; Tongay, Sefaattin; Ko, Changhyun; Suh, Joonki; Weber-Bargioni, Alexander; Wu, Junqiao; Yang, Li; Schuck, P James

    2017-02-28

    Broadband optoelectronics such as artificial light harvesting technologies necessitate efficient and, ideally, tunable coupling of excited states over a wide range of energies. In monolayer MoS2, a prototypical two-dimensional layered semiconductor, the excited state manifold spans the visible electromagnetic spectrum and is comprised of an interconnected network of excitonic and free-carrier excitations. Here, photoluminescence excitation spectroscopy is used to reveal the energetic and spatial dependence of broadband excited state coupling to the ground-state luminescent excitons of monolayer MoS2. Photoexcitation of the direct band gap excitons is found to strengthen with increasing energy, demonstrating that interexcitonic coupling across the Brillouin zone is more efficient than previously reported, and thus bolstering the import and appeal of these materials for broadband optoelectronic applications. Narrow excitation resonances that are superimposed on the broadband photoexcitation spectrum are identified and coincide with the energetic positions of the higher-energy excitons and the electronic band gap as predicted by first-principles calculations. Identification of such features outlines a facile route to measure the optical and electronic band gaps and thus the exciton binding energy in the more sophisticated device architectures that are necessary for untangling the rich many-body phenomena and complex photophysics of these layered semiconductors. In as-grown materials, the excited states exhibit microscopic spatial variations that are characteristic of local carrier density fluctuations, similar to charge puddling phenomena in graphene. Such variations likely arise from substrate inhomogeneity and demonstrate the possibility to use substrate patterning to tune local carrier density and dynamically control excited states for designer optoelectronics.

  10. Probability-based non-local means filter for speckle noise suppression in optical coherence tomography images.

    PubMed

    Yu, Hancheng; Gao, Jianlin; Li, Aiting

    2016-03-01

    In this Letter, a probability-based non-local means filter is proposed for speckle reduction in optical coherence tomography (OCT). Originally developed for additive white Gaussian noise, the non-local means filter is not suitable for multiplicative speckle noise suppression. This Letter presents a two-stage non-local means algorithm using the uncorrupted probability of each pixel to effectively reduce speckle noise in OCT. Experiments on real OCT images demonstrate that the proposed filter is competitive with other state-of-the-art speckle removal techniques and able to accurately preserve edges and structural details with small computational cost.

  11. Characterization of optical turbulence at the GREGOR solar telescope: temporal and local behavior and its influence on the solar observations

    NASA Astrophysics Data System (ADS)

    Sprung, D.; Sucher, E.; Stein, K.; von der Lühe, O.; Berkefeld, Th.

    2016-10-01

    Local atmospheric turbulence at the telescope level is regarded as a major reason for affecting the performance of the adaptive optics systems using wavelengths in the visible and infrared for solar observations. During the day the air masses around the telescope dome are influenced by flow distortions. Additionally heating of the infrastructure close to telescope causes thermal turbulence. Thereby optical turbulence is produced and leads to quality changes in the local seeing throughout the day. Image degradation will be yielded affecting the performance of adaptive optical systems. The spatial resolution of the solar observations will be reduced. For this study measurements of the optical turbulence, represented by the structure function parameter of the refractive index Cn2 were performed on several locations at the GREGOR telescope at the Teide observatory at Tenerife at the Canary Islands / Spain. Since September 2012 measurements of Cn2 were carried out between the towers of the Vacuum Tower Telescope (VTT) and of GREGOR with a laser-scintillometer. The horizontal distance of the measurement path was about 75 m. Additional from May 2015 up to March 2016 the optical turbulence was determined at three additional locations close to the solar telescope GREGOR. The optical turbulence is derived from sonic anemometer measurements. Time series of the sonic temperature are analyzed and compared to the direct measurements of the laser scintillometer. Meteorological conditions are investigated, especially the influence of the wind direction. Turbulence of upper atmospheric layers is not regarded. The measured local turbulence is compared to the system performance of the GREGOR telescopes. It appears that the mountain ridge effects on turbulence are more relevant than any local causes of seeing close to the telescope. Results of these analyses and comparison of nearly one year of measurements are presented and discussed.

  12. PARAMETRIC STUDY OF TISSUE OPTICAL CLEARING BY LOCALIZED MECHANICAL COMPRESSION USING COMBINED FINITE ELEMENT AND MONTE CARLO SIMULATION.

    PubMed

    Vogt, William C; Shen, Haiou; Wang, Ge; Rylander, Christopher G

    2010-07-01

    Tissue Optical Clearing Devices (TOCDs) have been shown to increase light transmission through mechanically compressed regions of naturally turbid biological tissues. We hypothesize that zones of high compressive strain induced by TOCD pins produce localized water displacement and reversible changes in tissue optical properties. In this paper, we demonstrate a novel combined mechanical finite element model and optical Monte Carlo model which simulates TOCD pin compression of an ex vivo porcine skin sample and modified spatial photon fluence distributions within the tissue. Results of this simulation qualitatively suggest that light transmission through the skin can be significantly affected by changes in compressed tissue geometry as well as concurrent changes in tissue optical properties. The development of a comprehensive multi-domain model of TOCD application to tissues such as skin could ultimately be used as a framework for optimizing future design of TOCDs.

  13. Typicality approach to the optical conductivity in thermal and many-body localized phases

    NASA Astrophysics Data System (ADS)

    Steinigeweg, Robin; Herbrych, Jacek; Pollmann, Frank; Brenig, Wolfram

    2016-11-01

    We study the frequency dependence of the optical conductivity Reσ (ω ) of the Heisenberg spin-1/2 chain in the thermal and near the transition to the many-body localized phase induced by the strength of a random z -directed magnetic field. Using the method of dynamical quantum typicality, we calculate the real-time dynamics of the spin-current autocorrelation function and obtain the Fourier transform Reσ (ω ) for system sizes much larger than accessible to standard exact-diagonalization approaches. We find that the low-frequency behavior of Reσ (ω ) is well described by Reσ (ω ) ≈σdc+a |ω| α , with α ≈1 in a wide range within the thermal phase and close to the transition. We particularly detail the decrease of σdc in the thermal phase as a function of increasing disorder for strong exchange anisotropies. We further find that the temperature dependence of σdc is consistent with the existence of a mobility edge.

  14. Method for optical coherence tomography image classification using local features and earth mover's distance

    NASA Astrophysics Data System (ADS)

    Sun, Yankui; Lei, Ming

    2009-09-01

    Optical coherence tomography (OCT) is a recent imaging method that allows high-resolution, cross-sectional imaging through tissues and materials. Over the past 18 years, OCT has been successfully used in disease diagnosis, biomedical research, material evaluation, and many other domains. As OCT is a recent imaging method, until now surgeons have limited experience using it. In addition, the number of images obtained from the imaging device is too large, so we need an automated method to analyze them. We propose a novel method for automated classification of OCT images based on local features and earth mover's distance (EMD). We evaluated our algorithm using an OCT image set which contains two kinds of skin images, normal skin and nevus flammeus. Experimental results demonstrate the effectiveness of our method, which achieved classification accuracy of 0.97 for an EMD+KNN scheme and 0.99 for an EMD+SVM (support vector machine) scheme, much higher than the previous method. Our approach is especially suitable for nonhomogeneous images and could be applied to a wide range of OCT images.

  15. THE LOCAL ENVIRONMENT OF ULTRALUMINOUS X-RAY SOURCES VIEWED BY XMM-NEWTON's OPTICAL MONITOR

    SciTech Connect

    Berghea, C. T.; Dudik, R. P.; Tincher, J.; Winter, L. M. E-mail: rachel.dudik@usno.navy.mil

    2013-10-20

    We have used XMM-Newton's Optical Monitor (OM) images to study the local environment of a sample of 27 ultraluminous X-ray sources (ULXs) in nearby galaxies. UVW1 fluxes were extracted from 100 pc regions centered on the ULX positions. We find that at least 4 ULXs (out of 10 published) have spectral types that are consistent with previous literature values. In addition, the colors are similar to those of young stars. For the highest-luminosity ULXs, the UVW1 fluxes may have an important contribution from the accretion disk. We find that the majority of ULXs are associated with recent star formation. Many of the ULXs in our sample are located inside young OB associations or star-forming regions (SFRs). Based on their colors, we estimated ages and masses for SFRs located within 1 kpc from the ULXs in our sample. The resolution of the OM was insufficient to detect young dense superclusters, but some of these SFRs are massive enough to contain such clusters. Only three ULXs have no associated SFRs younger than ∼50 Myr. The age and mass estimates for clusters were used to test runaway scenarios. The data are, in general, compatible with stellar-mass binaries accreting at super-Eddington rates and ejected by natal kicks. We also tested the hypothesis that ULXs are sub-Eddington accreting intermediate mass black holes ejected by three-body interactions; however, this is not supported well by the data.

  16. Vertical optical antennas integrated with spiral ring gratings for large local electric field enhancement and directional radiation.

    PubMed

    Liu, Baoan; Wang, Dongxing; Shi, Chuan; Crozier, Kenneth B; Yang, Tian

    2011-05-23

    We propose a device for reproducible achievement of enormous enhancement of local electric field intensities. In each device, a metallic spiral ring grating is employed for efficient excitation of local surface plasmon resonance in the tiny gap of a vertically oriented optical antenna. Radiation from the optical antenna is collimated by the ring grating which facilitates efficient collection. As a numerical example, for a gold nanosphere placed one nanometer above the center of a gold spiral ring grating, our simulations predict an increase in local electric field intensity of up to seven orders of magnitude compared to planewave illumination, and collection efficiencies of up to 68% by an objective with a numerical aperture of 0.7. Single molecule SERS application is discussed.

  17. Localization and segmentation of optic disc in retinal images using circular Hough transform and grow-cut algorithm

    PubMed Central

    Abdullah, Muhammad; Barman, Sarah A.

    2016-01-01

    Automated retinal image analysis has been emerging as an important diagnostic tool for early detection of eye-related diseases such as glaucoma and diabetic retinopathy. In this paper, we have presented a robust methodology for optic disc detection and boundary segmentation, which can be seen as the preliminary step in the development of a computer-assisted diagnostic system for glaucoma in retinal images. The proposed method is based on morphological operations, the circular Hough transform and the grow-cut algorithm. The morphological operators are used to enhance the optic disc and remove the retinal vasculature and other pathologies. The optic disc center is approximated using the circular Hough transform, and the grow-cut algorithm is employed to precisely segment the optic disc boundary. The method is quantitatively evaluated on five publicly available retinal image databases DRIVE, DIARETDB1, CHASE_DB1, DRIONS-DB, Messidor and one local Shifa Hospital Database. The method achieves an optic disc detection success rate of 100% for these databases with the exception of 99.09% and 99.25% for the DRIONS-DB, Messidor, and ONHSD databases, respectively. The optic disc boundary detection achieved an average spatial overlap of 78.6%, 85.12%, 83.23%, 85.1%, 87.93%, 80.1%, and 86.1%, respectively, for these databases. This unique method has shown significant improvement over existing methods in terms of detection and boundary extraction of the optic disc. PMID:27190713

  18. Localization and segmentation of optic disc in retinal images using circular Hough transform and grow-cut algorithm.

    PubMed

    Abdullah, Muhammad; Fraz, Muhammad Moazam; Barman, Sarah A

    2016-01-01

    Automated retinal image analysis has been emerging as an important diagnostic tool for early detection of eye-related diseases such as glaucoma and diabetic retinopathy. In this paper, we have presented a robust methodology for optic disc detection and boundary segmentation, which can be seen as the preliminary step in the development of a computer-assisted diagnostic system for glaucoma in retinal images. The proposed method is based on morphological operations, the circular Hough transform and the grow-cut algorithm. The morphological operators are used to enhance the optic disc and remove the retinal vasculature and other pathologies. The optic disc center is approximated using the circular Hough transform, and the grow-cut algorithm is employed to precisely segment the optic disc boundary. The method is quantitatively evaluated on five publicly available retinal image databases DRIVE, DIARETDB1, CHASE_DB1, DRIONS-DB, Messidor and one local Shifa Hospital Database. The method achieves an optic disc detection success rate of 100% for these databases with the exception of 99.09% and 99.25% for the DRIONS-DB, Messidor, and ONHSD databases, respectively. The optic disc boundary detection achieved an average spatial overlap of 78.6%, 85.12%, 83.23%, 85.1%, 87.93%, 80.1%, and 86.1%, respectively, for these databases. This unique method has shown significant improvement over existing methods in terms of detection and boundary extraction of the optic disc.

  19. Realizability Is Controllability

    NASA Astrophysics Data System (ADS)

    Lohmann, Niels; Wolf, Karsten

    A choreography describes the interaction between services. It may be used for specification purposes, for instance serving as a contract in the design of an inter-organizational business process. Typically, not all describable interactions make sense which motivates the study of the realizability problem for a given choreography.

  20. Realizing Their Potential.

    ERIC Educational Resources Information Center

    Orloff, Jeffrey H., Ed.

    The report contains the proceedings of the Third Annual Northern Virginia Conference on Gifted/Talented Education. Titles and authors of papers presented include "Realizing Your Potential" (H. Lyon), "Developing the Gifts of All Children" (W. Barbe), "What is Leadership Training for the Gifted?" (D. Sisk), "Theoretic Foundations of Differential…

  1. Effect of deviation from local thermodynamic equilibrium on the Goldberg-Unno method. [turbulence effects on optical density in the solar photosphere

    NASA Technical Reports Server (NTRS)

    Troyan, V. I.

    1974-01-01

    The dependence of turbulent velocity on optical depth was studied by use of the Goldberg-Unno method, with allowance made for the influence of deviation from the local thermodynamic equilibrium. It was found that allowance for deviation from local thermodynamic equilibrium displaces the curve of dependence of turbulent velocity on optical depth along two axes.

  2. Local domains of motor cortical activity revealed by fiber-optic calcium recordings in behaving nonhuman primates

    PubMed Central

    Adelsberger, Helmuth; Zainos, Antonio; Alvarez, Manuel; Romo, Ranulfo; Konnerth, Arthur

    2014-01-01

    Brain mapping experiments involving electrical microstimulation indicate that the primary motor cortex (M1) directly regulates muscle contraction and thereby controls specific movements. Possibly, M1 contains a small circuit “map” of the body that is formed by discrete local networks that code for specific movements. Alternatively, movements may be controlled by distributed, larger-scale overlapping circuits. Because of technical limitations, it remained unclear how movement-determining circuits are organized in M1. Here we introduce a method that allows the functional mapping of small local neuronal circuits in awake behaving nonhuman primates. For this purpose, we combined optic-fiber–based calcium recordings of neuronal activity and cortical microstimulation. The method requires targeted bulk loading of synthetic calcium indicators (e.g., OGB-1 AM) for the staining of neuronal microdomains. The tip of a thin (200 µm) optical fiber can detect the coherent activity of a small cluster of neurons, but is insensitive to the asynchronous activity of individual cells. By combining such optical recordings with microstimulation at two well-separated sites of M1, we demonstrate that local cortical activity was tightly associated with distinct and stereotypical simple movements. Increasing stimulation intensity increased both the amplitude of the movements and the level of neuronal activity. Importantly, the activity remained local, without invading the recording domain of the second optical fiber. Furthermore, there was clear response specificity at the two recording sites in a trained behavioral task. Thus, the results provide support for movement control in M1 by local neuronal clusters that are organized in discrete cortical domains. PMID:24344287

  3. Local domains of motor cortical activity revealed by fiber-optic calcium recordings in behaving nonhuman primates.

    PubMed

    Adelsberger, Helmuth; Zainos, Antonio; Alvarez, Manuel; Romo, Ranulfo; Konnerth, Arthur

    2014-01-07

    Brain mapping experiments involving electrical microstimulation indicate that the primary motor cortex (M1) directly regulates muscle contraction and thereby controls specific movements. Possibly, M1 contains a small circuit "map" of the body that is formed by discrete local networks that code for specific movements. Alternatively, movements may be controlled by distributed, larger-scale overlapping circuits. Because of technical limitations, it remained unclear how movement-determining circuits are organized in M1. Here we introduce a method that allows the functional mapping of small local neuronal circuits in awake behaving nonhuman primates. For this purpose, we combined optic-fiber-based calcium recordings of neuronal activity and cortical microstimulation. The method requires targeted bulk loading of synthetic calcium indicators (e.g., OGB-1 AM) for the staining of neuronal microdomains. The tip of a thin (200 µm) optical fiber can detect the coherent activity of a small cluster of neurons, but is insensitive to the asynchronous activity of individual cells. By combining such optical recordings with microstimulation at two well-separated sites of M1, we demonstrate that local cortical activity was tightly associated with distinct and stereotypical simple movements. Increasing stimulation intensity increased both the amplitude of the movements and the level of neuronal activity. Importantly, the activity remained local, without invading the recording domain of the second optical fiber. Furthermore, there was clear response specificity at the two recording sites in a trained behavioral task. Thus, the results provide support for movement control in M1 by local neuronal clusters that are organized in discrete cortical domains.

  4. Integrated local binary pattern texture features for classification of breast tissue imaged by optical coherence microscopy.

    PubMed

    Wan, Sunhua; Lee, Hsiang-Chieh; Huang, Xiaolei; Xu, Ting; Xu, Tao; Zeng, Xianxu; Zhang, Zhan; Sheikine, Yuri; Connolly, James L; Fujimoto, James G; Zhou, Chao

    2017-03-08

    This paper proposes a texture analysis technique that can effectively classify different types of human breast tissue imaged by Optical Coherence Microscopy (OCM). OCM is an emerging imaging modality for rapid tissue screening and has the potential to provide high resolution microscopic images that approach those of histology. OCM images, acquired without tissue staining, however, pose unique challenges to image analysis and pattern classification. We examined multiple types of texture features and found Local Binary Pattern (LBP) features to perform better in classifying tissues imaged by OCM. In order to improve classification accuracy, we propose novel variants of LBP features, namely average LBP (ALBP) and block based LBP (BLBP). Compared with the classic LBP feature, ALBP and BLBP features provide an enhanced encoding of the texture structure in a local neighborhood by looking at intensity differences among neighboring pixels and among certain blocks of pixels in the neighborhood. Fourty-six freshly excised human breast tissue samples, including 27 benign (e.g. fibroadenoma, fibrocystic disease and usual ductal hyperplasia) and 19 breast carcinoma (e.g. invasive ductal carcinoma, ductal carcinoma in situ and lobular carcinoma in situ) were imaged with large field OCM with an imaging area of 10 × 10 mm(2) (10, 000 × 10, 000 pixels) for each sample. Corresponding H&E histology was obtained for each sample and used to provide ground truth diagnosis. 4310 small OCM image blocks (500 × 500 pixels) each paired with corresponding H&E histology was extracted from large-field OCM images and labeled with one of the five different classes: adipose tissue (n = 347), fibrous stroma (n = 2,065), breast lobules (n = 199), carcinomas (pooled from all sub-types, n = 1,127), and background (regions outside of the specimens, n = 572). Our experiments show that by integrating a selected set of LBP and the two new variant (ALBP and BLBP) features at multiple scales, the

  5. Local multipoint distribution system (LDMS) versus free-space optical (FSO) networks

    NASA Astrophysics Data System (ADS)

    Willebrand, Heinz A.; Clark, Gerald R.; Willson, Bryan; Andreu von Euw, Christian G.; Roy, Joe; Mayhew, Laurel M.

    2001-11-01

    This paper compares two emerging broadband access methodologies, Free Space Optics (FSO) and Local Multipoint Distribution System (LMDS) and the atmospheric propagation characteristics of each when exposed to a dynamically changing channel. The comparison focuses on bandwidth, availability, and distance requirements for the new broadband market and how LMDS and FSO can be used to meet these requirements. Possible network topologies and their associated costs are examined. This comparison takes into account the total cost of deployment, including equipment costs, installation fees, access fees, and spectrum licensing fees. LMDS and FSO are compared on speed of deployment, scalability, aggregate bandwidth, and bandwidth per customer. Present and projected capabilities of each technology are considered for their suitability in different locations in the network, from the Wide Area Network (WAN), to the Metropolitan Area Network (MAN), all the way to Last Mile Access. There is a discussion on the relative performance of LMDS and FSO, focusing on the different factors that can affect link availability. Since network design is a large factor in assuring overall reliability, the flexibility of each technology with regard to network design is compared. LMDS and FSO are both line of sight, space-propagated technologies, and as such, they are both susceptible to path impediments and atmospheric attenuation, dispersion, scattering, and absorption. LMDS and FSO are affected very differently by different meteorological phenomena. Problematic atmospheric conditions are, specifically scintillation, rainfall, and fog, are examined. In addition to a discussion of these conditions, various techniques for minimizing atmospheric and environmental effects are investigated. The paper concludes with a summary of findings and recommendations for a number of broadband wireless applications.

  6. Realizing Controllable Quantum States

    NASA Astrophysics Data System (ADS)

    Takayanagi, Hideaki; Nitta, Junsaku

    -- 4. Mesoscopic superconductivity with unconventional superconductor or ferromagnet. Ultraefficient microrefrigerators realized with ferromagnet-superconductor junctions / F. Giazotto et al. Anomalous charge transport in triplet superconductor junctions by the synergy effect of the proximity effect and the mid gap Andreev resonant states / Y. Tanaka and S. Kashiwaya. Paramagnetic and glass states in superconductive YBa[symbol]Cu[symbol]O[symbol] ceramics of sub-micron scale grains / H. Deguchi et al. Quantum properties of single-domain triplet superconductors / A. M. Gulian and K. S. Wood. A numerical study of Josephson current in p wave superconducting junctions / Y. Asano et al. Tilted bi-crystal sapphire substrates improve properties of grain boundary YBa[symbol]Cu[symbol]O[symbol] junctions and extend their Josephson response to THZ frequencies / E. Stepantsov et al. Circuit theory analysis of AB-plane tunnel junctions of unconventional superconductor Bi[symbol]Sr[symbol]Ca[symbol]Cu[symbol]O[symbol] / I. Shigeta et al. Transport properties of normal metal/anisotropic superconductor junctions in the eutectic system Sr[symbol]RuO[symbol]Ru / M. Kawamura et al. Macroscopic quantum tunneling in d-wave superconductor Josephson / S. Kawabata et al. Quasiparticle states of high-T[symbol] oxides observed by a Zeeman magnetic field response / S. Kashiwaya et al. Experimentally realizable devices for controlling the motion of magnetic flux quanta in anisotropic superconductors: vortex lenses, vortex diodes and vortex pumps / S. Savel'ev and F. Nori. Stability of vortex-antivortex "molecules" in mesoscopic superconducting triangles / V. R. Misko et al. Superconducting network with magnetic decoration - Hofstadter butterfly in spatially modulated magnetic field / Y. Iye et al. Observation of paramagnetic supercurrent in mesoscopic superconducting rings and disks using multiple-small-tunnel-junction method / A. Kanda et al. Guidance of vortices in high

  7. Determination of local optical properties of the rat barrel cortex during neural activation: Monte-Carlo approach to light propagation

    NASA Astrophysics Data System (ADS)

    Migacheva, E. V.; Chamot, S. R.; Seydoux, O.; Weber, B.; Depeursinge, C.; Marquet, P.; Magistretti, P. J.

    2010-04-01

    Spatially-spectrally-resolved reflectance measurements allow in vivo measuring the optical coefficients of absorption and scattering within the cortical tissue. This method, if applied to neural tissue during enhanced activity, could allow a straightforward monitoring of the blood oxygen saturation changes occurring in the brain cortex during hemodynamic responses. Furthermore, it may provide valuable information on possible absorption and scattering changes occurring during stimulation. The feasibility of such measurements was investigated by carrying a preliminary numerical study using a Monte-Carlo light propagation routine. Experimental parameters such as the geometry of the optical probe, baseline cortex optical coefficients retrieved from the literature and anatomical characteristics of the rat barrel cortex were used as an input for the simulations. The sensitivity of the probe to the local variations of optical coefficients was investigated with this numerical approach. Additionally, the influence of the barrel cortex dimensions and the probe positioning relatively to the activated region were studied for instrumental optimization purpose. It was found that typical variations of optical coefficients can be detected if the activated region of barrel cortex has a volume of typically 1 mm3 or larger. The decay of the probe sensitivity to changes was studied as a function of the depth of the activated region. The results showed that the best sensitivity is achieved by placing the light injection fiber of the optical probe aligned onto the center of the cylindrical barrel.

  8. Anderson localization of cold atomic gases with effective spin-orbit interaction in a quasiperiodic optical lattice

    NASA Astrophysics Data System (ADS)

    Zhou, Lu; Pu, Han; Zhang, Weiping

    2013-02-01

    We theoretically investigate the localization properties of a spin-orbit-coupled spin-1/2 particle moving in a one-dimensional quasiperiodic potential, which can be experimentally implemented using cold atoms trapped in a quasiperiodic optical lattice potential and external laser fields. We present the phase diagram in the parameter space of the disorder strength and those related to the spin-orbit coupling. The phase diagram is verified via multifractal analysis of the atomic wave functions and the numerical simulation of diffusion dynamics. We found that spin-orbit coupling can lead to spectra mixing (coexistence of extended and localized states) and the appearance of mobility edges.

  9. Optical protocols for terabit networks

    NASA Technical Reports Server (NTRS)

    Chua, P. L.; Lambert, J. L.; Morookian, J. M.; Bergman, L. A.

    1991-01-01

    This paper describes a new fiber-optic local area network technology providing 100X improvement over current technology, has full crossbar funtionality, and inherent data security. Based on optical code-division multiple access (CDMA), using spectral phase encoding/decoding of optical pulses, networking protocols are implemented entirely in the optical domain and thus conventional networking bottlenecks are avoided. Component and system issues for a proof-of-concept demonstration are discussed, as well as issues for a more practical and commercially exploitable system. Possible terrestrial and aerospace applications of this technology, and its impact on other technologies are explored. Some initial results toward realization of this concept are also included.

  10. Design and implementation of interface units for high speed fiber optics local area networks and broadband integrated services digital networks

    NASA Technical Reports Server (NTRS)

    Tobagi, Fouad A.; Dalgic, Ismail; Pang, Joseph

    1990-01-01

    The design and implementation of interface units for high speed Fiber Optic Local Area Networks and Broadband Integrated Services Digital Networks are discussed. During the last years, a number of network adapters that are designed to support high speed communications have emerged. This approach to the design of a high speed network interface unit was to implement package processing functions in hardware, using VLSI technology. The VLSI hardware implementation of a buffer management unit, which is required in such architectures, is described.

  11. On the local field method with the account of spatial dispersion. Application to the optical activity theory

    NASA Astrophysics Data System (ADS)

    Tyu, N. S.; Ekhilevsky, S. G.

    1992-07-01

    For the perfect molecular crystals the equations of the local field method (LFM) with the account of spatial dispersion are formulated. They are used to derive the expression for the crystal polarizability tensor. For the first time within the framework of this method the formula for the gyrotropy tensor of an arbitrary optically active molecular crystal is obtained. This formula is analog of well known relationships of Lorentz-Lorenz.

  12. Rapid localized heating of graphene coating on a silicon mold by induction for precision molding of polymer optics.

    PubMed

    Zhang, Lin; Zhou, Wenchen; Yi, Allen Y

    2017-04-01

    In compression molding of polymer optical components with micro/nanoscale surface features, rapid heating of the mold surface is critical for the implementation of this technology for large-scale applications. In this Letter, a novel method of a localized rapid heating process is reported. This process is based on induction heating of a thin conductive coating deposited on a silicon mold. Since the graphene coating is very thin (∼45  nm), a high heating rate of 10∼20°C/s can be achieved by employing a 1200 W 30 kHz electrical power unit. Under this condition, the graphene-coated surface and the polymer substrate can be heated above the polymer's glass transition temperature within 30 s and subsequently cooled down to room temperature within several tens of seconds after molding, resulting in an overall thermal cycle of about 3 min or shorter. The feasibility of this process was validated by fabrication of optical gratings, micropillar matrices, and microlens arrays on polymethylmethacrylate (PMMA) substrates with very high precision. The uniformity and surface geometries of the replicated optical elements are evaluated using an optical profilometer, a diffraction test setup, and a Shack-Hartmann wavefront sensor built with a molded PMMA microlens array. Compared with the conventional bulk heating molding process, this novel rapid localized induction heating process could improve replication efficiency with better geometrical fidelity.

  13. 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).

  14. Laser-optical method of visualization the local net of tissue blood vessels and its biomedical applications

    NASA Astrophysics Data System (ADS)

    Asimov, M. M.; Asimov, R. M.; Rubinov, A. N.

    2007-06-01

    New approach in laser-optical diagnostic methods of cell metabolism based on visualization the local net of tissue blood vessels is proposed. Optical model of laser - tissue interaction and algorithm of mathematical calculation of optical signals is developed. Novel technology of local tissue hypoxia elimination based on laser-induced photodissosiation of oxyhemoglobin in cutaneous blood vessels is developed. Method of determination of oxygen diffusion coefficient into tissue on the base of kinetics of tissue oxygenation TcPO II under the laser irradiation is proposed. The results of mathematical modeling the kinetic of oxygen distribution into tissue from arterial blood are presented. The possibility of calculation and determination of the level of TcPO II in zones with the disturbed blood microcirculation is demonstrated. The increase of the value of oxygen release rate more than for times under the irradiation by laser light is obtained. It is shown that the efficiency of laser-induced oxygenation by means of increasing oxygen concentration in blood plasma is comparable with the method of hyperbaric oxygenation (HBO) at the same time gaining advantages in local action. Different biomedical applications of developing method are discussed.

  15. High-efficiency localization of Na+-K+ ATPases on the cytoplasmic side by direct stochastic optical reconstruction microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Jiazhen; Gao, Jing; Qi, Miao; Wang, Jianzhong; Cai, Mingjun; Liu, Shuheng; Hao, Xian; Jiang, Junguang; Wang, Hongda

    2013-11-01

    We describe a concise and effective strategy towards precisely mapping Na+-K+ ATPases on the cytoplasmic side of cell membranes by direct stochastic optical reconstruction microscopy (dSTORM). We found that most Na+-K+ ATPases are localized in different sizes of clusters on human red blood cell (hRBC) membranes, revealed by Ripley's K-function analysis. Further evidence that cholesterol depletion causes the dispersion of Na+-K+ ATPase clusters indicates that such clusters could be localized in cholesterol-enriched domains. Our results suggest that Na+-K+ ATPases might aggregate within the lipid rafts to fulfill their functions.We describe a concise and effective strategy towards precisely mapping Na+-K+ ATPases on the cytoplasmic side of cell membranes by direct stochastic optical reconstruction microscopy (dSTORM). We found that most Na+-K+ ATPases are localized in different sizes of clusters on human red blood cell (hRBC) membranes, revealed by Ripley's K-function analysis. Further evidence that cholesterol depletion causes the dispersion of Na+-K+ ATPase clusters indicates that such clusters could be localized in cholesterol-enriched domains. Our results suggest that Na+-K+ ATPases might aggregate within the lipid rafts to fulfill their functions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03665k

  16. Nonautonomous spatiotemporal localized structures in the inhomogeneous optical fibers: Interaction and control

    SciTech Connect

    Dai Chaoqing; Wang Xiaogang; Zhang Jiefang

    2011-03-15

    Research Highlights: > The similarity transformation of (n + 1)-dimensional inhomogeneous NLSE are found. > From transformation, analytical self-similar waves and rogue waves are obtained. > Dynamical behaviors of self-similar waves in DDF are discussed. > The propagation and control of spatiotemporal self-similar waves are presented. - Abstract: We develop a systematic way to find the similarity transformation and investigate nonautonomous optical similariton dynamics for (n + 1)-dimensional nonlinear Schroedinger equation in the inhomogeneous optical fibers. A condition between the parameters of the mediums, which hints a exact balance between the dispersion/diffraction, nonlinearity and the gain/loss, has been obtained. Under this condition the optical similariton transmission in the dispersion-decreasing fibers (DDF) can be exactly controlled by proper dispersion management. Moreover, novel propagation dynamics of bright and dark similaritons on the background waves and optical rogue waves (rogons) in DDF are investigated too.

  17. Local observation and spectroscopy of optical modes in an active photonic-crystal microcavity.

    PubMed

    Louvion, N; Gérard, D; Mouette, J; de Fornel, F; Seassal, C; Letartre, X; Rahmani, A; Callard, S

    2005-03-25

    We report the direct, room-temperature, near-field mapping and spectroscopy of the optical modes of a photonic-crystal microcavity containing quantum wells. We use a near-field optical probe to reveal the imprint of the cavity mode structure on the quantum-well emission. Furthermore, near-field spectroscopy allows us to demonstrate the strong spatial and spectral dependence of the coupling between the sources and the microcavity. This knowledge will be essential in devising future nanophotonic devices.

  18. Health Rights and Realization

    PubMed Central

    Rushton, Simon

    2016-01-01

    In their hypothesis published in IJHPM, Lisa Forman and colleagues examined the prominence of the right to health and sexual and reproductive health rights (as well as related language) in four of the key reports that fed into the process of negotiating the Sustainable Development Goals (SDGs). Now that the SDGs have been formally adopted, this comment builds on some of the insights of Forman and colleagues to examine the extent to which those rights have been incorporated in SDGs 3 and 5. I argue that sexual and reproductive health rights are relatively well-covered within the SDGs. In terms of the right to health, however, the picture is much less clear. Some of the elements that make up that right are present and correct, but the SDGs have delivered no coherent vision of how a ‘right to health’ might actually be realized. An important task facing global health and human rights advocates is to continue pushing human rights framings so that progress is made both on meeting the SDGs and on realizing the right to health. PMID:27239886

  19. Diffractive-optical-element-based glossmeter and low coherence interferometer in assessment of local surface quality of paper

    NASA Astrophysics Data System (ADS)

    Peiponen, Kai-Erik; Alarousu, Erkki; Juuti, M.; Silvennoinen, Raimo V. J.; Oksman, A.; Myllylä, Risto A.; Prykäri, Tuukka

    2006-04-01

    The surface microroughness of paper has an important role on its gloss. Unfortunately, commercial glossmeters do not provide information on the local gloss of paper. In this study a low-coherence interferometer was employed for the assessment of the average surface roughness of fine, supercalendered, and Xerox papers by means of recorded topography maps. Furthermore, the local and average gloss were measured by a diffractive-optical-element-based glossmeter. This is the first time that the measurement of the local gloss of paper has been accomplished. The information on both surface roughness and gloss, obtained by the two devices in this study, should help papermakers in their research and development of optimal paper surface quality, which is crucial to optimal ink absorption in printing.

  20. The role of codeine phosphate premedication in fibre-optic bronchoscopy under insufficient local anaesthesia and midazolam sedation.

    PubMed

    Tsunezuka, Y; Sato, H; Tsukioka, T; Nakamura, Y; Watanabe, Y

    1999-06-01

    Midazolam is widely used as a sedative agent to produce amnesia in patients undergoing fibre-optic bronchoscopy. However, if a patient does not receive sufficient local anaesthesia, continuous severe cough and physical movement may interrupt the procedure and reduce its safety. We therefore examined whether codeine phosphate is a useful premedication for bronchoscopy. The study design was a randomized comparison between codeine phosphate and a placebo in patients undergoing light local anaesthesia and midazolam sedation. We used low dose local anaesthesia (5 ml of nebulized 2% xylocaine) on the assumption of insufficient local anaesthesia. Patients were allocated to receive codeine phosphate 0.4 mg kg-1 or a saline placebo 60 min before they were sedated with i.v. midazolam. If the patients exhibited severe cough during bronchoscopy, intrabronchial supplemental local anaesthesia (2% xylocaine solution in 1 ml increments) was instilled via a bronchoscope to the trachea and segmental bronchi to suppress the cough. The dose of supplemental xylocaine was assessed and the requirements were significantly lower in the codeine group compared to the placebo group: 36.4 +/- 10.2 mg vs. 95.1 +/- 24.6 mg, respectively. After bronchoscopy, patients were interviewed by a doctor to assess their willingness to undergo a repeat procedure if one was clinically indicated, but no significant difference was observed between the two groups. If local anaesthesia is insufficient, midazolam together with codeine phosphate premedication is useful for both the patient and the bronchoscopist.

  1. Time reversal optical tomography and decomposition methods for detection and localization of targets in highly scattering turbid media

    NASA Astrophysics Data System (ADS)

    Wu, Binlin

    New near-infrared (NIR) diffuse optical tomography (DOT) approaches were developed to detect, locate, and image small targets embedded in highly scattering turbid media. The first approach, referred to as time reversal optical tomography (TROT), is based on time reversal (TR) imaging and multiple signal classification (MUSIC). The second approach uses decomposition methods of non-negative matrix factorization (NMF) and principal component analysis (PCA) commonly used in blind source separation (BSS) problems, and compare the outcomes with that of optical imaging using independent component analysis (OPTICA). The goal is to develop a safe, affordable, noninvasive imaging modality for detection and characterization of breast tumors in early growth stages when those are more amenable to treatment. The efficacy of the approaches was tested using simulated data, and experiments involving model media and absorptive, scattering, and fluorescent targets, as well as, "realistic human breast model" composed of ex vivo breast tissues with embedded tumors. The experimental arrangements realized continuous wave (CW) multi-source probing of samples and multi-detector acquisition of diffusely transmitted signal in rectangular slab geometry. A data matrix was generated using the perturbation in the transmitted light intensity distribution due to the presence of absorptive or scattering targets. For fluorescent targets the data matrix was generated using the diffusely transmitted fluorescence signal distribution from the targets. The data matrix was analyzed using different approaches to detect and characterize the targets. The salient features of the approaches include ability to: (a) detect small targets; (b) provide three-dimensional location of the targets with high accuracy (~within a millimeter or 2); and (c) assess optical strength of the targets. The approaches are less computation intensive and consequently are faster than other inverse image reconstruction methods that

  2. Fiber-connected position localization sensor networks

    NASA Astrophysics Data System (ADS)

    Pan, Shilong; Zhu, Dan; Fu, Jianbin; Yao, Tingfeng

    2014-11-01

    Position localization has drawn great attention due to its wide applications in radars, sonars, electronic warfare, wireless communications and so on. Photonic approaches to realize position localization can achieve high-resolution, which also provides the possibility to move the signal processing from each sensor node to the central station, thanks to the low loss, immunity to electromagnetic interference (EMI) and broad bandwidth brought by the photonic technologies. In this paper, we present a review on the recent works of position localization based on photonic technologies. A fiber-connected ultra-wideband (UWB) sensor network using optical time-division multiplexing (OTDM) is proposed to realize high-resolution localization and moving the signal processing to the central station. A 3.9-cm high spatial resolution is achieved. A wavelength-division multiplexed (WDM) fiber-connected sensor network is also demonstrated to realize location which is independent of the received signal format.

  3. Extranodal right-optic nerve Rosai–Dorfman disease: A rare localization case report

    PubMed Central

    Nemir, Jakob; Trninic, Ines; Duric, Kresimir S.; Jakovcevic, Antonia; Mrak, Goran; Paladino, Josip

    2016-01-01

    Background: Rosai–Dorfman is a rare disease that usually occurs in young adults. It is characterized with massive painless cervical lymphadenopathy and histiocyte proliferation. Isolated intracranial involvement is extremely rare. Our aim is to present a new rare case of extranodal Rosai–Dorfman disease that involved the right optic nerve in a 4-year-old boy. Case Description: A 4-year-old boy with right-sided convergent strabismus and amblyopia lasting for 1 year was treated at the Department of pediatric ophthalmology. Initial optical fundus examination was normal. Examination repeated after 1 year noted the atrophy of the optic nerve papilla. Visual evoked potentials of the right eye showed normal findings of prechiasmatic visual pathway with severe dysfunction of the right optic nerve. Magnetic resonance imaging (MRI) of the brain and orbits showed expansive changed and elongated right optic nerve with contrast enhancement, and smaller lesion in the right temporal operculum region visible in T2 and fluid-attenuated inversion recovery sequence. Through small eyebrow “keyhole” osteoplastic frontoorbital craniotomy the fusiform enlarged (to 2 cm) right optic nerve was identified, resected between the eyeball and optic chiasm, and transferred for pathohistological analysis. Early postoperative course had no complications. Histological, immunohistochemical, and ultrastructural analyses revealed extranodal Rosai–Dorfman disease. Right periorbital edema was verified on the 7th postoperative day and regressed to supportive therapy. Control multi slice computed tomography (MSCT) and MRI of endocranium and orbits showed total tumor removal with no signs of complications. Conclusion: Although rare, extranodular intracranial Rosai–Dorfman disease should be taken into account in the differential diagnosis of intracranial and intraorbital lesions, especially in the pediatric age group. PMID:28194305

  4. Diffuse Optical Spectroscopy Evaluation of Treatment Response in Women with Locally Advanced Breast Cancer Receiving Neoadjuvant Chemotherapy1

    PubMed Central

    Falou, Omar; Soliman, Hany; Sadeghi-Naini, Ali; Iradji, Sara; Lemon-Wong, Sharon; Zubovits, Judit; Spayne, Jacqueline; Dent, Rebecca; Trudeau, Maureen; Boileau, Jean Francois; Wright, Frances C; Yaffe, Martin J.; Czarnota, Gregory J

    2012-01-01

    The aim of this study was to investigate the potential of diffuse optical spectroscopy for monitoring of patients with locally advanced breast cancer (LABC) undergoing neoadjuvant chemotherapy. Fifteen women receiving treatment for LABC had the affected breast scanned before; 1 week, 4 weeks, and 8 weeks after treatment initiation; and before surgery. Optical properties related to tissue microstructure and biochemical composition were obtained. Clinical and pathologic tumor response was evaluated using whole-mount pathology after mastectomy. Patients who responded to treatment demonstrated an initial increase followed by a drop in optical parameters measured in the whole breast, whereas nonresponding patients demonstrated only a drop in the same parameters 1 week after treatment initiation. Responding patients demonstrated a significant increase of 17% ± 7%, 8% ± 8%, 10% ± 7%, 11% ± 11%, and 16% ± 15% in deoxygenated hemoglobin, oxygenated hemoglobin, total hemoglobin concentrations, water percentage, and tissue optical index, 1 week after treatment initiation, respectively. In contrast, nonresponding patients had a decrease of 14% ± 9%, 18% ± 7%, 17% ± 7%, 29% ± 7%, and 32% ± 9% in their corresponding optical parameters. Deoxygenated hemoglobin concentration (with 100% sensitivity, 83% specificity) and water percentage (with 75% sensitivity, 100% specificity) were found to be the best predictors of treatment response at 1 week after starting treatment. The results of this study suggest that optical parameters can be potentially used to predict and monitor patients' responses to neoadjuvant chemotherapy and can form a basis for the customization of treatments in which inefficacious treatments can be switched to more efficacious therapies. PMID:22937175

  5. Algorithm for localized adaptive diffuse optical tomography and its application in bioluminescence tomography

    NASA Astrophysics Data System (ADS)

    Naser, Mohamed A.; Patterson, Michael S.; Wong, John W.

    2014-04-01

    A reconstruction algorithm for diffuse optical tomography based on diffusion theory and finite element method is described. The algorithm reconstructs the optical properties in a permissible domain or region-of-interest to reduce the number of unknowns. The algorithm can be used to reconstruct optical properties for a segmented object (where a CT-scan or MRI is available) or a non-segmented object. For the latter, an adaptive segmentation algorithm merges contiguous regions with similar optical properties thereby reducing the number of unknowns. In calculating the Jacobian matrix the algorithm uses an efficient direct method so the required time is comparable to that needed for a single forward calculation. The reconstructed optical properties using segmented, non-segmented, and adaptively segmented 3D mouse anatomy (MOBY) are used to perform bioluminescence tomography (BLT) for two simulated internal sources. The BLT results suggest that the accuracy of reconstruction of total source power obtained without the segmentation provided by an auxiliary imaging method such as x-ray CT is comparable to that obtained when using perfect segmentation.

  6. Performance evaluation of data center service localization based on virtual resource migration in software defined elastic optical network.

    PubMed

    Yang, Hui; Zhang, Jie; Ji, Yuefeng; Tan, Yuanlong; Lin, Yi; Han, Jianrui; Lee, Young

    2015-09-07

    Data center interconnection with elastic optical network is a promising scenario to meet the high burstiness and high-bandwidth requirements of data center services. In our previous work, we implemented cross stratum optimization of optical network and application stratums resources that allows to accommodate data center services. In view of this, this study extends the data center resources to user side to enhance the end-to-end quality of service. We propose a novel data center service localization (DCSL) architecture based on virtual resource migration in software defined elastic data center optical network. A migration evaluation scheme (MES) is introduced for DCSL based on the proposed architecture. The DCSL can enhance the responsiveness to the dynamic end-to-end data center demands, and effectively reduce the blocking probability to globally optimize optical network and application resources. The overall feasibility and efficiency of the proposed architecture are experimentally verified on the control plane of our OpenFlow-based enhanced SDN testbed. The performance of MES scheme under heavy traffic load scenario is also quantitatively evaluated based on DCSL architecture in terms of path blocking probability, provisioning latency and resource utilization, compared with other provisioning scheme.

  7. Optical switching of nematic liquid crystal film arising from induced electric field of localized surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Quint, Makiko T.; Delgado, Silverio; Paredes, John H.; Hirst, Linda S.; Ghosh, Sayantani

    2015-08-01

    We have developed an all-optical method to control the in- and out-of-plane spatial orientation of nematic liquid crystal (NLC) molecules by leveraging the highly localized electric fields produced in the near-field regime of gold nanoparticle (AuNP) layers. A 1-2 micron thick NLC film is deposited on a close-packed drop-cast AuNP layer, excited with tunable optical sources and the transmission of white light through it analyzed using polarization optics as a function of incident light wavelength, excitation power and sample temperature. Our findings, supported by simulations using discrete-dipole approximations, establish the optical switching effect to be repeatable, reversible, spectrally-selective, operational over a broad temperature range, including room temperature, and requiring very small on-resonance excitation intensity (0.3 W/cm2). For the case of the in-plane switching we have additionally demonstrated that controlling the incident excitation polarization can continuously vary the alignment of the NLC molecules, allowing for grayscale transmission.

  8. Local control of light polarization with low-temperature fiber optics.

    PubMed

    Mack, A H; Riordon, J; Dean, C R; Talbot, R; Gervais, G

    2007-06-01

    A fiber-optic-based polarization control system that uses a backreflection measurement scheme at low temperatures has been developed. This provides a stringent test of the light polarization state at the output of the fiber, allowing for determination and control of the degree of circular polarization; i.e., it can generate linear, right, or left circular polarization with cryogenic fibers. This polarization controller is paving the way toward the control and manipulation of nuclear spins in semiconductors via the optical Overhauser effect and could be used, for example, for the purpose of quantum information processing with the large nuclear spins of GaAs.

  9. Minimal invasive localization of the germinal disc in ovo for subsequent chicken sexing using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Burkhardt, Anke; Geissler, Stefan; Cimalla, Peter; Walther, Julia; Koch, Edmund

    2010-02-01

    Reason for using optical coherence tomography (OCT) to locate the germinal disc is the questionable and ethically alarming killing of male layer chickens because for the layer line only the females are necessary. To avoid this and to protect the animal rights, the sex of the fertilized chicken egg has to be determined as early as possible in the unincubated state. Because the information whether the chick becomes male or female can be found in the germinal disc an accurate localization for sexing is essential. The germinal disc is located somewhere on top of the yolk and has a diameter of approximately 4 - 5 mm. Different imaging methods like ultrasonography, 3D-X-ray micro computed tomography and magnetic resonance imaging were used for localization until now, but found to be impractical. The goal of this study is to prove if OCT can be a moderate approach for the precise in ovo localization. Because the eggshell is an impenetrable barrier for OCT and to minimize the penetration of germs a very small hole is placed in the eggshell and a fan-shaped optical scanning pattern is used.

  10. Acoustic Source Localization via Time Difference of Arrival Estimation for Distributed Sensor Networks Using Tera-Scale Optical Core Devices

    DOE PAGES

    Imam, Neena; Barhen, Jacob

    2009-01-01

    For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. These sensors rely heavily on battery-operated system components to achieve highly functional automation in signal and information processing. In order to keep communication requirements minimal, it is desirable to perform as much processing on the receiver platforms as possible. However, the complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot bemore » readily met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on the optical-core digital processing platform recently introduced by Lenslet Inc. This demonstration of considerably faster signal processing capability should be of substantial significance to the design and innovation of future generations of distributed sensor networks.« less

  11. Magnetic, optical, and electron transport properties of n -type CeO2: Small polarons versus Anderson localization

    NASA Astrophysics Data System (ADS)

    Kolodiazhnyi, Taras; Charoonsuk, Thitirat; Seo, Yu-Seong; Chang, Suyong; Vittayakorn, Naratip; Hwang, Jungseek

    2017-01-01

    We report magnetic susceptibility, electrical conductivity and optical absorption of Ce1 -xMxO2 where M = Nb,Ta and 0 ≤x ≤0.03 . The dc conductivity follows a simple thermally activated Arrhenius-type behavior in the T =70 -700 K range with a change in slope at T*≈155 K. The high-temperature activation energy shows gradual increase from ≈170 to 220 meV as the dopant concentration increases. The activation energy of the low-temperature conductivity shows a broad minimum of ≈77 meV at x ≈0.01 . Electron transport and localization mechanisms are analyzed in the framework of the Holstein small polaron, Anderson localization, and Jahn-Teller distortion models. The fit to the small polaron mobility is dramatically improved when, instead of the longitudinal phonons, the transverse optical phonons are considered in the phonon-assisted electron transport. This serves as an indirect evidence of a strong 4 f1 orbital interaction with the oxygen ligands, similar to the case of PrO2. Based on comparison of the experimental data to the models, it is proposed that the defect-induced random electric fields make the dominant contribution to the electron localization in donor-doped ceria.

  12. Brillouin optical time-domain analysis sensor with amplification of pump pulses and tolerant to non-local effects

    NASA Astrophysics Data System (ADS)

    Mompó, Juan José; Urricelqui, Javier; Loayssa, Alayn

    2016-05-01

    We demonstrate a simple technique to provide conventional Brillouin optical time-domain analysis sensor with compensation for pump pulse attenuation and tolerance to non-local effects. The technique is based on operating the sensor in loss configuration so that energy is transferred from the probe wave to the pump pulse that becomes amplified as it counter-propagates with the probe wave. Furthermore, the optical frequency of the probe wave is modulated along the fiber so that the pump pulse experiences a flat gain spectrum that equally amplifies all the spectral components of the pulse, hence, preventing distortion. The method is experimentally demonstrated in a 100-km fiber link, obtaining a measurement uncertainty of 1 MHz at the worst-contrast position.

  13. Optical properties of local surface plasmon resonance in Ag/ITO sliced nanosphere by the discrete dipole approximation

    NASA Astrophysics Data System (ADS)

    Haiwei, Mu; Jingwei, Lv; Zhaoting, Liu; Shijie, Zheng; Lin, Yang; Tao, Sun; Qiang, Liu; Chao, Liu

    2016-04-01

    Optical properties of localized surface plasmon resonances (LSPR) of Ag/ITO sliced nanosphere have been studied using discrete dipole approximation and plasmon hybridization theory. It is found that different morphologies of sliced nanosphere can induce distinctive features in the extinction spectra. In the meanwhile, gap distances and refractive index of the surrounding medium could modulate the plasmon hybridization and the LSPR shifting. At large separation, the shift of LSPR peaks for the nanosphere sliced in halves consisting of ITO and Ag is small and insensitive to the gap distance in the weak coupling, whereas smaller separation exhibits a distinct red shift. Additionally, multiple resonance peaks are excited for the nanosphere sliced in quarters consisting of ITO and Ag. In this situation, electric field is mainly distributed in the gap region of sliced nanosphere and the central point. These results indicate that different morphologies of sliced nanosphere could create abundant tunable LSPR modes, which provides potential for multiplex optical sensing.

  14. Fermi polaron in a one-dimensional quasiperiodic optical lattice: The simplest many-body localization challenge

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Wang, An-Bang; Yi, Su; Liu, Xia-Ji

    2016-05-01

    We theoretically investigate the behavior of a moving impurity immersed in a sea of fermionic atoms that are confined in a quasiperiodic (bichromatic) optical lattice within a standard variational approach. We consider both repulsive and attractive contact interactions for such a simple many-body localization problem of Fermi polarons. The variational approach enables us to access relatively large systems and therefore may be used to understand many-body localization in the thermodynamic limit. The energy and wave function of the polaron states are found to be strongly affected by the quasirandom lattice potential and their experimental measurements (i.e., via radio-frequency spectroscopy or quantum gas microscope) therefore provide a sensitive way to underpin the localization transition. We determine a phase diagram by calculating two critical quasirandom disorder strengths, which correspond to the onset of the localization of the ground-state polaron state and the many-body localization of all polaron states, respectively. Our predicted phase diagram could be straightforwardly examined in current cold-atom experiments.

  15. Moving object localization using optical flow for pedestrian detection from a moving vehicle.

    PubMed

    Hariyono, Joko; Hoang, Van-Dung; Jo, Kang-Hyun

    2014-01-01

    This paper presents a pedestrian detection method from a moving vehicle using optical flows and histogram of oriented gradients (HOG). A moving object is extracted from the relative motion by segmenting the region representing the same optical flows after compensating the egomotion of the camera. To obtain the optical flow, two consecutive images are divided into grid cells 14 × 14 pixels; then each cell is tracked in the current frame to find corresponding cell in the next frame. Using at least three corresponding cells, affine transformation is performed according to each corresponding cell in the consecutive images, so that conformed optical flows are extracted. The regions of moving object are detected as transformed objects, which are different from the previously registered background. Morphological process is applied to get the candidate human regions. In order to recognize the object, the HOG features are extracted on the candidate region and classified using linear support vector machine (SVM). The HOG feature vectors are used as input of linear SVM to classify the given input into pedestrian/nonpedestrian. The proposed method was tested in a moving vehicle and also confirmed through experiments using pedestrian dataset. It shows a significant improvement compared with original HOG using ETHZ pedestrian dataset.

  16. Understanding local forces in electrophoretic ink systems: utilizing optical tweezers to explore electrophoretic display devices

    NASA Astrophysics Data System (ADS)

    Wei, David L.; Dickinson, Mark R.; Smith, N.; Gleeson, Helen F.

    2016-09-01

    Optical tweezers can be used as a valuable tool to characterize electrophoretic display (EPD) systems. EPDs are ubiquitous with e-readers and are becoming a commonplace technology where reflective, low-power displays are required; yet the physics of some features crucial to their operation remains poorly defined. We utilize optical tweezers as a tool to understand the motion of charged ink particles within the devices and show that the response of optically trapped electrophoretic particles can be used to characterize electric fields within these devices. This technique for mapping the force can be compared to simulations of the electric field in our devices, thus demonstrating that the electric field itself is the sole governor of the particle motion in an individual-particle regime. By studying the individual-particle response to the electric field, we can then begin to characterize particle motion in `real' systems with many particles. Combining optical tweezing with particle tracking techniques, we can investigate deviations in many particle systems from the single-particle case.

  17. A Proposal to Localize Fermi GBM GRBs Through Coordinated Scanning of the GBM Error Circle via Optical Telescopes

    NASA Technical Reports Server (NTRS)

    Ukwatta, T. N.; Linnemann, J. T.; Tollefson, K.; Abeysekara, A. U.; Bhat, P. N.; Sonbas, E.; Gehrels, N.

    2011-01-01

    We investigate the feasibility of implementing a system that will coordinate ground-based optical telescopes to cover the Fermi GBM Error Circle (EC). The aim of the system is to localize GBM detected GRBs and facilitate multi-wavelength follow-up from space and ground. This system will optimize the observing locations in the GBM EC based on individual telescope location, Field of View (FoV) and sensitivity. The proposed system will coordinate GBM EC scanning by professional as well as amateur astronomers around the world. The results of a Monte Carlo simulation to investigate the feasibility of the project are presented.

  18. A new optimization approach for the calibration of an ultrasound probe using a 3D optical localizer.

    PubMed

    Dardenne, G; Cano, J D Gil; Hamitouche, C; Stindel, E; Roux, C

    2007-01-01

    This paper describes a fast procedure for the calibration of an ultrasound (US) probe using a 3D optical localizer. This calibration step allows us to obtain the 3D position of any point located on the 2D ultrasonic (US) image. To carry out correctly this procedure, a phantom of known geometric properties is probed and these geometries are found in the US images. A segmentation step is applied in order to obtain automatically the needed information in the US images and then, an optimization approach is performed to find the optimal calibration parameters. A new optimization method to estimate the calibration parameters for an ultrasound (US) probe is developed.

  19. Identification and localization of multiple intrastromal foreign bodies with anterior segment optical coherence tomography and ocular Pentacam.

    PubMed

    Al-Ghadeer, Huda A; Al-Assiri, Abdullah

    2014-04-01

    To report the clinical aspects and the imaging of a patient with intrastromal glass foreign bodies after a road traffic accident using both anterior segment optical coherence tomography (OCT) and ocular Pentacam. A detailed case report was made of the use of anterior segment OCT (AS-OCT) and ocular Pentacam to evaluate intrastromal foreign bodies. AS-OCT and Pentacam were valuable non-invasive tools in identification, localization and monitoring patients with intrastromal foreign bodies. This report demonstrates that AS-OCT and ocular Pentacam are effective and necessary procedures for both the diagnosis and follow-up of intracorneal foreign bodies.

  20. Large area and low power dielectrowetting optical shutter with local deterministic fluid film breakup

    NASA Astrophysics Data System (ADS)

    Zhao, R.; Cumby, B.; Russell, A.; Heikenfeld, J.

    2013-11-01

    A large area (>10 cm2) and low-power (0.1-10 Hz AC voltage, ˜10's μW/cm2) dielectrowetting optical shutter requiring no pixelation is demonstrated. The device consists of 40 μm interdigitated electrodes covered by fluid splitting features and a hydrophobic fluoropolymer. When voltage is removed, the fluid splitting features initiate breakup of the fluid film into small droplets resulting in ˜80% transmission. Both the dielectrowetting and fluid splitting follow theory, allowing prediction of alternate designs and further improved performance. Advantages include scalability, optical polarization independence, high contrast ratio, fast response, and simple construction, which could be of use in switchable windows or transparent digital signage.

  1. Selective broadcast interconnection - A novel scheme for fiber-optic local-area networks

    NASA Technical Reports Server (NTRS)

    Marhic, M. E.; Birk, Y.; Tobagi, F. A.

    1985-01-01

    A passive, unswitched scheme is introduced for directly interconnecting N stations, each of which has C transmitters and receivers. Implementations using fiber optics with spatial multiplexing and optionally wavelength multiplexing are discussed. This scheme utilizes the same resources as standard topologies with C parallel buses but outperforms them in two respects: (1) the aggregate throughput is proportional to C squared rather than to C; and (2) the power of each transmitter need reach only N/C, instead of N, receivers.

  2. Spin Localization of a Fermi Polaron in a Quasirandom Optical Lattice

    NASA Astrophysics Data System (ADS)

    Duncan, C. W.; Loft, N. J. S.; Öhberg, P.; Zinner, N. T.; Valiente, M.

    2017-03-01

    Recently, the topics of many-body localization (MBL) and one-dimensional strongly interacting few-body systems have received a lot of interest. These two topics have been largely developed separately. However, the generality of the latter as far as external potentials are concerned—including random and quasirandom potentials—and their shared spatial dimensionality, makes it an interesting way of dealing with MBL in the strongly interacting regime. Utilising tools developed for few-body systems we look to gain insight into the localization properties of the spin in a Fermi gas with strong interactions. We observe a delocalized-localized transition over a range of fillings of a quasirandom lattice. We find this transition to be of a different nature for low and high fillings, due to the diluteness of the system for low fillings.

  3. Fiber-optic localization by geometric space coding with a two-dimensional gray code

    NASA Astrophysics Data System (ADS)

    Zheng, Yunhui; Brady, David J.; Sullivan, Michaell E.; Guenther, Bob D.

    2005-07-01

    With the objective of monitoring motion within a room, we segment the two-dimensional (2D) floor space into discrete cells and encode each cell with a binary code word generated by a fiber. We design a set of k-neighbor-local codes to localize an extended object and, particularly when k=2, employ a 2D gray code to localize a human by tracking his or her footsteps. Methods for implementing the codes in a fiber web are discussed, and we demonstrate the experimental result with the fiber mat. The observed system performance confirms the theoretical analysis. The space coding technique is a promising low-cost candidate not only for human tracking but also for other applications such as human gait analysis.

  4. Tagging photons with gold nanoparticles as localized absorbers in optical measurements in turbid media

    PubMed Central

    Grabtchak, Serge; Callaghan, Kristen B.; Whelan, William M.

    2013-01-01

    We analyze a role of a localized inclusion as a probe for spatial distributions of migrating photons in turbid media. We present new experimental data and two-dimensional analysis of radiance detection of a localized absorptive inclusion formed by gold nanoparticles in Intralipid-1% when the target is translated along the line connecting the light source and detector. Data are analyzed using the novel analytical expression for the relative angular photon distribution function for radiance developed by extending the perturbation approach for fluence. Obtained photon maps allow predicting conditions for detectability of inclusions for which proximity to the detector is essential. PMID:24409396

  5. Simultaneous determination of optical constants, local thickness and roughness of ZnSe thin films by imaging spectroscopic reflectometry

    NASA Astrophysics Data System (ADS)

    Nečas, D.; Ohlídal, I.; Franta, D.; Ohlídal, M.; Vodák, J.

    2016-01-01

    A rough non-uniform ZnSe thin film on a GaAs substrate is optically characterised using imaging spectroscopic reflectometry (ISR) in the visible, UV and near IR region, applied as a standalone technique. A global-local data processing algorithm is used to fit spectra from all pixels together and simultaneously determine maps of the local film thickness, roughness and overlayer thickness as well as spectral dependencies of film optical constants determined for the sample as a whole. The roughness of the film upper boundary is modelled using scalar diffraction theory (SDT), for which an improved calculation method is developed to process the large quantities of experimental data produced by ISR efficiently. This method avoids expensive operations by expressing the series obtained from SDT using a double recurrence relation and it is shown that it essentially eliminates the necessity for any speed-precision trade-offs in the SDT calculations. Comparison of characterisation results with the literature and other techniques shows the ability of multi-pixel processing to improve the stability and reliability of least-squares data fitting and demonstrates that standalone ISR, coupled with suitable data processing methods, is viable as a characterisation technique, even for thin films that are relatively far from ideal and require complex modelling.

  6. A Crowd-Sourcing Indoor Localization Algorithm via Optical Camera on a Smartphone Assisted by Wi-Fi Fingerprint RSSI.

    PubMed

    Chen, Wei; Wang, Weiping; Li, Qun; Chang, Qiang; Hou, Hongtao

    2016-03-19

    Indoor positioning based on existing Wi-Fi fingerprints is becoming more and more common. Unfortunately, the Wi-Fi fingerprint is susceptible to multiple path interferences, signal attenuation, and environmental changes, which leads to low accuracy. Meanwhile, with the recent advances in charge-coupled device (CCD) technologies and the processing speed of smartphones, indoor positioning using the optical camera on a smartphone has become an attractive research topic; however, the major challenge is its high computational complexity; as a result, real-time positioning cannot be achieved. In this paper we introduce a crowd-sourcing indoor localization algorithm via an optical camera and orientation sensor on a smartphone to address these issues. First, we use Wi-Fi fingerprint based on the K Weighted Nearest Neighbor (KWNN) algorithm to make a coarse estimation. Second, we adopt a mean-weighted exponent algorithm to fuse optical image features and orientation sensor data as well as KWNN in the smartphone to refine the result. Furthermore, a crowd-sourcing approach is utilized to update and supplement the positioning database. We perform several experiments comparing our approach with other positioning algorithms on a common smartphone to evaluate the performance of the proposed sensor-calibrated algorithm, and the results demonstrate that the proposed algorithm could significantly improve accuracy, stability, and applicability of positioning.

  7. A Crowd-Sourcing Indoor Localization Algorithm via Optical Camera on a Smartphone Assisted by Wi-Fi Fingerprint RSSI

    PubMed Central

    Chen, Wei; Wang, Weiping; Li, Qun; Chang, Qiang; Hou, Hongtao

    2016-01-01

    Indoor positioning based on existing Wi-Fi fingerprints is becoming more and more common. Unfortunately, the Wi-Fi fingerprint is susceptible to multiple path interferences, signal attenuation, and environmental changes, which leads to low accuracy. Meanwhile, with the recent advances in charge-coupled device (CCD) technologies and the processing speed of smartphones, indoor positioning using the optical camera on a smartphone has become an attractive research topic; however, the major challenge is its high computational complexity; as a result, real-time positioning cannot be achieved. In this paper we introduce a crowd-sourcing indoor localization algorithm via an optical camera and orientation sensor on a smartphone to address these issues. First, we use Wi-Fi fingerprint based on the K Weighted Nearest Neighbor (KWNN) algorithm to make a coarse estimation. Second, we adopt a mean-weighted exponent algorithm to fuse optical image features and orientation sensor data as well as KWNN in the smartphone to refine the result. Furthermore, a crowd-sourcing approach is utilized to update and supplement the positioning database. We perform several experiments comparing our approach with other positioning algorithms on a common smartphone to evaluate the performance of the proposed sensor-calibrated algorithm, and the results demonstrate that the proposed algorithm could significantly improve accuracy, stability, and applicability of positioning. PMID:27007379

  8. Manipulation of local optical properties and structures in molybdenum-disulfide monolayers using electric field-assisted near-field techniques

    PubMed Central

    Nozaki, Junji; Fukumura, Musashi; Aoki, Takaaki; Maniwa, Yutaka; Yomogida, Yohei; Yanagi, Kazuhiro

    2017-01-01

    Remarkable optical properties, such as quantum light emission and large optical nonlinearity, have been observed in peculiar local sites of transition metal dichalcogenide monolayers, and the ability to tune such properties is of great importance for their optoelectronic applications. For that purpose, it is crucial to elucidate and tune their local optical properties simultaneously. Here, we develop an electric field-assisted near-field technique. Using this technique we can clarify and tune the local optical properties simultaneously with a spatial resolution of approximately 100 nm due to the electric field from the cantilever. The photoluminescence at local sites in molybdenum-disulfide (MoS2) monolayers is reversibly modulated, and the inhomogeneity of the charge neutral points and quantum yields is suggested. We successfully etch MoS2 crystals and fabricate nanoribbons using near-field techniques in combination with an electric field. This study creates a way to tune the local optical properties and to freely design the structural shapes of atomic monolayers using near-field optics. PMID:28378804

  9. Radial localization of edge modes in Alcator C-Mod pedestals using optical diagnostics

    NASA Astrophysics Data System (ADS)

    Theiler, C.; Terry, J. L.; Edlund, E.; Cziegler, I.; Churchill, R. M.; Hughes, J. W.; LaBombard, B.; Golfinopoulos, T.; the Alcator C-Mod Team

    2017-02-01

    Dedicated experiments in ion cyclotron range heated enhanced D-alpha (EDA) H-mode and I-mode plasmas have been performed on Alcator C-Mod to identify the location of edge fluctuations inside the pedestal and to determine their plasma frame phase velocity. For this purpose, measurements from gas puff imaging (GPI) and gas puff charge exchange recombination spectroscopy (GP-CXRS) have been collected using the same optical views. The data suggest that the EDA H-mode-specific quasi-coherent mode (QCM) is centered near the radial electric field (E r) well minimum and propagates along the ion diamagnetic drift direction in the plasma frame. The weakly coherent mode (WCM) and the geodesic acoustic mode observed in I-mode, on the other hand, are found to be located around the outer shear layer of the E r well. This results in a weak plasma frame phase velocity mostly along the electron diamagnetic drift direction for the WCM. The findings in these EDA H-mode plasmas differ from probe measurements in ohmic EDA H-mode (LaBombard et al 2014 Phys. Plasmas 21 056108), where the QCM was identified as an electron drift-wave located several mm outside the E r well minimum in a region of positive E r. To explore if instrumental effects of the optical diagnostics could be the cause of the difference, a synthetic diagnostic for GPI is introduced. This diagnostic reproduces amplitude ratios and relative radial shifts of the mode profiles determined from poloidally and toroidally oriented optics and, if instrumental effects related to GP-CXRS are also included, indicates that the measured location of the QCM and WCM relative to the E r well reported here is only weakly affected by instrumental effects.

  10. Three-dimensional localization of fluorescent targets in turbid media using time reversal optical tomography

    NASA Astrophysics Data System (ADS)

    Wu, Binlin; Cai, W.; Gayen, S. K.

    2012-12-01

    An optical tomography approach for locating fluorescent targets embedded inside a turbid medium is introduced. It uses multi-source probing and multi-detector signal acquisition to collect diffuse fluorescence signal, and time reversal matrix formalism with subspace based signal processing for image reconstruction. It could provide three-dimensional position co-ordinates of two small fluorescent targets embedded in Intralipid-20% suspension of thickness ˜60 times the transport mean free path with an accuracy of ˜1 mm. Fast reconstruction and high spatial resolution make the approach potentially suited for detecting and locating contrast-enhanced breast tumor at early stages of growth.

  11. Electronic and optical properties of free standing Pt nanowires using localized basis sets

    NASA Astrophysics Data System (ADS)

    Kumar, Arun; Kumar, Ashok; Ahluwalia, P. K.

    2012-06-01

    In this paper we have investigated structural, electronic and optical properties of free standing ultrathin NWs of Pt with different topologies using ab-initio SIESTA code. Dimer and ladder chains have found smallest and largest cohesive energy respectively. Electronic band structure and DOS calculations finds more bands and states respectively around Fermi level in ladder topology of Pt chains. It is found that linear and dimer chains act as a good reflector as compared to ladder and zig-zag topologies of Pt chains. Plasmonic frequency of zig-zag and ladder chains are found largest and smallest respectively.

  12. Dynamic measurement of local displacements within curing resin-based dental composite using optical coherence elastography

    NASA Astrophysics Data System (ADS)

    Tomlins, Peter H.; Rahman, Mohammed Wahidur; Donnan, Robert S.

    2016-04-01

    This study aimed to determine the feasibility of using optical coherence elastography to measure internal displacements during the curing phase of a light-activated, resin-based composite material. Displacement vectors were spatially mapped over time within a commercial dental composite. Measurements revealed that the orientation of cure-induced displacement vectors varied spatially in a complex manner; however, each vector showed a systematic evolution with time. Precision of individual displacements was estimated to be ˜1 to 2 μm, enabling submicrometer time-varying displacements to be detected.

  13. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope

    NASA Astrophysics Data System (ADS)

    Suran, Swathi; Bharadwaj, Krishna; Raghavan, Srinivasan; Varma, Manoj M.

    2016-04-01

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of specific ions in the solution. It is anticipated that this technique will find use in applications ranging from single-nanoparticles resolved sensing to studying nanoscale fluid-solid interface phenomena.

  14. Afocal Optical Flow Sensor for Reducing Vertical Height Sensitivity in Indoor Robot Localization and Navigation

    PubMed Central

    Yi, Dong-Hoon; Lee, Tae-Jae; Cho, Dong-Il “Dan”

    2015-01-01

    This paper introduces a novel afocal optical flow sensor (OFS) system for odometry estimation in indoor robotic navigation. The OFS used in computer optical mouse has been adopted for mobile robots because it is not affected by wheel slippage. Vertical height variance is thought to be a dominant factor in systematic error when estimating moving distances in mobile robots driving on uneven surfaces. We propose an approach to mitigate this error by using an afocal (infinite effective focal length) system. We conducted experiments in a linear guide on carpet and three other materials with varying sensor heights from 30 to 50 mm and a moving distance of 80 cm. The same experiments were repeated 10 times. For the proposed afocal OFS module, a 1 mm change in sensor height induces a 0.1% systematic error; for comparison, the error for a conventional fixed-focal-length OFS module is 14.7%. Finally, the proposed afocal OFS module was installed on a mobile robot and tested 10 times on a carpet for distances of 1 m. The average distance estimation error and standard deviation are 0.02% and 17.6%, respectively, whereas those for a conventional OFS module are 4.09% and 25.7%, respectively. PMID:25985164

  15. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope

    PubMed Central

    Suran, Swathi; Bharadwaj, Krishna; Raghavan, Srinivasan; Varma, Manoj M.

    2016-01-01

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of specific ions in the solution. It is anticipated that this technique will find use in applications ranging from single-nanoparticles resolved sensing to studying nanoscale fluid-solid interface phenomena. PMID:27112966

  16. Local electric fields in optical glasses during field-assisted ionic exchanges

    NASA Astrophysics Data System (ADS)

    Lupascu, Alexandru I.; Kevorkian, Antoine P.; Cristescu, Constantin P.; Popescu, Ion M.

    2000-02-01

    We study the phenomena connected with high concentration of incoming ions emerging during field-assisted migration in otpical glass. We find that ion dynamics are very different at concentrations higher and lower than a certain parameter called the transition concentration. To explain anomalies at high ionic concentrations, we introduce a supplementary local electric field. This field opposes to the field E0 existing in the glass at all concentrations of incoming ions and is connected with a local space charge. We investigate its dependence on concentration and on E0. These effects are studied using a model with concentration-dependent diffusion coefficients and mobilities. We present a method to obtain the concentration dependence of the relevant quantities. Theoretical curves are compared with experimental results measured in usual silicate glasses, during Ag+-Na+ exchanges.

  17. Cavity light bullets: three-dimensional localized structures in a nonlinear optical resonator.

    PubMed

    Brambilla, Massimo; Maggipinto, Tommaso; Patera, Giuseppe; Columbo, Lorenzo

    2004-11-12

    We consider the paraxial model for a nonlinear resonator with a saturable absorber beyond the mean-field limit. For accessible parametric domains we observe total radiation confinement and the formation of 3D localized bright structures. Different from freely propagating light bullets, here the self-organization proceeds from the resonator feedback, combined with diffraction and nonlinearity. Such "cavity" light bullets can be independently excited and erased by appropriate pulses, and once created, they endlessly travel the cavity round-trip.

  18. Optical eye tracking system for real-time noninvasive tumor localization in external beam radiotherapy

    SciTech Connect

    Via, Riccardo Fassi, Aurora; Fattori, Giovanni; Fontana, Giulia; Pella, Andrea; Tagaste, Barbara; Ciocca, Mario; Riboldi, Marco; Baroni, Guido; Orecchia, Roberto

    2015-05-15

    Purpose: External beam radiotherapy currently represents an important therapeutic strategy for the treatment of intraocular tumors. Accurate target localization and efficient compensation of involuntary eye movements are crucial to avoid deviations in dose distribution with respect to the treatment plan. This paper describes an eye tracking system (ETS) based on noninvasive infrared video imaging. The system was designed for capturing the tridimensional (3D) ocular motion and provides an on-line estimation of intraocular lesions position based on a priori knowledge coming from volumetric imaging. Methods: Eye tracking is performed by localizing cornea and pupil centers on stereo images captured by two calibrated video cameras, exploiting eye reflections produced by infrared illumination. Additionally, torsional eye movements are detected by template matching in the iris region of eye images. This information allows estimating the 3D position and orientation of the eye by means of an eye local reference system. By combining ETS measurements with volumetric imaging for treatment planning [computed tomography (CT) and magnetic resonance (MR)], one is able to map the position of the lesion to be treated in local eye coordinates, thus enabling real-time tumor referencing during treatment setup and irradiation. Experimental tests on an eye phantom and seven healthy subjects were performed to assess ETS tracking accuracy. Results: Measurements on phantom showed an overall median accuracy within 0.16 mm and 0.40° for translations and rotations, respectively. Torsional movements were affected by 0.28° median uncertainty. On healthy subjects, the gaze direction error ranged between 0.19° and 0.82° at a median working distance of 29 cm. The median processing time of the eye tracking algorithm was 18.60 ms, thus allowing eye monitoring up to 50 Hz. Conclusions: A noninvasive ETS prototype was designed to perform real-time target localization and eye movement monitoring

  19. Optical coherence tomography as approach for the minimal invasive localization of the germinal disc in ovo before chicken sexing

    NASA Astrophysics Data System (ADS)

    Burkhardt, Anke; Geissler, Stefan; Koch, Edmund

    2010-04-01

    In most industrial states a huge amount of newly hatched male layer chickens are usually killed immediately after hatching by maceration or gassing. The reason for killing most of the male chickens of egg producing races is their slow growth rate compared to races specialized on meat production. When the egg has been laid, the egg contains already a small disc of cells on the surface of the yolk known as the blastoderm. This region is about 4 - 5 mm in diameter and contains the information whether the chick becomes male or female and hence allows sexing of the chicks by spectroscopy and other methods in the unincubated state. Different imaging methods like sonography, 3D-X-ray micro computed tomography and magnetic resonance imaging were used for localization of the blastoderm until now, but found to be impractical for different reasons. Optical coherence tomography (OCT) enables micrometer-scale, subsurface imaging of biological tissue and could therefore be a suitable technique for an accurate localization. The intention of this study is to prove if OCT can be an appropriate approach for the precise in ovo localization.

  20. Local differences in calretinin immunoreactivity in the optic tectum of the ocellated dragonet.

    PubMed

    Ulama, Tim; Hofmann, Michael H

    2016-11-01

    The optic tectum of the ocellated dragonet (Synchiropus ocellatus) was studied with immunohistochemistry. Antibodies raised against the calcium binding protein calretinin (CR) revealed a lamination similar to that already reported for other ray finned fish. Most immunoreactive fibers could be observed in those layers receiving retinal afferents and most immunoreactive cells occur in the stratum periventriculare. However, there are marked differences in the presence of other calretinin-positive cell types and immunoreactive lamina between the dorsomedial and ventrolateral parts of the tectum. Synchiropus is a bottom dwelling fish with strong functional subdivisions of the visual system into dorsal and lateral visual fields. The differences in calretinin-positive cell bodies and fibers may be a sensitive indicator of functional differences of tectal circuitry.

  1. Advances in Simultaneous Localization and Mapping in Confined Underwater Environments Using Sonar and Optical Imaging

    DTIC Science & Technology

    2016-01-01

    disable rendering the planar patches and factors for the sake of visual clarity. In ( b ) and ( f ), we overlay the nodes with their local saliency score...0.4 0.5 0.6 0.7 R e la ti ve F re q u e n c y BA GICP (c) DVL beam residuals: (a) vs ( b ) Figure 4.14: The distribution of residual error for DVL range...bottom ( f ) White region from ( b ), bottom Figure D.2: Rectified stereo pair example. Vertical lines placed uniformly on a stereo pair that is not

  2. Localized dynamic light scattering: a new approach to dynamic measurements in optical microscopy.

    PubMed

    Meller, A; Bar-Ziv, R; Tlusty, T; Moses, E; Stavans, J; Safran, S A

    1998-03-01

    We present a new approach to probing single-particle dynamics that uses dynamic light scattering from a localized region. By scattering a focused laser beam from a micron-size particle, we measure its spatial fluctuations via the temporal autocorrelation of the scattered intensity. We demonstrate the applicability of this approach by measuring the three-dimensional force constants of a single bead and a pair of beads trapped by laser tweezers. The scattering equations that relate the scattered intensity autocorrelation to the particle position correlation function are derived. This technique has potential applications for measurement of biomolecular force constants and probing viscoelastic properties of complex media.

  3. Local heat treatment of high strength steels with zoom-optics and 10kW-diode laser

    NASA Astrophysics Data System (ADS)

    Baumann, Markus; Krause, Volker; Bergweiler, Georg; Flaischerowitz, Martin; Banik, Janko

    2012-03-01

    High strength steels enable new solutions for weight optimized car bodies without sacrificing crash safety. However, cold forming of these steels is limited due to the need of high press capacity, increased tool wear, and limitations in possible geometries. One can compensate for these drawbacks by local heat treatment of the blanks. In high-deformation areas the strength of the material is reduced and the plasticity is increased by diode laser irradiation. Local heat treatment with diode laser radiation could also yield key benefits for the applicability of press hardened parts. High strength is not desired all over the part. Joint areas or deformation zones for requested crash properties require locally reduced strength. In the research project "LOKWAB" funded by the German Federal Ministry of Education and Research (BMBF), heat treatment of high strength steels was investigated in cooperation with Audi, BMW, Daimler, ThyssenKrupp, Fraunhofer- ILT, -IWU and others. A diode laser with an output power of 10 kW was set up to achieve acceptable process speed. Furthermore a homogenizing zoom-optics was developed, providing a rectangular focus with homogeneous power density. The spot size in x- and y-direction can be changed independently during operation. With pyrometer controlled laser power the surface temperature is kept constant, thus the laser treated zone can be flexibly adapted to the needs. Deep-drawing experiments show significant improvement in formability. With this technique, parts can be manufactured, which can conventionally only be made of steel with lower strength. Locally reduced strength of press hardened serial parts was demonstrated.

  4. Realization of a primary spectrophotometric system

    NASA Astrophysics Data System (ADS)

    Škerović, V.; Vukadin, P.; Zarubica, V.; Zeković, Lj

    2008-08-01

    The first step in establishing measurement uniformity in spectrophotometry is the realization of a versatile, fully evaluated and documented measurement system, which may, after metrological validation, be upheld as the primary spectrophotometric standard. In this paper, the development and realization of the spectrophotometer—primary standard in the Laboratory for Photometry of Bureau of Measures and Precious Metals—are presented. The construction of the system, as well as its metrological characterization, is shown. Evaluation of systematic errors due to various influential quantities and physical effects, such as light beam geometry effects, inter-reflections, nonlinearities and others, is presented. The results of measurements of spectral transmittance made with neutral optical filters and the evaluation of total measurement uncertainty are presented. Validation of the results was preformed according to National Institute for Standards and Technologies (NIST) certified standards of spectral transmittance.

  5. Accessing Extreme Spatiotemporal Localization of High-Power Laser Radiation through Transformation Optics and Scalar Wave Equations.

    PubMed

    Fedorov, V Yu; Chanal, M; Grojo, D; Tzortzakis, S

    2016-07-22

    Although tightly focused intense ultrashort laser pulses are used in many applications from nano-processing to warm dense matter physics, their nonparaxial propagation implies the use of numerical simulations with vectorial wave equations or exact Maxwell solvers that have serious limitations and thus have hindered progress in this important field up to now. Here we present an elegant and robust solution that allows one to map the problem on one that can be addressed by simple scalar wave equations. The solution is based on a transformation optics approach and its validity is demonstrated in both the linear and the nonlinear regime. Our solution allows accessing challenging problems of extreme spatiotemporal localization of high power laser radiation that remain almost unexplored theoretically until now.

  6. Distribution of high-stability 10 GHz local oscillator over 100 km optical fiber with accurate phase-correction system.

    PubMed

    Wang, Siwei; Sun, Dongning; Dong, Yi; Xie, Weilin; Shi, Hongxiao; Yi, Lilin; Hu, Weisheng

    2014-02-15

    We have developed a radio-frequency local oscillator remote distribution system, which transfers a phase-stabilized 10.03 GHz signal over 100 km optical fiber. The phase noise of the remote signal caused by temperature and mechanical stress variations on the fiber is compensated by a high-precision phase-correction system, which is achieved using a single sideband modulator to transfer the phase correction from intermediate frequency to radio frequency, thus enabling accurate phase control of the 10 GHz signal. The residual phase noise of the remote 10.03 GHz signal is measured to be -70  dBc/Hz at 1 Hz offset, and long-term stability of less than 1×10⁻¹⁶ at 10,000 s averaging time is achieved. Phase error is less than ±0.03π.

  7. Hematoporphyrin-derivative optical-fluorescence-detection instrument for localization of bladder and bronchous carcinoma in situ

    NASA Astrophysics Data System (ADS)

    Mattiello, James; Hetzel, Fred W.

    1986-09-01

    The use of hematoporphyrin derivative (HpD), a drug which concentrates in cancer cells, causes a cytotoxic effect on these cells when irradiated with the appropriate wavelength of light. The HpD will fluoresce at a wavelength of 630 nm when excited by 405-nm light. Instruments which are able to cause and detect this fluorescence will assist the surgeon to locate regions of neoplasms which contain HpD. Once the neoplastic region is located, the surgeon can treat this region destroying the neoplastic cells. The recent construction and successful operation of a photodetection instrument for the localization of early carcinoma in situ of the bladder and bronchous in humans is discussed. This instrument is in some ways similar to previously described devices with major improvements due to the use of available electro-optical equipment and elimination of the need for modification or manufacture of special surgical ``scopes,'' thereby minimizing construction costs.

  8. Mixed-symmetry localized modes and breathers in binary mixtures of Bose-Einstein condensates in optical lattices

    SciTech Connect

    Cruz, H. A.; Brazhnyi, V. A.; Konotop, V. V.; Alfimov, G. L.; Salerno, M.

    2007-07-15

    We study localized modes in binary mixtures of Bose-Einstein condensates embedded in one-dimensional optical lattices. We report a diversity of asymmetric modes and investigate their dynamics. We concentrate on the cases where one of the components is dominant, i.e., has a much larger number of atoms than the other one, and where both components have the numbers of atoms of the same order but different symmetries. In the first case we propose a method of systematically obtaining the modes, considering the 'small' component as bifurcating from the continuum spectrum. A generalization of this approach combined with the use of the symmetry of the coupled Gross-Pitaevskii equations allows for obtaining breather modes, which are also presented.

  9. Immunocytochemical Localization of Amines and GABA in the Optic Lobe of the Butterfly, Papilio xuthus

    PubMed Central

    Hamanaka, Yoshitaka; Kinoshita, Michiyo; Homberg, Uwe; Arikawa, Kentaro

    2012-01-01

    Butterflies have sophisticated color vision. While the spectral organization of the compound eye has been well characterized in the Japanese yellow swallowtail butterfly, Papilio xuthus, neural mechanisms underlying its color vision are largely unexplored. Towards a better understanding of signal processing in the visual system of P. xuthus, we used immunocytochemical techniques to analyze the distribution of transmitter candidates, namely, histamine, serotonin, tyramine and γ-aminobutyric acid (GABA). Photoreceptor terminals in the lamina and medulla exhibited histamine immunoreactivity as demonstrated in other insects. The anti-histamine antiserum also labeled a few large medulla neurons. Medulla intrinsic neurons and centrifugal neurons projecting to the lamina showed serotonin immunoreactivity. Tyramine immunostaining was detected in a subset of large monopolar cells (LMCs) in the lamina, transmedullary neurons projecting to the lobula plate, and cell bodies surrounding the first optic chiasma. An anti-GABA antiserum labeled a subset of LMCs and populations of columnar and tangential neurons surrounding the medulla. Each of the four antisera also labeled a few centrifugal neurons that innervate the lobula complex from the central brain, suggesting that they have neuromodulatory roles. A distinctive feature we found in this study is the possibility that tyramine and GABA act as transmitters in LMCs of P. xuthus, which has not been reported in any other insects so far. PMID:22844431

  10. Cardiac-induced localized thoracic motion detected by a fiber optic sensing scheme

    NASA Astrophysics Data System (ADS)

    Allsop, Thomas; Lloyd, Glynn; Bhamber, Ranjeet S.; Hadzievski, Ljupco; Halliday, Michael; Webb, David J.; Bennion, Ian

    2014-11-01

    The cardiovascular health of the human population is a major concern for medical clinicians, with cardiovascular diseases responsible for 48% of all deaths worldwide, according to the World Health Organization. The development of new diagnostic tools that are practicable and economical to scrutinize the cardiovascular health of humans is a major driver for clinicians. We offer a new technique to obtain seismocardiographic signals up to 54 Hz covering both ballistocardiography (below 20 Hz) and audible heart sounds (20 Hz upward), using a system based on curvature sensors formed from fiber optic long period gratings. This system can visualize the real-time three-dimensional (3-D) mechanical motion of the heart by using the data from the sensing array in conjunction with a bespoke 3-D shape reconstruction algorithm. Visualization is demonstrated by adhering three to four sensors on the outside of the thorax and in close proximity to the apex of the heart; the sensing scheme revealed a complex motion of the heart wall next to the apex region of the heart. The detection scheme is low-cost, portable, easily operated and has the potential for ambulatory applications.

  11. Channel access schemes and fiber optic configurations for integrated-services local area networks. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Nassehi, M. Mehdi

    1987-01-01

    Local Area Networks are in common use for data communications and have enjoyed great success. Recently, there is a growing interest in using a single network to support many applications in addition to traditional data traffic. These additional applications introduce new requirements in terms of volume of traffic and real-time delivery of data which are not met by existing networks. To satisfy these requirements, a high-bandwidth tranmission medium, such as fiber optics, and a distributed channel access scheme for the efficient sharing of the bandwidth among the various applications are needed. As far as the throughput-delay requirements of the various application are concerned, a network structure along with a distributed channel access are proposed which incorporate appropriate scheduling policies for the transmission of outstanding messages on the network. A dynamic scheduling policy was devised which outperforms all existing policies in terms of minimizing the expected cost per message. A broadcast mechanism was devised for the efficient dissemination of all relevant information. Fiber optic technology is considered for the high-bandwidth transmisison medium.

  12. Structural and optical characterization of the local environment of Er3+ ions in PbO-ZnO tellurite glasses.

    PubMed

    Ramamoorthy, R K; Bhatnagar, A K; Rocca, F; Mattarelli, M; Montagna, M

    2012-12-19

    Erbium activated PbO-ZnO tellurite glasses ((70TeO(2)-(30-x)ZnO-xPbO)(0.99)-(Er(2)O(3))(0.01) (TZPE), (x = 5, 10, 15, 20)) were prepared by a melt quenching process and studied by optical absorption, luminescence, Raman and x-ray absorption spectroscopy measurements as a function of the PbO/ZnO ratio. The glass structure, as monitored by Raman scattering, shows important changes with the PbO/ZnO ratio, attributed to a glass former action of PbO. The local environment of Er(3+) ions, as measured by extended x-ray absorption spectroscopy, does not appreciably change as regards the first oxygen shell. However, the intensity of the optical transitions is quite sensitive to the PbO/ZnO ratio, indicating a progressive increase of the site symmetry with the PbO content. The emission probability and radiative lifetime of several excited states of Er(3+) ions were calculated using Judd-Ofelt analysis.

  13. Localized Surface Plasmon Resonance (LSPR)-Coupled Fiber-Optic Nanoprobe for the Detection of Protein Biomarkers.

    PubMed

    Wei, Jianjun; Zeng, Zheng; Lin, Yongbin

    2017-01-01

    Here is presented a miniaturized, fiber-optic (FO) nanoprobe biosensor based on the localized surface plasmon resonance (LSPR) at the reusable dielectric-metallic hybrid interface with a robust, gold nano-disk array at the fiber end facet. The nanodisk array is directly fabricated using electron beam lithography (EBL) and metal lift-off process. The free prostate-specific antigen (f-PSA) has been detected with a mouse anti-human prostate-specific antigen (PSA) monoclonal antibody (mAb) as a specific receptor linked with a self-assembled monolayer (SAM) at the LSPR-FO facet surfaces. Experimental investigation and data analysis found near field refractive index (RI) sensitivity at ~226 nm/RIU with the LSPR-FO nanoprobe, and demonstrated the lowest limit of detection (LOD) at 100 fg/mL (~3 fM) of f-PSA in PBS solutions. The SAM shows insignificant nonspecific binding to the target biomarkers in the solution. The control experimentation using 5 mg/mL bovine serum albumin in PBS and nonspecific surface test shows the excellent specificity and selectivity in the detection of f-PSA in PBS. These results indicate important progress toward a miniaturized, multifunctional fiber-optic technology that integrates informational communication and sensing function for developing a high-performance, label-free, point-of-care (POC) device.

  14. Development of fiber optic laser Doppler velocimeter for measurement of local blood velocity

    NASA Astrophysics Data System (ADS)

    Ohba, Kenkich; Fujiwara, Noboru

    1993-08-01

    In order to measure the local velocity field in opaque fluid flows like blood flow, a new laser Doppler velocimeter having a pickup consisting of a small distributed index lens attached to the tips of two fibers which are joined side by side in parallel has been newly developed. The distributed index lens is the shape of a truncated cone. The flow field around this sensor has been measured very precisely by means of an ordinary LDV. The effect of turbidity of fluid on the quality of the laser Doppler signal from this sensor has been examined by experiments. As a result, it has been shown that this LDV sensor has a high signal-to-noise ratio, and that the disturbance against flow by the sensor is very small, and it is very promising as a velocity sensor for opaque or semi-opaque fluid flow like blood flow.

  15. Super-resolution mbPAINT for optical localization of single-stranded DNA.

    PubMed

    Chen, Jixin; Bremauntz, Alberto; Kisley, Lydia; Shuang, Bo; Landes, Christy F

    2013-10-09

    We demonstrate the application of superlocalization microscopy to identify sequence-specific portions of single-stranded DNA (ssDNA) with sequence resolution of 50 nucleotides, corresponding to a spatial resolution of 30 nm. Super-resolution imaging was achieved using a variation of a single-molecule localization method, termed as "motion blur" point accumulation for imaging in nanoscale topography (mbPAINT). The target ssDNA molecules were immobilized on the substrate. Short, dye-labeled, and complementary ssDNA molecules stochastically bound to the target ssDNA, with repeated binding events allowing super-resolution. Sequence specificity was demonstrated via the use of a control, noncomplementary probe. The results support the possibility of employing relatively inexpensive short ssDNAs to identify gene sequence specificity with improved resolution in comparison to the existing methods.

  16. Muscle oxygenation measurement in humans by noninvasive optical spectroscopy and Locally Weighted Regression.

    PubMed

    Arakaki, Lorilee S L; Schenkman, Kenneth A; Ciesielski, Wayne A; Shaver, Jeremy M

    2013-06-27

    We have developed a method to make real-time, continuous, noninvasive measurements of muscle oxygenation (Mox) from the surface of the skin. A key development was measurement in both the visible and near infrared (NIR) regions. Measurement of both oxygenated and deoxygenated myoglobin and hemoglobin resulted in a more accurate measurement of Mox than could be achieved with measurement of only the deoxygenated components, as in traditional near-infrared spectroscopy (NIRS). Using the second derivative with respect to wavelength reduced the effects of scattering on the spectra and also made oxygenated and deoxygenated forms more distinguishable from each other. Selecting spectral bands where oxygenated and deoxygenated forms absorb filtered out noise and spectral features unrelated to Mox. NIR and visible bands were scaled relative to each other in order to correct for errors introduced by normalization. Multivariate Curve Resolution (MCR) was used to estimate Mox from spectra within each data set collected from healthy subjects. A Locally Weighted Regression (LWR) model was built from calibration set spectra and associated Mox values from 20 subjects using 2562 spectra. LWR and Partial Least Squares (PLS) allow accurate measurement of Mox despite variations in skin pigment or fat layer thickness in different subjects. The method estimated Mox in five healthy subjects with an RMSE of 5.4%.

  17. Remote ballistic emplacement of an electro-optical and acoustic target detection and localization system

    NASA Astrophysics Data System (ADS)

    West, Aaron; Mellini, Mark

    2015-05-01

    Near real time situational awareness in uncontrolled non line of sight (NLOS) and beyond line of sight (BLOS) environments is critical in the asymmetric battlefield of future conflicts. The ability to detect and accurately locate hostile forces in difficult terrain or urban environments can dramatically increase the survivability and effectiveness of dismounted soldiers, especially when they are limited to the resources available only to the small unit. The Sensor Mortar Network (SMortarNet) is a 60mm Intelligence, Surveillance, and Reconnaissance (ISR) mortar designed to give the Squad near real time situational awareness in uncontrolled NLOS environments. SMortarNet is designed to track targets both acoustically and electro optically and can fuse tracks between, the acoustic, EO, and magnetic modalities on board. The system is linked to other mortar nodes and the user via a masterless frequency hopping spread spectrum ad-hoc mesh radio network. This paper will discuss SMortarNet in the context of a squad level dismounted soldier, its technical capabilities, and its benefit to the small unit Warfighter. The challenges with ballistic remote emplacement of sensitive components and the on board signal processing capabilities of the system will also be covered. The paper will also address how the sensor network can be integrated with existing soldier infrastructure, such as the NettWarrior platform, for rapid transition to soldier systems. Networks of low power sensors can have many forms, but the more practical networks for warfighters are ad hoc radio-based systems that can be rapidly deployed and can leverage a range of assets available at a given time. The low power long life networks typically have limited bandwidth and may have unreliable communication depending on the network health, which makes autonomous sensors a critical component of the network. SMortarNet reduces data to key information features at the sensor itself. The smart sensing approach enables

  18. Plasmonic phase transition and phase retardation: essential optical characteristics of localized surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Yu; Lin, Chun-Hung; Chen, Wei-Ting

    2013-09-01

    Phase transition that occurs around the spectral position of localized surface plasmon resonance (LSPR) has various applications for light manipulation and refractive index sensing. Previous studies focused on phase responses of specific plasmonic structures, whereas the general theoretical analysis remains inadequate. In this study, we analytically modeled the phase spectra and the intensity spectra of silver nanodots with temporal coupled-mode theory. The phase transition occurs at the transmission dip, whereas the phase of reflection varies much more gradually. We further derived the equation for the slope of the phase at the transmission dip, which is a function of the rates of Ohmic dissipation and emission. The theoretical analysis is also applicable for wide varieties of LSPR systems and provides an intuitive physical mechanism for phase properties. Then, based on the fundamental discussion, we further investigated plasmonic phase retardation in anisotropic nanodots for the application of boosting the figure of merit (FOM) of refractive index sensing. The anisotropic nanodots induce plasmonic phase transitions, which spectrally split, for transmission waves polarized along the symmetric axes. Thus, anisotropy induces relative phase retardation in the narrow spectral region between the wavelengths of the LSPRs. We numerically manipulated the full width at half maximum of the ellipsometric spectra by adjusting the aspect ratio of the nanodots and observed an FOM of 24.3. In addition, experiments were performed to demonstrate the feasibility of this arrangement.Phase transition that occurs around the spectral position of localized surface plasmon resonance (LSPR) has various applications for light manipulation and refractive index sensing. Previous studies focused on phase responses of specific plasmonic structures, whereas the general theoretical analysis remains inadequate. In this study, we analytically modeled the phase spectra and the intensity spectra of

  19. Challenges in realizing ultraflat materials surfaces

    PubMed Central

    Nomura, Wataru; Stehlin, Fabrice; Soppera, Olivier; Naruse, Makoto; Ohtsu, Motoichi

    2013-01-01

    Summary Ultraflat surface substrates are required to achieve an optimal performance of future optical, electronic, or optoelectronic devices for various applications, because such surfaces reduce the scattering loss of photons, electrons, or both at the surfaces and interfaces. In this paper, we review recent progress toward the realization of ultraflat materials surfaces. First, we review the development of surface-flattening techniques. Second, we briefly review the dressed photon–phonon (DPP), a nanometric quasiparticle that describes the coupled state of a photon, an electron, and a multimode-coherent phonon. Then, we review several recent developments based on DPP-photochemical etching and desorption processes, which have resulted in angstrom-scale flat surfaces. To confirm that the superior flatness of these surfaces that originated from the DPP process, we also review a simplified mathematical model that describes the scale-dependent effects of optical near-fields. Finally, we present the future outlook for these technologies. PMID:24367757

  20. Field-effect modulation of the local density of optical states in a reflectarray metasurface (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kafaie Shirmanesh, Ghazaleh; Sokhoyan, Ruzan; Han, Seunghoon; Atwater, Harry A.

    2016-09-01

    During recent years, advances in the design of arrays of subwavelength optical elements with special electromagnetic properties have enabled quasi two-dimensional structures that control and manipulate electromagnetic phase, amplitude and polarization. Active control of the response of metasurfaces is possible using transparent conducting oxides such as Indium Tin Oxide (ITO) as a tunable active material [1]. Changing the complex permittivity of ITO by applying a voltage yields modulation of reflected wave phase and amplitude. To achieve this, we designed subwavelength antenna arrays consisting of a gold back reflector and gold fishbone antennas. Planar dielectric layers containing a gate tunable layer of ITO are sandwiched between the back reflector and the antenna. The obtained structure shows resonance around 1.5 µm. As a result, based on the 1.54 µm photoluminescence emission of Er doped Al2O3 films, we embedded trivalent erbium ions as quantum emitters inside an alumina host within the metasurface in order to enhance the local density of optical states (LDOS). Simulations indicate the designed structure shows a significant LDOS enhancement (of order of hundreds). By applying a bias between the antenna and the ITO layer, across an HfO2 gate dielectric, we can control the permittivity of ITO and hence dynamically modulate the decay rate of quantum emitters embedded within the structure. In this way, we can achieve LDOS enhancement modulation of about 325%. 1. Y. W Huang, H. W. H. Lee, R. Sokhoyan, R. Pala, K. Thyagarajan, S. Han, D. P. Tsai, H. A. Atwater, "Gate-tunable conducting oxide metasurfaces". (arXiv:1511.09380).

  1. Very large aperture optics for space applications

    NASA Astrophysics Data System (ADS)

    Horwath, T. G.; Smith, J. P.; Johnson, M. T.

    1994-09-01

    A new type of space optics technology is presented which promises the realization of very large apertures (tens of meters), while packagable into lightweight, small volume containers compatible with conventional launch vehicles. This technology makes use of thin foils of circular shape which are uniformly mass loaded around the perimeter. Once unfurled and set into rapid rotation about the transversal axis, the foil is stretched into a perfectly flat plane by the centrifugal forces acting on the peripheral masses. The simplest applications of this novel technology are optically flat reflectors, using metallized foils of Mylar, Kevlar, or Kapton. Other more complex optical components can be realized by use of binary optics techniques, such as depositing holograms by selective local microscale removal of the reflective surface. Electrostatic techniques, in conjunction with an auxiliary foil, under local, distributed real-time control of the optical parameters, allow implementation of functions like beam steering and focal length adjustments. Gas pressurization allows stronger curvatures and thus smaller focal ratios for non-imaging applications. Limits on aperture are imposed primarily by manufacturing capabilities. Applications of such large optics in space are numerous. They range from military, such as space based lasers, to the civilian ones of power beaming, solar energy collection, and astronomy. This paper examines this simple and innovative concept in detail, discusses deployment and attitude control issues and presents approaches for realization.

  2. Local detection efficiency of a NbN superconducting single photon detector explored by a scattering scanning near-field optical microscope.

    PubMed

    Wang, Qiang; Renema, Jelmer J; Engel, Andreas; van Exter, Martin P; de Dood, Michiel J A

    2015-09-21

    We propose an experiment to directly probe the local response of a superconducting single photon detector using a sharp metal tip in a scattering scanning near-field optical microscope. The optical absorption is obtained by simulating the tip-detector system, where the tip-detector is illuminated from the side, with the tip functioning as an optical antenna. The local detection efficiency is calculated by considering the recently introduced position-dependent threshold current in the detector. The calculated response for a 150 nm wide detector shows a peak close to the edge that can be spatially resolved with an estimated resolution of ∼ 20 nm, using a tip with parameters that are experimentally accessible.

  3. Towards AC-induced optimum control of dynamical localization

    NASA Astrophysics Data System (ADS)

    Revuelta, F.; Chacón, R.; Borondo, F.

    2015-05-01

    It is shown that dynamical localization (quantum suppression of classical diffusion) in the context of ultracold atoms in periodically shaken optical lattices subjected to time-periodic modulations having equidistant zeros depends on the impulse transmitted by the external modulation over half-period rather than on the modulation amplitude. This result provides a useful principle for optimally controlling dynamical localization in general periodic systems, which is capable of experimental realization.

  4. Optical density of states in ultradilute GaAsN alloy: Coexistence of free excitons and impurity band of localized and delocalized states

    SciTech Connect

    Bhuyan, Sumi; Pal, Bipul; Bansal, Bhavtosh; Das, Sanat K.; Dhar, Sunanda

    2014-07-14

    Optically active states in liquid phase epitaxy-grown ultra-dilute GaAsN are studied. The feature-rich low temperature photoluminescence spectrum has contributions from excitonic band states of the GaAsN alloy, and two types of defect states—localized and extended. The degree of delocalization for extended states both within the conduction and defect bands, characterized by the electron temperature, is found to be similar. The degree of localization in the defect band is analyzed by the strength of the phonon replicas. Stronger emission from these localized states is attributed to their giant oscillator strength.

  5. Multiple realizability and biological laws.

    PubMed

    Raerinne, Jani P; Eronen, Markus I

    2012-01-01

    We critically analyze Alexander Rosenberg's argument based on the multiple realizability of biological properties that there are no biological laws. The argument is intuitive and suggestive. Nevertheless, a closer analysis reveals that the argument rests on dubious assumptions about the nature of natural selection, laws of nature, and multiple realizability. We also argue that the argument is limited in scope, since it applies to an outmoded account of laws and the applicability of the argument to other more promising accounts of laws is questionable. Another concern of ours is that the relation between multiple realizability and natural selection is more complex than Rosenberg acknowledges. Finally, we claim that an explanation for why Rosenberg's argument appears persuasive and appealing is that the argument is based on an inflated concept of multiple realizability that rests on unreliable intuitions concerning what counts as a different realization of the same property. Consequently, we argue that the argument is at best inconclusive and at worst false insofar as its implications for the existence of biological laws are concerned.

  6. Electronic resonance and local field effects on the nonlinear optical activity of H-aggregate-forming stilbazolium amphiphiles

    SciTech Connect

    Xu, Z.; Lu, W.; Bohn, P.W.

    1995-05-04

    Stilbazolium dyes, which form H-aggregates upon condensation at the air-water interface, typically display nonlinear optical (NLO) activity far below what would be predicted on the basis of their large intrinsic molecular hyperpolarizability, {beta}. Three separate hypothesis have been put forward to explain this observation: structural inversion to produce a centrosymmetric head-to-tail structure, local field effects, which act to reduce the effective magnitude of the nonlinear driving field, and changes in electronic structure, which shift the electronic resonance frequencies for the aggregates. Investigation of the linear and nonlinear spectroscopy of the dye 4-(4-dihexadecylaminostyryl)-N-methylpyridinium iodide were performed on a series of samples in which the aggregation state of the structure was changed systematically, but without changing the composition of the film. These experiments show that, for this particular dye, changes in electronic structure upon aggregation comprise the most important factor in determining the reduction in second harmonic generation (SHG) efficiency of the aggregate. 23 refs., 4 figs.

  7. Stochastic optical reconstruction microscopy-based relative localization analysis (STORM-RLA) for quantitative nanoscale assessment of spatial protein organization.

    PubMed

    Veeraraghavan, Rengasayee; Gourdie, Robert G

    2016-11-07

    The spatial association between proteins is crucial to understanding how they function in biological systems. Colocalization analysis of fluorescence microscopy images is widely used to assess this. However, colocalization analysis performed on two-dimensional images with diffraction-limited resolution merely indicates that the proteins are within 200-300 nm of each other in the xy-plane and within 500-700 nm of each other along the z-axis. Here we demonstrate a novel three-dimensional quantitative analysis applicable to single-molecule positional data: stochastic optical reconstruction microscopy-based relative localization analysis (STORM-RLA). This method offers significant advantages: 1) STORM imaging affords 20-nm resolution in the xy-plane and <50 nm along the z-axis; 2) STORM-RLA provides a quantitative assessment of the frequency and degree of overlap between clusters of colabeled proteins; and 3) STORM-RLA also calculates the precise distances between both overlapping and nonoverlapping clusters in three dimensions. Thus STORM-RLA represents a significant advance in the high-throughput quantitative assessment of the spatial organization of proteins.

  8. Stochastic optical reconstruction microscopy–based relative localization analysis (STORM-RLA) for quantitative nanoscale assessment of spatial protein organization

    PubMed Central

    Veeraraghavan, Rengasayee; Gourdie, Robert G.

    2016-01-01

    The spatial association between proteins is crucial to understanding how they function in biological systems. Colocalization analysis of fluorescence microscopy images is widely used to assess this. However, colocalization analysis performed on two-dimensional images with diffraction-limited resolution merely indicates that the proteins are within 200–300 nm of each other in the xy-plane and within 500–700 nm of each other along the z-axis. Here we demonstrate a novel three-dimensional quantitative analysis applicable to single-molecule positional data: stochastic optical reconstruction microscopy–based relative localization analysis (STORM-RLA). This method offers significant advantages: 1) STORM imaging affords 20-nm resolution in the xy-plane and <50 nm along the z-axis; 2) STORM-RLA provides a quantitative assessment of the frequency and degree of overlap between clusters of colabeled proteins; and 3) STORM-RLA also calculates the precise distances between both overlapping and nonoverlapping clusters in three dimensions. Thus STORM-RLA represents a significant advance in the high-throughput quantitative assessment of the spatial organization of proteins. PMID:27307586

  9. Three-dimensional study of planar optical antennas made of split-ring architecture outperforming dipole antennas for increased field localization.

    PubMed

    Kilic, Veli Tayfun; Erturk, Vakur B; Demir, Hilmi Volkan

    2012-01-15

    Optical antennas are of fundamental importance for the strongly localizing field beyond the diffraction limit. We report that planar optical antennas made of split-ring architecture are numerically found in three-dimensional simulations to outperform dipole antennas for the enhancement of localized field intensity inside their gap regions. The computational results (finite-difference time-domain) indicate that the resulting field localization, which is of the order of many thousandfold, in the case of the split-ring resonators is at least 2 times stronger than the one in the dipole antennas resonant at the same operating wavelength, while the two antenna types feature the same gap size and tip sharpness.

  10. A bio-inspired, computational model suggests velocity gradients of optic flow locally encode ordinal depth at surface borders and globally they encode self-motion.

    PubMed

    Raudies, Florian; Ringbauer, Stefan; Neumann, Heiko

    2013-09-01

    Visual navigation requires the estimation of self-motion as well as the segmentation of objects from the background. We suggest a definition of local velocity gradients to compute types of self-motion, segment objects, and compute local properties of optical flow fields, such as divergence, curl, and shear. Such velocity gradients are computed as velocity differences measured locally tangent and normal to the direction of flow. Then these differences are rotated according to the local direction of flow to achieve independence of that direction. We propose a bio-inspired model for the computation of these velocity gradients for video sequences. Simulation results show that local gradients encode ordinal surface depth, assuming self-motion in a rigid scene or object motions in a nonrigid scene. For translational self-motion velocity, gradients can be used to distinguish between static and moving objects. The information about ordinal surface depth and self-motion can help steering control for visual navigation.

  11. Approximate Counting of Graphical Realizations.

    PubMed

    Erdős, Péter L; Kiss, Sándor Z; Miklós, István; Soukup, Lajos

    2015-01-01

    In 1999 Kannan, Tetali and Vempala proposed a MCMC method to uniformly sample all possible realizations of a given graphical degree sequence and conjectured its rapidly mixing nature. Recently their conjecture was proved affirmative for regular graphs (by Cooper, Dyer and Greenhill, 2007), for regular directed graphs (by Greenhill, 2011) and for half-regular bipartite graphs (by Miklós, Erdős and Soukup, 2013). Several heuristics on counting the number of possible realizations exist (via sampling processes), and while they work well in practice, so far no approximation guarantees exist for such an approach. This paper is the first to develop a method for counting realizations with provable approximation guarantee. In fact, we solve a slightly more general problem; besides the graphical degree sequence a small set of forbidden edges is also given. We show that for the general problem (which contains the Greenhill problem and the Miklós, Erdős and Soukup problem as special cases) the derived MCMC process is rapidly mixing. Further, we show that this new problem is self-reducible therefore it provides a fully polynomial randomized approximation scheme (a.k.a. FPRAS) for counting of all realizations.

  12. Approximate Counting of Graphical Realizations

    PubMed Central

    2015-01-01

    In 1999 Kannan, Tetali and Vempala proposed a MCMC method to uniformly sample all possible realizations of a given graphical degree sequence and conjectured its rapidly mixing nature. Recently their conjecture was proved affirmative for regular graphs (by Cooper, Dyer and Greenhill, 2007), for regular directed graphs (by Greenhill, 2011) and for half-regular bipartite graphs (by Miklós, Erdős and Soukup, 2013). Several heuristics on counting the number of possible realizations exist (via sampling processes), and while they work well in practice, so far no approximation guarantees exist for such an approach. This paper is the first to develop a method for counting realizations with provable approximation guarantee. In fact, we solve a slightly more general problem; besides the graphical degree sequence a small set of forbidden edges is also given. We show that for the general problem (which contains the Greenhill problem and the Miklós, Erdős and Soukup problem as special cases) the derived MCMC process is rapidly mixing. Further, we show that this new problem is self-reducible therefore it provides a fully polynomial randomized approximation scheme (a.k.a. FPRAS) for counting of all realizations. PMID:26161994

  13. Non-linear optics and local-field factors in liquid chloroform: A time-dependent density-functional theory study

    NASA Astrophysics Data System (ADS)

    Strubbe, David A.; Andrade, Xavier; Rubio, Angel; Louie, Steve G.

    2009-03-01

    Chloroform is often used as a solvent and reference when measuring non-linear optical properties of organic molecules. We calculate directly the non-linear susceptibilities of liquid chloroform at optical frequencies, using molecular dynamics and the Sternheimer equation in time-dependent density-functional theory [X. Andrade et al., J. Chem. Phys. 126, 184106 (2007)]. We compare the results to those of chloroform in the gas and solid phases, and experimental values, and make an ab initio calculation of the local-field factors which are needed to extract molecular properties from liquid calculations and experimental measurements.

  14. Localized plasmon excitation in metal nanoclusters as a tool to study thickness-dependent optical properties of copper phthalocyanine ultrathin films

    NASA Astrophysics Data System (ADS)

    Stenzel, O.; Stendal, A.; Röder, M.; Wilbrandt, S.; Drews, D.; Werninghaus, T.; von Borczyskowski, C.; Zahn, D. R. T.

    1998-03-01

    Thin film sandwich samples have been prepared of copper phthalocyanine ultrathin solid films with incorporated metal (silver, indium) nanoclusters, surrounded by an amorphous silicon environment. The samples were investigated by transmission electron microscopy in both lateral and cross-sectional geometries. In view of the optical properties, we observed a gradual blue wavelength shift of the localized metal cluster plasmon excitation for about 300 nm accompanying an equivalent copper phthalocyanine thickness increase from `zero' to a threshold thickness of about 4 nm. We attribute this behaviour to the formation of bulk-like optical properties of the copper phthalocyanine film, which is completed at the observed equivalent threshold thickness.

  15. Amorphization-induced strong localization of electronic states in CsPbBr3 and CsPbCl3 studied by optical absorption measurements

    NASA Astrophysics Data System (ADS)

    Kondo, S.; Sakai, T.; Tanaka, H.; Saito, T.

    1998-11-01

    Optical absorption spectra of amorphous CsPbX3 films (X=Br,Cl) are characterized by two Gaussian bands near the fundamental edge, with the optical energy gap largely blueshifted and the absorption intensity strongly reduced as compared with the crystalline films. The peak energies of the bands are close to those of the A and C bands of Pb-doped alkali halides. The spectral features are discussed in terms of a molecular orbital theory based on a quasicomplex Pb2+(X-)6 model similar to the complex model for the doped alkali halides. It is shown that not only Pb2+ 6s and 6p extended states near the band edges but also X- p states contributing to upper valence bands are localized by amorphization. The transitions from the localized Pb2+ 6s to 6p states produce the spin-orbit allowed 3P1 and dipole allowed 1P1 states responsible for the two Gaussians. The localized X- p states lie deeper in energy than the localized Pb2+ 6s state and only contribute to higher-energy absorption above the Gaussian bands, giving the reason for the reduced absorption near the fundamental edge. The blueshift of the optical energy gap is attributed to the disappearance of k dispersions for these one-electron states.

  16. Multiparametric monitoring of chemotherapy treatment response in locally advanced breast cancer using quantitative ultrasound and diffuse optical spectroscopy

    PubMed Central

    Tran, William T.; Childs, Charmaine; Chin, Lee; Slodkowska, Elzbieta; Sannachi, Lakshmanan; Tadayyon, Hadi; Watkins, Elyse; Wong, Sharon Lemon; Curpen, Belinda; Kaffas, Ahmed El; Al-Mahrouki, Azza; Sadeghi-Naini, Ali; Czarnota, Gregory J.

    2016-01-01

    Purpose This study evaluated pathological response to neoadjuvant chemotherapy using quantitative ultrasound (QUS) and diffuse optical spectroscopy imaging (DOSI) biomarkers in locally advanced breast cancer (LABC). Materials and Methods The institution's ethics review board approved this study. Subjects (n = 22) gave written informed consent prior to participating. US and DOSI data were acquired, relative to the start of neoadjuvant chemotherapy, at weeks 0, 1, 4, 8 and preoperatively. QUS parameters including the mid-band fit (MBF), 0-MHz intercept (SI), and the spectral slope (SS) were determined from tumor ultrasound data using spectral analysis. In the same patients, DOSI was used to measure parameters relating to tumor hemoglobin and composition. Discriminant analysis and receiver-operating characteristic (ROC) analysis was used to classify clinical and pathological response during treatment and to estimate the area under the curve (AUC). Additionally, multivariate analysis was carried out for pairwise QUS/DOSI parameter combinations using a logistic regression model. Results Individual QUS and DOSI parameters, including the (SI), oxy-hemoglobin (HbO2), and total hemoglobin (HbT) were significant markers for response after one week of treatment (p < 0.01). Multivariate (pairwise) combinations increased the sensitivity, specificity and AUC at this time; the SI + HbO2 showed a sensitivity/specificity of 100%, and an AUC of 1.0. Conclusions QUS and DOSI demonstrated potential as coincident markers for treatment response and may potentially facilitate response-guided therapies. Multivariate QUS and DOSI parameters increased the sensitivity and specificity of classifying LABC patients as early as one week after treatment. PMID:26942698

  17. The Application of Fibre Optics in Fibre Distributed Data Interface (FDDI) 100Mb/s Local Area Networks (LANs)

    NASA Astrophysics Data System (ADS)

    King, Timothy; Roworth, Don

    1987-09-01

    The Fibre Distributed Data Interface (FDDI) is a flexible, high-speed token-passing twin ring network which is being specified by ANSI to provide synchronous and asynchronous data transmission, as well as isochronous channels for real-time digitised speech and video. Unlike existing open standard LANs, where fibre optic variants have been introduced following successful implementation on conductive media, FDDI has been designed from the start as a fibre optic network. This has involved issues of standardisation in such areas as duplex optical connectors, fibre characteristics, optical bandwidth, bypass relays and keyed cable assemblies. This paper gives an overview of the fibre optics aspects of the development, including the overall optical design, special component requirements, and practical issues of application.

  18. Design and realization of CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Xiao, Zexin

    2008-02-01

    A project was presented that instrumental design of an economical CMOS microscope image sensor. A high performance, low price, black-white camera chip OV5116P was used as the core of the sensor circuit; Designing and realizing peripheral control circuit of sensor; Through the control on dial switch to realize different functions of the sensor chip in the system. For example: auto brightness level descending function on or off; gamma correction function on or off; auto and manual backlight compensation mode conversion and so on. The optical interface of sensor is designed for commercialization and standardization. The images of sample were respectively gathered with CCD and CMOS. Result of the experiment indicates that both performances were identical in several aspects as follows: image definition, contrast control, heating degree and the function can be adjusted according to the demand of user etc. The imperfection was that the CMOS with smaller field and higher noise than CCD; nevertheless, the maximal advantage of choosing the CMOS chip is its low cost. And its imaging quality conformed to requirement of the economical microscope image sensor.

  19. Taking Materials Design Into The Space Of Polymorphs: Structure Predictions And Realizability

    NASA Astrophysics Data System (ADS)

    Stevanovic, Vladan

    The phenomenon of polymorphism exemplifies the significance of structural degrees of freedom in determining physical properties of solids. Classic case is elemental carbon with markedly different mechanical, optical and electronic properties between its graphite and diamond forms. To harness the richness of this phenomenon and extend rational materials design into the space of polymorphs, there is a need for developing approaches that are capable of exploring systematically and efficiently the potential energy surface, and (desirably) assist in experimental realization of different structures. While the former presents a common place in the field of structure predictions, less attention is given to the latter. Namely, available experimental data indicate that the energy above the ground state alone is insufficient to quantify the realizability of different structures. For example, MgO crystallizes exclusively as the rocksalt despite the predicted existence of a number of low-energy structures. Similarly, ZnO is realized in the wurtzite, zincblende and a relatively high-energy rocksalt structure, again, apparently disregarding a number of theoretically predicted low-energy structures. In this talk I will present recent attempts to tackle these issues focused on partially ionic systems. The structure prediction part is carried out by performing local DFT relaxations on a large set of random supperlattices (RSLs) with atoms distributed randomly over different planes in a way that favors cation-anion coordination. Second, application of the RSL sampling to a range of binary ionic systems such as MgO, ZnO, SnO2 and other, reveals that the frequency of occurrence of a given structure offers an estimate of the volume of configuration space occupied by the corresponding local minimum, which is shown to be connected to the realizability of different structures. This work is part of the Center for Next Generation of Materials by Design, a US DOE funded Energy Frontier

  20. Realization of high performance random laser diodes

    NASA Astrophysics Data System (ADS)

    Yu, S. F.

    2011-03-01

    For the past four decades, extensive studies have been concentrated on the understanding of the physics of random lasing phenomena in scattering media with optical gain. Although lasing modes can be excited from the mirrorless scattering media, the characteristics of high scattering loss, multiple-direction emission, as well as multiple-mode oscillation prohibited them to be used as practical laser cavities. Furthermore, due to the difficulty of achieving high optical gain under electrical excitation, electrical excitation of random lasing action was seldom reported. Hence, mirrorless random cavities have never been used to realize lasers for practical applications -- CD, DVD, pico-projector, etc. Nowadays, studies of random lasing are still limited to the scientific research. Recently, the difficulty of achieving `battery driven' random laser diodes has been overcome by using nano-structured ZnO as the random medium and the careful design of heterojunctions. This lead to the first demonstration of room-temperature electrically pumped random lasing action under continuity wave and pulsed operation. In this presentation, we proposed to realize an array of quasi-one dimensional ZnO random laser diodes. We can show that if the laser array can be manipulated in a way such that every individual random laser can be coupled laterally to and locked with a particular phase relationship to its adjacent neighbor, the laser array can obtain coherent addition of random modes. Hence, output power can be multiplied and one lasing mode will only be supported due to the repulsion characteristics of random modes. This work was supported by HK PolyU grant no. 1-ZV6X.

  1. GENERAL: Direct implementation of a scalable non-local multi-qubit controlled phase gate via optical fibres and adiabatic passage

    NASA Astrophysics Data System (ADS)

    Tang, Yao-Xiang; Lin, Xiu-Min; Lin, Gong-Wei; Chen, Li-Bo; Huang, Xiu-Hua

    2008-12-01

    This paper presents a direct implementation scheme of the non-local multi-qubit controlled phase gate by using optical fibres and adiabatic passage. The smaller operation number for implementing the multi-qubit controlled phase gate and needlessness for addressing individually save physical resource and lower the difficulties of experiment. Meanwhile, the scheme is immune from some decoherence effects such as the atomic spontaneous emission and fibre loss. In principle, it is scalable.

  2. Local ensemble transform Kalman filter, a fast non-stationary control law for adaptive optics on ELTs: theoretical aspects and first simulation results.

    PubMed

    Gray, Morgan; Petit, Cyril; Rodionov, Sergey; Bocquet, Marc; Bertino, Laurent; Ferrari, Marc; Fusco, Thierry

    2014-08-25

    We propose a new algorithm for an adaptive optics system control law, based on the Linear Quadratic Gaussian approach and a Kalman Filter adaptation with localizations. It allows to handle non-stationary behaviors, to obtain performance close to the optimality defined with the residual phase variance minimization criterion, and to reduce the computational burden with an intrinsically parallel implementation on the Extremely Large Telescopes (ELTs).

  3. A Wearable Goggle Navigation System for Dual-Mode Optical and Ultrasound Localization of Suspicious Lesions: Validation Studies Using Tissue-Simulating Phantoms and an Ex Vivo Human Breast Tissue Model

    PubMed Central

    Wang, Dong; Gan, Qi; Ye, Jian; Yue, Jian; Wang, Benzhong; Povoski, Stephen P.; Martin, Edward W.; Hitchcock, Charles L.; Yilmaz, Alper; Tweedle, Michael F.; Shao, Pengfei; Xu, Ronald X.

    2016-01-01

    Surgical resection remains the primary curative treatment for many early-stage cancers, including breast cancer. The development of intraoperative guidance systems for identifying all sites of disease and improving the likelihood of complete surgical resection is an area of active ongoing research, as this can lead to a decrease in the need of subsequent additional surgical procedures. We develop a wearable goggle navigation system for dual-mode optical and ultrasound imaging of suspicious lesions. The system consists of a light source module, a monochromatic CCD camera, an ultrasound system, a Google Glass, and a host computer. It is tested in tissue-simulating phantoms and an ex vivo human breast tissue model. Our experiments demonstrate that the surgical navigation system provides useful guidance for localization and core needle biopsy of simulated tumor within the tissue-simulating phantom, as well as a core needle biopsy and subsequent excision of Indocyanine Green (ICG)—fluorescing sentinel lymph nodes. Our experiments support the contention that this wearable goggle navigation system can be potentially very useful and fully integrated by the surgeon for optimizing many aspects of oncologic surgery. Further engineering optimization and additional in vivo clinical validation work is necessary before such a surgical navigation system can be fully realized in the everyday clinical setting. PMID:27367051

  4. A Wearable Goggle Navigation System for Dual-Mode Optical and Ultrasound Localization of Suspicious Lesions: Validation Studies Using Tissue-Simulating Phantoms and an Ex Vivo Human Breast Tissue Model.

    PubMed

    Zhang, Zeshu; Pei, Jing; Wang, Dong; Gan, Qi; Ye, Jian; Yue, Jian; Wang, Benzhong; Povoski, Stephen P; Martin, Edward W; Hitchcock, Charles L; Yilmaz, Alper; Tweedle, Michael F; Shao, Pengfei; Xu, Ronald X

    2016-01-01

    Surgical resection remains the primary curative treatment for many early-stage cancers, including breast cancer. The development of intraoperative guidance systems for identifying all sites of disease and improving the likelihood of complete surgical resection is an area of active ongoing research, as this can lead to a decrease in the need of subsequent additional surgical procedures. We develop a wearable goggle navigation system for dual-mode optical and ultrasound imaging of suspicious lesions. The system consists of a light source module, a monochromatic CCD camera, an ultrasound system, a Google Glass, and a host computer. It is tested in tissue-simulating phantoms and an ex vivo human breast tissue model. Our experiments demonstrate that the surgical navigation system provides useful guidance for localization and core needle biopsy of simulated tumor within the tissue-simulating phantom, as well as a core needle biopsy and subsequent excision of Indocyanine Green (ICG)-fluorescing sentinel lymph nodes. Our experiments support the contention that this wearable goggle navigation system can be potentially very useful and fully integrated by the surgeon for optimizing many aspects of oncologic surgery. Further engineering optimization and additional in vivo clinical validation work is necessary before such a surgical navigation system can be fully realized in the everyday clinical setting.

  5. Silencing and enhancement of second-harmonic generation in optical gap antennas.

    PubMed

    Berthelot, Johann; Bachelier, Guillaume; Song, Mingxia; Rai, Padmnabh; Colas des Francs, Gérard; Dereux, Alain; Bouhelier, Alexandre

    2012-05-07

    Amplifying local electromagnetic fields by engineering optical interactions between individual constituents of an optical antenna is considered fundamental for efficient nonlinear wavelength conversion in nanometer-scale devices. In contrast to this general statement we show that high field enhancement does not necessarily lead to an optimized nonlinear activity. In particular, we demonstrate that second-harmonic responses generated at strongly interacting optical gap antennas can be significantly suppressed. Numerical simulations are confirming silencing of second-harmonic in these coupled systems despite the existence of local field amplification. We then propose a simple approach to restore and amplify the second-harmonic signal by changing the manner in which electrically-connected optical antennas are interacting in the charge-transfer plasmon regime. Our observations provide critical design rules for realizing optimal structures that are essential for a broad variety of nonlinear surface-enhanced characterizations and for realizing the next generation of electrically-driven optical antennas.

  6. PREFACE: Nanospintronics design and realization

    NASA Astrophysics Data System (ADS)

    Akai, Hisazumi; Katayama-Yoshida, Hiroshi; Kasai, Hideaki

    2004-12-01

    This special issue of Journal of Physics: Condensed Matter contains selected papers from the 1st International Conference on Nanospintronics Design and Realization (ICNDR 2004), which was held in Kyoto, Japan, 24--28 May 2004. This conference was organized by the Nanospintronics Design and Realization project members: Hideaki Kasai, Osaka (Chair of the Conference) Hisazumi Akai, Osaka Hajime Asahi, Osaka Wilson Agerico Diño, Osaka Hiroshi Harima, Kyoto Tomoyuki Kakeshita, Osaka Junjiro Kanamori, Kyoto Hiroshi Katayama-Yoshida, Osaka Koichi Kusakabe, Osaka Hiroshi Nakanishi, Osaka (Secretary) Tamio Oguchi, Hiroshima Teruo Ono, Osaka Naoshi Suzuki, Osaka Hitoshi Tabata, Osaka under the auspices of the Japan Ministry of Education, Culture, Sports, Science and Technology (MEXT) Special Coordination Funds for Promoting Science and Technology, and the sponsorship of Osaka University and the International Institute for Advanced Studies (IIAS). The conference is intended to provide an international forum for experimental and theoretical researchers, in the rapidly developing field of nanospintronics. It aims to: provide an overview of our current understanding of the physics of spin transport in (magnetic) semiconductors and hybrid magnetic/semiconductor structures; provide a venue to present and discuss the latest developments in using spin-dependent phenomena in nano-(opto-) electronics and computing applications; provide a venue for discussion and assessment of other possible means of exploiting the spin-dependent phenomena in future nano-(opto-) electronic and computing applications; address current (and foreseeable future) problems, of fundamental and applied nature, in an effort to bridge the physics and technology gap between semiconducting and magnetic materials. All of these being geared towards bringing about the realization of a functioning nanospintronics. A total of 127 delegates from 15 countries took part in ICNDR 2004, which was comprised of 62 invited

  7. Discrete Time Crystals: Rigidity, Criticality, and Realizations.

    PubMed

    Yao, N Y; Potter, A C; Potirniche, I-D; Vishwanath, A

    2017-01-20

    Despite being forbidden in equilibrium, spontaneous breaking of time translation symmetry can occur in periodically driven, Floquet systems with discrete time-translation symmetry. The period of the resulting discrete time crystal is quantized to an integer multiple of the drive period, arising from a combination of collective synchronization and many body localization. Here, we consider a simple model for a one-dimensional discrete time crystal which explicitly reveals the rigidity of the emergent oscillations as the drive is varied. We numerically map out its phase diagram and compute the properties of the dynamical phase transition where the time crystal melts into a trivial Floquet insulator. Moreover, we demonstrate that the model can be realized with current experimental technologies and propose a blueprint based upon a one dimensional chain of trapped ions. Using experimental parameters (featuring long-range interactions), we identify the phase boundaries of the ion-time-crystal and propose a measurable signature of the symmetry breaking phase transition.

  8. Discrete Time Crystals: Rigidity, Criticality, and Realizations

    NASA Astrophysics Data System (ADS)

    Yao, N. Y.; Potter, A. C.; Potirniche, I.-D.; Vishwanath, A.

    2017-01-01

    Despite being forbidden in equilibrium, spontaneous breaking of time translation symmetry can occur in periodically driven, Floquet systems with discrete time-translation symmetry. The period of the resulting discrete time crystal is quantized to an integer multiple of the drive period, arising from a combination of collective synchronization and many body localization. Here, we consider a simple model for a one-dimensional discrete time crystal which explicitly reveals the rigidity of the emergent oscillations as the drive is varied. We numerically map out its phase diagram and compute the properties of the dynamical phase transition where the time crystal melts into a trivial Floquet insulator. Moreover, we demonstrate that the model can be realized with current experimental technologies and propose a blueprint based upon a one dimensional chain of trapped ions. Using experimental parameters (featuring long-range interactions), we identify the phase boundaries of the ion-time-crystal and propose a measurable signature of the symmetry breaking phase transition.

  9. Realizing autonomy in responsive relationships

    PubMed Central

    Houtepen, Rob; Spreeuwenberg, Cor; Widdershoven, Guy

    2010-01-01

    The goal of this article is to augment the ethical discussion among nurses with the findings from empirical research on autonomy of older adults with type 2 diabetes mellitus. There are many factors influencing autonomy. These include: health conditions, treatment, knowledge, experience and skills, personal approach as well as familial patterns, type of relationship, life history and social context. Fifteen older adults with type 2 diabetes mellitus were interviewed in a nurse-led diabetes clinic. These participants perceive three processes which support autonomy in responsive relationships: preserving patterns of concern and interaction, nurturing collaborative responsibilities and being closely engaged in trustful and helpful family relations. People with diabetes realize autonomy in various responsive relationships in their unique life context. Next, we performed a literature review of care ethics and caring in nursing with regard to relational autonomy. We classified the literature in five strands of care: attitude-oriented, dialogue-oriented, activity-oriented, relationship-oriented and life-oriented. According to our respondents, autonomy in responsive relationships is fostered when patient, nurses, professionals of the health team and family members carry out care activities supported by a relational attitude of care. They can best realize autonomy in relationships with others when several essential aspects of care and caring are present in their lives. Therefore, we advocate a comprehensive approach to care and caring. PMID:20339930

  10. Dreams, Perception, and Creative Realization.

    PubMed

    Glaskin, Katie

    2015-10-01

    This article draws on the ethnography of Aboriginal Australia to argue that perceptual openness, extending from waking life into dreaming experience, provides an important cognitive framework for the apprehension of dreamt experience in these contexts. I argue that this perceptual openness is analogous to the "openness to experience" described as a personality trait that had been linked with dream recall frequency (among other things). An implication of identifying perceptual openness at a cultural rather than at an individual level is two-fold. It provides an example of the ways in which cultural differences affect perception, indicative of cognitive diversity; and, given the relationship between dreams and creativity suggested anecdotally and through research, a cultural orientation toward perceptual openness is also likely to have implications for the realization of creativity that occurs through dreams. Such creativity though cannot be separated from the relational context in which such dreamt material is elaborated and understood.

  11. A Cyclic Universe Numerically Realized

    NASA Astrophysics Data System (ADS)

    Duhe, William; Biswas, Tirthbar

    2013-04-01

    A unique way of realizing inflation has been proposed recently in the context of cyclic cosmology where the universe grows by a constant factor in each cycle. This leads to an overall exponential growth over many cycles. In a given cycle such a growth is possible if, for instance, ``heavy particles'' can decay into radiation (photons) leading to an increase in entropy. However, to sustain this mechanism over successive cycles, it is crucial to reproduce the heavy particles back through quantum scattering processes and re-establish thermal equilibrium between all the species. We attempt to prove the viability of a ``multiple bang'' scenario to produce known cosmological data as well as use it to predict fluctuations in the upcoming higher resolution plank telescope data. This paradigm opens doors for new investigations into the principles surrounding the content and origin of the universe.

  12. Local optical emission spectroscopy of excited species effused from an evaporation cell and a sputter source into dense plasmas - Basic studies for the deposition of thin gradient films.

    PubMed

    Bolt, H; Hemel, V; Koch, F; Nickel, H

    1996-06-01

    Space resolved optical emission spectroscopy has been applied to determine the distribution of excited species in dense plasmas which are used for the deposition of thin coatings. Typical electron densities and electron temperatures in the plasma facility PETRA ( Plasma Engineering and Technology Research Assembly) are in the range of n(e) = 10(12) cm(-3) and T(e) = 10 eV. During the deposition process material (Al) is evaporated from a vapour cell under controlled conditions. The vapour stream is guided into a dense plasma which is composed of inert gas, Ar or He, and hydrocarbon species produced from the dissociation of C(2)H(2). The evaporated Al-stream which travels with thermal velocity into a plasma of high electron density, is nearly completely ionized due to the short mean free path for electron impact ionization in the above mentioned parameter range. Optical emission spectroscopy has been applied to investigate the interaction processes between the vapour stream and the plasma as well as the transport of the ionized Al along the applied magnetic field. For the measurements space resolved optical emission spectroscopy with an in-situ translation mechanism of the optical fibre has been used to measure the local concentrations of excited Al neutrals and ions as well as the concentration of the background plasma species.

  13. Monitoring the response to neoadjuvant hormone therapy for locally advanced breast cancer using three-dimensional time-resolved optical mammography

    NASA Astrophysics Data System (ADS)

    Enfield, Louise; Cantanhede, Gabriel; Douek, Michael; Ramalingam, Vernie; Purushotham, Arnie; Hebden, Jem; Gibson, Adam

    2013-05-01

    Optical mammography is a functional imaging technique that uses near-infrared light to produce three-dimensional breast images of tissue oxygen saturation and hemoglobin concentration. It has been used to monitor the response to neoadjuvant chemotherapy in breast cancer patients. We present the first results on monitoring tumor response to hormone therapy using optical mammography. We present three case studies from postmenopausal women treated with neoadjuvant hormone therapy for locally advanced breast cancer. The women were scanned before starting treatment, once during treatment, and then before surgery. Changes in physiological and optical properties within the tumor and in the rest of the breast were evaluated. At the time of surgery, two patients partially responded to treatment and one did not respond. The patients that partially responded on ultrasound revealed a corresponding recovery to normal in the hemoglobin concentration images, whereas the nonresponder indicated an increase in hemoglobin concentration in the tumor compared to her pretreatment images. These case studies suggest that optical imaging of the breast during neoadjuvant hormone treatment can provide potentially valuable information, and that physiological changes within the tumor can be seen in response to treatment.

  14. Acoustic Source Localization via Time Difference of Arrival Estimation for Distributed Sensor Networks using Tera-scale Optical-Core Devices

    SciTech Connect

    Imam, Neena; Barhen, Jacob

    2009-01-01

    For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. These sensors rely heavily on battery-operated system components to achieve highly functional automation in signal and information processing. In order to keep communication requirements minimal, it is desirable to perform as much processing on the receiver platforms as possible. However, the complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot be readily met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on the optical-core digital processing platform recently introduced by Lenslet Inc. This demonstration of considerably faster signal processing capability should be of substantial significance to the design and innovation of future generations of distributed sensor networks.

  15. Spatial localization of discrete fluorescent inclusions with early photons: an analysis on the stability with respect to variations of optical properties

    NASA Astrophysics Data System (ADS)

    Bodi, Geoffroy; Bérubé-Lauzière, Yves

    2009-06-01

    We recently developed a time-domain technique for localizing in 3D discrete fluorescent inclusions embedded in a scattering medium. It exploits early photon arrival times (EPATs), that is the time of flight of early arriving photons at a detector determined via numerical constant fraction discrimination. Our localization technique requires the knowledge of the speed of propagation of diffuse light pulses in the turbid medium to convert measured propagation times to distances. We have developed an experimental method for measuring the speed of propagation of such pulses. We have shown that time differences between a reference detector position and other positions around the medium allow finding the position of the inclusion. Our technique allows localizing inclusions to millimeter precision in a thick 5 cm diameter turbid medium. Herein, we analyze the stability of EPAT differences introduced above and propagation speeds with respect to changes in the medium's optical properties for optical properties typical of biological tissues. As we target small animal imaging, we concentrate on optical properties of mouse organs and tissues. Our objective is to determine bounds to be expected on the precision that can be achieved when media properties can vary and determine the limits of validity of our localization technique. Our results show that EPAT differences and propagation speeds obtained by our approach can vary; these values depend on the medium. We study 5 kinds of mouse organs and tissues. Propagations speeds are between 2.97 × 107ms-1 and 5.52 × 107ms-1. Thus, it becomes important to evaluate the discrepancy between true geometrical distance differences and distances as obtained by our approach using a constant propagation speed and the measurement of EPAT differences. It is such discrepancies that ultimately determine the localization accuracy of our algorithm because if distance differences based on EPATs are far from true distances, our algorithm although it

  16. Immunocytochemical localization of neuropeptide Y, serotonin, substance P and β-endorphin in optic ganglia and brain of Metapenaeus ensis

    NASA Astrophysics Data System (ADS)

    Ye, Haihui; Wang, Guizhong; Jin, Zhuxing; Huang, Huiyang; Li, Shaojing

    2006-12-01

    By using immunocytochemistry method of Strept Avidin-Biotin-Complex, four kinds of antisera raised against rabbits were applied to observe the immunoreactive neurons and neuropils of serotonin (5-HT), neuropeptide Y (NPY), substance P (SP) and β-Endorphin (β-Ep) in optic ganglia and brain of Metapenaeus ensis. The results showed that, the 5-HT-immunoreactive cells were located in all the four neuropils of optic ganglia. Immunoreactivity of 5-HT was detected in anterior medial protocerebrum neuropils (AMPN), and the inner and outer lateral beside olfactory lobe (OL) of deutocerebrum. The presence of NPY-immunoreactive cells was found in all the four neuropils of the optic ganglia. NPY-immunoreactivity occurred in the anterior median cell cluster, lateral cell cluster of protocerebrum, and cell cluster beside OL and AMPN. SP-immunoreactivity was found in medulla terminalis (MT) of optic ganglia, and lateral cell cluster of protocerebrum and posterior lateral cell cluster of tritocerebrum. β-Ep-immunoreactive cells were in MT only. In conclusion, these specific distribution patterns of the four immunoreactive substances can be used as morphological clues for understanding their different neurophysiological functions.

  17. Direct-write graded index materials realized in protein hydrogels

    NASA Astrophysics Data System (ADS)

    Kaehr, Bryan; Scrymgeour, David A.

    2016-09-01

    The ability to create optical materials with arbitrary index distributions would prove transformative for optics design and applications. However, current fabrication techniques for graded index (GRIN) materials rely on diffusion profiles and therefore are unable to realize arbitrary distribution GRIN design. Here, we demonstrate the laser direct writing of graded index structures in protein-based hydrogels using multiphoton lithography. We show index changes spanning a range of 10-2, which is comparable with laser densified glass and polymer systems. Further, we demonstrate the conversion of these written density variation structures into SiO2, opening up the possibility of transforming GRIN hydrogels to a wide range of material systems.

  18. Enhanced optical output of InGaN/GaN near-ultraviolet light-emitting diodes by localized surface plasmon of colloidal silver nanoparticles.

    PubMed

    Hong, Sang-Hyun; Kim, Jae-Joon; Kang, Jang-Won; Jung, Yen-Sook; Kim, Dong-Yu; Yim, Sang-Youp; Park, Seong-Ju

    2015-09-25

    We report on the characteristics of localized surface plasmon (LSP)-enhanced near-ultraviolet light-emitting diodes (NUV-LEDs) fabricated by using colloidal silver (Ag) nanoparticles (NPs). Colloidal Ag NPs were deposited on the 20 nm thick p-GaN spacer layer using a spray process. The optical output power of NUV-LEDs with colloidal Ag NPs was increased by 48.7% at 20 mA compared with NUV-LEDs without colloidal Ag NPs. The enhancement was attributed to increased internal quantum efficiency caused by the resonance coupling between excitons in the multiple quantum wells and the LSPs in the Ag NPs.

  19. Phase singularity of surface plasmon polaritons generated by optical vortices.

    PubMed

    Tan, P S; Yuan, G H; Wang, Q; Zhang, N; Zhang, D H; Yuan, X-C

    2011-08-15

    We demonstrate an experimental result that shows the phase singularity of surface plasmon waves generated by the direct transform of optical vortices at normal incidence focused on a structureless metal surface. The near-field two-dimensional intensity distribution near the focal plane is experimentally examined by using near-field scanning optical microscopy and shows a good agreement with the finite-difference time-domain simulation result. The experimental realization demonstrates a potential of the proposed excitation scheme to be reconfigured locally with advantages over structures milled into optically thick metallic films for plasmonics applications involving plasmonic vortices.

  20. Local Group

    NASA Astrophysics Data System (ADS)

    Mateo, M.; Murdin, P.

    2000-11-01

    Not long after EDWIN HUBBLE established that galaxies are `island universes' similar to our home galaxy, the MILKY WAY, he realized that a few of these external galaxies are considerably closer to us than any others. In 1936 he first coined the term `Local Group' in his famous book The Realm of the Nebulae to identify our nearest galactic neighbors. More than 60 yr later, the galaxies of the Loca...

  1. Transmission-reflection analysis for localization of temporally successive multipoint perturbations in a distributed fiber-optic loss sensor based on Rayleigh backscattering.

    PubMed

    Spirin, Vasilii V

    2003-03-01

    A novel method is presented for the localization of multipoint loss-inducing perturbations in a distributed fiber-optic sensor. The proposed simple technique is based on measurement of the transmitted and the Rayleigh-backscattered powers of an unmodulated light launched into a sensing fiber. The positions of consecutive perturbations are determined by measuring the slopes of the dependence of normalized Rayleigh-backscattering power versus the square of normalized transmitted power. It is shown that these slopes uniquely depend on the positions of the disturbances along the test fiber. The method allows localization of any number of the perturbations that appear one after another at different positions along the test fiber without ambiguity. Good agreement is obtained between calculated and experimentally measured slopes for a loss that was consecutively induced near the source and remote ends of 2.844-km-long fiber.

  2. Anderson Localization of a non-interacting Bose-Einstein condensate with effective spin-orbit interaction in a quasiperiodic optical lattice

    NASA Astrophysics Data System (ADS)

    Zhou, Lu; Pu, Han; Zhang, Weiping

    2013-03-01

    We theoretically investigate the localization properties of a noninteracting atomic Bose-Einstein condensate moving in a one-dimensional quasiperiodic optical lattice potential in the tight-binding regime. The atoms are subject to effective spin-orbit coupling induced by external laser fields. We present the phase diagram in the parameter space of the disorder strength and those related to the effective spin-orbit coupling. The phase diagram are verified via multifractal analysis of the atomic wavefunctions. We found that spin-orbit coupling can lead to the spectra mixing (coexistence of extended and localized states) and the appearance of mobility edges. We acknowledge National Natural Science Foundation of China under Grant No 11004057, Shanghai Rising-Star Program under Grant No. 12QA1401000 and the ``Chen Guang'' project under Grant No 10CG24 for financial supports.

  3. Realization and performance of cryogenic selection mechanisms

    NASA Astrophysics Data System (ADS)

    Aitink-Kroes, Gabby; Bettonvil, Felix; Kragt, Jan; Elswijk, Eddy; Tromp, Niels

    2014-07-01

    Within Infra-Red large wavelength bandwidth instruments the use of mechanisms for selection of observation modes, filters, dispersing elements, pinholes or slits is inevitable. The cryogenic operating environment poses several challenges to these cryogenic mechanisms; like differential thermal shrinkage, physical property change of materials, limited use of lubrication, high feature density, limited space etc. MATISSE the mid-infrared interferometric spectrograph and imager for ESO's VLT interferometer (VLTI) at Paranal in Chile coherently combines the light from 4 telescopes. Within the Cold Optics Bench (COB) of MATISSE two concepts of selection mechanisms can be distinguished based on the same design principles: linear selection mechanisms (sliders) and rotating selection mechanisms (wheels).Both sliders and wheels are used at a temperature of 38 Kelvin. The selection mechanisms have to provide high accuracy and repeatability. The sliders/wheels have integrated tracks that run on small, accurately located, spring loaded precision bearings. Special indents are used for selection of the slider/wheel position. For maximum accuracy/repeatability the guiding/selection system is separated from the actuation in this case a cryogenic actuator inside the cryostat. The paper discusses the detailed design of the mechanisms and the final realization for the MATISSE COB. Limited lifetime and performance tests determine accuracy, warm and cold and the reliability/wear during life of the instrument. The test results and further improvements to the mechanisms are discussed.

  4. Laboratory realization of KP-solitons

    NASA Astrophysics Data System (ADS)

    Yeh, Harry; Li, Wenwen

    2014-03-01

    Kodama and his colleagues presented a classification theorem for exact soliton solutions of the quasi-two-dimensional Kadomtsev-Petviashvili (KP) equation. The classification theorem is related to non-negative Grassmann manifold, Gr(N, M) that is parameterized by a unique chord diagram based on the derangement of the permutation group. The cord diagram can infer the asymptotic behavior of the solution with arbitrary number of line solitons. Here we present the realization of a variety of the KP soliton formations in the laboratory environment. The experiments are performed in a water tank designed and constructed for precision experiments for long waves. The tank is equipped with a directional-wave maker, capable of generating arbitrary-shaped multi-dimensional waves. Temporal and spatial variations of water-surface profiles are captured using the Laser Induces Fluorescent method - a nonintrusive optical measurement technique with sub-millimeter precision. The experiments yield accurate anatomy of the KP soliton formations and their evolution behaviors. Physical interpretations are discussed for a variety of KP soliton formations predicted by the classification theorem.

  5. Cryogenic-temperature profiling of high-power superconducting lines using local and distributed optical-fiber sensors.

    PubMed

    Chiuchiolo, Antonella; Palmieri, Luca; Consales, Marco; Giordano, Michele; Borriello, Anna; Bajas, Hugues; Galtarossa, Andrea; Bajko, Marta; Cusano, Andrea

    2015-10-01

    This contribution presents distributed and multipoint fiber-optic monitoring of cryogenic temperatures along a superconducting power transmission line down to 30 K and over 20 m distance. Multipoint measurements were conducted using fiber Bragg gratings sensors coated with two different functional overlays (epoxy and poly methyl methacrylate (PMMA)) demonstrating cryogenic operation in the range 300-4.2 K. Distributed measurements exploited optical frequency-domain reflectometry to analyze the Rayleigh scattering along two concatenated fibers with different coatings (acrylate and polyimide). The integrated system has been placed along the 20 m long cryostat of a superconducting power transmission line, which is currently being tested at the European Organization for Nuclear Research (CERN). Cool-down events from 300-30 K have been successfully measured in space and time, confirming the viability of these approaches to the monitoring of cryogenic temperatures along a superconducting transmission line.

  6. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-05-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  7. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan; Jersey Inst Ansari, New; Jersey Inst, New

    2005-04-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  8. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-06-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  9. Optical Flow-Based Tracking of Needles and Needle-Tip Localization Using Circular Hough Transform in Ultrasound Images

    PubMed Central

    Ayvali, Elif; Desai, Jaydev P.

    2014-01-01

    Image-guided interventions have become the standard of care for needle-based procedures. The success of the image-guided procedures depends on the ability to precisely locate and track the needle. This work is primarily focused on 2D ultrasound-based tracking of a hollow needle (cannula) that is composed of straight segments connected by shape memory alloy actuators. An in-plane tracking algorithm based on optical flow was proposed to track the cannula configuration in real-time. Optical flow is a robust tracking algorithm that can easily run on a CPU. However, the algorithm does not perform well when it is applied to the ultrasound images directly due to the intensity variation in the images. The method presented in this work enables using the optical flow algorithm on ultrasound images to track features of the needle. By taking advantage of the bevel tip, Circular Hough transform was used to accurately locate the needle tip when the imaging is out-of-plane. Through experiments inside tissue phantom and ex-vivo experiments in bovine kidney, the success of the proposed tracking methods were demonstrated. Using the methods presented in this work, quantitative information about the needle configuration is obtained in real-time which is crucial for generating control inputs for the needle and automating the needle insertion. PMID:25503523

  10. Fractal superconductivity near localization threshold

    SciTech Connect

    Feigel'man, M.V.; Ioffe, L.B.; Kravtsov, V.E.; Cuevas, E.

    2010-07-15

    We develop a semi-quantitative theory of electron pairing and resulting superconductivity in bulk 'poor conductors' in which Fermi energy E{sub F} is located in the region of localized states not so far from the Anderson mobility edge E{sub c}. We assume attractive interaction between electrons near the Fermi surface. We review the existing theories and experimental data and argue that a large class of disordered films is described by this model. Our theoretical analysis is based on analytical treatment of pairing correlations, described in the basis of the exact single-particle eigenstates of the 3D Anderson model, which we combine with numerical data on eigenfunction correlations. Fractal nature of critical wavefunction's correlations is shown to be crucial for the physics of these systems. We identify three distinct phases: 'critical' superconductive state formed at E{sub F} = E{sub c}, superconducting state with a strong pseudo-gap, realized due to pairing of weakly localized electrons and insulating state realized at E{sub F} still deeper inside a localized band. The 'critical' superconducting phase is characterized by the enhancement of the transition temperature with respect to BCS result, by the inhomogeneous spatial distribution of superconductive order parameter and local density of states. The major new feature of the pseudo-gapped state is the presence of two independent energy scales: superconducting gap {Delta}, that is due to many-body correlations and a new 'pseudo-gap' energy scale {Delta}{sub P} which characterizes typical binding energy of localized electron pairs and leads to the insulating behavior of the resistivity as a function of temperature above superconductive T{sub c}. Two gap nature of the pseudo-gapped superconductor is shown to lead to specific features seen in scanning tunneling spectroscopy and point-contact Andreev spectroscopy. We predict that pseudo-gapped superconducting state demonstrates anomalous behavior of the optical

  11. Explicit field realizations of W algebras

    NASA Astrophysics Data System (ADS)

    Wei, Shao-Wen; Liu, Yu-Xiao; Zhang, Li-Jie; Ren, Ji-Rong

    2009-06-01

    The fact that certain nonlinear W2,s algebras can be linearized by the inclusion of a spin-1 current can provide a simple way to realize W2,s algebras from linear W1,2,s algebras. In this paper, we first construct the explicit field realizations of linear W1,2,s algebras with double scalar and double spinor, respectively. Then, after a change of basis, the realizations of W2,s algebras are presented. The results show that all these realizations are Romans-type realizations.

  12. Understanding dust emission in the Bodélé region by extracting locally mobilized dust aerosols from satellite Aerosol Optical Depth data using principal component analysis

    NASA Astrophysics Data System (ADS)

    Parajuli, Sagar Prasad; Yang, Zong-Liang

    2017-02-01

    Despite the increasing availability of satellite and ground-based Aerosol Optical Depth (AOD) data, their application in dust modeling is limited because these data do not differentiate locally mobilized dust from remotely advected dust and other aerosols. In this work, we extract the locally mobilized Dust Optical Depth (DOD) in the Bodélé region from historical AOD data through a principal component analysis of wind speed and AOD time series (2003-2012). Principal component analysis effectively identifies the correlated signature between wind speed and AOD making it possible to separate the dust component from AOD data. Using the reconstructed DOD, we then study the effect of key environmental variables, namely wind speed, soil moisture, soil temperature, vegetation, and boundary layer height on dust emission. Results show that all of these environmental variables are significantly correlated with the reconstructed DOD indicating their association with the dust emission process. The extraction technique described in this study can be extended to regional and global scales to identify the dust sources which are not adequately represented in regional and global dust models.

  13. Europium-Doped NaYF4 Nanocrystals as Probes for the Electric and Magnetic Local Density of Optical States throughout the Visible Spectral Range

    PubMed Central

    2016-01-01

    Absorption and emission in the ultraviolet, visible, and infrared spectral range are usually mediated by the electric-field component of light. Only some electronic transitions have significant “magnetic-dipole” character, meaning that they couple to the magnetic field of light. Nanophotonic control over magnetic-dipole emission has recently been demonstrated, and magnetic-dipole transitions have been used to probe the magnetic-field profiles of photonic structures. However, the library of available magnetic-dipole emitters is currently limited to red or infrared emitters and mostly doped solids. Here, we show that NaYF4 nanocrystals doped with Eu3+ have various electric- and magnetic-dipole emission lines throughout the visible spectral range from multiple excited states. At the same time, the colloidal nature of the nanocrystals allows easy handling. We demonstrate the use of these nanocrystals as probes for the radiative electric and magnetic local density of optical states in a planar mirror geometry. A single emission spectrum can reveal enhancement or suppression of the density of optical states at multiple frequencies simultaneously. Such nanocrystals may find application in the characterization of nanophotonic structures or as model emitters for studies into magnetic light–matter interaction at optical frequencies.

  14. Investigating carrier localization and transfer in InGaN/GaN quantum wells with V-pits using near-field scanning optical microscopy and correlation analysis

    NASA Astrophysics Data System (ADS)

    Kim, Minkwan; Choi, Sunghan; Lee, Joo-Hyung; Park, Chunghyun; Chung, Tae-Hoon; Baek, Jong Hyeob; Cho, Yong-Hoon

    2017-02-01

    The V-pits and potential fluctuations in InGaN/GaN multiple quantum wells (MQWs) are key factors for understanding the performance of InGaN/GaN-based light-emitting diodes (LEDs). However, photoluminescence (PL) measurements using conventional optical microscopy only provide ensemble information due to the spatial resolution limit, known as the diffraction barrier, which hinders the analysis of dislocations and potential fluctuations. Here, in order to investigate the influence of the V-pits and potential fluctuations on local optical properties, we performed nanoscopic luminescence mapping for standard and V-pit InGaN/GaN MQWs samples with different sized V-pits using near-field scanning optical microscopy (NSOM) with illumination mode (I-mode) at various laser excitation powers. From the nanoscopic PL mapping data, we could clearly observe luminescence features associated with dislocations and potential fluctuations in the InGaN/GaN MQWs. We also employed correlation analysis to quantitatively analyze the nanoscopic PL mapping data for the different MQWs samples. Based on the results of NSOM PL with I-mode and correlation analysis, we could demonstrate that carrier transfer in the MQWs sample with large sized V-pits is suppressed by deeper potential fluctuations and higher energy barriers compared to the standard sample.

  15. Investigating carrier localization and transfer in InGaN/GaN quantum wells with V-pits using near-field scanning optical microscopy and correlation analysis.

    PubMed

    Kim, MinKwan; Choi, Sunghan; Lee, Joo-Hyung; Park, ChungHyun; Chung, Tae-Hoon; Baek, Jong Hyeob; Cho, Yong-Hoon

    2017-02-13

    The V-pits and potential fluctuations in InGaN/GaN multiple quantum wells (MQWs) are key factors for understanding the performance of InGaN/GaN-based light-emitting diodes (LEDs). However, photoluminescence (PL) measurements using conventional optical microscopy only provide ensemble information due to the spatial resolution limit, known as the diffraction barrier, which hinders the analysis of dislocations and potential fluctuations. Here, in order to investigate the influence of the V-pits and potential fluctuations on local optical properties, we performed nanoscopic luminescence mapping for standard and V-pit InGaN/GaN MQWs samples with different sized V-pits using near-field scanning optical microscopy (NSOM) with illumination mode (I-mode) at various laser excitation powers. From the nanoscopic PL mapping data, we could clearly observe luminescence features associated with dislocations and potential fluctuations in the InGaN/GaN MQWs. We also employed correlation analysis to quantitatively analyze the nanoscopic PL mapping data for the different MQWs samples. Based on the results of NSOM PL with I-mode and correlation analysis, we could demonstrate that carrier transfer in the MQWs sample with large sized V-pits is suppressed by deeper potential fluctuations and higher energy barriers compared to the standard sample.

  16. Investigating carrier localization and transfer in InGaN/GaN quantum wells with V-pits using near-field scanning optical microscopy and correlation analysis

    PubMed Central

    Kim, MinKwan; Choi, Sunghan; Lee, Joo-Hyung; Park, ChungHyun; Chung, Tae-Hoon; Baek, Jong Hyeob; Cho, Yong-Hoon

    2017-01-01

    The V-pits and potential fluctuations in InGaN/GaN multiple quantum wells (MQWs) are key factors for understanding the performance of InGaN/GaN-based light-emitting diodes (LEDs). However, photoluminescence (PL) measurements using conventional optical microscopy only provide ensemble information due to the spatial resolution limit, known as the diffraction barrier, which hinders the analysis of dislocations and potential fluctuations. Here, in order to investigate the influence of the V-pits and potential fluctuations on local optical properties, we performed nanoscopic luminescence mapping for standard and V-pit InGaN/GaN MQWs samples with different sized V-pits using near-field scanning optical microscopy (NSOM) with illumination mode (I-mode) at various laser excitation powers. From the nanoscopic PL mapping data, we could clearly observe luminescence features associated with dislocations and potential fluctuations in the InGaN/GaN MQWs. We also employed correlation analysis to quantitatively analyze the nanoscopic PL mapping data for the different MQWs samples. Based on the results of NSOM PL with I-mode and correlation analysis, we could demonstrate that carrier transfer in the MQWs sample with large sized V-pits is suppressed by deeper potential fluctuations and higher energy barriers compared to the standard sample. PMID:28198804

  17. Optical full-depth refocusing of 3-D objects based on subdivided-elemental images and local periodic δ-functions in integral imaging.

    PubMed

    Ai, Ling-Yu; Dong, Xiao-Bin; Jang, Jae-Young; Kim, Eun-Soo

    2016-05-16

    We propose a new approach for optical refocusing of three-dimensional (3-D) objects on their real depth without a pickup-range limitation based on subdivided-elemental image arrays (sub-EIAs) and local periodic δ-function arrays (L-PDFAs). The captured EIA from the 3-D objects locating out of the pickup-range, is divided into a number of sub-EIAs depending on the object distance from the lens array. Then, by convolving these sub-EIAs with each L-PDFA whose spatial period corresponds to the specific object's depth, as well as whose size is matched to that of the sub-EIA, arrays of spatially-filtered sub-EIAs (SF-sub-EIAs) for each object depth can be uniquely extracted. From these arrays of SF-sub-EIAs, 3-D objects can be optically reconstructed to be refocused on their real depth. Operational principle of the proposed method is analyzed based on ray-optics. In addition, to confirm the feasibility of the proposed method in the practical application, experiments with test objects are carried out and the results are comparatively discussed with those of the conventional method.

  18. Realization Theory in Hilbert Space

    DTIC Science & Technology

    1985-07-01

    Furthermore, a sufficient condition is that G(t) e R P x m is locally of bounded variation and satisfies an estimate of the form (6.10) VAR G r Me wt [0...not be of bounded variation . In the same way there exist time invariant, causal, linear input-output operators T which cannot be represented in the form...6.12) Tu(t) - f d(s)u(t-s) , t e R 0 for some matrix function U(t) of bounded variation . -29- " " " """. r . .................. .. . . . iliI

  19. Disk Galaxies in the Outer Local Supercluster: Optical CCD Surface Photometry and Distribution of Galaxy Disk Parameter

    NASA Technical Reports Server (NTRS)

    Lu, N. Y.

    1998-01-01

    We report new B-band CCD surface photometry on a sample of 76 disk galaxies brighter than BT = 14.5 mag in the Uppsala General Catalogue of Galaxies, which are confined within a volume located in the outer part of the Local Supercluster.

  20. Robust strain mapping in optical coherence elastography by combining local phase-resolved measurements and cumulative displacement tracking

    NASA Astrophysics Data System (ADS)

    Zaitsev, Vladimir Y.; Matveyev, Alexander L.; Matveev, Lev A.; Gelikonov, Grigory V.; Gubarkova, Ekaterina; Gladkova, Natalia D.; Vitkin, Alex

    2016-03-01

    We report a novel hybrid method of robust strain mapping in compressional optical coherence elastography using combined phase measurements on sub-wavelength-scale and cumulative pixel-scale displacement tracking. This hybrid nature significantly extends the range of measurable displacements and strains in comparison with conventional direct phase-resolved measurements. As a result, the proposed strain-mapping method exhibits significantly increased robustness with respect to both additive noise and decorrelation noise produced by displacements and strains. The main advantages of the proposed approach are illustrated by numerical simulations. Experimental examples of obtained strain maps for phantoms and real biological tissues are also presented.

  1. [Realization of optic activatory mechanism in laser-medication impact].

    PubMed

    Gerasimenko, M Iu; Skovorod'ko, S N; Kondakova, O A; Varavva, A S; Barybin, V F; Mendeleev, V Ia

    2006-01-01

    Clinical, biochemical, experimental, heat physical studies and mathematical calculations have shown that combined effect of drug-laser can be differentiated into the following effects: photophoresis, light pressure and photodynamic effect.

  2. On the nonlocal predictions of quantum optics

    NASA Technical Reports Server (NTRS)

    Marshall, Trevor W.; Santos, Emilio; Vidiella-Barranco, Antonio

    1994-01-01

    We give a definition of locality in quantum optics based upon Bell's work, and show that locality has been violated in no experiment performed up to now. We argue that the interpretation of the Wigner function as a probability density gives a very attractive local realistic picture of quantum optics provided that this function is nonnegative. We conjecture that this is the case for all states which can be realized in the laboratory. In particular, we believe that the usual representation of 'single photon states' by a Fock state of the Hilbert space is not correct and that a more physical, although less simple mathematically, representation involves density matrices. We study in some detail the experiment showing anticorrelation after a beam splitter and prove that it naturally involves a positive Wigner function. Our (quantum) predictions for this experiment disagree with the ones reported in the literature.

  3. Localized surface plasmons modulated nonlinear optical processes in metal film-coupled and upconversion nanocrystals-coated nanoparticles (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lei, Dangyuan

    2016-09-01

    In the first part of this talk, I will show our experimental investigation on the linear and nonlinear optical properties of metal film-coupled nanosphere monomers and dimers both with nanometric gaps. We have developed a new methodology - polarization resolved spectral decomposition and color decoding to "visualizing" unambiguously the spectral and radiation properties of the complex plasmonic gap modes in these hybrid nanostructures. Single-particle spectroscopic measurements indicate that these hybrid nanostructures can simultaneously enhance several nonlinear optical processes, such as second harmonic generation, two-photon absorption induced luminescence, and hyper-Raman scattering. In the second part, I will show how the polarization state of the emissions from sub-10 nm upconversion nanocrystals (UCNCs) can be modulated when they form a hybrid complex with a gold nanorod (GNR). Our single-particle scattering experiments expose how an interplay between excitation polarization and GNR orientation gives rise to an extraordinary polarized nature of the upconversion emissions from an individual hybrid nanostructure. We support our results by numerical simulations and, using Förster resonance energy transfer theory, we uncover how an overlap between the UCNC emission and GNR extinction bands as well as the mutual orientation between emission and plasmonic dipoles jointly determine the polarization state of the UC emissions.

  4. Methods for investigating the local spatial anisotropy and the preferred orientation of cones in adaptive optics retinal images

    PubMed Central

    Cooper, Robert F.; Lombardo, Marco; Carroll, Joseph; Sloan, Kenneth R.; Lombardo, Giuseppe

    2016-01-01

    The ability to non-invasively image the cone photoreceptor mosaic holds significant potential as a diagnostic for retinal disease. Central to the realization of this potential is the development of sensitive metrics for characterizing the organization of the mosaic. Here we evaluated previously-described (Pum et al., 1990) and newly-developed (Fourier- and Radon-based) methods of measuring cone orientation in both simulated and real images of the parafoveal cone mosaic. The proposed algorithms correlated well across both simulated and real mosaics, suggesting that each algorithm would provide an accurate description of individual photoreceptor orientation. Despite the high agreement between algorithms, each performed differently in response to image intensity variation and cone coordinate jitter. The integration property of the Fourier transform allowed the Fourier-based method to be resistant to cone coordinate jitter and perform the most robustly of all three algorithms. Conversely, when there is good image quality but unreliable cone identification, the Radon algorithm performed best. Finally, in cases where both the image and cone coordinate reliability was excellent, the method of Pum et al. (1990) performed best. These descriptors are complementary to conventional descriptive metrics of the cone mosaic, such as cell density and spacing, and have the potential to aid in the detection of photoreceptor pathology. PMID:27484961

  5. A study of optical reflectance and localization modes of 1-D Fibonacci photonic quasicrystals using different graded dielectric materials

    NASA Astrophysics Data System (ADS)

    Singh, Bipin K.; Pandey, Praveen C.

    2014-06-01

    In this paper, we present an analytical study on the reflection properties of light through one-dimensional (1-D) quasi-periodic multilayer structures. The considered structures are as follows: F7, F8, F9, (F2)10, (F3)10 and some combinations such as: [(F2)10 (F7) (F2)10], [(F2)10 (F8) (F2)10], [(F3)10 (F7) (F3)10], [(F3)10 (F8) (F3)10], [(F2)10(F3)10], [(F2)10 (F7) (F3)10] and [(F2)10 (F8) (F3)10], where (Fj)n represents n period of the Fibonacci sequence of jth generation. These multilayer structures are considered of two types of layers. One type of layer is considered of graded material like normal, linear or exponential graded material, and the second type of layer is considered of constant refractive index material. Transfer matrix method is utilized to calculate the reflection spectra and localization modes of such structures in the frequency range 150-450 THz. This work would provide the basis of understanding of the effect of graded materials on the reflection and localization modes in Fibonacci photonic quasicrystal structures and obtained spectra can be used in the recognition of grading of materials. The considered heterostructures provide the broad reflection band and some localization modes in the calculated region.

  6. Realizing "value-added" metrology

    NASA Astrophysics Data System (ADS)

    Bunday, Benjamin; Lipscomb, Pete; Allgair, John; Patel, Dilip; Caldwell, Mark; Solecky, Eric; Archie, Chas; Morningstar, Jennifer; Rice, Bryan J.; Singh, Bhanwar; Cain, Jason; Emami, Iraj; Banke, Bill, Jr.; Herrera, Alfredo; Ukraintsev, Vladamir; Schlessinger, Jerry; Ritchison, Jeff

    2007-03-01

    The conventional premise that metrology is a "non-value-added necessary evil" is a misleading and dangerous assertion, which must be viewed as obsolete thinking. Many metrology applications are key enablers to traditionally labeled "value-added" processing steps in lithography and etch, such that they can be considered integral parts of the processes. Various key trends in modern, state-of-the-art processing such as optical proximity correction (OPC), design for manufacturability (DFM), and advanced process control (APC) are based, at their hearts, on the assumption of fine-tuned metrology, in terms of uncertainty and accuracy. These trends are vehicles where metrology thus has large opportunities to create value through the engineering of tight and targetable process distributions. Such distributions make possible predictability in speed-sorts and in other parameters, which results in high-end product. Additionally, significant reliance has also been placed on defect metrology to predict, improve, and reduce yield variability. The necessary quality metrology is strongly influenced by not only the choice of equipment, but also the quality application of these tools in a production environment. The ultimate value added by metrology is a result of quality tools run by a quality metrology team using quality practices. This paper will explore the relationships among present and future trends and challenges in metrology, including equipment, key applications, and metrology deployment in the manufacturing flow. Of key importance are metrology personnel, with their expertise, practices, and metrics in achieving and maintaining the required level of metrology performance, including where precision, matching, and accuracy fit into these considerations. The value of metrology will be demonstrated to have shifted to "key enabler of large revenues," debunking the out-of-date premise that metrology is "non-value-added." Examples used will be from critical dimension (CD

  7. Localized surface plasmon resonances in gold nano-patches on a gallium nitride substrate.

    PubMed

    D'Antonio, Palma; Inchingolo, Alessio Vincenzo; Perna, Giuseppe; Capozzi, Vito; Stomeo, Tiziana; De Vittorio, Massimo; Magno, Giovanni; Grande, Marco; Petruzzelli, Vincenzo; D'Orazio, Antonella

    2012-11-16

    In this paper we describe the design, fabrication and characterization of gold nano-patches, deposited on gallium nitride substrate, acting as optical nanoantennas able to efficiently localize the electric field at the metal-dielectric interface. We analyse the performance of the proposed device, evaluating the transmission and the electric field localization by means of a three-dimensional finite difference time domain (FDTD) method. We detail the fabrication protocol and show the morphological characterization. We also investigate the near-field optical transmission by means of scanning near-field optical microscope measurements, which reveal the excitation of a localized surface plasmon resonance at a wavelength of 633 nm, as expected by the FDTD calculations. Such results highlight how the final device can pave the way for the realization of a single optical platform where the active material and the metal nanostructures are integrated together on the same chip.

  8. Investigation of the linear and second-order nonlinear optical properties of molecular crystals within the local field theory.

    PubMed

    Seidler, Tomasz; Stadnicka, Katarzyna; Champagne, Benoît

    2013-09-21

    In this paper it is shown that modest calculations combining first principles evaluations of the molecular properties with electrostatic interaction schemes to account for the crystal environment effects are reliable for predicting and interpreting the experimentally measured electric linear and second-order nonlinear optical susceptibilities of molecular crystals within the experimental error bars. This is illustrated by considering two molecular crystals, namely: 2-methyl-4-nitroaniline and 4-(N,N-dimethylamino)-3-acetamidonitrobenzene. Three types of surrounding effects should be accounted for (i) the polarization due to the surrounding molecules, described here by static electric fields originating from their electric dipoles or charge distributions, (ii) the intermolecular interactions, which affect the geometry and particularly the molecular conformation, and (iii) the screening of the external electric field by the constitutive molecules. This study further highlights the role of electron correlation on the linear and nonlinear responses of molecular crystals and the challenge of describing frequency dispersion.

  9. Optical and local structural study of Gd doped ZrO{sub 2} thin films deposited by RF magnetron sputtering technique

    SciTech Connect

    Haque, S. Maidul Shinde, D. D.; Misal, J. S.; Jha, S. N.; Bhattacharyya, D.; Sahoo, N. K.

    2015-06-24

    ZrO{sub 2} samples with 0, 7, 9, 11, 13 % Gd doping have been prepared by RF magnetron sputtering deposition technique for solid oxide fuel cell application. The optical properties of the samples have been studied by transmission spectrophotometry and spectroscopic ellipsometry while the local structure surrounding Zr sites has been characterized by extended x-ray absorption fine structure (EXAFS) measurement at Zr K edge with synchrotron radiation. It has been observed that beyond 11% Gd doping, band gap decreases and refractive index increases significantly and also oxygen and Zr coordinations surrounding Zr sites increase which indicates the formation of Gd clustering in ZrO{sub 2} matrix beyond this doping concentration.

  10. Visualization of the Local Carrier Dynamics in an InGaN Quantum Well Using Dual-Probe Scanning Near-Field Optical Microscopy

    NASA Astrophysics Data System (ADS)

    Kaneta, Akio; Hashimoto, Tsuneaki; Nishimura, Katsuhito; Funato, Mitsuru; Kawakami, Yoichi

    2010-10-01

    We have developed dual-probe scanning near-field optical microscopy (SNOM) to visualize detailed carrier diffusion/recombination processes and applied it to the assessment of the local carrier dynamics in an InGaN single quantum well. It is clearly demonstrated that the carrier motion is strongly affected by the potential distribution within InGaN; potential ridges prevent carriers from diffusing outside them, whereas potential peaks cause carriers to travel a roundabout route around them. As a consequence, carriers anisotropically diffuse for several hundred nanometers along a specific direction toward a strong-photoluminescence domain. Thus, the dual-probe SNOM technique is a powerful nanoscopic tool, and may be versatile for characterizing photonic materials.

  11. Time-domain reflectance diffuse optical tomography with Mellin-Laplace transform for experimental detection and depth localization of a single absorbing inclusion

    PubMed Central

    Puszka, Agathe; Hervé, Lionel; Planat-Chrétien, Anne; Koenig, Anne; Derouard, Jacques; Dinten, Jean-Marc

    2013-01-01

    We show how to apply the Mellin-Laplace transform to process time-resolved reflectance measurements for diffuse optical tomography. We illustrate this method on simulated signals incorporating the main sources of experimental noise and suggest how to fine-tune the method in order to detect the deepest absorbing inclusions and optimize their localization in depth, depending on the dynamic range of the measurement. To finish, we apply this method to measurements acquired with a setup including a femtosecond laser, photomultipliers and a time-correlated single photon counting board. Simulations and experiments are illustrated for a probe featuring the interfiber distance of 1.5 cm and show the potential of time-resolved techniques for imaging absorption contrast in depth with this geometry. PMID:23577292

  12. Optical properties of silicon nanowire arrays formed by metal-assisted chemical etching: evidences for light localization effect

    NASA Astrophysics Data System (ADS)

    Osminkina, Liubov A.; Gonchar, Kirill A.; Marshov, Vladimir S.; Bunkov, Konstantin V.; Petrov, Dmitry V.; Golovan, Leonid A.; Talkenberg, Florian; Sivakov, Vladimir A.; Timoshenko, Victor Yu

    2012-09-01

    We study the structure and optical properties of arrays of silicon nanowires (SiNWs) with a mean diameter of approximately 100 nm and length of about 1-25 μm formed on crystalline silicon (c-Si) substrates by using metal-assisted chemical etching in hydrofluoric acid solutions. In the middle infrared spectral region, the reflectance and transmittance of the formed SiNW arrays can be described in the framework of an effective medium with the effective refractive index of about 1.3 (porosity, approximately 75%), while a strong light scattering for wavelength of 0.3 ÷ 1 μm results in a decrease of the total reflectance of 1%-5%, which cannot be described in the effective medium approximation. The Raman scattering intensity under excitation at approximately 1 μm increases strongly in the sample with SiNWs in comparison with that in c-Si substrate. This effect is related to an increase of the light-matter interaction time due to the strong scattering of the excitation light in SiNW array. The prepared SiNWs are discussed as a kind of `black silicon', which can be formed in a large scale and can be used for photonic applications as well as in molecular sensing.

  13. Analyzing Hydrogen Recombination Lines in the Infrared and Optical to Determine Extinction and SFRs of Local LIRGs

    NASA Astrophysics Data System (ADS)

    Payne, Anna; Inami, Hanae

    2015-01-01

    We report on measurements for dust extinction and star formation rates (SFRs) for luminous infrared galaxies (LIRGs). We utilized the hydrogen recombination lines Brα, Hα, and Hβ observed in the infrared and optical wavelengths with AKARI and the Lick Observatory's Kast Double spectrograph to produce spectra. By calculating Brα/Hα ratios for the target galaxies, extinction is estimated. A possible correlation between higher LIR, IR/UV, specific SFRs and higher Brα/Hα has been found. Through comparisons with Hα/Hβ, it may be possible to determine if Hα is, in fact, underestimating extinction, since Hα is more strongly affected by extinction compared to longer wavelengths such as Brα. The accuracy of using Hα in extinction corrections is important for SFR studies, and, thus, one goal is to find a more accurate reddening correction factor. Payne was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829).

  14. Optical properties of silicon nanowire arrays formed by metal-assisted chemical etching: evidences for light localization effect.

    PubMed

    Osminkina, Liubov A; Gonchar, Kirill A; Marshov, Vladimir S; Bunkov, Konstantin V; Petrov, Dmitry V; Golovan, Leonid A; Talkenberg, Florian; Sivakov, Vladimir A; Timoshenko, Victor Yu

    2012-09-25

    We study the structure and optical properties of arrays of silicon nanowires (SiNWs) with a mean diameter of approximately 100 nm and length of about 1-25 μm formed on crystalline silicon (c-Si) substrates by using metal-assisted chemical etching in hydrofluoric acid solutions. In the middle infrared spectral region, the reflectance and transmittance of the formed SiNW arrays can be described in the framework of an effective medium with the effective refractive index of about 1.3 (porosity, approximately 75%), while a strong light scattering for wavelength of 0.3 ÷ 1 μm results in a decrease of the total reflectance of 1%-5%, which cannot be described in the effective medium approximation. The Raman scattering intensity under excitation at approximately 1 μm increases strongly in the sample with SiNWs in comparison with that in c-Si substrate. This effect is related to an increase of the light-matter interaction time due to the strong scattering of the excitation light in SiNW array. The prepared SiNWs are discussed as a kind of 'black silicon', which can be formed in a large scale and can be used for photonic applications as well as in molecular sensing.

  15. Investigation of subcellular localization and dynamics of membrane proteins in living bacteria by combining optical micromanipulation and high-resolution microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Barroso Peña, Álvaro; Nieves, Marcos; Teper, Konrad; Wedlich-Soldner, Roland; Denz, Cornelia

    2016-09-01

    The plasma membrane serves as protective interface between cells and their environment. It also constitutes a hub for selective nutrient uptake and signal transduction. Increasing evidence over the last years indicates that, similar to eukaryotic cells, lateral membrane organization plays an important role in the regulation of prokaryotic signaling pathways. However, the mechanisms underlying this phenomenon are still poorly understood. Spatiotemporal characterization of bacterial signal transduction demands very sensitive high-resolution microscopy techniques due to the low expression levels of most signaling proteins and the small size of bacterial cells. In addition, direct study of subcellular confinement and dynamics of bacterial signaling proteins during the different stages of the signal transduction also requires immobilization in order to avoid cell displacement caused by Brownian motion, local fluid flows and bacterial self-propulsion. In this work we present a novel approach based on the combination of high resolution imaging and optical manipulation that enables the investigation of the distribution and dynamics of proteins at the bacterial plasma membrane. For this purpose, we combine the versatility of holographic optical tweezers (HOT) with the sensitivity and resolution of total internal reflection fluorescence (TIRF) microscopy. Furthermore, we discuss the implementation of microfluidic devices in our integrated HOT+TIRF system for the control of growth conditions of bacterial cells. The capabilities of our workstation provides thus new valuable insights into the fundamental cellular and physical mechanisms underlying the regulation of bacterial signal transduction.

  16. Ultrafast optics. Ultrafast optical control by few photons in engineered fiber.

    PubMed

    Nissim, R; Pejkic, A; Myslivets, E; Kuo, B P; Alic, N; Radic, S

    2014-07-25

    Fast control of a strong optical beam by a few photons is an outstanding challenge that limits the performance of quantum sensors and optical processing devices. We report that a fast and efficient optical gate can be realized in an optical fiber that has been engineered with molecular-scale accuracy. Highly efficient, distributed phase-matched photon-photon interaction was achieved in the fiber with locally controlled, nanometer-scale core variations. A three-photon input was used to manipulate a Watt-scale beam at a speed exceeding 500 gigahertz. In addition to very fast beam control, the results provide a path to developing a new class of sensitive receivers capable of operating at very high rates.

  17. Optical Spin Noise of a Single Hole Spin Localized in an (InGa)As Quantum Dot

    NASA Astrophysics Data System (ADS)

    Dahbashi, Ramin; Hübner, Jens; Berski, Fabian; Pierz, Klaus; Oestreich, Michael

    2014-04-01

    We advance spin noise spectroscopy to the ultimate limit of single spin detection. This technique enables the measurement of the spin dynamic of a single heavy hole localized in a flat (InGa)As quantum dot. Magnetic field and light intensity dependent studies reveal even at low magnetic fields a strong magnetic field dependence of the longitudinal heavy hole spin relaxation time with an extremely long T1 of ≥180 μs at 31 mT and 5 K. The wavelength dependence of the spin noise power discloses for finite light intensities an inhomogeneous single quantum dot spin noise spectrum which is explained by charge fluctuations in the direct neighborhood of the quantum dot. The charge fluctuations are corroborated by the distinct intensity dependence of the effective spin relaxation rate.

  18. Fiber optic TV direct

    NASA Technical Reports Server (NTRS)

    Kassak, John E.

    1991-01-01

    The objective of the operational television (OTV) technology was to develop a multiple camera system (up to 256 cameras) for NASA Kennedy installations where camera video, synchronization, control, and status data are transmitted bidirectionally via a single fiber cable at distances in excess of five miles. It is shown that the benefits (such as improved video performance, immunity from electromagnetic interference and radio frequency interference, elimination of repeater stations, and more system configuration flexibility) can be realized if application of the proven fiber optic transmission concept is used. The control system will marry the lens, pan and tilt, and camera control functions into a modular based Local Area Network (LAN) control network. Such a system does not exist commercially at present since the Television Broadcast Industry's current practice is to divorce the positional controls from the camera control system. The application software developed for this system will have direct applicability to similar systems in industry using LAN based control systems.

  19. New technology to realize printed radiating elements

    NASA Astrophysics Data System (ADS)

    Tarot, A. C.; Sharaiha, A.; Terret, C.; Garnier, Y.

    1995-05-01

    A plating process for low-cost dielectric substrates (like polypropylene or foam) has been developed by the CNET (Centre National d'Etudes des Telecommunications) in collaboration with LAM (Laboratoire Antennes et Microelectronique). This process allows the realization of printed radiating elements like microstrip antennas. An example of a multilayered printed antenna realized with this technology is presented with its performance.

  20. Rotating and Precessing Dissipative-Optical-Topological-3D Solitons

    NASA Astrophysics Data System (ADS)

    Veretenov, N. A.; Rosanov, N. N.; Fedorov, S. V.

    2016-10-01

    We predict and study a new type of three-dimensional soliton: asymmetric rotating and precessing stable topological-dissipative-optical localized structures in homogeneous media with saturable amplification and absorption. The crucial factor determining their dynamics is the ratio of the diffusion coefficients characterizing the frequency dispersion and angular selectivity (dichroism) of the scheme. These vortex solitons exist and are stable for overcritical values of the selectivity coefficients and can be realized in lasers of large sizes with saturable absorption.

  1. Identities in nonlinear realizations of supersymmetry

    NASA Astrophysics Data System (ADS)

    Liu, Haishan; Luo, Hui; Luo, Mingxing; Wang, Liucheng

    2012-11-01

    In this paper, we emphasize that a UV SUSY-breaking theory can be realized either linearly or nonlinearly. Both realizations form the dual descriptions of the UV SUSY-breaking theory. Guided by this observation, we find subtle identities involving the Goldstino field and matter fields in the standard nonlinear realization from trivial ones in the linear realization. Rather complicated integrands in the standard nonlinear realization are identified as total-divergences. Especially, identities only involving the Goldstino field reveal the self-consistency of the Grassmann algebra. As an application of these identities, we prove that the nonlinear Kahler potential without or with gauge interactions is unique, if the corresponding linear one is fixed. Our identities pick out the total-divergence terms and guarantee this uniqueness.

  2. Quantitative photoacoustic measurement of tissue optical absorption spectrum aided by an optical contrast agent.

    PubMed

    Rajian, Justin Rajesh; Carson, Paul L; Wang, Xueding

    2009-03-16

    In photoacoustic imaging, the intensity of photoacoustic signal induced by optical absorption in biological tissue is proportional to light energy deposition, which is the product of the absorption coefficient and the local light fluence. Because tissue optical properties are highly dependent on the wavelength, the spectrum of the local light fluence at a target tissue beneath the sample surface is different than the spectrum of the incident light fluence. Therefore, quantifying the tissue optical absorption spectrum by using a photoacoustic technique is not feasible without the knowledge of the local light fluence. In this work, a highly accurate photoacoustic measurement of the subsurface tissue optical absorption spectrum has been achieved for the first time by introducing an extrinsic optical contrast agent with known optical properties. From the photoacoustic measurements with and without the contrast agent, a quantified measurement of the chromophore absorption spectrum can be realized in a strongly scattering medium. Experiments on micro-flow vessels containing fresh canine blood buried in phantoms and chicken breast tissues were carried out in a wavelength range from 680 nm to 950 nm. Spectroscopic photoacoustic measurements of both oxygenated and deoxygenated blood specimens presented an improved match with the references when employing this technique.

  3. EDITORIAL: Optics of nanocomposite materials Optics of nanocomposite materials

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Malgosia; Tomita, Yasuo

    2009-02-01

    realization of multi-dimensionally structured materials, highly relevant for photonic and electronic applications. The local-field effects in nanostructured materials can provide a large enhancement of the nonlinear optical response and the improvement of the light amplifying properties. These areas are represented in this special issue, along with contributions to modelling of photonic crystal structures and holographic grating formation in polymers. Because nanocomposite materials provide a new method to improve the environmental stability of materials, as well as interesting optical properties, they should open new routes for applications in photonics. The Guest Editors would like to thank all the authors for their contributions and the referees for their efforts in reviewing the manuscripts. We would also like to thank the Editors of Journal of Optics A for suggesting this special issue and Julia Dickinson, the Publishing Editor, for her invaluable assistance.

  4. Experimental and theoretical studies on localized surface plasmon resonance based fiber optic sensor using graphene oxide coated silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Nayak, Jeeban Kumar; Parhi, Purnendu; Jha, Rajan

    2016-07-01

    An optical fiber based refractive index sensor using graphene oxide (GO) encapsulated silver nanoparticles (AgNPs) is reported. The AgNPs are encapsulated with a very thin layer of GO as it controls the inter-particle distance thereby preventing aggregation. The encapsulation also enhances the colloidal stability and prevents the oxidation of the AgNPs by separating them from direct contact with the aqueous medium. High-resolution transmission electron microscopy results support the formation of 1 nm thick GO around AgNPs of an average size of 35 nm. A Raman spectrometer and a UV-VIS spectrometer have been used to characterize and study the synthesized nanoparticles along with GO. Further, Raman spectra support a 64.72% increase in D-peak intensity and a 52.91% increase in G-peak intensity of the GO-encapsulated AgNPs (GOE-AgNPs) with respect to GO. Further, the GOE-AgNPs are immobilized on the core of functionalized plastic-cladded silica fiber. FESEM confirms the immobilization of the GOE-AgNPs on the fiber core. We observed that the peak absorbance changes by 87.55% with a 0.05 change in the refractive index. The sensitivity of the proposed fiber sensor is found to be 0.9406 ΔA/RIU along with a resolution of 12.8  ×  {{10}-4} RIU. MATLAB is used to calculate the absorbance of the AgNPs by considering the bound and free electron contribution along with the size-dependent dispersion of the nanoparticles. We found that the simulation results are in good agreement with the experimental results.

  5. Chiral quantum optics.

    PubMed

    Lodahl, Peter; Mahmoodian, Sahand; Stobbe, Søren; Rauschenbeutel, Arno; Schneeweiss, Philipp; Volz, Jürgen; Pichler, Hannes; Zoller, Peter

    2017-01-25

    Advanced photonic nanostructures are currently revolutionizing the optics and photonics that underpin applications ranging from light technology to quantum-information processing. The strong light confinement in these structures can lock the local polarization of the light to its propagation direction, leading to propagation-direction-dependent emission, scattering and absorption of photons by quantum emitters. The possibility of such a propagation-direction-dependent, or chiral, light-matter interaction is not accounted for in standard quantum optics and its recent discovery brought about the research field of chiral quantum optics. The latter offers fundamentally new functionalities and applications: it enables the assembly of non-reciprocal single-photon devices that can be operated in a quantum superposition of two or more of their operational states and the realization of deterministic spin-photon interfaces. Moreover, engineered directional photonic reservoirs could lead to the development of complex quantum networks that, for example, could simulate novel classes of quantum many-body systems.

  6. Chiral quantum optics

    NASA Astrophysics Data System (ADS)

    Lodahl, Peter; Mahmoodian, Sahand; Stobbe, Søren; Rauschenbeutel, Arno; Schneeweiss, Philipp; Volz, Jürgen; Pichler, Hannes; Zoller, Peter

    2017-01-01

    Advanced photonic nanostructures are currently revolutionizing the optics and photonics that underpin applications ranging from light technology to quantum-information processing. The strong light confinement in these structures can lock the local polarization of the light to its propagation direction, leading to propagation-direction-dependent emission, scattering and absorption of photons by quantum emitters. The possibility of such a propagation-direction-dependent, or chiral, light–matter interaction is not accounted for in standard quantum optics and its recent discovery brought about the research field of chiral quantum optics. The latter offers fundamentally new functionalities and applications: it enables the assembly of non-reciprocal single-photon devices that can be operated in a quantum superposition of two or more of their operational states and the realization of deterministic spin–photon interfaces. Moreover, engineered directional photonic reservoirs could lead to the development of complex quantum networks that, for example, could simulate novel classes of quantum many-body systems.

  7. Network realization of triplet-type quantum stochastic systems

    NASA Astrophysics Data System (ADS)

    Zhou, Shaosheng; Fu, Shizhou; Chen, Yuping

    2017-01-01

    This paper focuses on a problem of network synthesis for a class of quantum stochastic systems. The systems under consideration are of triplet-type form and stem from linear quantum optics and linear quantum circuits. A new quantum network realization approach is proposed by generalizing the scattering operator from the scalar form to a unitary matrix in network components. It shows that the triplet-type quantum stochastic system can be approximated by a quantum network which consists of some one-degree-of-freedom generalized open-quantum harmonic oscillators (1DGQHOs) via series, concatenation and feedback connections.

  8. Realizing Rec. 2020 color gamut with quantum dot displays.

    PubMed

    Zhu, Ruidong; Luo, Zhenyue; Chen, Haiwei; Dong, Yajie; Wu, Shin-Tson

    2015-09-07

    We analyze how to realize Rec. 2020 wide color gamut with quantum dots. For photoluminescence, our simulation indicates that we are able to achieve over 97% of the Rec. 2020 standard with quantum dots by optimizing the emission spectra and redesigning the color filters. For electroluminescence, by optimizing the emission spectra of quantum dots is adequate to render over 97% of the Rec. 2020 standard. We also analyze the efficiency and angular performance of these devices, and then compare results with LCDs using green and red phosphors-based LED backlight. Our results indicate that quantum dot display is an outstanding candidate for achieving wide color gamut and high optical efficiency.

  9. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-03-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  10. Absolute realization of low BRDF value

    NASA Astrophysics Data System (ADS)

    Liu, Zilong; Liao, Ningfang; Li, Ping; Wang, Yu

    2010-10-01

    Low BRDF value is widespread used in many critical domains such as space and military fairs. These values below 0.1 Sr-1 . So the Absolute realization of these value is the most critical issue in the absolute measurement of BRDF. To develop the Absolute value realization theory of BRDF , defining an arithmetic operators of BRDF , achieving an absolute measurement Eq. of BRDF based on radiance. This is a new theory method to solve the realization problem of low BRDF value. This theory method is realized on a self-designed common double orientation structure in space. By designing an adding structure to extend the range of the measurement system and a control and processing software, Absolute realization of low BRDF value is achieved. A material of low BRDF value is measured in this measurement system and the spectral BRDF value are showed within different angles allover the space. All these values are below 0.4 Sr-1 . This process is a representative procedure about the measurement of low BRDF value. A corresponding uncertainty analysis of this measurement data is given depend on the new theory of absolute realization and the performance of the measurement system. The relative expand uncertainty of the measurement data is 0.078. This uncertainty analysis is suitable for all measurements using the new theory of absolute realization and the corresponding measurement system.

  11. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES Electronic Transport Calculations Using Maximally-Localized Wannier Functions

    NASA Astrophysics Data System (ADS)

    Wang, Neng-Ping

    2011-01-01

    I present a method to calculate the ballistic transport properties of atomic-scale structures under bias. The electronic structure of the system is calculated using the Kohn-Sham scheme of density functional theory (DFT). The DFT eigenvectors are then transformed into a set of maximally localized Wannier functions (MLWFs) [N. Marzari and D. Vanderbilt, Phys. Rev. B 56 (1997) 12847]. The MLWFs are used as a minimal basis set to obtain the Hamitonian matrices of the scattering region and the adjacent leads, which are needed for transport calculation using the nonequilibrium Green's function formalism. The coupling of the scattering region to the semi-infinite leads is described by the self-energies of the leads. Using the nonequilibrium Green's function method, one calculates self-consistently the charge distribution of the system under bias and evaluates the transmission and current through the system. To solve the Poisson equation within the scheme of MLWFs I introduce a computationally efficient method. The method is applied to a molecular hydrogen contact in two transition metal monatomic wires (Cu and Pt). It is found that for Pt the I-V characteristics is approximately linear dependence, however, for Cu the I-V characteristics manifests a linear dependence at low bias voltages and exhibits apparent nonlinearity at higher bias voltages. I have also calculated the transmission in the zero bias voltage limit for a single CO molecule adsorbed on Cu and Pt monatomic wires. While a chemical scissor effect occurs for the Cu monatomic wire with an adsorbed CO molecule, it is absent for the Pt monatomic wire due to the contribution of d-orbitals at the Fermi energy.

  12. Realization of arbitrary discrete unitary transformations using spatial and internal modes of light

    NASA Astrophysics Data System (ADS)

    Dhand, Ish; Goyal, Sandeep K.

    2015-10-01

    Any lossless transformation on ns spatial and np internal modes of light can be described by an nsnp×nsnp unitary matrix, but there is no known procedure to effect an arbitrary nsnp×nsnp unitary matrix on light in ns spatial and np internal modes. We devise an algorithm to realize an arbitrary discrete unitary transformation on the combined spatial and internal degrees of freedom of light. Our realization uses beam splitters and operations on internal modes to effect arbitrary linear transformations. The number of beam splitters required to realize a unitary transformation is reduced as compared to existing realization by a factor np2/2 at the cost of increasing the number of internal optical elements by a factor of 2. Our algorithm thus enables the optical implementation of higher dimensional unitary transformations.

  13. On isotopic realizability of maps factored through a hyperplane

    NASA Astrophysics Data System (ADS)

    Melikhov, Sergey A.

    2004-08-01

    In this paper we study the isotopic realization problem, which is the question of isotopic realizability of a given (continuous) map f, that is, the possibility of a uniform approximation of f by a continuous family of embeddings g_t, t\\in \\lbrack 0,\\infty), under the condition that f is discretely realizable, that is, that there exists a uniform approximation of f by a sequence of embeddings h_n, n\\in\\mathbb N.For each n\\geqslant3 a map f\\colon S^n\\to\\mathbb R^{2n} is constructed that is discretely but not isotopically realizable and which, unlike all such previously known examples, is a locally flat topological immersion. For each n\\geqslant4 a map f\\colon S^n\\to\\mathbb R^{2n-1}\\subset\\mathbb R^{2n} is constructed that is discretely but not isotopically realizable. It is shown that for n\\equiv0,\\,1\\pmod4 any map f\\colon S^n\\to\\mathbb R^{2n-2}\\subset\\mathbb R^{2n} is isotopically realizable, and for n\\equiv2\\pmod4, so also is every map f\\colon S^n\\to\\mathbb R^{2n-3}\\subset\\mathbb R^{2n}. If n\\geqslant13 and n+1 is not a power of 2, an arbitrary map f\\colon S^n\\to\\mathbb R^{5 \\lbrack n/3 \\rbrack +3}\\subset\\mathbb R^{2n} is isotopically realizable.The main results are devoted to the isotopic realization problem for maps f of the form S^n\\stackrel{f}\\to S^n\\subset\\mathbb R^{2n}, n=2^l-1. It is established that if it has a negative solution, then the inverse images of points under the map f have a certain homology property connected with actions of the group of p-adic integers. The solution is affirmative if f is Lipschitzian and its van Kampen-Skopenkov thread has finite order. In connection with the proof the functors \\operatorname{Ext}_{\\square} and \\operatorname{Ext}_{\\bowtie} in the relative homology algebra of inverse spectra are introduced.

  14. Experimental realization of optomechanically induced non-reciprocity

    NASA Astrophysics Data System (ADS)

    Shen, Zhen; Zhang, Yan-Lei; Chen, Yuan; Zou, Chang-Ling; Xiao, Yun-Feng; Zou, Xu-Bo; Sun, Fang-Wen; Guo, Guang-Can; Dong, Chun-Hua

    2016-10-01

    Non-reciprocal devices, such as circulators and isolators, are indispensable components in classical and quantum information processing in integrated photonic circuits. Aside from these applications, the non-reciprocal phase shift is of fundamental interest for exploring exotic topological photonics, such as the realization of chiral edge states and topological protection. However, incorporating low-optical-loss magnetic materials into a photonic chip is technically challenging. In this study we experimentally demonstrate non-magnetic non-reciprocity using optomechanical interactions in a whispering gallery microresonator, as proposed in a previous work. Optomechanically induced non-reciprocal transparency and amplification are observed and a non-reciprocal phase shift of up to 40° is also demonstrated. The underlying mechanism of optomechanically induced non-reciprocity has great potential for all-optical controllable isolators and circulators, as well as non-reciprocal phase shifters in integrated photonic chips.

  15. Direct-write graded index materials realized in protein hydrogels

    DOE PAGES

    Kaehr, Bryan; Scrymgeour, David A.

    2016-09-20

    Here, the ability to create optical materials with arbitrary index distributions would prove transformative for optics design and applications. However, current fabrication techniques for graded index (GRIN) materials rely on diffusion profiles and therefore are unable to realize arbitrary distribution GRIN design. Here, we demonstrate the laser direct writing of graded index structures in protein-based hydrogels using multiphoton lithography. We show index changes spanning a range of 10–2, which is comparable with laser densified glass and polymer systems. Further, we demonstrate the conversion of these written density variation structures into SiO2, opening up the possibility of transforming GRIN hydrogels tomore » a wide range of material systems.« less

  16. Direct-write graded index materials realized in protein hydrogels

    SciTech Connect

    Kaehr, Bryan; Scrymgeour, David A.

    2016-09-20

    Here, the ability to create optical materials with arbitrary index distributions would prove transformative for optics design and applications. However, current fabrication techniques for graded index (GRIN) materials rely on diffusion profiles and therefore are unable to realize arbitrary distribution GRIN design. Here, we demonstrate the laser direct writing of graded index structures in protein-based hydrogels using multiphoton lithography. We show index changes spanning a range of 10–2, which is comparable with laser densified glass and polymer systems. Further, we demonstrate the conversion of these written density variation structures into SiO2, opening up the possibility of transforming GRIN hydrogels to a wide range of material systems.

  17. Optical manipulation of single flux quanta

    PubMed Central

    Veshchunov, I. S.; Magrini, W.; Mironov, S. V.; Godin, A. G.; Trebbia, J.-B.; Buzdin, A. I.; Tamarat, Ph.; Lounis, B.

    2016-01-01

    Magnetic field can penetrate into type II superconductors in the form of Abrikosov vortices, which are magnetic flux tubes surrounded by circulating supercurrents often trapped at defects referred to as pinning sites. Although the average properties of the vortex matter in superconductors can be tuned with magnetic fields, temperature or electric currents, handling of individual Abrikosov vortices remains challenging and has been demonstrated only with sophisticated scanning local probe microscopies. Here we introduce a far-field optical method based on local heating of the superconductor with a focused laser beam to realize a fast and precise manipulation of individual vortices, in the same way as with optical tweezers. This simple approach provides the perfect basis for sculpting the magnetic flux profile in superconducting devices like a vortex lens or a vortex cleaner, without resorting to static pinning or ratchet effects. PMID:27677835

  18. Optical manipulation of single flux quanta

    NASA Astrophysics Data System (ADS)

    Veshchunov, I. S.; Magrini, W.; Mironov, S. V.; Godin, A. G.; Trebbia, J.-B.; Buzdin, A. I.; Tamarat, Ph.; Lounis, B.

    2016-09-01

    Magnetic field can penetrate into type II superconductors in the form of Abrikosov vortices, which are magnetic flux tubes surrounded by circulating supercurrents often trapped at defects referred to as pinning sites. Although the average properties of the vortex matter in superconductors can be tuned with magnetic fields, temperature or electric currents, handling of individual Abrikosov vortices remains challenging and has been demonstrated only with sophisticated scanning local probe microscopies. Here we introduce a far-field optical method based on local heating of the superconductor with a focused laser beam to realize a fast and precise manipulation of individual vortices, in the same way as with optical tweezers. This simple approach provides the perfect basis for sculpting the magnetic flux profile in superconducting devices like a vortex lens or a vortex cleaner, without resorting to static pinning or ratchet effects.

  19. Optical manipulation of single flux quanta.

    PubMed

    Veshchunov, I S; Magrini, W; Mironov, S V; Godin, A G; Trebbia, J-B; Buzdin, A I; Tamarat, Ph; Lounis, B

    2016-09-28

    Magnetic field can penetrate into type II superconductors in the form of Abrikosov vortices, which are magnetic flux tubes surrounded by circulating supercurrents often trapped at defects referred to as pinning sites. Although the average properties of the vortex matter in superconductors can be tuned with magnetic fields, temperature or electric currents, handling of individual Abrikosov vortices remains challenging and has been demonstrated only with sophisticated scanning local probe microscopies. Here we introduce a far-field optical method based on local heating of the superconductor with a focused laser beam to realize a fast and precise manipulation of individual vortices, in the same way as with optical tweezers. This simple approach provides the perfect basis for sculpting the magnetic flux profile in superconducting devices like a vortex lens or a vortex cleaner, without resorting to static pinning or ratchet effects.

  20. Full-field optical micro-angiography

    NASA Astrophysics Data System (ADS)

    Wang, Mingyi; Zeng, Yaguang; Liang, Xianjun; Lu, Xuanlong; Feng, Guanping; Han, Dingan; Yang, Guojian

    2014-02-01

    We present a detailed description of full-field optical micro-angiography on the basis of frequency-domain laser speckle imaging with intensity fluctuation modulation (LSI-IFM). The imaging approach works based on the instantaneous local intensity fluctuation realized via the combination of short exposure and low sampling rate of a camera and appropriate magnification of a microscope. In vivo experiments on mouse ear verify the theoretical description we made for the imaging mechanism and demonstrate the ability of LSI-IFM as optical micro-angiography. By introducing a fundus camera into LSI-IFM system, our approach has a potential application in label-free retina optical micro-angiography.

  1. Nonlinear realizations and the orbit method

    SciTech Connect

    Gonera, Joanna

    2013-11-15

    Given a symmetry group one can construct the invariant dynamics using the technique of nonlinear realizations or the orbit method. The relationship between these methods is discussed. Few examples are presented.

  2. Adaptive-optics SLO imaging combined with widefield OCT and SLO enables precise 3D localization of fluorescent cells in the mouse retina.

    PubMed

    Zawadzki, Robert J; Zhang, Pengfei; Zam, Azhar; Miller, Eric B; Goswami, Mayank; Wang, Xinlei; Jonnal, Ravi S; Lee, Sang-Hyuck; Kim, Dae Yu; Flannery, John G; Werner, John S; Burns, Marie E; Pugh, Edward N

    2015-06-01

    Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has recently been used to achieve exquisite subcellular resolution imaging of the mouse retina. Wavefront sensing-based AO typically restricts the field of view to a few degrees of visual angle. As a consequence the relationship between AO-SLO data and larger scale retinal structures and cellular patterns can be difficult to assess. The retinal vasculature affords a large-scale 3D map on which cells and structures can be located during in vivo imaging. Phase-variance OCT (pv-OCT) can efficiently image the vasculature with near-infrared light in a label-free manner, allowing 3D vascular reconstruction with high precision. We combined widefield pv-OCT and SLO imaging with AO-SLO reflection and fluorescence imaging to localize two types of fluorescent cells within the retinal layers: GFP-expressing microglia, the resident macrophages of the retina, and GFP-expressing cone photoreceptor cells. We describe in detail a reflective afocal AO-SLO retinal imaging system designed for high resolution retinal imaging in mice. The optical performance of this instrument is compared to other state-of-the-art AO-based mouse retinal imaging systems. The spatial and temporal resolution of the new AO instrumentation was characterized with angiography of retinal capillaries, including blood-flow velocity analysis. Depth-resolved AO-SLO fluorescent images of microglia and cone photoreceptors are visualized in parallel with 469 nm and 663 nm reflectance images of the microvasculature and other structures. Additional applications of the new instrumentation are discussed.

  3. Adaptive-optics SLO imaging combined with widefield OCT and SLO enables precise 3D localization of fluorescent cells in the mouse retina

    PubMed Central

    Zawadzki, Robert J.; Zhang, Pengfei; Zam, Azhar; Miller, Eric B.; Goswami, Mayank; Wang, Xinlei; Jonnal, Ravi S.; Lee, Sang-Hyuck; Kim, Dae Yu; Flannery, John G.; Werner, John S.; Burns, Marie E.; Pugh, Edward N.

    2015-01-01

    Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has recently been used to achieve exquisite subcellular resolution imaging of the mouse retina. Wavefront sensing-based AO typically restricts the field of view to a few degrees of visual angle. As a consequence the relationship between AO-SLO data and larger scale retinal structures and cellular patterns can be difficult to assess. The retinal vasculature affords a large-scale 3D map on which cells and structures can be located during in vivo imaging. Phase-variance OCT (pv-OCT) can efficiently image the vasculature with near-infrared light in a label-free manner, allowing 3D vascular reconstruction with high precision. We combined widefield pv-OCT and SLO imaging with AO-SLO reflection and fluorescence imaging to localize two types of fluorescent cells within the retinal layers: GFP-expressing microglia, the resident macrophages of the retina, and GFP-expressing cone photoreceptor cells. We describe in detail a reflective afocal AO-SLO retinal imaging system designed for high resolution retinal imaging in mice. The optical performance of this instrument is compared to other state-of-the-art AO-based mouse retinal imaging systems. The spatial and temporal resolution of the new AO instrumentation was characterized with angiography of retinal capillaries, including blood-flow velocity analysis. Depth-resolved AO-SLO fluorescent images of microglia and cone photoreceptors are visualized in parallel with 469 nm and 663 nm reflectance images of the microvasculature and other structures. Additional applications of the new instrumentation are discussed. PMID:26114038

  4. Ultratransparent Media and Transformation Optics with Shifted Spatial Dispersions

    NASA Astrophysics Data System (ADS)

    Luo, Jie; Yang, Yuting; Yao, Zhongqi; Lu, Weixin; Hou, Bo; Hang, Zhi Hong; Chan, C. T.; Lai, Yun

    2016-11-01

    By using pure dielectric photonic crystals, we demonstrate the realization of ultratransparent media, which allow near 100% transmission of light for all incident angles and create aberration-free virtual images. The ultratransparency effect is well explained by spatially dispersive effective medium theory for photonic crystals, and verified by both simulations and proof-of-principle microwave experiments. Designed with shifted elliptical equal frequency contours, such ultratransparent media not only provide a low-loss and feasible platform for transformation optics devices at optical frequencies, but also enable new freedom for phase manipulation beyond the local medium framework.

  5. Ultratransparent Media and Transformation Optics with Shifted Spatial Dispersions.

    PubMed

    Luo, Jie; Yang, Yuting; Yao, Zhongqi; Lu, Weixin; Hou, Bo; Hang, Zhi Hong; Chan, C T; Lai, Yun

    2016-11-25

    By using pure dielectric photonic crystals, we demonstrate the realization of ultratransparent media, which allow near 100% transmission of light for all incident angles and create aberration-free virtual images. The ultratransparency effect is well explained by spatially dispersive effective medium theory for photonic crystals, and verified by both simulations and proof-of-principle microwave experiments. Designed with shifted elliptical equal frequency contours, such ultratransparent media not only provide a low-loss and feasible platform for transformation optics devices at optical frequencies, but also enable new freedom for phase manipulation beyond the local medium framework.

  6. Local geological dust in the area of Rome (Italy): linking mineral composition, size distribution and optical properties to radiative transfer modelling

    NASA Astrophysics Data System (ADS)

    Pietrodangelo, Adriana; Salzano, Roberto; Bassani, Cristiana; Pareti, Salvatore; Perrino, Cinzia

    2015-04-01

    Airborne mineral dust plays a key role in the energy balance of the Earth - atmosphere coupled system. The microphysical and optical properties of dust drive the direct radiative effects and are in turn influenced by the dust mineralogical composition. The latter varies largely, depending on the geology of the source region. Knowledge gaps still exist about relationships between the scattering and absorption of solar and terrestrial radiation by mineral dust and its mineralogical, size distribution and particle morphology features; this also affects the reliability of radiative transfer (RT) modelling estimates (Hansell et al., 2011). In this study, these relationships were investigated focusing on the crustal suspended PM10 dust, sourced from outcropping rocks of the local geological domains around Rome (Latium, Italy). The mineral composition variability of the Latium rocks ranges from the silicate-dominated (volcanics domain) to the calcite-dominated (travertine), through lithological materials composed in different proportions by silicates, silica and calcite, mainly (limestone series, siliciclastic series) (Cosentino et al., 2009). This peculiarity of the Latium region was thus exploited to investigate the behavior of the size distribution, optical properties and radiative transfer at BOA (Bottom Of Atmosphere) of the suspended dust PM10 fraction with the variability of mineral composition. Elemental source profiles of the same dust samples were previously determined (Pietrodangelo et al., 2013). A multi-faceted analysis was performed, and outcomes from the following approaches were merged: individual-particle scanning electron microscopy combined with X-ray energy-dispersive microanalysis (SEM XEDS), bulk mineralogical analysis by X-ray diffraction (XRD), size distribution fit of the individual-particle data set and modelling of the dust optical and radiative properties. To this aim, the 6SV atmospheric radiative transfer code (Kotchenova et al., 2008

  7. Robust sampling-sourced numerical retrieval algorithm for optical energy loss function based on log-log mesh optimization and local monotonicity preserving Steffen spline

    NASA Astrophysics Data System (ADS)

    Maglevanny, I. I.; Smolar, V. A.

    2016-01-01

    We introduce a new technique of interpolation of the energy-loss function (ELF) in solids sampled by empirical optical spectra. Finding appropriate interpolation methods for ELFs poses several challenges. The sampled ELFs are usually very heterogeneous, can originate from various sources thus so called "data gaps" can appear, and significant discontinuities and multiple high outliers can be present. As a result an interpolation based on those data may not perform well at predicting reasonable physical results. Reliable interpolation tools, suitable for ELF applications, should therefore satisfy several important demands: accuracy and predictive power, robustness and computational efficiency, and ease of use. We examined the effect on the fitting quality due to different interpolation schemes with emphasis on ELF mesh optimization procedures and we argue that the optimal fitting should be based on preliminary log-log scaling data transforms by which the non-uniformity of sampled data distribution may be considerably reduced. The transformed data are then interpolated by local monotonicity preserving Steffen spline. The result is a piece-wise smooth fitting curve with continuous first-order derivatives that passes through all data points without spurious oscillations. Local extrema can occur only at grid points where they are given by the data, but not in between two adjacent grid points. It is found that proposed technique gives the most accurate results and also that its computational time is short. Thus, it is feasible using this simple method to address practical problems associated with interaction between a bulk material and a moving electron. A compact C++ implementation of our algorithm is also presented.

  8. Optical signatures of a hypercritical 1D potential in a 2D Dirac metal

    NASA Astrophysics Data System (ADS)

    Jiang, Bor-Yuan; Ni, Guangxin; Pan, Cheng; Fei, Zhe; Cheng, Bin; Lau, Chun Ning; Bockrath, Marc; Basov, Dimitri; Fogler, Michael

    Generation of quasi-bound states in graphene near strong charged perturbations is a solid-state analog of atomic collapse of superheavy elements or particle production by hypothetical cosmic strings. We show, for the case of a linelike perturbation, that as the perturbation grows in strength, quasi-bound states are generated sequentially. Each of these critical events is signaled by a sharp change in the local optical conductivity. Tunable linelike perturbations can be realized in experiment using nanowire or nanotube electrostatic gates. We report measurements of local conductivity for such systems obtained through near-field optical microscopy.

  9. Optical energy storage and reemission based weak localization of light and accompanying random lasing action in disordered Nd{sup 3+} doped (Pb, La)(Zr, Ti)O{sub 3} ceramics

    SciTech Connect

    Xu, Long; Zhao, Hua; Xu, Caixia; Zhang, Siqi; Zhang, Jingwen

    2014-08-14

    Multi-mode random lasing action and weak localization of light were evidenced and studied in normally transparent but disordered Nd{sup 3+} doped (Pb,La)(Zr,Ti)O{sub 3} ceramics. Noticeable localized zone and multi-photon process were observed under strong pumping power. A tentative phenomenological physical picture was proposed by taking account of diffusive process, photo-induced scattering, and optical energy storage process as dominant factors in elucidating the weak localization of light observed. Both the decreased transmittance (increased reflectivity) of light and the observed long lasting fading-off phenomenon supported the physical picture proposed by us.

  10. Dynamic Neurovascular Coupling and Uncoupling during Ictal Onset, Propagation, and Termination Revealed by Simultaneous In Vivo Optical Imaging of Neural Activity and Local Blood Volume

    PubMed Central

    Zhao, Mingrui; Schwartz, Theodore H.

    2013-01-01

    Traditional models of ictal propagation involve the concept of an initiation site and a progressive outward march of activation. The process of neurovascular coupling, whereby the brain supplies oxygenated blood to metabolically active neurons presumably results in a similar outward cascade of hyperemia. However, ictal neurovascular coupling has never been assessed in vivo using simultaneous measurements of membrane potential change and hyperemia with wide spatial sampling. In an acute rat ictal model, using simultaneous intrinsic optical signal (IOS) and voltage-sensitive dye (VSD) imaging of cerebral blood volume and membrane potential changes, we demonstrate that seizures consist of multiple dynamic multidirectional waves of membrane potential change with variable onset sites that spread through a widespread network. Local blood volume evolves on a much slower spatiotemporal scale. At seizure onset, the VSD waves extend beyond the IOS signal. During evolution, spatial correlation with hemodynamic signal only exists briefly at the maximal spread of the VSD signal. At termination, the IOS signal extends spatially and temporally beyond the VSD waves. Hence, vascular reactivity evolves in a separate but parallel fashion to membrane potential changes resulting in a mechanism of neurovascular coupling and uncoupling, which is as dynamic as the seizure itself. PMID:22499798

  11. Interaction of Nd dopants with broadband emission centers in Bi2O3-B2O3 glass: local energy balance and its influence on optical properties

    NASA Astrophysics Data System (ADS)

    Ishii, Masashi; Fuchi, Shingo; Takeda, Yoshikazu

    2015-10-01

    Chemical and energetic interactions between broadband infrared intrinsic emission centers (IECs) of bismuthates and extrinsic emission centers (EECs) of Nd2O3 dopants were optically and electronically investigated. Although no visible absorption from the IEC was found in untreated Bi2O3-B2O3 glass, it was clearly observed after a moderate thermal treatment of  <200 °C, indicating chemical activity of O-deficient sites as the origin of IECs. On the other hand, Nd2O3 doping chemically stabilized the Bi2O3-B2O3 glass and suppressed IEC formation. By using a microwave measurement sensitive to electric dipoles, we found a ‘switching’ in local energy balance resulting from the Nd2O3 doping. This was explained by metallization of the O-deficient sites in the Bi2O3-B2O3 glass and multi-phonon excitation of IEC and EEC complexes in the Nd2O3-Bi2O3-B2O3 glass phosphor. Although the electric dipole observed by the microwave measurement was not necessarily caused by IEC, emission properties of the IEC and EEC complexes were consistent with energy balance switching; emissions from IECs after thermal treatment were quenched by EECs with multi-phonon excitation.

  12. Interaction of Nd dopants with broadband emission centers in Bi2O3-B2O3 glass: local energy balance and its influence on optical properties.

    PubMed

    Ishii, Masashi; Fuchi, Shingo; Takeda, Yoshikazu

    2015-10-07

    Chemical and energetic interactions between broadband infrared intrinsic emission centers (IECs) of bismuthates and extrinsic emission centers (EECs) of Nd2O3 dopants were optically and electronically investigated. Although no visible absorption from the IEC was found in untreated Bi2O3-B2O3 glass, it was clearly observed after a moderate thermal treatment of  <200 °C, indicating chemical activity of O-deficient sites as the origin of IECs. On the other hand, Nd2O3 doping chemically stabilized the Bi2O3-B2O3 glass and suppressed IEC formation. By using a microwave measurement sensitive to electric dipoles, we found a 'switching' in local energy balance resulting from the Nd2O3 doping. This was explained by metallization of the O-deficient sites in the Bi2O3-B2O3 glass and multi-phonon excitation of IEC and EEC complexes in the Nd2O3-Bi2O3-B2O3 glass phosphor. Although the electric dipole observed by the microwave measurement was not necessarily caused by IEC, emission properties of the IEC and EEC complexes were consistent with energy balance switching; emissions from IECs after thermal treatment were quenched by EECs with multi-phonon excitation.

  13. Investigation of the local structure of Cu2+ ions doped in alkali lead tetraborate glasses by their electron paramagnetic resonance and optical spectra

    NASA Astrophysics Data System (ADS)

    Wu, Ying; Chen, Zhi

    2014-06-01

    The local structure of the Cu2+ centers in alkali lead tetraborate glasses was theoretically studied based on the optical spectra data and high-order perturbation formulas of the spin Hamiltonian parameters (electron paramagnetic resonance g factors g∥, g⊥ and hyperfine structure constants A∥, A⊥) for a 3d9 ion in a tetragonally elongated octahedron. In these formulas, the relative axial elongation of the ligand O2- octahedron around the Cu2+ due to the Jahn-Teller effect is taken into account by considering the contributions to the g factors from the tetragonal distortion which is characterized by the tetragonal crystal-field parameters Ds and Dt. From the calculations, the ligand O2- octahedral around Cu2+ is determined to suffer about 19.2% relative elongation along the C4 axis of the alkali lead tetraborate glass system, and a negative sign for A∥ and a positive sign for A⊥ for these Cu2+ centers are suggested in the discussion.

  14. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-01-01

    Call for Papers: Optical Access Networks

    Guest Editors Jun Zheng, University of Ottawa Nirwan Ansari, New Jersey Institute of Technology

    Submission Deadline: 1 June 2005

    Background

    With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the

  15. Two approaches for realizing traceability in nanoscale dimensional metrology

    NASA Astrophysics Data System (ADS)

    Dai, Gaoliang; Koenders, Ludger; Fluegge, Jens; Bosse, Harald

    2016-09-01

    Traceability is a fundamental issue for nanoscale dimensional metrology. The lack of traceability in measurements inhibits the comparison of tools from different manufacturers and limits knowledge about the real size of fabricated features. Two approaches for realizing traceability in nanometrology, referred to as a top-down approach and a bottom-up approach, are presented. Following the top-down approach, for instance, realized using metrological atomic force microscopes, the dimension of nanostructures is derived from the displacement of the scanner, which is directly measured by laser interferometers whose optical frequency is calibrated to an iodine frequency-stabilized laser. Thus, the measurement result is directly traceable with an unbroken chain to the International System of Units-the meter. However, to achieve subnanometer measurement accuracy, which is far smaller than the optical wavelength (632.8 nm in this study), the subdivision of the interference fringe is essential for obtaining desired measurement resolution and accuracy. On the contrary, with the bottom-up approach, the dimension of nanostructures is determined using the silicon crystal lattice as an internal ruler. Due to the small dimension of the crystal lattice constant (e.g., d111=0.313 nm), the bottom-up approach offers measurements with potential highest accuracy. The crystal lattice constant can be traceably calibrated to the meter by, e.g., a combined optical and x-ray interferometer; thus, the traceability of the bottom-up approach is also ensured. The consistency of the two approaches is experimentally confirmed in this paper.

  16. Dual focused coherent beams for three-dimensional optical trapping and continuous rotation of metallic nanostructures

    PubMed Central

    Xu, Xiaohao; Cheng, Chang; Zhang, Yao; Lei, Hongxiang; Li, Baojun

    2016-01-01

    Metallic nanoparticles and nanowires are extremely important for nanoscience and nanotechnology. Techniques to optically trap and rotate metallic nanostructures can enable their potential applications. However, because of the destabilizing effects of optical radiation pressure, the optical trapping of large metallic particles in three dimensions is challenging. Additionally, the photothermal issues associated with optical rotation of metallic nanowires have far prevented their practical applications. Here, we utilize dual focused coherent beams to realize three-dimensional (3D) optical trapping of large silver particles. Continuous rotation of silver nanowires with frequencies measured in several hertz is also demonstrated based on interference-induced optical vortices with very low local light intensity. The experiments are interpreted by numerical simulations and calculations. PMID:27386838

  17. Dual focused coherent beams for three-dimensional optical trapping and continuous rotation of metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Xu, Xiaohao; Cheng, Chang; Zhang, Yao; Lei, Hongxiang; Li, Baojun

    2016-07-01

    Metallic nanoparticles and nanowires are extremely important for nanoscience and nanotechnology. Techniques to optically trap and rotate metallic nanostructures can enable their potential applications. However, because of the destabilizing effects of optical radiation pressure, the optical trapping of large metallic particles in three dimensions is challenging. Additionally, the photothermal issues associated with optical rotation of metallic nanowires have far prevented their practical applications. Here, we utilize dual focused coherent beams to realize three-dimensional (3D) optical trapping of large silver particles. Continuous rotation of silver nanowires with frequencies measured in several hertz is also demonstrated based on interference-induced optical vortices with very low local light intensity. The experiments are interpreted by numerical simulations and calculations.

  18. Maxwell's demons realized in electronic circuits

    NASA Astrophysics Data System (ADS)

    Koski, Jonne V.; Pekola, Jukka P.

    2016-12-01

    We review recent progress in making the former gedanken experiments of Maxwell's demon [1] into real experiments in a lab. In particular, we focus on realizations based on single-electron tunneling in electronic circuits. We first present how stochastic thermodynamics can be investigated in these circuits. Next we review recent experiments on an electron-based Szilard engine. Finally, we report on experiments on single-electron tunneling-based cooling, overviewing the recent realization of a Coulomb gap refrigerator, as well as an autonomous Maxwell's demon.

  19. Paradigms for Realizing Machine Learning Algorithms.

    PubMed

    Agneeswaran, Vijay Srinivas; Tonpay, Pranay; Tiwary, Jayati

    2013-12-01

    The article explains the three generations of machine learning algorithms-with all three trying to operate on big data. The first generation tools are SAS, SPSS, etc., while second generation realizations include Mahout and RapidMiner (that work over Hadoop), and the third generation paradigms include Spark and GraphLab, among others. The essence of the article is that for a number of machine learning algorithms, it is important to look beyond the Hadoop's Map-Reduce paradigm in order to make them work on big data. A number of promising contenders have emerged in the third generation that can be exploited to realize deep analytics on big data.

  20. Realizing actual feedback control of complex network

    NASA Astrophysics Data System (ADS)

    Tu, Chengyi; Cheng, Yuhua

    2014-06-01

    In this paper, we present the concept of feedbackability and how to identify the Minimum Feedbackability Set of an arbitrary complex directed network. Furthermore, we design an estimator and a feedback controller accessing one MFS to realize actual feedback control, i.e. control the system to our desired state according to the estimated system internal state from the output of estimator. Last but not least, we perform numerical simulations of a small linear time-invariant dynamics network and a real simple food network to verify the theoretical results. The framework presented here could make an arbitrary complex directed network realize actual feedback control and deepen our understanding of complex systems.

  1. Full-duplex RoF link with broadband mm-wave signal in W-band based on WDM-PON access network with optical mm-wave local oscillator broadcasting

    NASA Astrophysics Data System (ADS)

    Ma, Jianxin; Zhang, Ruijiao; Li, Yanjie; Zhang, Qi; Yu, Jianguo

    2015-02-01

    A novel full-duplex link with an optical mm-wave local oscillator broadcasting for broadband millimeter (mm)-wave wireless access in W-band is proposed based on the WDM-PON-RoF. In our scheme, a universal optical mm-wave local oscillator in W-band is distributed over the whole network to up-convert the downlink IF optical signal, which not only improves the spectrum efficiency by reducing the bandwidth requirement of each downlink, but also decreases the degradation caused by the fiber chromatic dispersion. Moreover, since the incoherently down-converted uplink signal is modulated on the reused blank optical carrier extracted from the downlink signal, the base stations (BSs) need no optical source, and so its structure is simplified. The numerical simulation results agree well with the theoretical analysis and show that the proposed full-duplex link for the W-band wireless access based on WDM-PON-RoF maintains good performance with cost effective implement.

  2. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-02-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  3. Transition of radiative recombination channels from delocalized states to localized states in a GaInP alloy with partial atomic ordering: a direct optical signature of Mott transition?

    NASA Astrophysics Data System (ADS)

    Su, Z. C.; Ning, J. Q.; Deng, Z.; Wang, X. H.; Xu, S. J.; Wang, R. X.; Lu, S. L.; Dong, J. R.; Yang, H.

    2016-03-01

    Anderson localization is a predominant phenomenon in condensed matter and materials physics. In fact, localized and delocalized states often co-exist in one material. They are separated by a boundary called the mobility edge. Mott transition may take place between these two regimes. However, it is widely recognized that an apparent demonstration of Anderson localization or Mott transition is a challenging task. In this article, we present a direct optical observation of a transition of radiative recombination dominant channels from delocalized (i.e., local extended) states to Anderson localized states in the GaInP base layer of a GaInP/GaAs single junction solar cell by the means of the variable-temperature electroluminescence (EL) technique. It is found that by increasing temperature, we can boost a remarkable transition of radiative recombination dominant channels from the delocalized states to the localized states. The delocalized states are induced by the local atomic ordering domains (InP/GaP monolayer superlattices) while the localized states are caused by random distribution of indium (gallium) content. The efficient transfer and thermal redistribution of carriers between the two kinds of electronic states was revealed to result in both a distinct EL mechanism transition and an electrical resistance evolution with temperature. Our study gives rise to a self-consistent precise picture for carrier localization and transfer in a GaInP alloy, which is an extremely technologically important energy material for fabricating high-efficiency photovoltaic devices.

  4. Flexible-rate optical packet generation/detection and label swapping for optical label switching networks

    NASA Astrophysics Data System (ADS)

    Wu, Zhongying; Li, Juhao; Tian, Yu; Ge, Dawei; Zhu, Paikun; Chen, Yuanxiang; Chen, Zhangyuan; He, Yongqi

    2017-03-01

    In recent years, optical label switching (OLS) gains lots of attentions due to its intrinsic advantages to implement protocol, bit-rate, granularity and data format transparency packet switching. In this paper, we propose a novel scheme to realize flexible-rate optical packet switching for OLS networks. At the transmitter node, flexible-rate packet is generated by parallel modulating different combinations of optical carriers generated from the optical multi-carrier generator (OMCG), among which the low-speed optical label occupies one carrier. At the switching node, label is extracted and re-generated in label processing unit (LPU). The payloads are switched based on routing information and new label is added after switching. At the receiver node, another OMCG serves as local oscillators (LOs) for optical payloads coherent detection. The proposed scheme offers good flexibility for dynamic optical packet switching by adjusting the payload bandwidth and could also effectively reduce the number of lasers, modulators and receivers for packet generation/detection. We present proof-of-concept demonstrations of flexible-rate packet generation/detection and label swapping in 12.5 GHz grid. The influence of crosstalk for cascaded label swapping is also investigated.

  5. Banach spaces that realize minimal fillings

    NASA Astrophysics Data System (ADS)

    Bednov, B. B.; Borodin, P. A.

    2014-04-01

    It is proved that a real Banach space realizes minimal fillings for all its finite subsets (a shortest network spanning a fixed finite subset always exists and has the minimum possible length) if and only if it is a predual of L_1. The spaces L_1 are characterized in terms of Steiner points (medians). Bibliography: 25 titles.

  6. Banach spaces that realize minimal fillings

    SciTech Connect

    Bednov, B. B.; Borodin, P. A. E-mail: pborodin@inbox.ru

    2014-04-30

    It is proved that a real Banach space realizes minimal fillings for all its finite subsets (a shortest network spanning a fixed finite subset always exists and has the minimum possible length) if and only if it is a predual of L{sub 1}. The spaces L{sub 1} are characterized in terms of Steiner points (medians). Bibliography: 25 titles. (paper)

  7. Shrinkage estimation of the realized relationship matrix

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The additive relationship matrix plays an important role in mixed model prediction of breeding values. For genotype matrix X (loci in columns), the product XX' is widely used as a realized relationship matrix, but the scaling of this matrix is ambiguous. Our first objective was to derive a proper ...

  8. Incorporating local land use regression and satellite aerosol optical depth in a hybrid model of spatiotemporal PM2.5 exposures in the Mid-Atlantic states.

    PubMed

    Kloog, Itai; Nordio, Francesco; Coull, Brent A; Schwartz, Joel

    2012-11-06

    Satellite-derived aerosol optical depth (AOD) measurements have the potential to provide spatiotemporally resolved predictions of both long and short-term exposures, but previous studies have generally shown moderate predictive power and lacked detailed high spatio- temporal resolution predictions across large domains. We aimed at extending our previous work by validating our model in another region with different geographical and metrological characteristics, and incorporating fine scale land use regression and nonrandom missingness to better predict PM(2.5) concentrations for days with or without satellite AOD measures. We start by calibrating AOD data for 2000-2008 across the Mid-Atlantic. We used mixed models regressing PM(2.5) measurements against day-specific random intercepts, and fixed and random AOD and temperature slopes. We used inverse probability weighting to account for nonrandom missingness of AOD, nested regions within days to capture spatial variation in the daily calibration, and introduced a penalization method that reduces the dimensionality of the large number of spatial and temporal predictors without selecting different predictors in different locations. We then take advantage of the association between grid-cell specific AOD values and PM(2.5) monitoring data, together with associations between AOD values in neighboring grid cells to develop grid cell predictions when AOD is missing. Finally to get local predictions (at the resolution of 50 m), we regressed the residuals from the predictions for each monitor from these previous steps against the local land use variables specific for each monitor. "Out-of-sample" 10-fold cross-validation was used to quantify the accuracy of our predictions at each step. For all days without AOD values, model performance was excellent (mean "out-of-sample" R(2) = 0.81, year-to-year variation 0.79-0.84). Upon removal of outliers in the PM(2.5) monitoring data, the results of the cross validation procedure was

  9. Optical biosensors

    PubMed Central

    Damborský, Pavel; Švitel, Juraj

    2016-01-01

    Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. PMID:27365039

  10. Realization-Based System Identification with Applications

    NASA Astrophysics Data System (ADS)

    Miller, Daniel N.

    The identification of dynamic system behavior from experimentally measured or computationally simulated data is fundamental to the fields of control system design, modal analysis, and defect detection. In this dissertation, methods for system identification are developed based on classical linear system realization theory. The common methods of state-space realization from a measured, discrete-time impulse response are generalized to the following additional types of experiments: measured step responses, arbitrary sets of input-output data, and estimated cross-covariance functions of input-output data. The methods are particularly well suited to systems with large input and/or output dimension, for which classical system identification methods based on maximum likelihood estimation may fail due to their reliance on non-convex optimizations. The realization-based methods by themselves require a finite number of linear algebraic operations. Because these methods implicitly optimize cost functions that are linear in state-space parameters, they may be augmented with convex constraints to form convex optimization problems. Several common behavioral constraints are translated into eigenvalue constraints stated as linear matrix inequalities, and the realization-based methods are converted into semidefinite programming problems. Some additional constraints on transient and steady-state behavior are derived and incorporated into a quadratic program, which is solved following the semidefinite program. The newly developed realization-based methods are applied to two experiments: the aeroelastic response of a fighter aircraft and the transient thermal behavior of a light-emitting diode. The algorithms for each experiment are implemented in two freely available software packages.

  11. In situ optical sequencing and structure analysis of a trinucleotide repeat genome region by localization microscopy after specific COMBO-FISH nano-probing

    NASA Astrophysics Data System (ADS)

    Stuhlmüller, M.; Schwarz-Finsterle, J.; Fey, E.; Lux, J.; Bach, M.; Cremer, C.; Hinderhofer, K.; Hausmann, M.; Hildenbrand, G.

    2015-10-01

    Trinucleotide repeat expansions (like (CGG)n) of chromatin in the genome of cell nuclei can cause neurological disorders such as for example the Fragile-X syndrome. Until now the mechanisms are not clearly understood as to how these expansions develop during cell proliferation. Therefore in situ investigations of chromatin structures on the nanoscale are required to better understand supra-molecular mechanisms on the single cell level. By super-resolution localization microscopy (Spectral Position Determination Microscopy; SPDM) in combination with nano-probing using COMBO-FISH (COMBinatorial Oligonucleotide FISH), novel insights into the nano-architecture of the genome will become possible. The native spatial structure of trinucleotide repeat expansion genome regions was analysed and optical sequencing of repetitive units was performed within 3D-conserved nuclei using SPDM after COMBO-FISH. We analysed a (CGG)n-expansion region inside the 5' untranslated region of the FMR1 gene. The number of CGG repeats for a full mutation causing the Fragile-X syndrome was found and also verified by Southern blot. The FMR1 promotor region was similarly condensed like a centromeric region whereas the arrangement of the probes labelling the expansion region seemed to indicate a loop-like nano-structure. These results for the first time demonstrate that in situ chromatin structure measurements on the nanoscale are feasible. Due to further methodological progress it will become possible to estimate the state of trinucleotide repeat mutations in detail and to determine the associated chromatin strand structural changes on the single cell level. In general, the application of the described approach to any genome region will lead to new insights into genome nano-architecture and open new avenues for understanding mechanisms and their relevance in the development of heredity diseases.

  12. A localized and propagating SPR, and molecular imprinting based fiber-optic ascorbic acid sensor using an in situ polymerized polyaniline-Ag nanocomposite

    NASA Astrophysics Data System (ADS)

    Shrivastav, Anand M.; Usha, Sruthi P.; Gupta, Banshi D.

    2016-08-01

    We report a successful approach for the fabrication and characterization of a fiber-optic sensor for ascorbic acid (AA) detection, using a molecularly imprinted polyaniline-Ag (PANI-Ag) nanocomposite layer based on the combined phenomena of surface plasmon resonance (SPR) and localized SPR (LSPR). The PANI-Ag nanocomposite is synthesized by an in situ polymerization process and AA imprints are prepared on the polymeric composite. The confirmation of the PANI-Ag nanocomposite and AA imprinting is performed using various characterization methods such as x-ray diffraction (XRD), UV-vis, Fourier transform infrared spectroscopy and scanning electron microscopy. From XRD, the size of Ag nanoparticles is analyzed. The absorbance spectra are recorded for samples of different concentrations of AA around the sensing region of the probe. An increase in peak absorbance wavelength with the increase in AA concentration is observed with a linear response for the concentration range from 10-8 M to 10-6 M. The sensor possesses a high sensitivity of 45.1 nm log-1 M near an AA concentration of 10-8 M. The limit of detection (LOD) and limit of quantification of the sensor are found to be 7.383 × 10-11 M and 4.16 × 10-10 M, respectively. The LOD of the sensor is compared to studies reported in the literature and is found to be the lowest. The sensor possesses several other advantages such as cost effectiveness, selectivity, and low response time (<5 s), along with abilities of remote sensing and online monitoring.

  13. Detection of swine-origin influenza A (H1N1) viruses using a localized surface plasmon coupled fluorescence fiber-optic biosensor.

    PubMed

    Chang, Ying-Feng; Wang, Sheng-Fan; Huang, Jason C; Su, Li-Chen; Yao, Ling; Li, Ying-Chang; Wu, Suh-Chin; Chen, Yi-Ming A; Hsieh, Jo-Ping; Chou, Chien

    2010-11-15

    Swine-origin influenza A (H1N1) virus (S-OIV) was identified as a new reassortant strain of influenza A virus in April 2009 and led to an influenza pandemic. Accurate and timely diagnoses are crucial for the control of influenza disease. We developed a localized surface plasmon coupled fluorescence fiber-optic biosensor (LSPCF-FOB) which combines a sandwich immunoassay with the LSP technique using antibodies against the hemagglutinin (HA) proteins of S-OIVs. The detection limit of the LSPCF-FOB for recombinant S-OIV H1 protein detection was estimated at 13.9 pg/mL, which is 10(3)-fold better than that of conventional capture ELISA when using the same capture antibodies. For clinical S-OIV isolates measurement, meanwhile, the detection limit of the LSPCF-FOB platform was calculated to be 8.25 × 10(4)copies/mL, compared with 2.06 × 10(6)copies/mL using conventional capture ELISA. Furthermore, in comparison with the influenza A/B rapid test, the detection limit of the LSPCF-FOB for S-OIV was almost 50-fold in PBS solution and 25-fold lower in mimic solution, which used nasal mucosa from healthy donors as the diluent. The findings of this study therefore indicate that the high detection sensitivity and specificity of the LSPCF-FOB make it a potentially effective diagnostic tool for clinical S-OIV infection and this technique has the potential to be applied to the development of other clinical microbe detection platforms.

  14. Measurement of type-I edge localized mode pulse propagation in scrape-off layer using optical system of motional Stark effect diagnostics in JT-60U

    NASA Astrophysics Data System (ADS)

    Suzuki, T.; Oyama, N.; Asakura, N.

    2010-04-01

    Propagation of plasma ejected by type-I edge localized mode (ELM) has been measured in scrape-off layer (SOL) of the JT-60U tokamak, using optical system of motional Stark effect (MSE) diagnostics as beam emission spectroscopy (BES) diagnostics through a new technique developed. This MSE/BES system measures Dα emission from heating neutral beam excited by collisions with the ejected plasma, as well as background light (e.g., bremsstrahlung). While spatio-temporal change in the beam emission gives information on propagation of the ejected plasma, the background light that is observed simultaneously in all spatial channels veils the information. In order to separate the beam emission and the background light, a two-wavelength detector is newly introduced into the MSE/BES system. The detector observes simultaneously at the same spatial point in two distinct wavelengths using two photomultiplier tubes through two interference filters. One of the filters is adjusted to the central wavelength of the beam emission for the MSE diagnostics, and the other is outside the beam emission spectrum. Eliminating the background light, temporal change in the net beam emission in the SOL has been evaluated. Comparing conditionally averaged beam emission with respect to 594 ELMs in a discharge at five spatial channels (0.02-0.3 m outside the main plasma near equatorial plane), radial velocity of the ELM pulse propagation in SOL is evaluated to be 0.8-1.8 km/s (˜1.4 km/s for least-mean-squared fitting).

  15. Statistical analysis of accurate prediction of local atmospheric optical attenuation with a new model according to weather together with beam wandering compensation system: a season-wise experimental investigation

    NASA Astrophysics Data System (ADS)

    Arockia Bazil Raj, A.; Padmavathi, S.

    2016-07-01

    Atmospheric parameters strongly affect the performance of Free Space Optical Communication (FSOC) system when the optical wave is propagating through the inhomogeneous turbulent medium. Developing a model to get an accurate prediction of optical attenuation according to meteorological parameters becomes significant to understand the behaviour of FSOC channel during different seasons. A dedicated free space optical link experimental set-up is developed for the range of 0.5 km at an altitude of 15.25 m. The diurnal profile of received power and corresponding meteorological parameters are continuously measured using the developed optoelectronic assembly and weather station, respectively, and stored in a data logging computer. Measured meteorological parameters (as input factors) and optical attenuation (as response factor) of size [177147 × 4] are used for linear regression analysis and to design the mathematical model that is more suitable to predict the atmospheric optical attenuation at our test field. A model that exhibits the R2 value of 98.76% and average percentage deviation of 1.59% is considered for practical implementation. The prediction accuracy of the proposed model is investigated along with the comparative results obtained from some of the existing models in terms of Root Mean Square Error (RMSE) during different local seasons in one-year period. The average RMSE value of 0.043-dB/km is obtained in the longer range dynamic of meteorological parameters variations.

  16. Foveated optics

    NASA Astrophysics Data System (ADS)

    Bryant, Kyle R.

    2016-05-01

    Foveated imaging can deliver two different resolutions on a single focal plane, which might inexpensively allow more capability for military systems. The following design study results provide starting examples, lessons learned, and helpful setup equations and pointers to aid the lens designer in any foveated lens design effort. Our goal is to put robust sensor in a small package with no moving parts, but still be able to perform some of the functions of a sensor in a moving gimbal. All of the elegant solutions are out (for various reasons). This study is an attempt to see if lens designs can solve this problem and realize some gains in performance versus cost for airborne sensors. We determined a series of design concepts to simultaneously deliver wide field of view and high foveal resolution without scanning or gimbals. Separate sensors for each field of view are easy and relatively inexpensive, but lead to bulky detectors and electronics. Folding and beam-combining of separate optical channels reduces sensor footprint, but induces image inversions and reduced transmission. Entirely common optics provide good resolution, but cannot provide a significant magnification increase in the foveal region. Offsetting the foveal region from the wide field center may not be physically realizable, but may be required for some applications. The design study revealed good general guidance for foveated optics designs with a cold stop. Key lessons learned involve managing distortion, telecentric imagers, matching image inversions and numerical apertures between channels, reimaging lenses, and creating clean resolution zone splits near internal focal planes.

  17. Optical symbolic substitution: edge detection using Prewitt, Sobel, and Roberts operators.

    PubMed

    Cherri, A K; Karim, M A

    1989-11-01

    Edge detection schemes based on Prewitt, Sobel, and Roberts operators are realized using optical symbolic substitution. The corresponding optical systems are compared in terms of hardware and performance.

  18. Omnidirectional beacon-localization using a catadioptric system.

    PubMed

    Shen, Thomas C; Drost, Robert J; Sadler, Brian M; Rzasa, John R; Davis, Christopher C

    2016-04-04

    We present a catadioptric beacon localization system that can provide mobile network nodes with omnidirectional situational awareness of neighboring nodes. In this system, a receiver composed of a hyperboloidal mirror and camera is used to estimate the azimuth, elevation, and range of an LED beacon. We provide a general framework for understanding the propagation of error in the angle-of-arrival estimation and then present an experimental realization of such a system. The situational awareness provided by the proposed system can enable the alignment of communication nodes in an optical wireless network, which may be particularly useful in addressing RF-denied environments.

  19. Physical realization of quantum teleportation for a nonmaximal entangled state

    SciTech Connect

    Tanaka, Yoshiharu; Asano, Masanari; Ohya, Masanori

    2010-08-15

    Recently, Kossakowski and Ohya (K-O) proposed a new teleportation scheme which enables perfect teleportation even for a nonmaximal entangled state [A. Kossakowski and M. Ohya, Infinite Dimensional Analysis Quantum Probability and Related Topics 10, 411 (2007)]. To discuss a physical realization of the K-O scheme, we propose a model based on quantum optics. In our model, we take a superposition of Schroedinger's cat states as an input state being sent from Alice to Bob, and their entangled state is generated by a photon number state through a beam splitter. When the average photon number for our input states is equal to half the number of photons into the beam splitter, our model has high fidelity.

  20. Physical realization of quantum teleportation for a nonmaximal entangled state

    NASA Astrophysics Data System (ADS)

    Tanaka, Yoshiharu; Asano, Masanari; Ohya, Masanori

    2010-08-01

    Recently, Kossakowski and Ohya (K-O) proposed a new teleportation scheme which enables perfect teleportation even for a nonmaximal entangled state [A. Kossakowski and M. Ohya, Infinite Dimensional Analysis Quantum Probability and Related Topics0219-025710.1142/S021902570700283X 10, 411 (2007)]. To discuss a physical realization of the K-O scheme, we propose a model based on quantum optics. In our model, we take a superposition of Schrödinger’s cat states as an input state being sent from Alice to Bob, and their entangled state is generated by a photon number state through a beam splitter. When the average photon number for our input states is equal to half the number of photons into the beam splitter, our model has high fidelity.