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Sample records for optically realizable localized

  1. Local heating realization by reverse thermal cloak

    PubMed Central

    Hu, Run; Wei, Xuli; Hu, Jinyan; Luo, Xiaobing

    2014-01-01

    Transformation thermodynamics, as one of the important branches among the extensions of transformation optics, has attracted plentiful attentions and interests recently. The result of transformation thermodynamics, or called as “thermal cloak”, can realize isothermal region and hide objects from heat. In this paper, we presented the concept of “reverse thermal cloak” to correspond to the thermal cloak and made a simple engineering definition to identify them. By full-wave simulations, we verified that the reverse thermal cloak can concentrate heat and realize local heating. The performance of local heating depends on the anisotropic dispersion of the cloaking layer's thermal conductivity. Three-dimensional finite element simulations demonstrated that the reverse thermal cloak can be used to heat up objects. Besides pre-engineered metamaterials, such reverse thermal cloak can even be realized with homogenous materials by alternating spoke-like structure or Hashin coated-sphere structure. PMID:24398592

  2. Local heating realization by reverse thermal cloak.

    PubMed

    Hu, Run; Wei, Xuli; Hu, Jinyan; Luo, Xiaobing

    2014-01-01

    Transformation thermodynamics, as one of the important branches among the extensions of transformation optics, has attracted plentiful attentions and interests recently. The result of transformation thermodynamics, or called as "thermal cloak", can realize isothermal region and hide objects from heat. In this paper, we presented the concept of "reverse thermal cloak" to correspond to the thermal cloak and made a simple engineering definition to identify them. By full-wave simulations, we verified that the reverse thermal cloak can concentrate heat and realize local heating. The performance of local heating depends on the anisotropic dispersion of the cloaking layer's thermal conductivity. Three-dimensional finite element simulations demonstrated that the reverse thermal cloak can be used to heat up objects. Besides pre-engineered metamaterials, such reverse thermal cloak can even be realized with homogenous materials by alternating spoke-like structure or Hashin coated-sphere structure. PMID:24398592

  3. Physically realizable entanglement by local continuous measurements

    SciTech Connect

    Mascarenhas, Eduardo; Santos, Marcelo Franca; Cavalcanti, Daniel; Vedral, Vlatko

    2011-02-15

    Quantum systems prepared in pure states evolve into mixtures under environmental action. Continuously realizable ensembles (or physically realizable) are the pure state decompositions of those mixtures that can be generated in time through continuous measurements of the environment. Here, we define continuously realizable entanglement as the average entanglement over realizable ensembles. We search for the measurement strategy to maximize and minimize this quantity through observations on the independent environments that cause two qubits to disentangle in time. We then compare it with the entanglement bounds (entanglement of formation and entanglement of assistance) for the unmonitored system. For some relevant noise sources the maximum realizable entanglement coincides with the upper bound, establishing the scheme as an alternative to protect entanglement. However, for local strategies, the lower bound of the unmonitored system is not reached.

  4. Experimental Realization of a Reflective Optical Limiter

    NASA Astrophysics Data System (ADS)

    Vella, Jarrett H.; Goldsmith, John H.; Browning, Andrew T.; Limberopoulos, Nicholaos I.; Vitebskiy, Ilya; Makri, Eleana; Kottos, Tsampikos

    2016-06-01

    Optical limiters transmit low-intensity light, while blocking laser radiation with excessively high irradiance or fluence. A typical optical limiter involves a nonlinear material which is transparent at low light intensity and becomes opaque when the light intensity exceeds a certain level. Most of the high-level radiation is absorbed by the nonlinear material causing irreversible damage. This fundamental problem could be solved if the state of the nonlinear material changed from transparent to highly reflective (not absorptive) when the intensity becomes too high. None of the known nonlinear optical materials display such a property. A solution can be provided by a nonlinear photonic structure. In this communication, we report the experimental realization of a reflective optical limiter. The design is based on a planar microcavity composed of alternating SiO2 and Si3N4 layers with a single GaAs defect layer in the middle. At low intensity, the planar microcavity displays a strong resonant transmission via a cavity mode. As the intensity increases, two-photon absorption in GaAs kicks in, initially resulting in the microcavity-enhanced light absorption. A further increase in light intensity, though, suppresses the cavity mode along with the resonant transmission; the entire planar microcavity turns highly reflective within a broad frequency range covering the entire photonic band gap. This seemingly counterintuitive behavior is a general feature of resonant transmission via a cavity mode with purely nonlinear absorption.

  5. Localization of Free Field Realizations of Affine Lie Algebras

    NASA Astrophysics Data System (ADS)

    Futorny, Vyacheslav; Grantcharov, Dimitar; Martins, Renato A.

    2015-04-01

    We use localization technique to construct new families of irreducible modules of affine Kac-Moody algebras. In particular, localization is applied to the first free field realization of the affine Lie algebra or, equivalently, to imaginary Verma modules.

  6. Fiber optic gyros: the vision realized

    NASA Astrophysics Data System (ADS)

    Pavlath, George A.

    2006-08-01

    Over thirty five years have elapsed since the fiber optic gyro was proposed by Vali and Shorthill. In those decades, fiber gyros have matured. They are competing head to head with existing technologies such as mechanical gyros and RLGs in tactical, navigation and strategic applications and are winning. Northrop Grumman has produced the majority of fiber optic gyros and fiber optic gyro based inertial products in the world. This paper will cover the various Northrop fiber gyro products, the platforms they are used on, as well as production and top level system data.

  7. Realizing optical magnetism from dielectric metamaterials.

    PubMed

    Ginn, James C; Brener, Igal; Peters, David W; Wendt, Joel R; Stevens, Jeffrey O; Hines, Paul F; Basilio, Lorena I; Warne, Larry K; Ihlefeld, Jon F; Clem, Paul G; Sinclair, Michael B

    2012-03-01

    We demonstrate, for the first time, an all-dielectric metamaterial composite in the midinfrared based on micron-sized, high-index tellurium dielectric resonators. Dielectric resonators are desirable compared to conventional metallodielectric metamaterials at optical frequencies as they are largely angular invariant, free of Ohmic loss, and easily integrated into three-dimensional volumes. Measurements and simulation provide evidence of optical magnetism, which could be used for infrared magnetic mirrors, hard or soft surfaces, and subwavelength cavities. PMID:22463666

  8. 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.

  9. Realization of an all optical exciton-polariton router

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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.

  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). PMID:23839206

  12. Perturbative analysis of spectral singularities and their optical realizations

    NASA Astrophysics Data System (ADS)

    Mostafazadeh, Ali; Rostamzadeh, Saber

    2012-08-01

    We develop a perturbative method of computing spectral singularities of a Schrödinger operator defined by a general complex potential that vanishes outside a closed interval. These can be realized as zero-width resonances in optical gain media and correspond to a lasing effect that occurs at the threshold gain. Their time-reversed copies yield coherent perfect absorption of light that is also known as antilasing. We use our general results to establish the exactness of the nth-order perturbation theory for an arbitrary complex potential consisting of n delta functions, obtain an exact expression for the transfer matrix of these potentials, and examine spectral singularities of complex barrier potentials of arbitrary shape. In the context of optical spectral singularities, these correspond to inhomogeneous gain media.

  13. 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.

  14. 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.

  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. Quantum homogenization for continuous variables: Realization with linear optical elements

    NASA Astrophysics Data System (ADS)

    Nagaj, Daniel; Štelmachovič, Peter; Bužek, Vladimír; Kim, Myungshik

    2002-12-01

    Recently Ziman et al. [Phys. Rev. A 65, 042105 (2002)] have introduced a concept of a universal quantum homogenizer which is a quantum machine that takes as input a given (system) qubit initially in an arbitrary state ρ and a set of N reservoir qubits initially prepared in the state ξ. The homogenizer realizes, in the limit sense, the transformation such that at the output each qubit is in an arbitrarily small neighborhood of the state ξ irrespective of the initial states of the system and the reservoir qubits. In this paper we generalize the concept of quantum homogenization for qudits, that is, for d-dimensional quantum systems. We prove that the partial-swap operation induces a contractive map with the fixed point which is the original state of the reservoir. We propose an optical realization of the quantum homogenization for Gaussian states. We prove that an incoming state of a photon field is homogenized in an array of beam splitters. Using Simon's criterion, we study entanglement between outgoing beams from beam splitters. We derive an inseparability condition for a pair of output beams as a function of the degree of squeezing in input beams.

  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. Realization of the Hofstadter Hamiltonian with ultracold atoms in optical lattices.

    PubMed

    Aidelsburger, M; Atala, M; Lohse, M; Barreiro, J T; Paredes, B; Bloch, I

    2013-11-01

    We demonstrate the experimental implementation of an optical lattice that allows for the generation of large homogeneous and tunable artificial magnetic fields with ultracold atoms. Using laser-assisted tunneling in a tilted optical potential, we engineer spatially dependent complex tunneling amplitudes. Thereby, atoms hopping in the lattice accumulate a phase shift equivalent to the Aharonov-Bohm phase of charged particles in a magnetic field. We determine the local distribution of fluxes through the observation of cyclotron orbits of the atoms on lattice plaquettes, showing that the system is described by the Hofstadter model. Furthermore, we show that for two atomic spin states with opposite magnetic moments, our system naturally realizes the time-reversal-symmetric Hamiltonian underlying the quantum spin Hall effect; i.e., two different spin components experience opposite directions of the magnetic field. PMID:24237530

  19. Spin-wave based realization of optical computing primitives

    SciTech Connect

    Csaba, G. Papp, A.; Porod, W.

    2014-05-07

    We use micromagnetic simulations to demonstrate that spin waves can perform optically inspired, non-Boolean computing algorithms. We propose and design coherent spin-wave sources and phase shifters, which act akin to the key components of an optical signal processing system. We show that the functionality of the proposed on-chip spin-wave based signal processing system is similar to known optical computing devices. We argue that such computing system can serve as a practical, energy efficient, and integrated component of nanoscale image processing systems.

  20. Experimental realization of spectral shaping using nonlinear optical holograms.

    PubMed

    Leshem, Anat; Shiloh, Roy; Arie, Ady

    2014-09-15

    We experimentally demonstrate the spectral shaping of a signal generated by a three-wave mixing process using a nonlinear spectral hologram. These holograms are based on binary spatial modulation of the second-order nonlinear coefficient. Here we present the first experimental realization, to the best of our knowledge, of this concept, encoding a nonlinear hologram in a KTiOPO(4) crystal by electric field poling. Two different spectra in the form of the second-order Hermite-Gauss function and the Airy function are shown using the sum-frequency generation process. PMID:26466274

  1. From Cartesian to polar: a new POLICRYPS geometry for realizing circular optical diffraction gratings.

    PubMed

    Alj, Domenico; Caputo, Roberto; Umeton, Cesare

    2014-11-01

    We report on the realization of a liquid crystal (LC)-based optical diffraction grating showing a polar symmetry of the director alignment. This has been obtained as a natural evolution of the POLICRYPS technique, which enables the realization of highly efficient, switchable, planar diffraction gratings. Performances exhibited in the Cartesian geometry are extended to the polar one by exploiting the spherical aberration produced by simple optical elements. This enables producing the required highly stable polar pattern that allows fabricating a circular optical diffraction grating. Results are promising for their possible application in fields in which a rotational structure of the optical beam is needed. PMID:25361314

  2. Two novel schemes for probabilistic remote state preparation and the physical realization via the linear optics

    NASA Astrophysics Data System (ADS)

    Wei, Jiahua; Dai, Hong-Yi; Zhang, Ming; Yang, Le; Kuang, Jingsong

    2016-05-01

    In this paper, we put forward two novel schemes for probabilistic remote preparation of an arbitrary quantum state with the aid of appropriate local unitary operations when the sender and the receiver only have partial information of non-maximally entangled state, respectively. The concrete implementation procedures of the novel proposals are given in detail. Additionally, the physical realizations of our proposals are discussed based on the linear optics. Because of that neither the sender nor the receiver need to know fully the information of the partially entangled state, our schemes are useful to not only expand the application range of quantum entanglement, but also enlarge the research field of probabilistic remote state preparation (RSP).

  3. Localization in optics - Quasiperiodic media

    NASA Astrophysics Data System (ADS)

    Kohmoto, Mahito; Sutherland, Bill; Iguchi, K.

    1987-06-01

    An experiment to probe the (quasi)localization of the photon is proposed, in which optical layers are constructed following the Fibonacci sequence. The transmission coefficient has a rich structure as a function of the wavelength of light and, in fact, is multifractal. For particular wavelengths for which the resonance conditions is satisfied, the light propagation has scaling with respect to the number of layers, as well as an interesting fluctuation.

  4. 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. PMID:23609666

  5. Realization of binary radial diffractive optical elements by two-photon polymerization technique.

    PubMed

    Osipov, Vladimir; Pavelyev, Vladimir; Kachalov, Denis; Zukauskas, Albertas; Chichkov, Boris

    2010-12-01

    Application of the two-photon polymerization (2PP) technique for the fabrication of submicron-size relief of radial binary diffractive optical elements (DOE's) is studied. Binary DOE's for the formation of special longitudinal intensity distribution (axial light segment) are realized. Interferometric investigations of the diffractive relief produced by the 2PP-technique and investigations of optical properties of the formed elements are presented. Results of computer simulations are in good agreement with the experimental observations. PMID:21164925

  6. 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. PMID:20531907

  7. Large third-order optical nonlinearity realized in symmetric nonpolar carotenoids

    NASA Astrophysics Data System (ADS)

    Fujiwara, Masazumi; Yamauchi, Kensei; Sugisaki, Mitsuru; Yanagi, Kazuhiro; Gall, Andrew; Robert, Bruno; Cogdell, Richard J.; Hashimoto, Hideki

    2008-10-01

    We show that a very large enhancement of third-order optical nonlinearity (γ) of π -conjugated molecules can be realized without a major redshift of the absorption spectrum that disturbs optical transparency in the visible region. By changing the number (n) of C=C bonds of β carotene (n=11) from 7 to 15, a remarkable 3.4-fold increase in the γ value was observed when n=15 relative to that of β carotene. This enhancement of γ mainly originates from three-photon resonance of a lowest optically allowed excited state. The controversial higher-lying essential state is not important for generating the large value of γ .

  8. Realization of an all-dielectric zero-index optical metamaterial

    NASA Astrophysics Data System (ADS)

    Moitra, Parikshit; Yang, Yuanmu; Anderson, Zachary; Kravchenko, Ivan I.; Briggs, Dayrl P.; Valentine, Jason

    2013-10-01

    Metamaterials offer unprecedented flexibility for manipulating the optical properties of matter, including the ability to access negative index, ultrahigh index and chiral optical properties. Recently, metamaterials with near-zero refractive index have attracted much attention. Light inside such materials experiences no spatial phase change and extremely large phase velocity, properties that can be applied for realizing directional emission, tunnelling waveguides, large-area single-mode devices and electromagnetic cloaks. However, at optical frequencies, the previously demonstrated zero- or negative-refractive-index metamaterials have required the use of metallic inclusions, leading to large ohmic loss, a serious impediment to device applications. Here, we experimentally demonstrate an impedance-matched zero-index metamaterial at optical frequencies based on purely dielectric constituents. Formed from stacked silicon-rod unit cells, the metamaterial has a nearly isotropic low-index response for transverse-magnetic polarized light, leading to angular selectivity of transmission and directive emission from quantum dots placed within the material.

  9. Realization of all-optical AND-OR logic gates using the Z-scan method

    NASA Astrophysics Data System (ADS)

    Dhinaa, A. N.; Palanisamy, P. K.; Murali, K.

    2013-10-01

    The NLO properties of organic materials have been studied with the single-beam Z-scan technique using a CW laser beam. A He-Ne laser operated at 632.8 nm with a power output of 12 mW is used for this study. A closed-aperture setup is used to measure the nonlinear refractive index of Patent blue V dye dissolved in distilled water. The material exhibits negative nonlinearity. Optical limiting behavior has been observed for this dye. Further, we have modified the Z-scan setup suitably to realize all-optical AND and OR logic gates.

  10. 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.

  11. 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.

  12. 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. PMID:26196826

  13. 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.

  14. Realizing non-Abelian gauge potentials in optical square lattices: an application to atomic Chern insulators

    NASA Astrophysics Data System (ADS)

    Goldman, N.; Gerbier, F.; Lewenstein, M.

    2013-07-01

    We describe a scheme to engineer non-Abelian gauge potentials on a square optical lattice using laser-induced transitions. We emphasize the case of two-electron atoms, where the electronic ground state g is laser-coupled to a metastable state e within a state-dependent optical lattice. In this scheme, the alternating pattern of lattice sites hosting g and e states depicts a chequerboard structure, allowing for laser-assisted tunnelling along both spatial directions. In this configuration, the nuclear spin of the atoms can be viewed as a ‘flavour’ quantum number undergoing non-Abelian tunnelling along nearest-neighbour links. We show that this technique can be useful to simulate the equivalent of the Haldane quantum Hall model using cold atoms trapped in square optical lattices, offering an interesting route to realize Chern insulators. The emblematic Haldane model is particularly suited to investigate the physics of topological insulators, but requires, in its original form, complex hopping terms beyond nearest-neighbouring sites. In general, this drawback inhibits a direct realization with cold atoms, using standard laser-induced tunnelling techniques. We demonstrate that a simple mapping allows us to express this model in terms of matrix hopping operators that are defined on a standard square lattice. This mapping is investigated for two models that lead to anomalous quantum Hall phases. We discuss the practical implementation of such models, exploiting laser-induced tunnelling methods applied to the chequerboard optical lattice.

  15. 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.

  16. Extraordinarily Large Optical Cross Section for Localized Single Nanoresonator

    NASA Astrophysics Data System (ADS)

    Zhou, Ming; Shi, Lei; Zi, Jian; Yu, Zongfu

    2015-07-01

    Using an optical nanoresonator to realize extreme concentration of light at subwavelength nanoscale dimensions is of both fundamental and practical significance. Unfortunately, the optical cross section of an isotropic nanoresonator is determined by the resonant wavelength, which unfavorably limits the highest concentration ratio. Here we show that the cross section of a localized subwavelength resonator can be drastically enhanced by orders of magnitude. A single microscopic nanoresonator could exhibit a macroscopic optical cross section. We further show that the enhancement can be implemented in simple dielectric structures that are readily compatible with optoelectronic integration. The giant optical cross section of a nano-object provides a versatile platform to create extremely strong light-matter interactions at the nanoscale.

  17. Real-time realizations of the Bayesian Infrasonic Source Localization Method

    NASA Astrophysics Data System (ADS)

    Pinsky, V.; Arrowsmith, S.; Hofstetter, A.; Nippress, A.

    2015-12-01

    The Bayesian Infrasonic Source Localization method (BISL), introduced by Mordak et al. (2010) and upgraded by Marcillo et al. (2014) is destined for the accurate estimation of the atmospheric event origin at local, regional and global scales by the seismic and infrasonic networks and arrays. The BISL is based on probabilistic models of the source-station infrasonic signal propagation time, picking time and azimuth estimate merged with a prior knowledge about celerity distribution. It requires at each hypothetical source location, integration of the product of the corresponding source-station likelihood functions multiplied by a prior probability density function of celerity over the multivariate parameter space. The present BISL realization is generally time-consuming procedure based on numerical integration. The computational scheme proposed simplifies the target function so that integrals are taken exactly and are represented via standard functions. This makes the procedure much faster and realizable in real-time without practical loss of accuracy. The procedure executed as PYTHON-FORTRAN code demonstrates high performance on a set of the model and real data.

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

    PubMed Central

    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

    2010-01-01

    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. PMID:21098305

  19. 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

    2010-12-01

    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. PMID:21098305

  20. Practical Realization of Massively Parallel Fiber -Free-Space Optical Interconnects

    NASA Astrophysics Data System (ADS)

    Gruber, Matthias; Jahns, Jürgen; El Joudi, El Mehdi; Sinzinger, Stefan

    2001-06-01

    We propose a novel approach to realizing massively parallel optical interconnects based on commercially available multifiber ribbons with MT-type connectors and custom-designed planar-integrated free-space components. It combines the advantages of fiber optics, that is, a long range and convenient and flexible installation, with those of (planar-integrated) free-space optics, that is, a wide range of implementable functions and a high potential for integration and parallelization. For the interface between fibers and free-space optical systems a low-cost practical solution is presented. It consists of using a metal connector plate that was manufactured on a computer-controlled milling machine. Channel densities are of the order of 100 /mm2 between optoelectronic VLSI chips and the free-space optical systems and 1 /mm2 between the free-space optical systems and MT-type fiber connectors. Experiments in combination with specially designed planar-integrated test systems prove that multiple one-to-one and one-to-many interconnects can be established with not more than 10% uniformity error.

  1. 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.

  2. Realizing the Harper Hamiltonian with laser-assisted tunneling in optical lattices.

    PubMed

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

    2013-11-01

    We experimentally implement the Harper Hamiltonian for neutral particles in optical lattices using laser-assisted tunneling and a potential energy gradient provided by gravity or magnetic field gradients. This Hamiltonian describes the motion of charged particles in strong magnetic fields. Laser-assisted tunneling processes are characterized by studying the expansion of the atoms in the lattice. The band structure of this Hamiltonian should display Hofstadter's butterfly. For fermions, this scheme should realize the quantum Hall effect and chiral edge states. PMID:24237531

  3. On-demand nanodevice with electrical and neuromorphic multifunction realized by local ion migration.

    PubMed

    Yang, Rui; Terabe, Kazuya; Liu, Guangqiang; Tsuruoka, Tohru; Hasegawa, Tsuyoshi; Gimzewski, James K; Aono, Masakazu

    2012-11-27

    A potential route to extend Moore's law beyond the physical limits of existing materials and device architectures is to achieve nanotechnology breakthroughs in materials and device concepts. Here, we discuss an on-demand WO(3-x)-based nanoionic device where electrical and neuromorphic multifunctions are realized through externally induced local migration of oxygen ions. The device is found to possess a wide range of time scales of memorization, resistance switching, and rectification varying from volatile to permanent in a single device, and these can furthermore be realizable in both two- or three-terminal systems. The gradually changing volatile and nonvolatile resistance states are experimentally demonstrated to mimic the human brain's forgetting process for short-term memory and long-term memory.We propose this nanoionic device with its on-demand electrical and neuromorphic multifunction has a unique paradigm shifting potential for the fabrication of configurable circuits, analog memories, digital-neural fused networks, and more in one device architecture. PMID:23102535

  4. 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. PMID:27067248

  5. Optofluidic realization and retaining of cell–cell contact using an abrupt tapered optical fibre

    PubMed Central

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

    2013-01-01

    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. PMID:23771190

  6. Precise realization of the thermal radiation environment for an optical lattice clock

    NASA Astrophysics Data System (ADS)

    Beloy, Kyle; Sherman, Jeff; Phillips, Nathaniel; Hinkley, Nathan; Oates, Chris; Ludlow, Andrew

    2013-05-01

    The Stark shift due to thermal radiation contributes one of the largest known perturbations to the clock transition frequency of optical lattice clocks. Consequently, the uncertainty stemming from this shift has played a dominant role in the total uncertainty of these standards. Following recent works focused on atomic response factors (e.g., the differential polarizability), uncertainty in this perturbation is now limited by imprecise knowledge of the environment itself. Here we present progress towards precise realization of the thermal radiation environment in a Yb optical lattice clock by trapping the atoms in a highly uniform radiation shield at a well-known temperature. We characterize the non-ideal aspects of this approach, including less than unit emissivity, contamination of the blackbody environment from the ambient environment, and thermal non-uniformities.

  7. 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.

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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 μm3) than a line-defect-based buried-heterostructure nanocavity (16 000 and 2.2 μm3). 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.

  11. 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

  12. 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;

  13. 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).

  14. Demon-like algorithmic quantum cooling and its realization with quantum optics

    NASA Astrophysics Data System (ADS)

    Xu, Jin-Shi; Yung, Man-Hong; Xu, Xiao-Ye; Boixo, Sergio; Zhou, Zheng-Wei; Li, Chuan-Feng; Aspuru-Guzik, Alán; Guo, Guang-Can

    2014-02-01

    Simulation of the low-temperature properties of many-body systems remains one of the major challenges in theoretical and experimental quantum information science. We present, and demonstrate experimentally, a universal (pseudo) cooling method that is applicable to any physical system that can be simulated by a quantum computer. This method allows us to distil and eliminate hot components of quantum states like a quantum Maxwell's demon. The experimental implementation is realized with a quantum optical network, and the results are in full agreement with theoretical predictions (with fidelity higher than 0.978). Applications of the proposed pseudo-cooling method include simulations of the low-temperature properties of physical and chemical systems that are intractable with classical methods.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Realization of optical XOR and OR gates using asymmetric Y-structure in a two dimensional photonic crystal

    NASA Astrophysics Data System (ADS)

    Rath, Smruti; Dash, Sonali P.; Hota, Mihir; Tripathy, Sukanta K.

    2012-07-01

    We propose an asymmetric Y-structure in a 2D photonic crystal consisting of TiO2 rods in air. The structure is then optimized by taking out the rods so as to create defects at different points, to realize optical XOR and OR operations. To verify our proposition, we use FDTD method to simulate the wave propagation inside the proposed asymmetric waveguide. Simulation results showed that, the said optimized design can really act as optical OR and XOR gate.

  1. 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

  2. Experimental realization of strong effective magnetic fields in an optical lattice.

    PubMed

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

    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. PMID:22243087

  3. Columnar deformation of human red blood cell by highly localized fiber optic Bessel beam stretcher

    PubMed Central

    Lee, Sungrae; Joo, Boram; Jeon, Pyo Jin; Im, Seongil; Oh, Kyunghwan

    2015-01-01

    A single human red blood cell was optically stretched along two counter-propagating fiber-optic Bessel-like beams in an integrated lab-on-a-chip structure. The beam enabled highly localized stretching of RBC, and it induced a nonlinear mechanical deformation to finally reach an irreversible columnar shape that has not been reported. We characterized and systematically quantified this optically induced mechanical deformation by the geometrical aspect ratio of stretched RBC and the irreversible stretching time. The proposed RBC mechanism can realize a versatile and compact opto-mechanical platform for optical diagnosis of biological substances in the single cell level. PMID:26601005

  4. Columnar deformation of human red blood cell by highly localized fiber optic Bessel beam stretcher.

    PubMed

    Lee, Sungrae; Joo, Boram; Jeon, Pyo Jin; Im, Seongil; Oh, Kyunghwan

    2015-11-01

    A single human red blood cell was optically stretched along two counter-propagating fiber-optic Bessel-like beams in an integrated lab-on-a-chip structure. The beam enabled highly localized stretching of RBC, and it induced a nonlinear mechanical deformation to finally reach an irreversible columnar shape that has not been reported. We characterized and systematically quantified this optically induced mechanical deformation by the geometrical aspect ratio of stretched RBC and the irreversible stretching time. The proposed RBC mechanism can realize a versatile and compact opto-mechanical platform for optical diagnosis of biological substances in the single cell level. PMID:26601005

  5. Optically controlled local nanosoldering of metal nanowires

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Liu, Guoping; Yang, Hangbo; Wang, Wei; Luo, Si; Dai, Shuowei; Qiu, Min

    2016-05-01

    Nanojoining (including nanowelding, nanosoldering, etc.) of metal nanomaterials offers the opportunity of constructing complex structures and advanced functional devices at the nanoscale. In comparison with nanowelding, nanosoldering does not involve the melting of base metal and shows considerable mechanical strength and good thermal and electrical conductivity. Here, an optically controlled local nanosoldering technique, which ensures the nanostructures to be bonded while their original structural integrity is retained, is proposed and demonstrated. Typical elemental devices (V-shaped, T-shaped, and X-shaped nanostructures) are formed with this nanosoldering technique. The conductivity of one V-shaped junction is enhanced by 500 times after nanosoldering. This facile nanosoldering technique provides an avenue to locally manipulate light, charge, heat, and mass transport at the nanoscale and is thereby expected to benefit the development of nanophotonics and nanoelectronics.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. 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. PMID:25202898

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

    PubMed Central

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

    2015-01-01

    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. PMID:25779977

  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

    2015-01-01

    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. PMID:25779977

  10. 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…

  11. Broadband optical gain via interference in the free electron laser: principles and proposed realizations.

    PubMed

    Rostovtsev, Y V; Kurizki, G; Scully, M O

    2001-08-01

    We propose experimentally simplified schemes of an optically dispersive interface region between two coupled free electron lasers (FELs), aimed at achieving a much broader gain bandwidth than in a conventional FEL or a conventional optical klystron composed of two separated FELs. The proposed schemes can universally enhance the gain of FELs, regardless of their design, when operated in the short pulsed regime. PMID:11497719

  12. 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.

  13. 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.

  14. Realization of an all-optical zero to pi cross-phase modulation jump.

    PubMed

    Camacho, Ryan M; Dixon, P Ben; Glasser, Ryan T; Jordan, Andrew N; Howell, John C

    2009-01-01

    We report on the experimental demonstration of an all-optical pi cross-phase modulation jump. By performing a preselection, an optically induced unitary transformation, and then a postselection on the polarization degree of freedom, the phase of the output beam acquires either a zero or pi phase shift (with no other possible values). The postselection results in optical loss in the output beam. An input state may be chosen near the resulting phase singularity, yielding a pi phase shift even for weak interaction strengths. The scheme is experimentally demonstrated using a coherently prepared dark state in a warm atomic cesium vapor. PMID:19257193

  15. Asymmetrical optical lenslet array realized by spatial light modulator for measuring toroidal surfaces.

    PubMed

    Zhao, L P; Bai, N; Li, X

    2008-12-20

    The Shack-Hartmann wavefront sensor (SHWS) recently has been extensively researched for optical surface metrology due to its extendable dynamic range compared with interferometry technique. In this paper, we proposed to use a digital SHWS to measure toroidal surfaces, which are widely used in many optical systems due to their different symmetries and curvatures in the X and Y directions. For what is believed to be the first time, an asymmetrical optical lenslet array implemented by a spatial light modulator was presented to tackle the measurement challenge. This unconventional design approach has a great advantage to provide different optical powers in the X and Y directions so that focusing spots can be formed and captured on the detector plane for accurate centroid finding and precise wavefront evaluation for 3D shape reconstruction of the toroidal surface. A digital SHWS system with this extraordinary microlens array was built to verify the design concept, and the experimental results were presented and analyzed. PMID:19104529

  16. 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 \

  17. Fano resonant Ge2Sb2Te5 nanoparticles realize switchable lateral optical force.

    PubMed

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

    2016-03-14

    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. PMID:26898233

  18. 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.

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

    PubMed

    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

  20. 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

  1. 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.

  2. 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

  3. Design and realization of highly stable porous silicon optical biosensor based on proteins from extremophiles

    NASA Astrophysics Data System (ADS)

    De Stefano, Luca; Rotiroti, Lucia; Rea, Ilaria; De Tommasi, Edoardo; Vitale, Annalisa; Rossi, Mosè; Rendina, Ivo; D'Auria, Sabato

    2007-05-01

    The interaction between an analyte and a biological recognition system is normally detected in biosensors by the transducer element which converts the molecular event into a measurable effect, such as an electrical or optical signal. Porous silicon microstructures have unique optical and morphological properties that can be exploited in biosensing. The large specific surface area (even greater than 500 m2/cm 3) and the resonant optical response allow detecting the effect of a change in refractive index of liquid solutions, which interact with the porous matrix, with very high sensitivity. Moreover, the porous silicon surface can be chemically modified to link the bioprobe which recognize the target analytes, in order to enhance the selectivity and specificity of the sensor device. The molecular probe we used was purified by an extremophile organism, Thermococcus litoralis: the protein is very stable in a wide range of temperatures even if with different behavior respect to the interaction with the ligand.

  4. 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.

  5. 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.

  6. Realization of all-optical logic gates through three core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Uthayakumar, T.; Vasantha Jayakantha Raja, R.; Porsezian, K.

    2013-06-01

    We present the practical design of novel three core photonic crystal fiber (TPCF) for optical switching and logic operations by employing all optical control. To accomplish the proposed aim, we put forth two types of symmetrical TPCF designs, one with cores of planar geometry and the other with equilateral triangular geometry. The dynamics of the individual pulse parameters through the proposed geometries are analyzed numerically using split step Fourier method (SSFM). The steering characteristics of the coupler are demonstrated by the transmission curve. The truth tables expressing Boolean algebra for different logic operations are constructed from the transmission curves of the individual coupler configurations. Out of all configurations, we observe that the chloroform filled triangular core demonstrates all the logic operations namely OR, NOR, AND, NAND, X-OR, X-NOR and NOT with low input power. A figure of merit of logic gates (FOMEL) is also made to compare the performance of all the logic gates.

  7. Narrow linewidth laser system realized by linewidth transfer using a fiber-based frequency comb for the magneto-optical trapping of strontium.

    PubMed

    Akamatsu, Daisuke; Nakajima, Yoshiaki; Inaba, Hajime; Hosaka, Kazumoto; Yasuda, Masami; Onae, Atsushi; Hong, Feng-Lei

    2012-07-01

    A narrow linewidth diode laser system at 689 nm is realized by phase-locking an extended cavity diode laser to one tooth of a narrow linewidth optical frequency comb. The optical frequency comb is phase-locked to a narrow linewidth laser at 1064 nm, which is frequency stabilized to a high-finesse optical cavity. We demonstrate the magneto-optical trapping of Sr using an intercombination transition with the developed laser system. PMID:22772290

  8. 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.

  9. 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.

  10. Experimental Realization of Plaquette Resonating Valence-Bond States with Ultracold Atoms in Optical Superlattices

    NASA Astrophysics Data System (ADS)

    Nascimbène, S.; Chen, Y.-A.; Atala, M.; Aidelsburger, M.; Trotzky, S.; Paredes, B.; Bloch, I.

    2012-05-01

    The concept of valence-bond resonance plays a fundamental role in the theory of the chemical bond and is believed to lie at the heart of many-body quantum physical phenomena. Here we show direct experimental evidence of a time-resolved valence-bond quantum resonance with ultracold bosonic atoms in an optical lattice. By means of a superlattice structure we create a three-dimensional array of independent four-site plaquettes, which we can fully control and manipulate in parallel. Moreover, we show how small-scale plaquette resonating valence-bond (RVB) states with s- and d-wave symmetry can be created and characterized. We anticipate our findings to open the path towards the creation and analysis of many-body RVB states in ultracold atomic gases.

  11. Throughput compensation through optical proximity correction for realization of an extreme-ultraviolet pellicle

    NASA Astrophysics Data System (ADS)

    Ko, Ki-Ho; Mo, Soo-Yeon; Kim, In-Seon; Oh, Hye-Keun

    2016-03-01

    The absorption of extreme-ultraviolet (EUV) pellicle could be the most critical problem because the EUV source power is still not good enough for achieving mass production. We found that the transmission loss due to the EUV pellicle could be compensated through proper optical proximity correction (OPC) of a pellicled mask. Patterning results of OPCed masks with different transmission pellicles are shown for various 1D and 2D patterns. From the results, it is clearly shown that we do not need to increase the dose to avoid the throughput loss even if a pellicle which has 80 % one-pass transmission is used. Therefore, the EUV pellicle manufacturing would be much easier because we can use much thicker film with higher absorption.

  12. 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.

  13. 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. PMID:27472623

  14. 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

  15. Acousto-optical confirmation of the localized wave phenomena

    SciTech Connect

    Lewis, D.K.

    1992-09-09

    An acousto-optical measurement method is described which was used to conduct proof of principle experiments for a novel acoustic pulse system. The pulse theory, the Localized Wave pulse, is discussed and the system explained and described. The results of the experiments confirm the Localized Wave theory.

  16. 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

  17. In-vivo local determination of tissue optical properties

    NASA Astrophysics Data System (ADS)

    Bevilacqua, Frederic; Piguet, D.; Marquet, Pierre; Gross, Jeffrey D.; Tromberg, Bruce J.; Depeursinge, Christian D.

    1997-12-01

    Local and superficial optical characterization of biological tissues can be achieved by measuring the spatially resolved diffuse reflectance at small source-detector separations. The sensitivity of the signal to the phase function, absorption and scattering coefficients were studied using Monte Carlo simulations. Measurements of spatially resolved reflectance were performed in vivo on human brain with source-detector separations from 0.3 to 1.5 mm. Distinct optical properties were found between normal cortex, astrocytoma of optic nerve and normal optic nerve.

  18. In-vivo local determination of tissue optical properties

    NASA Astrophysics Data System (ADS)

    Bevilacqua, Frederic P.; Piguet, Dominique; Marquet, Pierre; Gross, Jeffrey D.; Tromberg, Bruce J.; Depeursinge, Christian D.

    1998-01-01

    Local and superficial optical characterization of biological tissues can be achieved by measuring the spatially resolved diffuse reflectance at small source-detector separations. The sensitivity of the signal to the phase function, absorption and scattering coefficients were studied using Monte Carlo simulations. Measurements of spatially resolved reflectance were performed in vivo on human brain with source-detector separations from 0.3 to 1.5 mm. Distinct optical properties were found between normal cortex, astrocytoma of optic nerve and normal optic nerve.

  19. Robust multi-scale superpixel classification for optic cup localization.

    PubMed

    Tan, Ngan-Meng; Xu, Yanwu; Goh, Wooi Boon; Liu, Jiang

    2015-03-01

    This paper presents an optimal model integration framework to robustly localize the optic cup in fundus images for glaucoma detection. This work is based on the existing superpixel classification approach and makes two major contributions. First, it addresses the issues of classification performance variations due to repeated random selection of training samples, and offers a better localization solution. Second, multiple superpixel resolutions are integrated and unified for better cup boundary adherence. Compared to the state-of-the-art intra-image learning approach, we demonstrate improvements in optic cup localization accuracy with full cup-to-disc ratio range, while incurring only minor increase in computing cost. PMID:25453464

  20. 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.

  1. 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

    2015-01-01

    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

  2. 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

  3. Optical cable fault locating using Brillouin optical time domain reflectometer and cable localized heating method

    NASA Astrophysics Data System (ADS)

    Lu, Y. G.; Zhang, X. P.; Dong, Y. M.; Wang, F.; Liu, Y. H.

    2007-07-01

    A novel optical cable fault location method, which is based on Brillouin optical time domain reflectometer (BOTDR) and cable localized heating, is proposed and demonstrated. In the method, a BOTDR apparatus is used to measure the optical loss and strain distribution along the fiber in an optical cable, and a heating device is used to heat the cable at its certain local site. Actual experimental results make it clear that the proposed method works effectively without complicated calculation. By means of the new method, we have successfully located the optical cable fault in the 60 km optical fiber composite power cable from Shanghai to Shengshi, Zhejiang. A fault location accuracy of 1 meter was achieved. The fault location uncertainty of the new optical cable fault location method is at least one order of magnitude smaller than that of the traditional OTDR method.

  4. Direct laser writing of polymeric nanostructures via optically induced local thermal effect

    NASA Astrophysics Data System (ADS)

    Tong, Quang Cong; Nguyen, Dam Thuy Trang; Do, Minh Thanh; Luong, Mai Hoang; Journet, Bernard; Ledoux-Rak, Isabelle; Lai, Ngoc Diep

    2016-05-01

    We demonstrate the fabrication of desired structures with feature size below the diffraction limit by use of a positive photoresist. The direct laser writing technique employing a continuous-wave laser was used to optically induce a local thermal effect in a positive photoresist, which then allowed the formation of solid nanostructures. This technique enabled us to realize multi-dimensional sub-microstructures by use of a positive photoresist, with a feature size down to 57 nm. This mechanism acting on positive photoresists opens a simple and low-cost way for nanofabrication.

  5. Optical probe, local fields, and Lorentz factor in ferroelectrics

    NASA Astrophysics Data System (ADS)

    Blinov, L. M.; Lazarev, V. V.; Palto, S. P.; Yudin, S. G.

    2014-06-01

    An optical probe is suggested that allows measurements of the local field and Lorentz factor ( L) in ferroelectric medium. The copolymer poly (vinylidene fluoride/trifluoroethylene) is mixed with Pd-tetraphenylporphyrin (TPP-Pd) that has a very narrow absorption band. Thus, TPP-Pd serves as a molecular optical probe of the local field. During the switching of the electric field lower than the coercive one the factor L of an unpolarized ferroelectric mixture is found to be of about 1/3 that corresponds to the random distribution of molecular dipoles in the ferroelectric. With increasing field, the dipole orientation acquires a lower symmetry and L tends to zero as predicted by lattice sum calculations for vinylidene fluoride. The knowledge of the field dependence of L and the usage of the optical probe makes it possible to measure directly the local and macroscopic fields in the individual elements of various ferroelectric-dielectric heterostructures.

  6. Cooling and long-lived single-site localization of an ion in an optical lattice

    NASA Astrophysics Data System (ADS)

    Bylinskii, Alexei; Karpa, Leon; Gangloff, Dorian; Cetina, Marko; Vuletic, Vladan

    2013-05-01

    We report on localization of a continuously cooled single ion by a one-dimensional optical lattice. The ion is confined in a hybrid trap formed by an optical dipole potential produced by the standing-wave field of an optical cavity and a two-dimensional radio-frequency Paul trap transverse to the cavity axis. A lattice-assisted resolved Raman sideband process cools the ion to energies 20 times lower than the depth of the lattice potential, close to the vibrational ground state. We observe ion localization by measuring its displacement in the presence of a periodically driven electric field parallel to the lattice. We demonstrate full suppression of the driven ion motion due to optical localization to a single lattice site on a time-scale of 100 μs, which is 100 times longer than the vibrational period of the ion in the lattice site. At a longer time scale of 1 ms, driven motion is suppressed to 50%. The presented system paves the way to the realization of novel experiments studying classical and quantum friction models, and many-body physics with long-range interactions in periodic potentials. Army Research Office, National Science Foundation, National Science and Engineering Research Council of Canada, Alexander von Humboldt Foundation.

  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. An easy way to realize SPR aptasensor: A multimode plastic optical fiber platform for cancer biomarkers detection.

    PubMed

    Cennamo, Nunzio; Pesavento, Maria; Lunelli, Lorenzo; Vanzetti, Lia; Pederzolli, Cecilia; Zeni, Luigi; Pasquardini, Laura

    2015-08-01

    The introduction of new compact systems for sensitive, fast and simplified analysis is currently playing a substantial role in the development of point-of-care solutions aimed to assist both prognosis and diagnosis. Here we report a simple and low cost biosensor based on Surface Plasmon Resonance (SPR) taking advantage of a plastic optical fiber (POF) for the detection of Vascular endothelial growth factor (VEGF), selected as a circulating protein potentially associated with cancer. Our system is based onto two crucial aspects. By one hand, the functional layer which allows the transduction signal is based on DNA aptamers, short oligonucleotide sequences that bind to non-nucleic acid targets with high affinity and specificity. By the other hand, the light guiding structure is based on a POF with a planar gold layer as the sensing region, which is particularly suitable for bioreceptors implementation. The sensor revealed to be really useful in the interface characterization. The developed system is relatively easy to realize and could well address the development of a rapid, portable and low cost diagnostic platform, with a sensitivity in the nanomolar range. PMID:26048828

  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. 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. PMID:17392887

  13. 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

  14. Terabit optical local area networks for multiprocessing systems.

    PubMed

    Szymanski, T H; Au, A; Lafrenière-Roula, M; Tyan, V; Supmonchai, B; Wong, J; Zerrouk, B; Obenaus, S T

    1998-01-10

    The design of a scalable optical local area network formultiprocessing systems is described. Each workstation has aparallel-fiber-ribbon optical link to a centralized complementarymetal-oxide silicon (CMOS) switch core, implemented on a singlecompact printed circuit board (PCB). When the Motorola Optobusfiber technology is used, each workstation has a data bandwidth of 6.4Gbits/s to the core. A centralized switch core interconnecting 32workstations supports a 204-Gbit/s aggregate data bandwidth. Theswitch core is based on a conventional broadcast-and-selectarchitecture, implemented with parallel CMOS integrated circuits(IC's). The switch core scales well; by incorporation of theCMOS optoelectronic IC's with optical input-output, the electricalcore can be reduced to a single-chip optoelectronic IC with terabitcapacities. A prototype of an optoelectronic switch core has been fabricated and is described. The appeal of the architectureincludes its reliance on commercially available parallel-fibertechnology, its reliance on the well-developed markets of local areanetworks and networks of workstations, and its smooth scalability from the electrical to optical domains as technology matures. PMID:18268582

  15. Terabit Optical Local Area Networks for Multiprocessing Systems

    NASA Astrophysics Data System (ADS)

    Szymanski, Ted H.; Au, Albert; Lafrenière-Roula, Myriam; Tyan, Victor; Supmonchai, Boonchuay; Wong, James; Zerrouk, Belkacem; Obenaus, Stefan Thomas

    1998-01-01

    The design of a scalable optical local area network for multiprocessing systems is described. Each workstation has a parallel-fiber-ribbon optical link to a centralized complementary metal-oxide silicon (CMOS) switch core, implemented on a single compact printed circuit board (PCB). When the Motorola Optobus fiber technology is used, each workstation has a data bandwidth of 6.4 Gbits /s to the core. A centralized switch core interconnecting 32 workstations supports a 204-Gbit /s aggregate data bandwidth. The switch core is based on a conventional broadcast-and-select architecture, implemented with parallel CMOS integrated circuits (IC s). The switch core scales well; by incorporation of the CMOS optoelectronic IC s with optical input -output, the electrical core can be reduced to a single-chip optoelectronic IC with terabit capacities. A prototype of an optoelectronic switch core has been fabricated and is described. The appeal of the architecture includes its reliance on commercially available parallel-fiber technology, its reliance on the well-developed markets of local area networks and networks of workstations, and its smooth scalability from the electrical to optical domains as technology matures.

  16. 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. PMID:25372937

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

    NASA Astrophysics Data System (ADS)

    Cheng, Yongshan; Adhikari, S. K.

    2011-02-01

    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 , Nature (London)NATUAS0028-083610.1038/nature07071 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.

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

    DOEpatents

    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.

  19. 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.

  20. Design and realization of test system for testing parallelism and jumpiness of optical axis of photoelectric equipment

    NASA Astrophysics Data System (ADS)

    Shi, Sheng-bing; Chen, Zhen-xing; Qin, Shao-gang; Song, Chun-yan; Jiang, Yun-hong

    2014-09-01

    With the development of science and technology, photoelectric equipment comprises visible system, infrared system, laser system and so on, integration, information and complication are higher than past. Parallelism and jumpiness of optical axis are important performance of photoelectric equipment,directly affect aim, ranging, orientation and so on. Jumpiness of optical axis directly affect hit precision of accurate point damage weapon, but we lack the facility which is used for testing this performance. In this paper, test system which is used fo testing parallelism and jumpiness of optical axis is devised, accurate aim isn't necessary and data processing are digital in the course of testing parallelism, it can finish directly testing parallelism of multi-axes, aim axis and laser emission axis, parallelism of laser emission axis and laser receiving axis and first acuualizes jumpiness of optical axis of optical sighting device, it's a universal test system.

  1. 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

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

    PubMed

    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

  3. 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.

  4. Analysis and experimental realization of locally resonant phononic plates carrying a periodic array of beam-like resonators

    NASA Astrophysics Data System (ADS)

    Xiao, Yong; Wen, Jihong; Huang, Lingzhi; Wen, Xisen

    2014-01-01

    We present theoretical examination and experimental demonstration of locally resonant (LR) phononic plates consisting of a periodic array of beam-like resonators attached to a thin homogeneous plate. Such phononic plates feature unique wave physics due to the coexistence of localized resonance and structural periodicity. We demonstrate that a low-frequency complete band gap for flexural plate waves can be created in the proposed structure owing to the interaction between the localized resonant modes of the beam-like resonators and the flexural wave modes of the host plate. We show that the location and width of the complete band gap can be dramatically tuned by changing the properties of the beam-like resonators. To understand the opening mechanism and evolution behaviour of the complete band gap, some approximate but explicit models are provided and discussed. We further perform experimental measurements of a specimen fabricated by an array of double-stacked aluminum beam-like resonators attached to a thin aluminum plate with 5 cm structure periodicity. The experimental results evidence a complete band gap extending from 465 to 860 Hz, matching well with our theoretical prediction. The LR phononic plates proposed in this work can find potential applications in attenuation of low-frequency mechanical vibrations and insulation of low-frequency audible sound.

  5. Controlling the localization and migration of optical excitation

    NASA Astrophysics Data System (ADS)

    Andrews, David L.; Bradshaw, David S.

    2012-09-01

    possibilities for technical application is emerging. For example, applications can be envisaged for new forms of all-optical switching and transistor action. There is also interest in engaging with the interplay of optical excitation and local nanoscale force, exploiting local responses to changes in dispersion forces, accompanying molecular energy transfer.

  6. 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.

  7. Local measurement of optically induced photocurrent in semiconductor structures

    NASA Astrophysics Data System (ADS)

    Benesova, Marketa; Dobis, Pavel; Tomanek, Pavel; Uhdeova, Nadezda

    2003-07-01

    Photocurrent (PC) spectroscopic techniques have demonstrated to be helpful experimental method to investigate the local properties of bulk semiconductors, microstructures, surfaces and interfaces. We have measured locally induced PC of semiconductor quantum structures using a technique of reflection Scanning Near-field Optical Microscope (r-SNOM) in combination with Ti:Sapphire laser and tuning dye laser and with He-Ne laser. The r-SNOM employs an uncoated and/or Au-metalized single-mode fiber tip both in illumination and collection mode. Taking opportunity of the high lateral resolution of the microscope and combining it with fast micro-PL, it is possible to locate e.g. defects in a multiple quantum well grown by molecular beam epitaxy. Near-field characteristics of measured quantities are also discussed.

  8. 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.

  9. A heuristic approach to the realization of the wide-band optical diode effect in photonic crystal waveguides

    NASA Astrophysics Data System (ADS)

    Khavasi, Amin; Rezaei, Mohsen; Fard, Ali P.; Mehrany, Khashayar

    2013-07-01

    In this paper a highly efficient optical diode is demonstrated in photonic crystal waveguides with broken spatial symmetry. The structure is made of isotropic linear materials and does not need high power optical beams or strong magnetic fields. While the proposed structure shows almost complete light transmission (>99%) in one direction, it blocks light transmission in the opposite direction. This unidirectional transmission is retained within a wide range of frequencies (>4% of central frequency). In order to achieve an optical diode effect, the optical mode of the waveguide is manipulated by designing an ultra-compact mode converter and an efficient mode filter. The dimensions of the proposed mode converter are less than two wavelengths long.

  10. Localization of cortical tissue optical changes during seizure activity in vivo with optical coherence tomography

    PubMed Central

    Eberle, Melissa M.; Hsu, Mike S.; Rodriguez, Carissa L.; Szu, Jenny I.; Oliveira, Michael C.; Binder, Devin K.; Park, B. Hyle

    2015-01-01

    Optical coherence tomography (OCT) is a high resolution, minimally invasive imaging technique, which can produce depth-resolved cross-sectional images. In this study, OCT was used to detect changes in the optical properties of cortical tissue in vivo in mice during the induction of global (pentylenetetrazol) and focal (4-aminopyridine) seizures. Through the use of a confidence interval statistical method on depth-resolved volumes of attenuation coefficient, we demonstrated localization of regions exhibiting both significant positive and negative changes in attenuation coefficient, as well as differentiating between global and focal seizure propagation. PMID:26137382

  11. Design of a waveguide with optics axes tilted by 45° and realized by ion-exchange on glass

    NASA Astrophysics Data System (ADS)

    Jordan, Elodie; Ghibaudo, Elise; Bouchard, Aude; Blanc-Mignon, Marie-Françoise; Jamon, Damien; Royer, François; Broquin, Jean-Emmanuel

    2016-02-01

    The fabrication of on-chip optical isolators to protect integrated optical sources is one of the major challenges of research in integrated optics. Their operation principle is based on the control of the guided-wave polarization and the most common structures are composed of a polarization splitter, a non-reciprocal rotator based on the Faraday effect, and a reciprocal rotator. The reciprocal rotator is a device that rotates the wave polarization by 45°. This can be achieved by creating a relative phase shift between the waveguide's two polarization eigen states or by twisting its optics axis thanks to an appropriate shaping of its core. In this work, we propose the design and simulation of a waveguide with optics axes tilted by 45° fabricated by two cascaded field-assisted ion exchanges on a glass substrate and an encapsulation. The dependences of the proposed design on process time, temperature, applied voltage and photolithography over-etching are investigated. The final device exhibits a 45.1° rotation of its optical axes and less than 5% variation on the C+L telecommunication band.

  12. 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.

  13. Local optical and electric characteristics of solar cells

    NASA Astrophysics Data System (ADS)

    Tománek, Pavel; Škarvada, Pavel; Grmela, Lubomír

    2009-10-01

    Today photovoltaic cells are divided into two principal types: higher-efficiency but quite expensive crystalline silicon solar cells (either monocrystalline or multicrystalline), and lower-cost thin-film solar cells, usually composed of amorphous silicon, polycrystalline silicon, cadmium telluride, or copper indium gallium diselenide. In both cases their operation is based on a large-area pn junction. Their efficiency is generally limited by defects and impurities, which include grain boundaries, dislocations, and transition metals. A wide variety of defects can be formed in a silicon crystals during and after their growth. Some of defects arise on cell surface during its life-time such as scratches. These surface damages are origin of lower light-trapping efficiency. Many of defects do not cause cell malfunction, but generate local microplasmas, which are conductive and hence reduce overall cell efficiency. A number of defects of various kinds, some of them being of local character only, can not be observed with classical methods in such large-area junctions. Therefore a use of more precise scanning probe microscopes represents a novel approach to surface investigations with superresolving features. The paper presents results of experimental study of high resolution map of induced photocurrent and local electroluminescence in monocrystalline silicon solar cells. Photovoltaic solar cells are evaluated by I-V electric measurement, Far-field and Near-field Optical Beam Induced photocurrent (NOBIC), as well as by Scanning Near-field Optical Microscope (SNOM) topography and reflection. The correlation between reflection and transport characteristics indicates power of this diagnostic tool.

  14. Shared Access Optical Networks For The Local Loop

    NASA Astrophysics Data System (ADS)

    Payne, D. B.; Stern, J. R.

    1988-09-01

    The application of single mode fibre to the local network environment opens up major opportunities for service provision via shared access networks. Previous technologies (copper pair, coaxial cable and multimode fibre) had bandwidth limitation problems that placed a severe restriction on both the level of resource sharing and the service package that could be delivered. The enormous bandwidth capability of single mode fibre can be used to provide significant resource sharing without incurring fundamental restrictions on the capacity of the services carried. The paper briefly outlines some of the activities within British Telecom on shared access systems. Early systems concepts were either based on fibre feeders to remote multiplexers for the delivery of telephony and data services to large customers or the use of advanced wavelength multiplexing techniques over passive optical networks for the transmission of wideband services to business and residential customers. Recently activity has concentrated on a passive optical network that shows good potential for the economic provision of telephony services. The structure of the network allows the later addition of broadband services via additional wavelengths without disturbing existing telephony/data customers. The basic network has a fibre feeder from the exchange to passive optical splitters housed at the Cabinet and Distribution Points (DP). Each customer receives a fibre from DP and via this a TDM multiplex broadcast from the exchange which carries the customer's traffic. The customer equipment accesses the time slots destined for the customer and delivers the data via a suitable interface to provide the services required. Customers transmit back to the exchange in a time multiplex synchronised by a ranging protocol that sets an appropriate delay in the customer equipment to avoid collisions at the optical combiners in the DPs and Cabinet. Present studies are considering a total optical split of 128 ways with a

  15. Miniature Schwarzschild objective as a micro-optical component free of main aberrations: concept, design, and first realization with silicon-glass micromachining.

    PubMed

    Baranski, Maciej; Passilly, Nicolas; Bargiel, Sylwester; Froehly, Luc; Gorecki, Christophe

    2016-04-01

    This paper presents the conception of a new micro-optical component fabricated within the wafer-level approach: a micromachined reflective objective, the so-called micro-Schwarzschild objective, characterized by superior optical performances than widespread microlenses. The system, made of two vertically integrated mirrors, works in transmission similarly as microlenses. While the specific geometric configuration of the two-mirrors allows elimination of most common optical aberrations, the reflective architecture provides inherent achromaticity. This paper presents in detail the optical design and analyzes fabrication tolerances. It also describes a fabrication flow chart based on silicon micromachining done at the wafer level that could allow production of thousands of such micro-optical devices within a single fabrication run. The realized prototype employs the two-step KOH etching process to generate the micromirror pairs followed by glass reflow for the secondary mirror generation and selective metallic deposition. Despite an insufficient mirror quality attributed to this specific silicon etching technique and highlighted by the reflective configuration, the objective fabrication in terms of alignment, bonding, and coating is shown as feasible. PMID:27139684

  16. 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

  17. Local Optical Probe of Motion and Stress in a NEMS

    NASA Astrophysics Data System (ADS)

    Reserbat-Plantey, Antoine; Marty, Laëtitia; Arcizet, Olivier; Bendiab, Nedjma; Bouchiat, Vincent

    2012-02-01

    Nanoelectromechanical systems (NEMSs) are emerging nanoscale elements at the crossroads between mechanics, optics and electronics, with significant potential for actuation and sensing applications. The reduction of dimensions compared to their micronic counterparts brings new effects including sensitivity to very low mass, resonant frequencies in the radiofrequency range, mechanical non-linearities and observation of quantum mechanical effects. An important issue of NEMS is the understanding of fundamental physical properties conditioning dissipation mechanisms, known to limit mechanical quality factors and to induce aging due to material degradation. There is a need for detection methods tailored for these systems which allow probing motion and stress at the nanometer scale. Here, we show a non-invasive local optical probe for the quantitative measurement of motion and stress within a multilayer graphene NEMS provided by a combination of Fizeau interferences, Raman spectroscopy and electrostatically actuated mirror. Interferometry provides a calibrated measurement of the motion, resulting from an actuation ranging from a quasi-static load up to the mechanical resonance while Raman spectroscopy allows a purely spectral detection of mechanical resonance at the nanoscale. Such spectroscopic detection reveals the coupling between a strained nano-resonator and the energy of an inelastically scattered photon, and thus offers a new approach for optomechanics.

  18. 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.

  19. 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

  20. Intra-fraction setup variability: IR optical localization vs. X-ray imaging in a hypofractionated patient population

    PubMed Central

    2011-01-01

    Background The purpose of this study is to investigate intra-fraction setup variability in hypo-fractionated cranial and body radiotherapy; this is achieved by means of integrated infrared optical localization and stereoscopic kV X-ray imaging. Method and Materials We analyzed data coming from 87 patients treated with hypo-fractionated radiotherapy at cranial and extra-cranial sites. Patient setup was realized through the ExacTrac X-ray 6D system (BrainLAB, Germany), consisting of 2 infrared TV cameras for external fiducial localization and X-ray imaging in double projection for image registration. Before irradiation, patients were pre-aligned relying on optical marker localization. Patient position was refined through the automatic matching of X-ray images to digitally reconstructed radiographs, providing 6 corrective parameters that were automatically applied using a robotic couch. Infrared patient localization and X-ray imaging were performed at the end of treatment, thus providing independent measures of intra-fraction motion. Results According to optical measurements, the size of intra-fraction motion was (median ± quartile) 0.3 ± 0.3 mm, 0.6 ± 0.6 mm, 0.7 ± 0.6 mm for cranial, abdominal and lung patients, respectively. X-ray image registration estimated larger intra-fraction motion, equal to 0.9 ± 0.8 mm, 1.3 ± 1.2 mm, 1.8 ± 2.2 mm, correspondingly. Conclusion Optical tracking highlighted negligible intra-fraction motion at both cranial and extra-cranial sites. The larger motion detected by X-ray image registration showed significant inter-patient variability, in contrast to infrared optical tracking measurement. Infrared localization is put forward as the optimal strategy to monitor intra-fraction motion, featuring robustness, flexibility and less invasivity with respect to X-ray based techniques. PMID:21496255

  1. Magnetizm Localization and Hole Localization in Fermionic Atoms Loaded on Optical Lattice

    NASA Astrophysics Data System (ADS)

    Okumura, Masahiko; Yamada, Susumu; Taniguchi, Nobuhiko; Machida, Masahiko

    2009-03-01

    In order to study an interplay of disorder, correlation, and spin imbalance on antiferromagnetism, we systematically explore the ground state of one-dimensional spin-imbalanced Fermionic atoms loaded on an optical lattice by using the density-matrix renormalization group method [1]. We find that disorders localize the antiferromagnetic spin density wave induced by imbalanced fermions and the increase of the disorder magnitude shrinks the areas of the localized antiferromagnetized regions. Moreover, the antiferromagnetism finally disappears above a large disorder. We also study hole doped cases [2]. Concentrating on the doped-hole density profile, we find in a large U/t regime that the clean system exhibits a simple fluid-like behavior whereas finite disorders create locally Mott regions which expand their area with increasing the disorder strength contrary to the conventional sense. References [1] M. Okumura, S. Yamada, N. Taniguchi, and M. Machida, arXiv:0810:3953. [2] M. Okumura, S. Yamada, N. Taniguchi, and M. Machida, Phys. Rev. Lett. 101 016407 (2008).

  2. Locally Controlled Deeply Saturated Fiber Optic Parametric Amplifiers

    NASA Astrophysics Data System (ADS)

    Nissim, Ron Reuven

    A new class of highly efficient Optical Parametric Amplifiers (OPA) is explored in this dissertation, which have the potential to reduce the power requirement on the pump and enable new functionalities. This originates from the simple notion that figure of merit (FoM) of an OPA is proportional to the product of the pump power and amplifier's length and nonlinearity. Silica fibers have been developed for over five decades and offer unparalleled transparency. By merely extending the fiber, i.e. the amplifier's length, a high FoM amplifier can be formed while keeping the pump at a moderate, sub-Watt power level. Unfortunately, optical fibers are inherently non-uniform. Their core size fluctuates along the fiber on a nanometer scale which is on the order of the fiber's molecular constituents. It is currently established that the performance of a fiber-based OPA (FOPA) is dictated by its stochastic nature. In fact, given a moderate pump power level, the highly efficient OPA will be required to maintain a strict phase matching condition across hundreds of meters. Facing this challenge, this dissertation focuses on a locally-controlled, high FoM FOPA. A high FoM FOPA operates in the deeply saturated regime in which a weak signal saturates the amplifier and depletes the pump power, effectively generating an inverse response of the pump output power to the signal input power. Given FOPAs' inhomogeneous nature, the performance limit of deeply saturated FOPAs is studied. So far, FOPAs have been commonly treated as a uniform entity; however, this study discovers unique features of the system which originate from and are strongly influenced by the fiber's inhomogeneous nature. One major example is the non-reciprocal response of deeply saturated FOPAs. It was found that deeply saturated FOPAs perform very highly, as the pump can respond to a rapidly varying (sub-THz) weak (sub-muW) signal. This is a novel method which obtained orders of magnitude improvement over current

  3. 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

  4. Optical tracking of local surface wave for skin viscoelasticity.

    PubMed

    Guan, Yubo; Lu, Mingzhu; Shen, Zhilong; Wan, Mingxi

    2014-06-01

    Rapid and effective determination of biomechanical properties is important in examining and diagnosing skin thermal injury. Among the methods used, viscoelasticity quantification is one of the most effective methods in determining such properties. This study aims to rapidly determine skin viscoelasticity by optically tracking the local surface wave. New elastic and viscous coefficients were proposed to indicate skin viscoelasticity based on a single impulse response of the skin. Experiments were performed using fresh porcine skin samples. Surface wave was generated in a single impulse using a vibrator with a ball-tipped device and was detected using a laser Doppler vibrometer. The motions along the depth direction were monitored using an ultrasound system. The ultrasound monitoring results indicated the multi-layered viscoelasticity of the epidermis and dermis. The viscoelastic coefficients from four healthy samples show a potential viscoelasticity variation of porcine skin. In one sample, the two coefficients were evidently higher than those in a healthy area if the skin was slightly burned. These results indicate that the proposed method is sensitive, effective, and quick in determining skin viscoelasticity. PMID:24674744

  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. 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…

  7. 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.

  8. Realization of single-phase BaSi2 films by vacuum evaporation with suitable optical properties and carrier lifetime for solar cell applications

    NASA Astrophysics Data System (ADS)

    Hara, Kosuke O.; Nakagawa, Yoshihiko; Suemasu, Takashi; Usami, Noritaka

    2015-07-01

    We have realized BaSi2 films by a simple vacuum evaporation technique for solar cell applications. X-ray diffraction analysis shows that single-phase BaSi2 films are formed on alkali-free glass substrates at 500 and 600 °C while impurity phases coexist on quartz or soda-lime glass substrates or at a substrate temperature of 400 °C. The mechanism of film growth is discussed by analyzing the residue on the evaporation boat. An issue on the fabricated films is cracking due to thermal mismatch, as observed by secondary electron microscopy. Optical characterizations by transmittance and reflectance spectroscopy show that the evaporated films have high absorption coefficients, reaching 2 × 104 cm-1 for a photon energy of 1.5 eV, and have indirect absorption edges of 1.14-1.21 eV, which are suitable for solar cells. The microwave-detected photoconductivity decay measurement reveals that the carrier lifetime is approximately 0.027 µs, corresponding to the diffusion length of 0.84 µm, which suggests the potential effective usage of photoexcited carriers.

  9. Bose-Hubbard model with ferromagnetic-like occupation-parity couplings and its realization in imbalanced fermionic superfluids in tubular optical lattices

    NASA Astrophysics Data System (ADS)

    Sun, Kuei; Bolech, Carlos J.

    2014-03-01

    We study a Bose-Hubbard model with a nearest-neighbor occupation-parity coupling that can be considered as energy cost for a domain-wall link between two adjacent sites if their occupation parity is different (one even and the other odd). Our analysis shows that the parity coupling has non-trivial interplay with the tunneling and onsite repulsion, resulting in several exotic quantum phases. For example, a uniform system with zero tunneling can exhibit a pair-liquid phase or phase separation of two Mott insulators, while a trapped system with finite tunneling shows a wedding-cake structure of only even-filling Mott insulators or a structure of central regular superfluid and outer pair superfluid. In addition, we find similar physics in a recent experimental system of imbalanced Fermi gases in optical lattices producing a 2D array of 1D tubes, with the presence of an oscillatory superfluid order parameter (the Fulde-Ferrell-Larkin-Ovchinnikov or FFLO state). We show that the unpaired majority fermions on each tube have a bosonic behavior with cross-tube tunneling, on-tube repulsion, and interplay with the spatial parity of the FFLO order that contributes to the occupation-parity coupling. Therefore, such system provides a realization of our model in two dimensions. Supported by the DARPA-ARO Award No. W911NF-07-1-0464 and by the University of Cincinnati.

  10. 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.

  11. Optical Detection of Local Electric Field Dynamics in Solutions by Waveguide-integrated Graphene Device

    NASA Astrophysics Data System (ADS)

    Horng, Jason; Balch, Halleh; Feng Wang Team

    The spatio-temporal dynamics of local electric fields in ionic solutions plays a central role in various chemical and biological processes ranging from batteries technologies to neuron signaling. A non-invasive, precise detection scheme for measuring local electric fields dynamics has long been sought for. Here, we report a sensitive, high-speed, high spatial resolution optical imaging method for local electric fields based on the unique optoelectronic properties of graphene. With enhancement from a waveguide involving critical coupling concept, we show that our graphene optical sensor provides an ideal platform for studying dynamics of local electric field fluctuations in different nonequilibrium solutions.

  12. Realization of Hardy’s thought experiment using classical light

    NASA Astrophysics Data System (ADS)

    Zhang, Xiong; Sun, Yifan; Song, Xinbing; Zhang, Xiangdong

    2016-09-01

    We report the realization of Hardy’s thought experiment in classical optical systems. Two different classical optical experiments are implemented. One is based on orbital angular momentum and polarization correlation in a classical optical beam, and the other is based on non-local classical correlation from two separated classical optical beams. All experimental results show that they are analogous to Hardy’s paradox experiments. This means that Hardy’s non-locality proof without inequalities, which is usually used in a quantum system, can also be achieved in classical optical systems.

  13. Fundus optic disc localization and segmentation method based on phase congruency.

    PubMed

    Geng, Lei; Shao, Yi-Ting; Xiao, Zhi-Tao; Zhang, Fang; Wu, Jun; Li, Min; Shan, Chun-Yan

    2014-01-01

    It has been demonstrated that shape, area and depth of the optic disc are relevant indices of diabetic retinopathy. In this paper, we present a new fundus optic disc localization and segmentation method based on phase congruency (PC). Firstly, in order to highlight the optic disc, channel images with the highest contrast between optic disc and background are selected in LAB, YUV, YIQ and HSV spaces respectively. Secondly, with the use of PC, features of four selected channel images can be extracted. Multiplication operation is then used to enhance PC detection results. Thirdly, window scanning and gray accumulating are utilized to locate the optic disc. Finally, iterative OTSU automatic threshold segmentation and Hough transform are performed on location images, before the final optic disc segmentation result can be obtained. The experimental results showed that the proposed method can effectively and accurately perform optic disc location and segmentation. PMID:25227031

  14. Research in high speed fiber optics local area networks

    NASA Astrophysics Data System (ADS)

    Tobagi, F. A.

    1986-02-01

    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.

  15. 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

  16. 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

    2016-01-01

    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

  17. Spatiotemporal localized modes in PT-symmetric optical media

    SciTech Connect

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

    2014-09-15

    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. - Highlights: • Spatiotemporal LMs of a (3+1)-dimensional NLSE in PT-symmetric potentials are obtained. • Phase switches and transverse power-flow density of LM are examined. • Dynamical behaviors of LMs in three kinds of inhomogeneous media are studied.

  18. 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

  19. 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. PMID:23389189

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

    NASA Astrophysics Data System (ADS)

    Tobagi, Fouad A.

    1988-09-01

    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.

  1. Free-space optical technology and distribution architecture for broadband metro and local services

    NASA Astrophysics Data System (ADS)

    Dodley, J. P.; Britz, David M.; Bowen, D. J.; Lundgren, Carl W.

    2001-02-01

    12 This paper addresses the hardware and operational requirements for broadband metro and local services using line of sight wireless Free Space Optical Communication (FSOC) optical links. The primary considerations for successful optical wireless service provisions include link availability, type of service and integration into existing fiber optic networks. A comprehensive link analysis for broadband access services is presented. This paper addresses FSOC critical atmospheric transmission impairments and describes one possible FSOC/network fiber optic interface and routing scenario. This paper will also detail methods to restor FSOC service links that have failed due to atmospheric impairments. This paper will detail the use of secondary radio (mm wave or ISM band radio) link architectures to provide critical transmission back-up for data, emergency and voice call services. An FSOC back-up link for existing millimeter-wave radio local services is also discussed. A co-operative network of FSOC links is discussed for achieving availability requirements for metro and local distribution services. This paper also describes one possible rooftop routing scenario using optical cross- connect architectures located at each node of the local FSOC access network. Rooftop routing will utilize the technology flexibility and system redundancy described above to provide high `five nines' metro service availability. This paper will also describe a proposed FSOC test installation to study link architectures, performance of such links, and vendor product interface and evaluation.

  2. 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

  3. The local density of optical states of a metasurface.

    PubMed

    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

  4. The local density of optical states of a metasurface

    NASA Astrophysics Data System (ADS)

    Lunnemann, Per; Koenderink, A. Femius

    2016-02-01

    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.

  5. Fast localization of optic disc and fovea in retinal images for eye disease screening

    NASA Astrophysics Data System (ADS)

    Yu, H.; Barriga, S.; Agurto, C.; Echegaray, S.; Pattichis, M.; Zamora, G.; Bauman, W.; Soliz, P.

    2011-03-01

    Optic disc (OD) and fovea locations are two important anatomical landmarks in automated analysis of retinal disease in color fundus photographs. This paper presents a new, fast, fully automatic optic disc and fovea localization algorithm developed for diabetic retinopathy (DR) screening. The optic disc localization methodology comprises of two steps. First, the OD location is identified using template matching and directional matched filter. To reduce false positives due to bright areas of pathology, we exploit vessel characteristics inside the optic disc. The location of the fovea is estimated as the point of lowest matched filter response within a search area determined by the optic disc location. Second, optic disc segmentation is performed. Based on the detected optic disc location, a fast hybrid level-set algorithm which combines the region information and edge gradient to drive the curve evolution is used to segment the optic disc boundary. Extensive evaluation was performed on 1200 images (Messidor) composed of 540 images of healthy retinas, 431 images with DR but no risk of macular edema (ME), and 229 images with DR and risk of ME. The OD location methodology obtained 98.3% success rate, while fovea location achieved 95% success rate. The average mean absolute distance (MAD) between the OD segmentation algorithm and "gold standard" is 10.5% of estimated OD radius. Qualitatively, 97% of the images achieved Excellent to Fair performance for OD segmentation. The segmentation algorithm performs well even on blurred images.

  6. Developing interface localized liquid dielectrophoresis for optical applications

    NASA Astrophysics Data System (ADS)

    McHale, Glen; Brown, Carl V.; Newton, Michael I.; Wells, Gary G.; Sampara, Naresh

    2012-11-01

    Electrowetting charges the solid-liquid interface to change the contact area of a droplet of a conducting liquid. It is a powerful technique used to create variable focus liquid lenses, electronic paper and other devices, but it depends upon ions within the liquid. Liquid dielectrophoresis (L-DEP) is a bulk force acting on the dipoles throughout a dielectric liquid and is not normally considered to be a localized effect acting at the interface between the liquid and a solid or other fluid. In this work, we show theoretically how non-uniform electric fields generated by interdigitated electrodes can effectively convert L-DEP into an interface localized form. We show that for droplets of sufficient thickness, the change in the cosine of the contact angle is proportional to the square of the applied voltage and so obeys a similar equation to that for electrowetting - this we call dielectrowetting. However, a major difference to electrowetting is that the strength of the effect is controlled by the electrode spacing and the liquid permittivity rather than the properties of an insulator in a sandwich structure. Experimentally, we show that that this dielectrowetting equation accurately describes the contact angle of a droplet of oil viewed across parallel interdigitated electrodes. Importantly, the induced spreading can be complete, such that contact angle saturation does not occur. We then show that for thin films, L-DEP can shape the liquid-air interface creating a spatially periodic wrinkle and that such a wrinkle can be used to create a voltage programmable phase diffraction grating.

  7. Theoretical modeling of a Localized Surface Plasmon Resonance (LSPR) based fiber optic temperature sensor

    NASA Astrophysics Data System (ADS)

    Algorri, J. F.; García-Cámara, B.; García-García, A.; Urruchi, V.; Sánchez-Pena, J. M.

    2014-05-01

    A localized surface plasmon resonance based fiber optic sensor for temperature sensing has been analyzed theoretically. The effects of the size of the spherical metal nanoparticle on the performance of the sensor have been studied in detail. The high sensitivity of localized surface plasmon resonances to refraction index changes, in collaboration with the high thermo-optic coefficients of Liquid Crystal materials, has result in a fiber optical sensor with high temperature sensitivity. This sensitivity has been demonstrated to be dependent on nanoparticle size. Maximum sensitivities of 4nm/°C can be obtained for some specific temperature ranges. The proposed sensor will be low cost, and will have all the typical advantages of fiber optic sensors.

  8. Phase shifts in precision atom interferometry due to the localization of atoms and optical fields

    SciTech Connect

    Wicht, A.; Sarajlic, E.; Hensley, J.M.; Chu, S.

    2005-08-15

    We discuss details of momentum transfer in the interaction between localized atoms and localized optical fields which are relevant to precision atom interferometry. Specifically, we consider a {lambda}-type atom coherently driven between its ground states by a bichromatic optical field. We assume that the excited state can be eliminated adiabatically from the time evolution. It is shown that the average recoil momentum is given by the phase gradient of the two-photon field at the 'position' of the atom, provided that the optical field can be described by a function which is separable in position and time and that the atomic wave function is symmetric and well localized within the optical field envelope. The result does not require the optical fields to have a Gaussian spatial dependence. Our discussion provides the basis for the analysis of systematic errors in precision atom interferometry arising from optical wave-front curvature, wave-front distortion, and the Gouy phase shift of Gaussian beams. We apply our result to the atom interferometer experiment of Chu and co-workers which measures the fine-structure constant.

  9. Local x-ray structure analysis of optically manipulated biological micro-objects

    SciTech Connect

    Cojoc, Dan; Ferrari, Enrico; Santucci, Silvia C.; Amenitsch, Heinz; Sartori, Barbara; Rappolt, Michael; Marmiroli, Benedetta; Burghammer, Manfred; Riekel, Christian

    2010-12-13

    X-ray diffraction using micro- and nanofocused beams is well suited for nanostructure analysis at different sites of a biological micro-object. To conduct in vitro studies without mechanical contact, we developed object manipulation by optical tweezers in a microfluidic cell. Here we report x-ray microdiffraction analysis of a micro-object optically trapped in three dimensions. We revealed the nanostructure of a single starch granule at different points and investigated local radiation damage induced by repeated x-ray exposures at the same position, demonstrating high stability and full control of the granule orientation by multiple optical traps.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Ishii, Satoshi; Narimanov, Evgenii

    2015-12-01

    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.

  12. 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

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

    PubMed

    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

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

    PubMed

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

    2016-03-28

    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 (λ(em) = 532 nm) at half the excitation wavelength (λ(ex) = 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). PMID:26956197

  16. Acoustic Source Localization via Distributed Sensor Networks using Tera-scale Optical-Core Devices

    SciTech Connect

    Imam, Neena; Barhen, Jacob; Wardlaw, Michael

    2008-01-01

    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. 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 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 an optical-core digital processing platform recently introduced by Lenslet Inc. They investigate key concepts of threat-detection algorithms such as Time Difference Of Arrival (TDOA) estimation via sensor data correlation in the time domain with the purpose of implementation on the optical-core processor. they illustrate their results with the aid of numerical simulation and actual optical hardware runs. The major accomplishments of this research, in terms of computational speedup and numerical accurcy achieved via the deployment of optical processing technology, should be of substantial interest to the acoustic signal processing community.

  17. 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.

  18. Effects of optical attenuation and consumption of a photobleaching initiator on local initiation rates in photopolymerizations.

    SciTech Connect

    Terrones, Guillermo ); Pearlstein, Arne J.

    2000-11-01

    Optical attenuation is important in many photopolymerization applications. For a photobleaching initiator, we develop an unsteady one-dimensional model accounting for initiator consumption and light intensity variation, and derive relationships for the spatial and temporal variation of the local initiator concentration and initiation rate.

  19. Suppression of ion transport due to long-lived subwavelength localization by an optical lattice.

    PubMed

    Karpa, Leon; Bylinskii, Alexei; Gangloff, Dorian; Cetina, Marko; Vuletić, Vladan

    2013-10-18

    We report the localization of an ion by a one-dimensional optical lattice in the presence of an applied external force. The ion is confined radially by a radio frequency trap and axially by a combined electrostatic and optical-lattice potential. Using a resolved Raman sideband technique, one or several ions are cooled to a mean vibrational number =(0.1±0.1) along the optical lattice. We measure the average position of a periodically driven ion with a resolution down to λ/40, and demonstrate localization to a single lattice site for up to 10 ms. This opens new possibilities for studying many-body systems with long-range interactions in periodic potentials, as well as fundamental models of friction. PMID:24182262

  20. Suppression of Ion Transport due to Long-Lived Subwavelength Localization by an Optical Lattice

    NASA Astrophysics Data System (ADS)

    Karpa, Leon; Bylinskii, Alexei; Gangloff, Dorian; Cetina, Marko; Vuletić, Vladan

    2013-10-01

    We report the localization of an ion by a one-dimensional optical lattice in the presence of an applied external force. The ion is confined radially by a radio frequency trap and axially by a combined electrostatic and optical-lattice potential. Using a resolved Raman sideband technique, one or several ions are cooled to a mean vibrational number ⟨n⟩=(0.1±0.1) along the optical lattice. We measure the average position of a periodically driven ion with a resolution down to λ/40, and demonstrate localization to a single lattice site for up to 10 ms. This opens new possibilities for studying many-body systems with long-range interactions in periodic potentials, as well as fundamental models of friction.

  1. Optical memory using localized photoinduced anisotropy in a synthetic dye-polymer

    NASA Astrophysics Data System (ADS)

    Kuo, Chai-Pei

    1991-07-01

    We present a read/write/erase all-optical memory that fully utilizes local photoinduced birefringence in a synthetic dye-polymer. Memory reading is based on an optical vector-matrix inner product. The intrinsic chromatic characteristics of the proposed memory storage medium is the key to a novel form of nonmechanical parallel memory storage. Green light at 514.5 nm writes a spatial pattern and read light at 632 nm reads it. The dynamic memory material is an improved polyvinyl-alcohol (PVA) polymer film doped with Azo dye. Unique to this material is low optical power, no significant memory degradation after the recording process, and local information erasure or rewrite at any time. The material operates at room temperature with no sealing requirements.

  2. Routes Towards Anderson-Like Localization of Bose-Einstein Condensates in Disordered Optical Lattices

    NASA Astrophysics Data System (ADS)

    Schulte, T.; Drenkelforth, S.; Kruse, J.; Ertmer, W.; Arlt, J.; Sacha, K.; Zakrzewski, J.; Lewenstein, M.

    2005-10-01

    We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters.

  3. Routes Towards Anderson-Like Localization of Bose-Einstein Condensates in Disordered Optical Lattices

    SciTech Connect

    Schulte, T.; Drenkelforth, S.; Kruse, J.; Ertmer, W.; Arlt, J.; Sacha, K.; Zakrzewski, J.; Lewenstein, M.

    2005-10-21

    We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters.

  4. Tuning Localized Surface Plasmon Resonance in Scanning Near-Field Optical Microscopy Probes.

    PubMed

    Vasconcelos, Thiago L; Archanjo, Bráulio S; Fragneaud, Benjamin; Oliveira, Bruno S; Riikonen, Juha; Li, Changfeng; Ribeiro, Douglas S; Rabelo, Cassiano; Rodrigues, Wagner N; Jorio, Ado; Achete, Carlos A; Cançado, Luiz Gustavo

    2015-06-23

    A reproducible route for tuning localized surface plasmon resonance in scattering type near-field optical microscopy probes is presented. The method is based on the production of a focused-ion-beam milled single groove near the apex of electrochemically etched gold tips. Electron energy-loss spectroscopy and scanning transmission electron microscopy are employed to obtain highly spatially and spectroscopically resolved maps of the milled probes, revealing localized surface plasmon resonance at visible and near-infrared wavelengths. By changing the distance L between the groove and the probe apex, the localized surface plasmon resonance energy can be fine-tuned at a desired absorption channel. Tip-enhanced Raman spectroscopy is applied as a test platform, and the results prove the reliability of the method to produce efficient scattering type near-field optical microscopy probes. PMID:26027751

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

    NASA Astrophysics Data System (ADS)

    Cheng, Yongshan; Adhikari, S. K.

    2011-08-01

    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.

  6. 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.

  7. 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

  8. 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.

  9. Robust Non-Local Multi-Atlas Segmentation of the Optic Nerve.

    PubMed

    Asman, Andrew J; Delisi, Michael P; Mawn; Galloway, Robert L; Landman, Bennett A

    2013-03-13

    Labeling or segmentation of structures of interest on medical images plays an essential role in both clinical and scientific understanding of the biological etiology, progression, and recurrence of pathological disorders. Here, we focus on the optic nerve, a structure that plays a critical role in many devastating pathological conditions - including glaucoma, ischemic neuropathy, optic neuritis and multiple-sclerosis. Ideally, existing fully automated procedures would result in accurate and robust segmentation of the optic nerve anatomy. However, current segmentation procedures often require manual intervention due to anatomical and imaging variability. Herein, we propose a framework for robust and fully-automated segmentation of the optic nerve anatomy. First, we provide a robust registration procedure that results in consistent registrations, despite highly varying data in terms of voxel resolution and image field-of-view. Additionally, we demonstrate the efficacy of a recently proposed non-local label fusion algorithm that accounts for small scale errors in registration correspondence. On a dataset consisting of 31 highly varying computed tomography (CT) images of the human brain, we demonstrate that the proposed framework consistently results in accurate segmentations. In particular, we show (1) that the proposed registration procedure results in robust registrations of the optic nerve anatomy, and (2) that the non-local statistical fusion algorithm significantly outperforms several of the state-of-the-art label fusion algorithms. PMID:24478826

  10. 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.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  13. 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

  14. Local scattering stress distribution on surface of a spherical cell in optical stretcher

    NASA Astrophysics Data System (ADS)

    Bareil, Paul B.; Sheng, Yunlong; Chiou, Arthur

    2006-12-01

    We calculate stress distribution on the surface of a spherical cell trapped by two counter propagating beams in the optical stretcher in the ray optics regime. We demonstrate that the local scattering stress is perpendicular to the spherical refractive surface regardless of incident angle, polarization and the reflectance and transmittance at the surface. We explain the apparition of peaks in the stress distribution, which were not revealed in the existing theory. We consider the divergence of the incident beams from the fibers, and express the stress distribution as a function of fiber-to-cell distance. The new theory can predict the cell’s deformation more precisely.

  15. Localized linear operators: application to image sequence compression using optical signal processing

    NASA Astrophysics Data System (ADS)

    Guha, Dipnarayan

    2003-10-01

    This paper discusses about the extension of Gabor Expansions to the optical domain and the design of an efficient filter bank to provide adaptive equalization in the light of Optical Signal Processing. The isomorphism between this localized linear operator and the filter design fundamentals are examined in the framework of image sequence compression. A new and efficient technique to perform Gabor expansion of Optical signals is introduced. The multi-resolution representation of data is considered in particular. A new approach to filter bank design in optical domain, using matrix formulation is introduced. Using this approach, an efficient optical filter bank with low complexity and good frequency response is designed. It is interesting to note that this design is a mathematical model of the quincunx filter bank. The characteristics of this optical filter bank are compared with that of other commonly used short kernel filter banks, for video compression applications. The approach is based on multi-resolution representation of data, which is generated by the filter bank proposed in this work. The use of multi-resolution data structure in conjunction with other components of the system allows a simple and efficient implementation. Simulations on typical image sequences show that it is possible to perform generic coding with reduced complexity and good efficiency.

  16. 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…

  17. 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.

  18. Local-density approximation for confined bosons in an optical lattice

    SciTech Connect

    Bergkvist, Sara; Henelius, Patrik; Rosengren, Anders

    2004-11-01

    We investigate local and global properties of the one-dimensional Bose-Hubbard model with an external confining potential, describing an atomic condensate in an optical lattice. Using quantum Monte Carlo techniques we demonstrate that a local-density approximation, which relates the unconfined and the confined model, yields quantitatively correct results in most of the interesting parameter range. We also examine claims of universal behavior in the confined system, and demonstrate the origin of a previously calculated fine structure in the experimentally accessible momentum distribution.

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

    NASA Astrophysics Data System (ADS)

    Lu, Yong; Zhang, Zhifei

    2016-03-01

    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.

  20. Spectral Doppler optical coherence tomography imaging of localized ischemic stroke in a mouse model

    NASA Astrophysics Data System (ADS)

    Yu, Lingfeng; Nguyen, Elaine; Liu, Gangjun; Choi, Bernard; Chen, Zhongping

    2010-11-01

    We report the use of spectral Doppler optical coherence tomography imaging (SDOCTI) for quantitative evaluation of dynamic blood circulation before and after a localized ischemic stroke in a mouse model. Rose Bengal photodynamic therapy (PDT) is used as a noninvasive means for inducing localized ischemia in cortical microvasculature of the mouse. Fast, repeated Doppler optical coherence tomography scans across vessels of interest are performed to record flow dynamic information with high temporal resolution. Doppler-angle-independent flow indices are used to quantify vascular conditions before and after the induced ischemia by the photocoagulation of PDT. The higher (or lower) flow resistive indices are associated with higher (or lower) resistance states that are confirmed by laser speckle flow index maps (of laser speckle imaging). Our in vivo experiments shows that SDOCTI can provide complementary quantified flow information that is an alternative to blood volume measurement, and can be used as a means for cortical microvasculature imaging well suited for small animal studies.

  1. 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. PMID:26520498

  2. Integral localized approximation description of ordinary Bessel beams and application to optical trapping forces

    PubMed Central

    Ambrosio, Leonardo A.; Hernández-Figueroa, Hugo E.

    2011-01-01

    Ordinary Bessel beams are described in terms of the generalized Lorenz-Mie theory (GLMT) by adopting, for what is to our knowledge the first time in the literature, the integral localized approximation for computing their beam shape coefficients (BSCs) in the expansion of the electromagnetic fields. Numerical results reveal that the beam shape coefficients calculated in this way can adequately describe a zero-order Bessel beam with insignificant difference when compared to other relative time-consuming methods involving numerical integration over the spherical coordinates of the GLMT coordinate system, or quadratures. We show that this fast and efficient new numerical description of zero-order Bessel beams can be used with advantage, for example, in the analysis of optical forces in optical trapping systems for arbitrary optical regimes. PMID:21750767

  3. Dendrimeric nano-glue material for localized surface plasmon resonance-based fiber-optic sensors

    NASA Astrophysics Data System (ADS)

    Satija, Jitendra; Mukherji, Soumyo

    2012-09-01

    In this study, we have investigated dendrimeric architecture as "nano-glue" material for RI-sensitive fiber-optic sensors. Dendrimers are immobilized on fiber-optic probes using a simple method that includes dipping, rinsing and drying of probes at room temperature. Dendrimer binding was confirmed by contact angle measurement and fluorescein isothiocyanate binding studies. These functionalized probes were coated with gold nanoparticles to develop localized surface plasmon resonance-based refractive index sensor. RI sensitivity measurement revealed that the dendrimeric matrix enhanced the RI sensitivity by 1.4-fold compared to two-dimensional amino-silanized sensor matrices. This suggests that dendrimer molecules are better choice as "nano-glue" material for fiber-optic sensors.

  4. Effects of varying local temperature on the optical properties of cells in-vitro.

    PubMed

    Ahmad, Iftikhar; Rehman, Abdul; Khan, Junaid A; Rafi, Muhammad; Khurshid, Ahmat; Nisar, Hasan; Zaidi, S S Z; Ikram, Masroor

    2015-09-01

    Increase in local temperature during light exposure of biological tissues plays an important role in determining the fate of most therapeutic modalities. Variations in the optical properties (absorption coefficient, scattering coefficient, anisotropy factor, optical depth etc.) of two cancer cell lines "Rhobdomyosarcoma and Cervical carcinoma" due to gradual increase in temperature were determine quantitatively with a double integrating sphere system. It was observed that all three coefficients showed decreasing tendency as the temperature increases for both the cell lines except for scattering coefficient of HeLa which remain constant within error limit. Anisotropy factor for both cell lines increased indicating temperature dependent subcellular density variations. Temperature dependent optical properties information may lead to precise dosimetry and could help clinicians for predicting the therapeutic modality outcome. PMID:26073913

  5. Development of Miniaturized Fiber-Optic Laser Doppler Velocimetry Sensor for Measurement of Local Blood Velocity

    NASA Astrophysics Data System (ADS)

    Tajikawa, Tsutomu; Takeshige, Mitsuhiko; Ishihara, Wataru; Kohri, Shimpei; Ohba, Kenkichi

    A new miniaturized fiber-optic laser Doppler velocimetry (LDV) sensor has been developed, which is capable of measuring the local velocity in various semi-opaque and opaque fluid flows, particularly whole blood velocity in vessels. The sensor has a convex lens-like fiber tip as a pickup and an improved optical transmission system with markedly decreased stray light. This paper describes methods for fabricating fiber tips like concave and convex lens and the characteristics of the optical sensor system equipped with the fabricated fiber tip. Conventional fiber-optic LDV sensors developed up to now have not been capable of measuring such opaque fluids because scattered light from scattering particles as erythrocytes has very low intensity, which makes signal-to-noise ratio of Doppler signal received by a sensor pickup significantly decreased. To overcome these problems, convex lens-like fiber tips have been fabricated by chemical etching, in which quartz fibers of multimode graded refractive index have been etched in aqueous solutions of hydrogen fluoride and ammonium fluoride under the appropriately controlled condition of the concentration of the solution, the etching duration time and the etchant temperature to obtain the desired curvature radius of the lens-like surface of the fiber tip. In this fiber-optic sensor, a laser beam emitted from the fiber tip can be focused at any position from about 0.1 to 0.5 mm distant from the fiber tip according to its curvature radius. The convex lens-like etched tip totally reduced the intensity of undesired reflecting light at the fiber end by 1/2 to 1/6 compared with normal cut fiber tip. Consequently, this fiber-optic LDV sensor system is capable of measuring the local flow velocity in semi-opaque and opaque fluids, whose turbidity was about five times higher than by any kinds of previous sensors.

  6. 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

  7. 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.

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

    DOE PAGESBeta

    Caselli, Niccolò; La China, Federico; Bao, Wei; Riboli, Francesco; Gerardino, Annamaria; Li, Lianhe; Linfield, Edmund H.; Pagliano, Francesco; Fiore, Andrea; Schuck, P. James; et al

    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

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

    PubMed

    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

  10. Localized surface plasmon coupled fluorescence fiber-optic biosensor with gold nanoparticles.

    PubMed

    Hsieh, Bao-Yu; Chang, Ying-Feng; Ng, Ming-Yaw; Liu, Wei-Chih; Lin, Chao-Hsiung; Wu, Hsieh-Ting; Chou, Chien

    2007-05-01

    A novel fiber-optic biosensor based on a localized surface plasmon coupled fluorescence (LSPCF) system is proposed and developed. This biosensor consists of a biomolecular complex in a sandwich format of . It is immobilized on the surface of an optical fiber where a complex forms the fluorescence probe and is produced by mixing Cy5-labeled antibody and protein A conjugated gold nanoparticles (Au-PA). The LSPCF is excited by localized surface plasmon on the GNP surface where the evanescent field is applied near the core surface of the optical fiber. At the same time, the fluorescence signal is detected by a photomultiplier tube located beside the unclad optical fiber with high collection efficiency. Experimentally, this novel LSPCF biosensor is able to detect mouse immunoglobulin G (IgG) at a minimum concentration of 1 pg/mL (7 fM) during the biomolecular interaction of the IgG with anti-mouse IgG. The analysis is expanded by a discussion of the amplification of the LSPCF intensity by GNP coupling, and overall, this LSPCF biosensor is confirmed experimentally as a biosensor with very high sensitivity. PMID:17378542

  11. 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.

  12. 200-Mbps optical integrated circuit design and first iteration realizations in 1.2- and 0.8-micron Bi-CMOS technology

    NASA Astrophysics Data System (ADS)

    Snyman, Lukas W.; Chaing, C.-T.; Bogalecki, Alfons; Du Plessis, Monuko; Aharoni, Herzl

    2004-07-01

    A prototype Silicon CMOS Optical Integrated Circuit (Si CMOS OEIC) was designed and simulated using standard 0.8 micron Bi-CMOS silicon integrated circuit technology. The circuit consisted of an integrated silicon light emitting source, an optical wave-guiding structure, two integrated optical detectors and two high-gain CMOS transimpedance analogue amplifiers. Simulations with MicroSim PSpice software predict a utilizable bandwidth capability of up to 220 MHz for the trans-impedance amplifier for detected photo-currents at the input of the amplifier in the range of 1 nA to 100 nA and driving a 10mV to 1 V signal into a 100 kΩ load. First iteration OEIC structures were realised in 1.2 micron CMOS technology for various source-waveguide-detector arrangements. Current signal ranging from 1nA to 1 micro-amp was detected at detectors. The technology seems favorable for first-iteration implementation for digital communications on chip up to 200Mbps.

  13. Nonlinear localized modes in dipolar Bose-Einstein condensates in two-dimensional optical lattices

    NASA Astrophysics Data System (ADS)

    Rojas-Rojas, Santiago; Naether, Uta; Delgado, Aldo; Vicencio, Rodrigo A.

    2016-09-01

    We analyze the existence and properties of discrete localized excitations in a Bose-Einstein condensate loaded into a periodic two-dimensional optical lattice, when a dipolar interaction between atoms is present. The dependence of the Number of Atoms (Norm) on the energy of solutions is studied, along with their stability. Two important features of the system are shown, namely, the absence of the Norm threshold required for localized solutions to exist in finite 2D systems, and the existence of regions in the parameter space where two fundamental solutions are simultaneously unstable. This feature enables mobility of localized solutions, which is an uncommon feature in 2D discrete nonlinear systems. With attractive dipolar interaction, a non-trivial behavior of the Norm dependence is obtained, which is well described by an analytical model.

  14. Backscattering enhancement of light by nanoparticles positioned in localized optical intensity peaks

    NASA Astrophysics Data System (ADS)

    Chen, Zhigang; Li, Xu; Taflove, Allen; Backman, Vadim

    2006-02-01

    We report what we believe to be a novel backscattering phenomenon associated with localized optical intensity peaks (spanning as little as 43 nm) arising at the shadow-side surfaces of plane-wave-illuminated dielectric microcylinders of noncircular cross sections. Namely, for nanometer-scale dielectric particles positioned within the localized intensity peaks, their backscattering of visible light is enhanced by several orders of magnitude relative to the case of isolated nanoparticles (i.e., Rayleigh scattering). The positions of the localized intensity peaks can be quickly scanned along the microcylinder surface by changing either the incident wavelength or angle. This combination of giant backscattering enhancement of nanoparticles and ease and rapidity of scanning may present advantages relative to the use of fragile, mechanically scanned, near-field probes. Potential applications include visible-light detection, characterization, and manipulation of nanoparticles.

  15. Isoform-specific localization of Nogo protein in the optic pathway of mouse embryos.

    PubMed

    Wang, Liqing; Wang, Jun; Ma, Ding; Taylor, Jeremy S H; Chan, Sun-On

    2016-08-01

    Expression of Nogo protein was investigated in the optic pathway of embryonic mice by using isoform-specific antibodies Bianca and 11C7, which recognize Nogo-A/B and Nogo-A, respectively. Our previous reports from using antibody N18 have shown that Nogo is localized on the radial glia in the retina and at the midline of the ventral diencephalon in mouse embryos during the ingrowth of retinal ganglion cells (RGCs) axons. This glial-specific localization is markedly different from findings in other studies. This study showed Nogo-A/B primarily on radial glia in the retina at E13 and then later on retinal ganglion cells and axons at E14 and E15, whereas Nogo-A was expressed preferentially by RGCs and their axons. In the ventral diencephalon, Nogo-A/B was expressed strongly on radial glia, particularly in those located in the midline region of the chiasm but also on RGC axons. In Nogo-A knockout embryos, the isoform Nogo-B (revealed by Bianca) was observed on radial glia in the ventral diencephalon and on RGCs and their axons. We concluded that Nogo-A is localized on the ganglion cells and retinal axons, whereas Nogo-B is expressed by the radial glia in the optic pathway. Nogo-B may play an important role in guiding axon growth in decisive regions of the visual pathway, which include the optic disc and the optic chiasm. J. Comp. Neurol. 524:2322-2334, 2016. © 2016 Wiley Periodicals, Inc. PMID:26718118

  16. Optical properties of surfaces with supercell ab initio calculations: Local-field effects

    NASA Astrophysics Data System (ADS)

    Tancogne-Dejean, Nicolas; Giorgetti, Christine; Véniard, Valérie

    2015-12-01

    Surface optical and electronic properties are crucial for material science and have implications in fields as various as nanotechnology, nonlinear optics, and spectroscopies. In particular, the huge variation of electronic density perpendicular to the surface is expected to play a key role in absorption due to local-field effects. Numerous state-of-the-art theoretical and numerical ab initio formalisms developed for studying these properties are based on supercell approaches, in reciprocal space, due to their efficiency. In this paper, we show that the standard scheme fails for the out-of-plane optical response of the surface. This response is interpreted using the "effective-medium theory" with vacuum and also in terms of interaction between replicas, as the supercell approach implies a periodicity which is absent in the real system. We propose an alternative formulation, also based on the supercell, for computing the macroscopic dielectric function. Application to the clean Si(001) 2 ×1 surface allows us to present the effect of the local fields for both peak positions and line shape on the bulk and surface contributions. It shows how local fields built up for the in-plane and out-of-plane dielectric responses of the surface. In addition to their conceptual impact, our results explain why the standard approach gives reliable predictions for the in-plane components, leading to correct reflectance anisotropy spectra. Our scheme can be further generalized to other low-dimensional geometries, such as clusters or nanowires, and open the way to nonlinear optics for surfaces.

  17. Surgical breast cancer localization via coherent measurement of endogenous optical properties

    NASA Astrophysics Data System (ADS)

    Zysk, Adam Michael

    This dissertation describes investigations of microscopic endogenous optical contrast sources in normal and diseased breast tissues. Emphasis has been placed on investigation of the scattering and refractive index properties that can be detected using coherence-based optical techniques. Studies have been conducted in various biological systems, including isolated cells, animal models, and surgically excised human specimens. These investigations have shown that coherence-based techniques can measure clinically relevant scattering and refractive index changes with high sensitivity, allowing for accurate differentiation between breast tissue types. These findings have been applied to the clinical problems of metastatic cell identification and biopsy needle localization. The latter is important due to the high rate of nondiagnostic tissue removal using current guidance techniques. Up to 10% of the approximately one million breast needle biopsies performed every year in the United States yield incorrect samples and inconclusive diagnoses, often resulting in additional surgical procedures. This poor outcome is due in large part to the inability of clinicians to spatially localize suspicious tissues during biopsy procedures. This problem has been addressed with the development of a clinically compatible fiber optic needle device capable of accurately measuring refractive index and scattering in situ. Preliminary intraoperative investigations with this device have yielded promising results.

  18. Method for non-optical quantification of in situ local soft tissue biomechanics.

    PubMed

    Tarsi, Grant M; Gould, Russell A; Chung, Jaebum A; Xu, Andrew Z; Bozkurt, Alper; Butcher, Jonathan T

    2013-07-26

    Soft tissues exhibit significant biomechanical changes as they grow, adapt, and remodel under a variety of normal and pathogenic stimuli. Biomechanical measurement of intact soft tissues is challenging because of its large strain and nonlinear behavior. Tissue distention through applied vacuum pressure is an attractive method for acquiring local biomechanical information minimally invasive and non-destructive, but the current requirement for optical strain measurement limits its use. In this study, we implemented a novel flexible micro-electrode array placed within a cylindrical probe tip. We hypothesized that upon tissue distention, contact with each electrode would result in a precipitous voltage drop (from the resistive connection formed between input and output electrodes) across the array. Hence, tissue distention (strain) can be derived directly from the electrode array geometry. In pilot studies, we compared the electrode array measurements directly against optical deformation measurements in-situ of agar tissue phantoms and freshly isolated porcine tissue. Our results demonstrate that the probe derived stress-strain profiles and modulus measurements were statistically indistinguishable from optical measurement. We further show that electrode geometry can be scaled down to 50μm in size (length and width) and spaced 50μm apart without impairing measurement accuracy. These results establish a promising new method for minimally invasive local soft tissue biomechanical measurement, which may be useful for applications such as disease diagnosis and health monitoring. PMID:23791186

  19. Graphene-Silver-Induced Self-Polarized PVDF-Based Flexible Plasmonic Nanogenerator Toward the Realization for New Class of Self Powered Optical Sensor.

    PubMed

    Sinha, Tridib Kumar; Ghosh, Sujoy Kumar; Maiti, Rishi; Jana, Santanu; Adhikari, Basudam; Mandal, Dipankar; Ray, Samit K

    2016-06-22

    Plasmonic characteristics of graphene-silver (GAg) nanocomposite coupled with piezoelectric property of Poly(vinylidene fluoride) (PVDF) have been utilized to realize a new class of self-powered flexible plasmonic nanogenerator (PNG). A few layer graphene has been prepared in a facile and cost-effective method and GAg doped PVDF hybrid nanocomposite (PVGAg) is synthesized in a one-pot method. The PNG exhibits superior piezoelectric energy conversion efficiency (∼15%) under the dark condition. The plasmonic behavior of GAg nanocomposite makes the PNG highly responsive to the visible light illumination that leads to ∼50% change in piezo-voltage and ∼70% change in piezo-current, leading to enhanced energy conversion efficiency up to ∼46.6%. The piezoelectric throughput of PNG (e.g., capacitor charging performance) has been monitored during the detection of the different wavelengths of visible light illumination and showed maximum selectivity to the green light. The simultaneous mechanical energy harvesting and visible-light detection capabilities of the PNG are attractive for futuristic self-powered optoelectronic smart sensors and devices. PMID:27266368

  20. Successful product realization strategies

    NASA Astrophysics Data System (ADS)

    Peeples, John; Boulton, William R.

    1995-02-01

    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.

  1. 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.

  2. Local measurement in Freon R123 two-phase vertical upflow using bi-optical probe

    SciTech Connect

    Saito, T.; Matsutani, K.; Iwase, T.; Sunami, T.; Tomomatsu, K.; Ueno, T.; Osaki, T.

    1995-12-31

    In the U-bend region of steam generator of PWR plant, the authors have experienced some tube failures due to flow induced vibration. In this project, the thermal hydraulic and flow induced vibration tests are planned using the model steam generator equipped with the large scale U-bend tube bundle and the Freon two-phase flow loop. The objectives of this project are to verify the reliability of U-bend tubes and to upgrade the technologies to evaluate the thermal hydraulic behaviors in U-bend region and the flow induced vibration of U-bend tubes. The void fraction and interfacial velocity are key parameters for the flow induced vibration phenomena. So, it is important to measure the void fraction and interfacial velocity precisely. In order to confirm the capability of bi-optical probe for the measurement of those key parameters in the Freon two-phase flow, the authors performed the verification test of bi-optical probe. This paper describes the results of the verification test of bi-optical probe. The verification test has been performed using a single pipe. The void fractions and interfacial velocities have been measured at some local positions in the single pipe using bi-optical probe.

  3. Bifunctional electro-optical nanoprobe to real-time detect local biochemical processes in single cells.

    PubMed

    Zheng, Xin Ting; Hu, Weihua; Wang, Houxiao; Yang, Hongbin; Zhou, Wei; Li, Chang Ming

    2011-07-15

    A bifunctional electro-optical nanoprobe with integrated nanoring electrode and optical nanotip was fabricated and investigated to simultaneously detect both electrical and optical signals in real-time with high spatial resolution. Concurrent measurements of the oxidant generation and the intracellular antioxidant levels in single cells correlate the stronger oxidant generation with an altered initial antioxidant response in the breast cancer cells in comparison to the normal ones suggesting that the cell malignancy is associated with the strength of oxidative stress, and the higher antioxidant level may be the cause of the drug resistance. While the optical detection indicates the fluctuation of the intracellular redox homeostasis, the chronoamperometric signals allow quantitative real-time detection of the H₂O₂ release and decay. Furthermore, the nanoscale probe enables localized simultaneous detections thus discovering that activated enzymes responsible for the oxidative stress target at specific membrane regions. This method promises applications in study of the dynamics of important physiological processes, and provides the opportunity to unravel the interplay of various signaling pathways. PMID:21632233

  4. 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.

  5. Local optical absorption spectra of h-BN–MoS2 van der Waals heterostructure revealed by scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Nozaki, Junji; Kobayashi, Yu; Miyata, Yasumitsu; Maniwa, Yutaka; Watanabe, Kenji; Taniguchi, Takashi; Yanagi, Kazuhiro

    2016-06-01

    Van der Waals (vdW) heterostructures, in which different two-dimensional layered materials are stacked, can exhibit unprecedented optical properties. Development of a technique to clarify local optical properties of vdW heterostructures is of great importance for the correct understanding of their backgrounds. Here, we examined local optical absorption spectra of h-BN–MoS2 vdW heterostructures by scanning near-field microscopy measurements with a spatial resolution of 100 nm. In an as-grown sample, there was almost no site dependence of their optical absorption spectra. However, in a degraded sample where defects and deformations were artificially induced, a significant site-dependence of optical absorption spectra was observed.

  6. Symmetry breaking in a localized interacting binary Bose-Einstein condensate in a bichromatic optical lattice

    NASA Astrophysics Data System (ADS)

    Cheng, Yongshan; Adhikari, S. K.

    2010-02-01

    By direct numerical simulation of the time-dependent Gross-Pitaevskii equation using the split-step Fourier spectral method, we study different aspects of the localization of a cigar-shaped interacting binary (two-component) Bose-Einstein condensate (BEC) in a one-dimensional bichromatic quasiperiodic optical-lattice potential, as used in a recent experiment on the localization of a BEC [Roati , Nature 453, 895 (2008)]. We consider two types of localized states: (i) when both localized components have a maximum of density at the origin x=0, and (ii) when the first component has a maximum of density and the second a minimum of density at x=0. In the noninteracting case, the density profiles are symmetric around x=0. We numerically study the breakdown of this symmetry due to interspecies and intraspecies interactions acting on the two components. Where possible, we have compared the numerical results with a time-dependent variational analysis. We also demonstrate the stability of the localized symmetry-broken BEC states under small perturbation.

  7. Localization of a Bose-Einstein-condensate vortex in a bichromatic optical lattice

    SciTech Connect

    Adhikari, S. K.

    2010-04-15

    By numerical simulation of the time-dependent Gross-Pitaevskii equation we show that a weakly interacting or noninteracting Bose-Einstein condensate (BEC) vortex can be localized in a three-dimensional bichromatic quasiperiodic optical-lattice (OL) potential generated by the superposition of two standing-wave polarized laser beams with incommensurate wavelengths. We also study the localization of a (nonrotating) BEC in two and three dimensions by bichromatic OL potentials along orthogonal directions. This is a generalization of the localization of a BEC in a one-dimensional bichromatic OL as studied in a recent experiment [Roati et al., Nature 453, 895 (2008)]. We demonstrate the stability of the localized state by considering its time evolution in the form of a stable breathing oscillation in a slightly altered potential for a large period of time. Finally, we consider the localization of a BEC in a random one-dimensional potential in the form of several identical repulsive spikes arbitrarily distributed in space.

  8. 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.

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

    SciTech Connect

    Kozyreff, G.; Gelens, L.

    2011-08-15

    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.

  10. Three-dimensional optical disk data storage via the localized alteration of a format hologram.

    PubMed

    McLeod, R R; Daiber, A J; Honda, T; McDonald, M E; Robertson, T L; Slagle, T; Sochava, S L; Hesselink, L

    2008-05-10

    Three-dimensional optical data storage is demonstrated in an initially homogenous volume by first recording a reflection grating in a holographic photopolymer. This causes the entire volume to be weakly reflecting to a confocal read/write head. Superposition of two or three such gratings with slightly different k-vectors creates a track and layer structure that specialized servo detection optics can use to lock the focus to these deeply-buried tracks. Writing is accomplished by locally modifying the reflectivity of the preexisting hologram. This modification can take the form of ablation, inelastic deformation via heating at the focus, or erasure via linear or two-photon continued polymerization in the previously unexposed fringes of the hologram. Storage by each method is demonstrated with up to eight data layers separated by as little as 12 microns. PMID:18470266

  11. Quantifying local density of optical states of nanorods by fluorescence lifetime imaging

    PubMed Central

    Liu, Jing; Jiang, Xunpeng; Ishii, Satoshi; Shalaev, Vladimir; Irudayaraj, Joseph

    2014-01-01

    In this letter, we demonstrate a facile far-field approach to quantify the near-field local density of optical states (LDOS) of a nanorod using CdTe quantum dots (QDs) emitters tethered to the surface of nanorods as beacons for optical read-outs. Radiative decay rate was extracted to quantify the LDOS; our analysis indicates that the LDOS of the nanorod enhance both the radiative and nonradiative decay of QD, particularly radiative decay of QDs at the end of nanorod is enhanced by 1.17 times greater than that at the waist, while the nonradiative decay was uniformly enhanced over the nanorod. To the best of our knowledge, our effort constitutes the first to map the LDOS of a nanostructure via far-field method, to provide clarity on the interaction mechanism between emitters and the nanostructure, and to be potentially employed in the LDOS mapping of high-throughput nanostructures. PMID:25408619

  12. Enhanced Optical Transmission Mediated by Localized Plasmons in Anisotropic, 3D Nanohole Arrays

    PubMed Central

    Yang, Jiun-Chan; Gao, Hanwei; Suh, Jae Yong; Zhou, Wei; Lee, Min Hyung; Odom, Teri W.

    2010-01-01

    This paper describes 3D nanohole arrays whose high optical transmission is mediated more by localized surface plasmon (LSP) excitations than by surface plasmon polaritons (SPPs). First, LSPs on 3D hole arrays lead to optical transmission an order of magnitude higher than 2D planar hole arrays. Second, LSP-mediated transmission is broadband and more tunable than SPP-enhanced transmission which is restricted by Bragg coupling. Third, for the first time, two types of surface plasmons can be selectively excited and manipulated on the same plasmonic substrate. This new plasmonic substrate fabricated by high-throughput nanolithography techniques paves the way for cutting-edge optoelectronic and biomedical applications. PMID:20698633

  13. Optical bullet-tracking algorithms for weapon localization in urban environments

    SciTech Connect

    Roberts, R S; Breitfeller, E F

    2006-03-31

    Localization of the sources of small-arms fire, mortars, and rocket propelled grenades is an important problem in urban combat. Weapons of this type produce characteristic signatures, such as muzzle flashes, that are visible in the infrared. Indeed, several systems have been developed that exploit the infrared signature of muzzle flash to locate the positions of shooters. However, systems based on muzzle flash alone can have difficulty localizing weapons if the muzzle flash is obscured or suppressed. Moreover, optical clutter can be problematic to systems that rely on muzzle flash alone. Lawrence Livermore National Laboratory (LLNL) has developed a projectile tracking system that detects and localizes sources of small-arms fire, mortars and similar weapons using the thermal signature of the projectile rather than a muzzle flash. The thermal signature of a projectile, caused by friction as the projectile travels along its trajectory, cannot be concealed and is easily discriminated from optical clutter. The LLNL system was recently demonstrated at the MOUT facility of the Aberdeen Test Center [1]. In the live-fire demonstration, shooters armed with a variety of small-arms, including M-16s, AK-47s, handguns, mortars and rockets, were arranged at several positions in around the facility. Experiments ranged from a single-weapon firing a single-shot to simultaneous fire of all weapons on full automatic. The LLNL projectile tracking system was demonstrated to localize multiple shooters at ranges up to 400m, far greater than previous demonstrations. Furthermore, the system was shown to be immune to optical clutter that is typical in urban combat. This paper describes the image processing and localization algorithms designed to exploit the thermal signature of projectiles for shooter localization. The paper begins with a description of the image processing that extracts projectile information from a sequence of infrared images. Key to the processing is an adaptive spatio

  14. Novel approach to realizing quasi-phase-matched gallium arsenide optical parametric oscillators for use in mid-IR laser systems

    NASA Astrophysics Data System (ADS)

    Mason, Paul D.; McBrearty, Euan J.; Orchard, David A.; Harris, Michael R.; Lewis, Keith L.

    2004-06-01

    Most of the applications that require frequency agile solid state laser systems for use in the mid-infrared are centred on the development of optical parametric oscillators. These exploit the non-linear optical characteristics of non-centrosymmetric materials, in particular the chalcopyrite class of materials that includes AgGaSe2 and ZnGeP2. Whilst such materials are generally difficult to produce, major strides have been made in recent years to optimise crystal growth processes which have enabled the generation of moderate laser output powers. Other approaches have been centred on the use of periodically poled lithium niobate and diffusion bonded gallium arsenide. The latter system is particularly attractive because it exploits a readily available crystalline material, but its implementation is difficult because of the need for an ultra-clean processing environment and relatively high bonding temperatures. This paper describes progress in the development of a new, low-temperature approach for achieving quasi-phase matched gallium arsenide by bonding with an index-matched chalcogenide glass. A major advantage of this approach is the tolerance to GaAs wafer thickness variations and to defects at the surface of the GaAs wafers. Several glass compositions in the germanium-arsenic-selenium-tellurium system have the desired refractive indices, but only some provide the characteristics necessary to ensure the formation of stable low-loss bonds. The glass bonding process begins by RF sputtering films of the glass from pre-manufactured targets onto each side of individual GaAs substrates. These coated substrates are then assembled in a vacuum oven and uniaxially pressed under carefully controlled conditions until a single composite assembly is formed. Issues such as glass purity, the integrity of the sputtering process and choice of pressing conditions are important in ensuring that a high quality non-linear crystal is produced.

  15. Characterizing Dust Attenuation in Local Star-forming Galaxies: UV and Optical Reddening

    NASA Astrophysics Data System (ADS)

    Battisti, A. J.; Calzetti, D.; Chary, R.-R.

    2016-02-01

    The dust attenuation for a sample of ∼10,000 local (z ≲ 0.1) star-forming galaxies is constrained as a function of their physical properties. We utilize aperture-matched multiwavelength data available from the Galaxy Evolution Explorer and the Sloan Digital Sky Survey to ensure that regions of comparable size in each galaxy are being analyzed. We follow the method of Calzetti et al. and characterize the dust attenuation through the UV power-law index, β, and the dust optical depth, which is quantified using the difference in Balmer emission line optical depth, {τ }Bl={τ }{{H}β }-{τ }{{H}α }. The observed linear relationship between β and {τ }Bl is similar to the local starburst relation, but the large scatter (σint = 0.44) suggests that there is significant variation in the local universe. We derive a selective attenuation curve over the range 1250 Å < λ < 8320 Å and find that a single attenuation curve is effective for characterizing the majority of galaxies in our sample. This curve has a slightly lower selective attenuation in the UV compared to previously determined curves. We do not see evidence to suggest that a 2175 Å feature is significant in the average attenuation curve. Significant positive correlations are seen between the amount of UV and optical reddening and galaxy metallicity, mass, star formation rate (SFR), and SFR surface density. This provides a potential tool for gauging attenuation where the stellar population is unresolved, such as at high z.

  16. Distributed characterization of localized and stationary dynamic Brillouin gratings in polarization maintaining optical fibers.

    PubMed

    Chiarello, Fabrizio; Sengupta, Dipankar; Palmieri, Luca; Santagiustina, Marco

    2016-03-21

    We experimentally generate localized and stationary dynamic Brillouin gratings in a 5 m long polarization maintaining fiber by phase-modulation of the pumps with a pseudo-random bit sequence. The dynamic Brillouin gratings are characterized in terms of length, bandwidth, group delay and group delay ripple, optical signal-to-noise ratio and peak to sidelobe ratio by measuring the distribution of the complex reflected signal along the fiber through swept-wavelength interferometry. By numerical processing, the performance of an optimal modulation format enabling null off-peak reflections are estimated and compared to the pseudo-random bit sequence case. PMID:27136783

  17. 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.

  18. Optical pump-probe measurements of local nuclear spin coherence in semiconductor quantum wells.

    PubMed

    Sanada, H; Kondo, Y; Matsuzaka, S; Morita, K; Hu, C Y; Ohno, Y; Ohno, H

    2006-02-17

    We demonstrate local manipulation and detection of nuclear spin coherence in semiconductor quantum wells by an optical pump-probe technique combined with pulse rf NMR. The Larmor precession of photoexcited electron spins is monitored by time-resolved Kerr rotation (TRKR) as a measure of nuclear magnetic field. Under the irradiation of resonant pulsed rf magnetic fields, Rabi oscillations of nuclear spins are traced by TRKR signals. The intrinsic coherence time evaluated by a spin-echo technique reveals the dependence on the orientation of the magnetic field with respect to the crystalline axis as expected by the nearest neighbor dipole-dipole interaction. PMID:16606048

  19. 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

    2010-11-01

    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. PMID:21164762

  20. X-ray and Optical Properties of an Unbiased Sample of Local AGN

    NASA Astrophysics Data System (ADS)

    Winter, Lisa M.; Mushotzky, R.; Tueller, J.; Lewis, K.; Reynolds, C.

    2007-12-01

    The SWIFT Burst Alert Telescope (BAT), while not focused on a Gamma-ray burst, conducts an all-sky survey in the 14 - 195 keV band. After the first 9 months, the BAT has detected a sample of 153 local (z ˜ 0.03) AGN at a flux limit of a few times 10-11 erg/s/cm-2 (Tueller et al. 2007). Since the AGN were detected at very high X-ray energies, they are an unbiased sample towards column densities below 1025 cm-2. We present the X-ray and optical properties of a sample of the BAT AGN.

  1. Modal analysis of the impact of the boundaries on transverse Anderson localization in a one-dimensional disordered optical lattice

    NASA Astrophysics Data System (ADS)

    Abaie, Behnam; Hosseini, Seyed Rasoul; Karbasi, Salman; Mafi, Arash

    2016-04-01

    Impact of the boundaries on transversely localized modes of a truncated one-dimensional disordered optical lattice is numerically studied. The results show lower modal number density near the boundaries compared with the bulk, while the average decay rate of the tail of localized modes is the same near the boundaries as in the bulk. It is suggested that the perceived suppressed localization near the boundaries is due to a lower mode density: on average, it is less probable to excite a localized mode near the boundaries; however, once it is excited, its localization is with the same exponential decay rate as any other localized mode.

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Vanoort, Johannes M.; Scanlan, Ronald M.; Tenkate, Herman H. J.

    1994-10-01

    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 Nb3Sn accelerator dipole magnet are presented. Finally, the possible use of this system as a quench localization system is proposed.

  5. 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.

  6. Realization of a minimal disturbance quantum measurement.

    PubMed

    Sciarrino, F; Ricci, M; De Martini, F; Filip, R; Mista, L

    2006-01-20

    We report the first experimental realization of an "optimal" quantum device able to perform a minimal disturbance measurement on polarization encoded qubits saturating the theoretical boundary established between the classical knowledge acquired of any input state, i.e., a "classical guess," and the fidelity of the same state after disturbance due to measurement. The device has been physically realized by means of a linear optical qubit manipulation, postselection measurement, and a classical feed-forward process. PMID:16486551

  7. Realization of high capacity transmission in fiber optic communication systems using Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) technique

    NASA Astrophysics Data System (ADS)

    Malekmohammadi, Amin; Mahdiraji, Ghafour Amouzad; Abas, Ahmad Fauzi; Abdullah, Mohamad Khazani; Mokhtar, Makhfudzah; Rasid, Mohd Fadlee A.

    2009-08-01

    An electrical multiplexing technique, namely Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) is reported for high-speed optical fiber communication systems. It is demonstrated that 40 Gb/s (4 × 10 Gb/s) AP-DCDM system shows a clear advantage over conventional 40 Gb/s RZ-OOK with 50% duty cycle in terms of dispersion tolerance and spectral efficiency. At 40 Gb/s its tolerance to chromatic dispersion (CD) is 124 ps/nm and 194 ps/nm for the worst and the best user, respectively. These values are higher than that of 40 Gb/s RZ-OOK, which is around 100 ps/nm. The spectral efficiency, receiver sensitivity and OSNR for different number of channels are discussed. Comparison against other modulation formats namely duobinary, Non-Return-to-Zero (NRZ)-OOK and RZ-Differential Quadrature Phase-Shift Keying (RZ-DQPSK) at 40 Gb/s are made. It is shown that AP-DCDM has the best receiver sensitivity (-32 dBm) and better CD tolerance (±200 ps/nm) than NRZ-OOK and RZ-DQPSK. In reference to duobinary, AP-DCDM has better receiver sensitivity but worse dispersion tolerance.

  8. Quantum quenches of cold-atom gases in optical lattices: the influence of Anderson localization

    NASA Astrophysics Data System (ADS)

    Hooley, Chris; Quintanilla, Jorge; Scarola, Vito

    2014-03-01

    We consider the following kind of non-equilibrium experiment. An ultracold fluid of fermions is prepared in a potential consisting of three parts: an optical lattice; a short-range-correlated disorder potential of finite strength; and a shallow harmonic trapping potential. After the fluid has equilibrated, the minimum of the harmonic potential is suddenly ``jumped'' to the side by a finite distance, d. The observables of interest are the subsequent evolution of the density distribution and phase correlations in the fluid. This kind of experiment is theoretically interesting because it contains two energy-dependent length scales: the localization length of the single-particle orbitals due to the disorder potential, ξ and the ``Bragg localization length'' of the single-particle orbitals due to the combined effect of the harmonic trap and optical lattice, lB. We present numerical results on the evolution of the density distributions and phase correlations in such cases, for a range of strengths of the disorder. In addition, we provide an approximate analytical framework for understanding our results in terms of the relative size of the length scales ξ and lB at the Fermi energy. Possibilities for further work are also discussed.

  9. 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

    2014-01-01

    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

  10. 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

  11. 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.

  12. 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. PMID:27370440

  13. 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.

  14. Tuning the Magneto-Optical Response of Nanosize Ferromagnetic Ni Disks Using the Phase of Localized Plasmons

    NASA Astrophysics Data System (ADS)

    Maccaferri, Nicolò; Berger, Andreas; Bonetti, Stefano; Bonanni, Valentina; Kataja, Mikko; Qin, Qi Hang; van Dijken, Sebastiaan; Pirzadeh, Zhaleh; Dmitriev, Alexandre; Nogués, Josep; Åkerman, Johan; Vavassori, Paolo

    2013-10-01

    We explore the influence of the phase of localized plasmon resonances on the magneto-optical activity of nanoferromagnets. We demonstrate that these systems can be described as two orthogonal damped oscillators coupled by the spin-orbit interaction. We prove that only the spin-orbit induced transverse plasmon plays an active role on the magneto-optical properties by controlling the relative amplitude and phase lag between the two oscillators. Our theoretical predictions are fully confirmed by magneto-optical Kerr effect and optical extinction measurements in nanostructures of different size and shape.

  15. 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.

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

    PubMed

    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. PMID:26931870

  17. 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

  18. 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

  19. 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…

  20. 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.

  1. Access protocols and network architectures for very high-speed optical fiber local area networks

    NASA Astrophysics Data System (ADS)

    Ganti, Sudhaker N. M.

    1993-10-01

    The single mode optical fiber possesses an enormous bandwidth of more than 30 THz in the low-loss optical region of 1.3 and 1.5 microns. Through wavelength division multiplexing (WDM), the optical fiber bandwidth can be divided into a set of high-speed channels, where each channel is assigned its own unique wavelength. An M x M passive optical star coupler is a simple broadcast medium, in which light energy incident at any input is uniformly coupled (or distributed) to all the outputs. Thus, a passive star along with the WDM channels can be used to configure a local area network (LAN). In this LAN, users require tunable devices to access a complete or a partial set of the WDM channels. Due to these multiple channels, many concurrent packet transmissions corresponding to different user pairs are possible and thus the total system throughput can be much higher than the data rates of each individual channel. To fairly arbitrate the data channels among the users, media access protocols are needed. Depending upon the number of data channels and the number of users, two possible situations arise. In the first case, the number of users is much larger than the number of data channels and in the second, the number of users equals the number of channels. In both cases, data channel contention may arise if multiple users access the same given channel and must be resolved. This thesis proposes media access protocols for passive optical star networks. All the proposed protocols are slotted in nature, i.e., the time axis on each channel is divided into slots. The well known Slotted-ALOHA and Reservation ALOHA protocols are extended to the multichannel network environment. The thesis also proposes switching protocols (equal number of channels and users), contention-based reservation protocols for this network architecture. To interconnect these star networks, a multi-control channel protocol is also proposed along with two interconnecting techniques. Since there are multiple data

  2. Optical studies of the charge localization and delocalization in conducting polymers

    NASA Astrophysics Data System (ADS)

    Kim, Youngmin

    A systematic charge transport study on the thermochromism of polyaniline (PAN) doped with a plasticizing dopant, and on a field effect device using conducting poly (3,4-ethylenedioxythiophene) (PEDOT) as its active material, was made at optical (20--45,000 cm-1) frequencies to probe the charge localization and delocalization phenomena and the insulator to metal transition (IMT) in the inhomogeneous conducting polymer system. Temperature dependent reflectance [20--8000 cm -1 (2.5 meV--1eV)] of the PAN sample, together with absorbance and do transport study done by Dr. Pron at the Laboratoire de Physique des Metaux Synthetiques in Grenoble, France, shows spectral weight loss in the infrared region but the reflectance in the very low frequency (below 100 cm-1) remains unaffected. There are two localization transitions. The origin of the 200 K localization transition that affect >˜15% of the electrons is the glass transition emanating from the dopants. The transition principally affects the IR response in the range of 200--8000 cm -1. The low temperature (<75K) localization transition affects the few electrons that provide the high conductivity. It is suggested that these electrons are localized by disorder at the lowest temperature and become delocalized through phonon induced delocalization as the temperature increases to 75K. It is noted that this temperature is typical of a Debye temperature in many organic materials. The thermocromism is attributed to the weak localization to strong localization transition through the glass transition temperature. Below the glass transition temperature (Tg), the lattice is "frozen" in configuration that reduces the charge delocalization and lead to cause increase of strongly localized polarons. Time variation of source-drain current, real-time IR reflectance [20--8000 cm-1 (2.5 meV--1eV)] modulation, and real-time UV/VIS/NIR absorbance [380--2400 nm (0.5--3.3 eV)] modulation were measured to investigate the field induced charge

  3. Metal-dielectric composite optical structures with novel dynamic tunable localized surface-plasmonic effects

    NASA Astrophysics Data System (ADS)

    Feng, Yuyang; Willatzen, Morten; Andersen, Niels L.

    2007-05-01

    A tunable MEMS sub-wavelength surface plasmonic apparatus is proposed based on localized surface-plasmon resonance effects. Optical tunneling is obtained through Surface Plasmon Polaritons (SPP) and Localized Surface Plasmon (LSP) by using a periodic sub-wavelength narrow-grooved metal-dielectric-metal (MDM) composite structure. Only p-polarized light can excite the SPP and LSP resonantly. The excited LSP mode with a strong field enhancement at the incident side grooves, resonantly excites the LSP mode on the other side of the thin structure. Then, with matched radiative modes, photons are radiated and tunneled. Nano/micro electromechanical actuation of small elastic deformations makes it possible to dynamically tune the localized surface plasmons via shape changes. Numerical simulations based on the Finite-Difference Time-Domain (FDTD) method are carried out on sub-wavelength structures and the results discussed. The MDM concept provides a new method to achieve real-time, dynamic tunable control and manipulation of light transmission and reflection via LSP which is different from novel tunable SPP apparatus where refractive index modulation is obtained using a voltage-controlled liquid crystal or tunable spaced air-gapped micro-prisms based on a convential SPP arrangement. This is important for the manipulation of LSP and plasmonic device design applications. Furthermore, a proposed Localized Surface Plasmon Resonance (LSPR) sensor mechanism with MDM-LSPR are demonstrated with numerical results. We believe that the MDM-LSPR is a novel principle for LSPR sensors in dielectric sensing for chemical or biologic applications which compares to current LSPR sensors with nano-particle LSPR and nanosphere lithography (NSL).

  4. 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

  5. Coexisting localized and extended optical Bloch states in a periodic deep wire array microcavity

    NASA Astrophysics Data System (ADS)

    Löchner, Franz J. F.; Mischok, Andreas; Brückner, Robert; Lyssenko, Vadim G.; Zakhidov, Alexander A.; Fröb, Hartmut; Leo, K.

    2015-09-01

    We embed periodic SiO2 wires in an organic microcavity, producing a rectangular potential by the different optical thicknesses of the active layer due to the additional SiO2 layer. By μ -photoluminescence spectroscopy, we observe the energy dispersion of the photons and obtain discrete localized below and extended Bloch states above the potential barrier, respectively, showing that electro-magnetic waves can behave like massive particles, such as electrons, in crystal lattices. We investigate the dependencies on wire width and period and use the Kronig-Penney model to describe the photon energy dispersion, including an "effective mass" of a photon propagating through a microcavity implying polarization splitting. We obtain excellent agreement between experiment, simulation and analytical calculation.

  6. 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.

  7. Optical Evidence of Itinerant-Localized Crossover of 4f Electrons in Cerium Compounds

    NASA Astrophysics Data System (ADS)

    Kimura, Shin-ichi; Kwon, Yong Seung; Matsumoto, Yuji; Aoki, Haruyoshi; Sakai, Osamu

    2016-08-01

    Cerium (Ce)-based heavy-fermion materials have a characteristic double-peak structure (mid-IR peak) in the optical conductivity [σ(ω)] spectra originating from the strong conduction (c)-f electron hybridization. To clarify the behavior of the mid-IR peak at a low c-f hybridization strength, we compared the σ(ω) spectra of the isostructural antiferromagnetic and heavy-fermion Ce compounds with the calculated unoccupied density of states and the spectra obtained from the impurity Anderson model. With decreasing c-f hybridization intensity, the mid-IR peak shifts to the low-energy side owing to the renormalization of the unoccupied 4f state, but suddenly shifts to the high-energy side owing to the f-f on-site Coulomb interaction at a slight localized side from the quantum critical point (QCP). This finding gives us information on the change in the electronic structure across QCP.

  8. 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.

  9. Measuring binding kinetics of biomolecular interactions using a localized surface plasmon couple fluorescence fiber optic biosensor

    NASA Astrophysics Data System (ADS)

    Chang, Ying-Feng; Hsieh, Jo-Ping; Su, Li-Chen; Li, Ying-Chang; Lee, Cheng-Chung; Chou, Chien

    2010-08-01

    In this study, we describe a novel method for analyzing protein-protein binding kinetics at ultra-low concentration (1 pg/mL) using a localized surface plasmon coupled fluorescence fiber-optic biosensor (LSPCF-FOB). The association and dissociation rate constants, ka and kd, respectively, for the binding kinetics of the mouse IgG/ anti-mouse IgG interaction have been calculated to be ka = (5.9928+/-3.1540)x106 M-1s-1 and kd = (1.0587+/-0.5572)x10-3 s-1. The theoretical basis of this analytical approach is a rapid-mixing model integrated with a two-compartment model; has been experimentally verified in this study as well. The LSPCF-FOB provides a potentially alternative option for characterizing the interaction of biomolecules at ultra-low concentrations.

  10. Automatic registration of optical imagery with 3d lidar data using local combined mutual information

    NASA Astrophysics Data System (ADS)

    Parmehr, E. G.; Fraser, C. S.; Zhang, C.; Leach, J.

    2013-10-01

    Automatic registration of multi-sensor data is a basic step in data fusion for photogrammetric and remote sensing applications. The effectiveness of intensity-based methods such as Mutual Information (MI) for automated registration of multi-sensor image has been previously reported for medical and remote sensing applications. In this paper, a new multivariable MI approach that exploits complementary information of inherently registered LiDAR DSM and intensity data to improve the robustness of registering optical imagery and LiDAR point cloud, is presented. LiDAR DSM and intensity information has been utilised in measuring the similarity of LiDAR and optical imagery via the Combined MI. An effective histogramming technique is adopted to facilitate estimation of a 3D probability density function (pdf). In addition, a local similarity measure is introduced to decrease the complexity of optimisation at higher dimensions and computation cost. Therefore, the reliability of registration is improved due to the use of redundant observations of similarity. The performance of the proposed method for registration of satellite and aerial images with LiDAR data in urban and rural areas is experimentally evaluated and the results obtained are discussed.

  11. Underwater Threat Source Localization: Processing Sensor Network TDOAs with a Terascale Optical Core Device

    SciTech Connect

    Barhen, Jacob; Imam, Neena

    2007-01-01

    Revolutionary computing technologies are defined in terms of technological breakthroughs, which leapfrog over near-term projected advances in conventional hardware and software to produce paradigm shifts in computational science. For underwater threat source localization using information provided by a dynamical sensor network, one of the most promising computational advances builds upon the emergence of digital optical-core devices. In this article, we present initial results of sensor network calculations that focus on the concept of signal wavefront time-difference-of-arrival (TDOA). The corresponding algorithms are implemented on the EnLight processing platform recently introduced by Lenslet Laboratories. This tera-scale digital optical core processor is optimized for array operations, which it performs in a fixed-point-arithmetic architecture. Our results (i) illustrate the ability to reach the required accuracy in the TDOA computation, and (ii) demonstrate that a considerable speed-up can be achieved when using the EnLight 64a prototype processor as compared to a dual Intel XeonTM processor.

  12. 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

    2016-09-01

    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 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. PMID:27557281

  13. Realizations of Galilei algebras

    NASA Astrophysics Data System (ADS)

    Nesterenko, Maryna; Pošta, Severin; Vaneeva, Olena

    2016-03-01

    All inequivalent realizations of the Galilei algebras of dimensions not greater than five are constructed using the algebraic approach proposed by Shirokov. The varieties of the deformed Galilei algebras are discussed and families of one-parametric deformations are presented in explicit form. It is also shown that a number of well-known and physically interesting equations and systems are invariant with respect to the considered Galilei algebras or their deformations.

  14. Local Optical Closure Using Single Particle Mixing State Observations during the 2010 DOE CARES Campaign

    NASA Astrophysics Data System (ADS)

    Zaveri, R. A.; Arnott, W. P.; Atkinson, D. B.; Barnard, J.; Beranek, J.; Cappa, C. D.; Chand, D.; Dubey, M. K.; Easter, R. C.; Flowers, B. A.; Gyawali, M. S.; Jobson, B. T.; Pekour, M. S.; Riemer, N. S.; Subramanian, R.; Song, C.; Zelenyuk, A.

    2011-12-01

    /soot absorption photometer (PSAP). Other supporting measurements include aerosol size distribution and key trace gases (NOx, NOy, O3, and volatile organic compounds). The combined data thus provides a unique opportunity to characterize BC aging and its effect on optical properties. In this paper, we will present results from a local optical closure study for selected 10-minute samples at the T0 urban site using the particle-resolved version of the comprehensive aerosol model MOSAIC coupled to a shell/core Mie code. Sensitivity of the predicted optical properties to various measurements and model representations of particle composition, mixing state, size bin resolution, and refractive indices will be examined.

  15. 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

  16. Optical frequency comb-based local oscillator phase noise cancellation in time-delay-interferometer for gravitational wave detection

    NASA Astrophysics Data System (ADS)

    Yu, Nan

    Time-delay-interferometer (TDI) is well established as an effective technique to mitigate laser phase noises in laser interferometer gravitational wave detection (GWD). Just as important in the TDI scheme is the ability to suppress the rf local oscillator noise (LO) in the optical heterodyne measurements. We show that LO noises can be effectively and elegantly cancelled by employing optical frequency combs in which the rf signal phases are coherent with the optical phases. In addition, the deployment of optical combs eliminates the need for separate ultra-stable oscillators. This is a simpler and more reliable approach than the modulation scheme, and it can be applied to the most generalized TDI combinations. In this proposed effort, we will investigate the application of optical combs in TDI and demonstrate in a test bed simultaneous noise cancellations in both ranging lasers and rf LOs in a generalized TDI configuration.

  17. Realization of Simple Quantum Algorithms with Circuit Quantum Electrodynamics

    NASA Astrophysics Data System (ADS)

    Dicarlo, Leonardo

    2010-03-01

    Superconducting circuits have made considerable progress in the requirements of quantum coherence, universal gate operations and qubit readout necessary to realize a quantum computer. However, simultaneously meeting these requirements makes the solid-state realization of few-qubit processors, as previously implemented in nuclear magnetic resonance, ion-trap and optical systems, an exciting challenge. We present the realization of a two-qubit superconducting processor based on circuit quantum electrodynamics (cQED), and report progress by the Yale cQED team towards a four-qubit upgrade. The architecture employs a microwave transmission-line cavity as a quantum bus coupling multiple transmon qubits. Unitary control is achieved by concatenation of high-fidelity single-qubit rotations induced via resonant microwave tones, and multi-qubit adiabatic phase gates realized by local flux control of qubit frequencies. Qubit readout uses the cavity as a quadratic detector, such that a single, calibrated measurement channel gives direct access to multi-qubit correlations. We present generation of Bell states; entanglement quantification by strong violation of Clauser-Horne-Shimony-Holt inequalities; and implementations of the Grover search and Deutsch-Jozsa algorithms. We report experimental progress in extending adiabatic phase gates and joint readout to four qubits, and improving qubit coherence on the road to realizing more complex quantum algorithms. Research done in collaboration with J. M. Chow, J. M. Gambetta, Lev S. Bishop, B. R. Johnson, D. I. Schuster, A. Nunnenkamp, J. Majer, A. Blais, L. Frunzio, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf.

  18. Electronic Document Imaging and Optical Storage Systems for Local Governments: An Introduction. Local Government Records Technical Information Series. Number 21.

    ERIC Educational Resources Information Center

    Schwartz, Stanley F.

    This publication introduces electronic document imaging systems and provides guidance for local governments in New York in deciding whether such systems should be adopted for their own records and information management purposes. It advises local governments on how to develop plans for using such technology by discussing its advantages and…

  19. 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

  20. Localized Surface Plasmon Resonance with Five-Branched Gold Nanostars in a Plastic Optical Fiber for Bio-Chemical Sensor Implementation

    PubMed Central

    Cennamo, Nunzio; D'Agostino, Girolamo; Donà, Alice; Dacarro, Giacomo; Pallavicini, Piersandro; Pesavento, Maria; Zeni, Luigi

    2013-01-01

    In this paper a refractive index sensor based on localized surface plasmon resonance (LSPR) in a Plastic Optical Fiber (POF), is presented and experimentally tested. LSPR is achieved exploiting five-branched gold nanostars (GNS) obtained using Triton X-100 in a seed-growth synthesis. They have the uncommon feature of three localized surface plasmon resonances. The strongest LSPRs fall in two ranges, one in the 600–900 nm range (LSPR 2) and the other one in the 1,100–1,600 nm range (LSPR 3), both sensible to refractive index changes. Anyway, due to the extremely strong attenuation (>102 dB/m) of the employed POF in the 1,100–1,600 nm range, only LSPR 2 will be exploited for refractive index change measurements, useful for bio-chemical sensing applications, as a proof of principle of the possibility of realizing a compact, low cost and easy-to-use GNS based device. PMID:24172284

  1. 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.

  2. 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.

  3. Measurement of local currents in superconductors using an in-situ high field magneto-optical microscope

    SciTech Connect

    Wijngaarden, R.J.; Surdeanu, R.; Griessen, R.

    1997-08-01

    A contactless method is used to measure the local current density in superconductors at fields up to 7 T with a spatial resolution better than 1 {mu}m. The local currents are derived from magneto-optical images using a powerful inversion scheme. The interpretation of global experimental data on flux flow, flux creep and relaxation phenomena is hindered if the magnetic moment of the sample as a whole is measured, while the current flow in the sample is not uniform. This problem can be overcome by the local measurement of the currents flowing in the sample that is discussed below.

  4. 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. PMID:26974099

  5. 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.

  6. Localization and migration of phase singularities in the edge-diffracted optical-vortex beams

    NASA Astrophysics Data System (ADS)

    Bekshaev, Aleksandr; Chernykh, Aleksey; Khoroshun, Anna; Mikhaylovskaya, Lidiya

    2016-02-01

    When a circularly-symmetric light beam with optical vortex (OV) diffracts at an opaque screen with the sharp edge, the OV core is displaced from the beam axis and, in case of the m-charged incident OV, decomposed into |m| single-charged ones. By means of numerical simulations and based on examples of incident beams with topological charges |m| = 1, 2, 3 we show that, while the screen edge monotonously advances towards the beam axis, the OVs in the diffracted beam cross section move away from the incident beam axis along spiral-like trajectories. The trajectories contain fine structure details that reflect the nature and peculiar spatial configuration of the diffracting beam. For the Kummer beams’ diffraction, the trajectories contain self-crossings and regions of ‘backward’ rotation (loops); in the case of Laguerre-Gaussian beams, the trajectories are smoother. The numerical results are supported by analytical approximations and conform to experiments. The general shape of the trajectories and their local behavior show high sensitivity to the diffraction conditions (spatial structure of the diffracting beam, its disposition with respect to the screen edge, etc), which can be used in diverse metrological applications.

  7. Impact of local compressive stress on the optical transitions of single organic dye molecules

    NASA Astrophysics Data System (ADS)

    Stöttinger, Sven; Hinze, Gerald; Diezemann, Gregor; Oesterling, Ingo; Müllen, Klaus; Basché, Thomas

    2014-03-01

    The ability to mechanically control the optical properties of individual molecules is a grand challenge in nanoscience and could enable the manipulation of chemical reactivity at the single-molecule level. In the past, light has been used to alter the emission wavelength of individual molecules or modulate the energy transfer quantum yield between them. Furthermore, tensile stress has been applied to study the force dependence of protein folding/unfolding and of the chemistry and photochemistry of single molecules, although in these mechanical experiments the strength of the weakest bond limits the amount of applicable force. Here, we show that compressive stress modifies the photophysical properties of individual dye molecules. We use an atomic force microscope tip to prod individual molecules adsorbed on a surface and follow the effect of the applied force on the electronic states of the molecule by fluorescence spectroscopy. Applying a localized compressive force on an isolated molecule induces a stress that is redistributed throughout the structure. Accordingly, we observe reversible spectral shifts and even shifts that persist after retracting the microscope tip, which we attribute to transitions to metastable states. Using quantum-mechanical calculations, we show that these photophysical changes can be associated with transitions among the different possible conformers of the adsorbed molecule.

  8. 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. PMID:27190713

  9. 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

  10. Optical induction scheme for assembling nondiffracting aperiodic Vogel spirals

    SciTech Connect

    Diebel, Falko Rose, Patrick; Boguslawski, Martin; Denz, Cornelia

    2014-05-12

    We introduce an experimental approach to realize aperiodic photonic lattices based on multiplexing of nondiffracting Bessel beams. This holographic optical induction scheme takes advantage of the well localized Bessel beam as a basis to assemble two-dimensional photonic lattices. We present the realization of an optically induced two-dimensional golden-angle Vogel spiral lattice, which belongs to the family of deterministic aperiodic structures. With our technique, a very broad class of photonic refractive index landscapes now becomes accessible to optical induction, which could not be realized with established distributed holographic techniques.

  11. Optical induction scheme for assembling nondiffracting aperiodic Vogel spirals

    NASA Astrophysics Data System (ADS)

    Diebel, Falko; Rose, Patrick; Boguslawski, Martin; Denz, Cornelia

    2014-05-01

    We introduce an experimental approach to realize aperiodic photonic lattices based on multiplexing of nondiffracting Bessel beams. This holographic optical induction scheme takes advantage of the well localized Bessel beam as a basis to assemble two-dimensional photonic lattices. We present the realization of an optically induced two-dimensional golden-angle Vogel spiral lattice, which belongs to the family of deterministic aperiodic structures. With our technique, a very broad class of photonic refractive index landscapes now becomes accessible to optical induction, which could not be realized with established distributed holographic techniques.

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

    PubMed

    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 Ca(2+) 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 Ca(2+), measured optically with GCaMP6s. We show that action potentials, measured electrophysiologically, can be induced with this approach. We demonstrate activation of local Ca(2+) transients and Ca(2+) 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. 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

    2014-01-01

    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

  14. 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.

  15. Investigation into local cell mechanics by atomic force microscopy mapping and optical tweezer vertical indentation.

    PubMed

    Coceano, G; Yousafzai, M S; Ma, W; Ndoye, F; Venturelli, L; Hussain, I; Bonin, S; Niemela, J; Scoles, G; Cojoc, D; Ferrari, E

    2016-02-12

    Investigating the mechanical properties of cells could reveal a potential source of label-free markers of cancer progression, based on measurable viscoelastic parameters. The Young's modulus has proved to be the most thoroughly studied so far, however, even for the same cell type, the elastic modulus reported in different studies spans a wide range of values, mainly due to the application of different experimental conditions. This complicates the reliable use of elasticity for the mechanical phenotyping of cells. Here we combine two complementary techniques, atomic force microscopy (AFM) and optical tweezer microscopy (OTM), providing a comprehensive mechanical comparison of three human breast cell lines: normal myoepithelial (HBL-100), luminal breast cancer (MCF-7) and basal breast cancer (MDA-MB-231) cells. The elastic modulus was measured locally by AFM and OTM on single cells, using similar indentation approaches but different measurement parameters. Peak force tapping AFM was employed at nanonewton forces and high loading rates to draw a viscoelastic map of each cell and the results indicated that the region on top of the nucleus provided the most meaningful results. OTM was employed at those locations at piconewton forces and low loading rates, to measure the elastic modulus in a real elastic regime and rule out the contribution of viscous forces typical of AFM. When measured by either AFM or OTM, the cell lines' elasticity trend was similar for the aggressive MDA-MB-231 cells, which were found to be significantly softer than the other two cell types in both measurements. However, when comparing HBL-100 and MCF-7 cells, we found significant differences only when using OTM. PMID:26683826

  16. Investigation into local cell mechanics by atomic force microscopy mapping and optical tweezer vertical indentation

    NASA Astrophysics Data System (ADS)

    Coceano, G.; Yousafzai, M. S.; Ma, W.; Ndoye, F.; Venturelli, L.; Hussain, I.; Bonin, S.; Niemela, J.; Scoles, G.; Cojoc, D.; Ferrari, E.

    2016-02-01

    Investigating the mechanical properties of cells could reveal a potential source of label-free markers of cancer progression, based on measurable viscoelastic parameters. The Young’s modulus has proved to be the most thoroughly studied so far, however, even for the same cell type, the elastic modulus reported in different studies spans a wide range of values, mainly due to the application of different experimental conditions. This complicates the reliable use of elasticity for the mechanical phenotyping of cells. Here we combine two complementary techniques, atomic force microscopy (AFM) and optical tweezer microscopy (OTM), providing a comprehensive mechanical comparison of three human breast cell lines: normal myoepithelial (HBL-100), luminal breast cancer (MCF-7) and basal breast cancer (MDA-MB-231) cells. The elastic modulus was measured locally by AFM and OTM on single cells, using similar indentation approaches but different measurement parameters. Peak force tapping AFM was employed at nanonewton forces and high loading rates to draw a viscoelastic map of each cell and the results indicated that the region on top of the nucleus provided the most meaningful results. OTM was employed at those locations at piconewton forces and low loading rates, to measure the elastic modulus in a real elastic regime and rule out the contribution of viscous forces typical of AFM. When measured by either AFM or OTM, the cell lines’ elasticity trend was similar for the aggressive MDA-MB-231 cells, which were found to be significantly softer than the other two cell types in both measurements. However, when comparing HBL-100 and MCF-7 cells, we found significant differences only when using OTM.

  17. Photonic realization of the quantum Rabi model.

    PubMed

    Crespi, A; Longhi, S; Osellame, R

    2012-04-20

    We realize a photonic analog simulator of the quantum Rabi model, based on light transport in femtosecond-laser-written waveguide superlattices, which provides an experimentally accessible test bed to explore the physics of light-matter interaction in the deep strong coupling regime. Our optical setting enables us to visualize dynamical regimes not yet accessible in cavity or circuit quantum electrodynamics, such as the bouncing of photon number wave packets in parity chains of Hilbert space. PMID:22680717

  18. Fiber optic line for RoF systems with remote and local pump EDFA

    NASA Astrophysics Data System (ADS)

    Vinogradova, Irina L.; Sultanov, Albert K.; Meshkov, Ivan K.; Andrianova, Anna V.; Grakhova, Elizaveta P.; Ishmiyarov, Arsen A.; Zainullin, Airat R.

    2015-03-01

    The article is devoted to the research of a method providing positive chirp of a signal on a long-haul fiber optic line. The modeling of an optical pulse duration and its chirp functions on an offered segment has allowed to estimate the parameters of a segment - distance between regeneration points and capacity level of additional radiation. The method is interesting for high-speed transmission when there is no availability to use the electronic or fiber optic chromatic dispersion compensation modules.

  19. Realizing topological Mott insulators from the RKKY interaction

    NASA Astrophysics Data System (ADS)

    Liu, Tianhan; Douçot, Benoît; Le Hur, Karyn

    2016-05-01

    We engineer topological insulating phases in a fermion-fermion mixture on the honeycomb lattice, without resorting to artificial gauge fields or spin-orbit couplings and considering only local interactions. Essentially, upon integrating out the fast component (characterized by a larger hopping amplitude) in a finite region of dopings, we obtain an effective interaction between the slow fermions at half-filling, which acquires a Haldane mass with opposite parity in the two valleys of the Dirac cones, thus triggering a quantum anomalous Hall effect. We carefully analyze the competition between the induced Semenoff-type mass (producing charge density wave orders in real space) versus the Haldane mass (quantum anomalous Hall phase), as a function of the chemical potential of the fast fermions. If the second species involves spin-1/2 particles, this interaction may induce a quantum spin Hall phase. Such fermion-fermion mixtures can be realized in optical lattices or in graphene heterostructures.

  20. 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.

  1. Nematicons and Their Electro-Optic Control: Light Localization and Signal Readdressing via Reorientation in Liquid Crystals

    PubMed Central

    Piccardi, Armando; Alberucci, Alessandro; Assanto, Gaetano

    2013-01-01

    Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies. Exploiting such a response at optical frequencies, self-focusing supports transverse localization of light and the propagation of self-confined beams and waveguides, namely “nematicons”. Nematicons can guide other light signals and interact with inhomogeneities and other beams. Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing. Hereby, we outline the main features of nematicons and review the outstanding progress achieved in the last twelve years on beam self-trapping and electro-optic readdressing. PMID:24108367

  2. Local nondestructive data reading in three-dimensional memory systems based on the optical Kerr effect

    SciTech Connect

    Zheltikov, Aleksei M; Koroteev, Nikolai I; Naumov, A N; Fedotov, Andrei B; Magnitskiy, Sergey A; Sidorov-Biryukov, D A

    1998-11-30

    An investigation was made of the characteristics of the optical Kerr effect in a spiropyran solution. It was found that this effect makes it possible to distinguish the coloured and uncoloured forms of spiropyran and that it represents a promising method for nondestructive data reading in three-dimensional optical memory systems based on photochromic materials. (letters to the editor)

  3. 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.

  4. 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.

  5. The UV-optical colour dependence of galaxy clustering in the local universe

    NASA Astrophysics Data System (ADS)

    Loh, Yeong-Shang; Rich, R. Michael; Heinis, Sébastien; Scranton, Ryan; Mallery, Ryan P.; Salim, Samir; Martin, D. Christopher; Wyder, Ted; Arnouts, Stéphane; Barlow, Tom A.; Forster, Karl; Friedman, Peter G.; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Seibert, Mark; Bianchi, Luciana; Donas, Jose; Heckman, Timothy M.; Lee, Young-Wook; Madore, Barry F.; Milliard, Bruno; Szalay, Alex S.; Welsh, Barry Y.

    2010-09-01

    We measure the UV-optical colour dependence of galaxy clustering in the local Universe. Using the clean separation of the red and blue sequences made possible by the NUV - r colour-magnitude diagram, we segregate the galaxies into red, blue and intermediate `green' classes. We explore the clustering as a function of this segregation by removing the dependence on luminosity and by excluding edge-on galaxies as a means of a non-model dependent veto of highly extincted galaxies. We find that ξ(rp, π) for both red and green galaxies shows strong redshift-space distortion on small scales - the `finger-of-God' effect, with green galaxies having a lower amplitude than is seen for the red sequence, and the blue sequence showing almost no distortion. On large scales, ξ(rp, π) for all three samples show the effect of large-scale streaming from coherent infall. On scales of 1h-1Mpc < rp < 10h-1Mpc, the projected auto-correlation function wp(rp) for red and green galaxies fits a power law with slope γ ~ 1.93 and amplitude r0 ~ 7.5 and 5.3, compared with γ ~ 1.75 and r0 ~ 3.9 h-1 Mpc for blue sequence galaxies. Compared to the clustering of a fiducial L* galaxy, the red, green and blue have a relative bias of 1.5, 1.1 and 0.9, respectively. The wp(rp) for blue galaxies display an increase in convexity at ~ 1 h-1 Mpc, with an excess of large-scale clustering. Our results suggest that the majority of blue galaxies are likely central galaxies in less massive haloes, while red and green galaxies have larger satellite fractions, and preferentially reside in virialized structures. If blue sequence galaxies migrate to the red sequence via processes like mergers or quenching that take them through the green valley, such a transformation may be accompanied by a change in environment in addition to any change in luminosity and colour.

  6. Localized planarization of optical damage using laser-based chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Matthews, Manyalibo J.; Elhadj, Selim; Guss, Gabe M.; Sridharan, Arun; Nielsen, Norman D.; Yoo, Jae-Hyuck; Lee, Daeho; Grigoropoulos, Costas

    2013-11-01

    We present a method to repair damaged optics using laser-based chemical vapor deposition (L-CVD). A CO2 laser is used to heat damaged silica regions and polymerize a gas precursor to form SiO2. Measured deposition rates and morphologies agree well with finite element modeling of a two-phase reaction. Along with optimizing deposition rates and morphology, we also show that the deposited silica is structurally identical to high-grade silica substrate and possesses high UV laser damage thresholds. Successful application of such a method could reduce processing costs, extend optic lifetime, and lead to more damage resistant laser optics used in high power applications.

  7. 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.

  8. 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

  9. Light Localization and Magneto-Optic Enhancement in Ni Antidot Arrays.

    PubMed

    Rollinger, Markus; Thielen, Philip; Melander, Emil; Östman, Erik; Kapaklis, Vassilios; Obry, Björn; Cinchetti, Mirko; García-Martín, Antonio; Aeschlimann, Martin; Papaioannou, Evangelos Th

    2016-04-13

    We reveal an explicit strategy to design the magneto-optic response of a magneto-plasmonic crystal by correlating near- and far-fields effects. We use photoemission electron microscopy to map the spatial distribution of the electric near-field on a nanopatterned magnetic surface that supports plasmon polaritons. By using different photon energies and polarization states of the incident light we reveal that the electric near-field is either concentrated in spots forming a hexagonal lattice with the same symmetry as the Ni nanopattern or in stripes oriented along the Γ-K direction of the lattice and perpendicular to the polarization direction. We show that the polarization-dependent near-field enhancement on the patterned surface is directly correlated to both the excitation of surface plasmon polaritons on the patterned surface as well as the enhancement of the polar magneto-optical Kerr effect. We obtain a relationship between the size of the enhanced magneto-optical behavior and the polarization and wavelength of optical excitation. The engineering of the magneto-optic response based on the plasmon-induced modification of the optical properties introduces the concept of a magneto-plasmonic meta-structure. PMID:27018661

  10. 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

  11. Determination of local optical response functions of nanostructures with increasing complexity by using single and coupled Lorentzian oscillator models

    NASA Astrophysics Data System (ADS)

    Aeschlimann, Martin; Brixner, Tobias; Fischer, Alexander; Hensen, Matthias; Huber, Bernhard; Kilbane, Deirdre; Kramer, Christian; Pfeiffer, Walter; Piecuch, Martin; Thielen, Philip

    2016-07-01

    We reconstruct the optical response of nanostructures of increasing complexity by fitting interferometric time-resolved photoemission electron microscopy (PEEM) data from an ultrashort (21 fs) laser excitation source with different harmonic oscillator-based models. Due to its high spatial resolution of ~40 nm, PEEM is a true near-field imaging system and enables in normal incidence mode a mapping of plasmon polaritons and an intuitive interpretation of the plasmonic behaviour. Using an actively stabilized Mach-Zehnder interferometer, we record two-pulse correlation signals with 50 as time resolution that contain information about the temporal plasmon polariton evolution. Spectral amplitude and phase of excited plasmon polaritons are extracted from the recorded phase-resolved interferometric two-pulse correlation traces. We show that the optical response of a plasmon polariton generated at a gold nanoparticle can be reconstructed from the interferometric two-pulse correlation signal using a single harmonic oscillator model. In contrast, for a corrugated silver surface, a system with increased plasmonic complexity, in general an unambiguous reconstruction of the local optical response based on coupled and uncoupled harmonic oscillators, fails. Whereas for certain local responses different models can be discriminated, this is impossible for other positions. Multidimensional spectroscopy offers a possibility to overcome this limitation.

  12. 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.

  13. A Bridge from Optical to Infrared Galaxies: Explaining Local Properties and Predicting Galaxy Counts and the Cosmic Background Radiation

    NASA Astrophysics Data System (ADS)

    Totani, Tomonori; Takeuchi, Tsutomu T.

    2002-05-01

    We give an explanation for the origin of various properties observed in local infrared galaxies and make predictions for galaxy counts and cosmic background radiation (CBR) using a new model extended from that for optical/near-infrared galaxies. Important new characteristics of this study are that (1) mass scale dependence of dust extinction is introduced based on the size-luminosity relation of optical galaxies and that (2) the large-grain dust temperature Tdust is calculated based on a physical consideration for energy balance rather than by using the empirical relation between Tdust and total infrared luminosity LIR found in local galaxies, which has been employed in most previous works. Consequently, the local properties of infrared galaxies, i.e., optical/infrared luminosity ratios, LIR-Tdust correlation, and infrared luminosity function are outputs predicted by the model, while these have been inputs in a number of previous models. Our model indeed reproduces these local properties reasonably well. Then we make predictions for faint infrared counts (in 15, 60, 90, 170, 450, and 850 μm) and CBR using this model. We found results considerably different from those of most previous works based on the empirical LIR-Tdust relation; especially, it is shown that the dust temperature of starbursting primordial elliptical galaxies is expected to be very high (40-80 K), as often seen in starburst galaxies or ultraluminous infrared galaxies in the local and high-z universe. This indicates that intense starbursts of forming elliptical galaxies should have occurred at z~2-3, in contrast to the previous results that significant starbursts beyond z~1 tend to overproduce the far-infrared (FIR) CBR detected by COBE/FIRAS. On the other hand, our model predicts that the mid-infrared (MIR) flux from warm/nonequilibrium dust is relatively weak in such galaxies making FIR CBR, and this effect reconciles the prima facie conflict between the upper limit on MIR CBR from TeV gamma

  14. Impact of intermediate localized states on nonlinear optical absorption of Ga-Ge-Se nanocolloidal solutions

    NASA Astrophysics Data System (ADS)

    Sebastian, Indu; Divya, S.; Nampoori, V. P. N.; Radhakrishnan, P.; Thomas, Sheenu

    2013-01-01

    We present the linear and nonlinear optical studies on nanocolloidal solutions of Ga9Ge27Se64 glass with varying concentrations. Optical bandgap of the material is found to vary with respect to the concentration of the solute in the solution. An intermediate peak in the band tail of the absorption spectra is observed due to the presence of energy band in the forbidden gap. The existence of fluorescence emission confirms the above argument. Nonlinear absorption is studied using open aperture Z-scan technique. The mechanism behind nonlinear absorption is predicted as two photon as well as two step photon absorption. Nonlinearity increases with decrease in optical bandgap which in turn depends on the concentration of the nanocolloidal solutions.

  15. Realizing Fractional Chern Insulators in Dipolar Systems

    NASA Astrophysics Data System (ADS)

    Yao, Norman; Gorshkov, Alexey; Laumann, Chris; Lauchli, Andreas; Ye, Jun; Lukin, Mikhail

    2013-05-01

    Strongly correlated quantum systems can exhibit exotic behavior controlled by topology. We predict that the ν = 1 / 2 fractional Chern insulator arises naturally in a two-dimensional array of driven, dipolar-interacting spins. As a specific implementation, we analyze how to prepare and detect synthetic gauge potentials for the rotational excitations of ultra-cold polar molecules trapped in a deep optical lattice. With the motion of the molecules pinned, under certain conditions, these rotational excitations (acting as effective spins) form a fractional Chern insulating state. We present a detailed experimental blueprint for its realization and demonstrate that the implementation is consistent with near-term capabilities. Prospects for the realization of such phases in solid-state dipolar systems are discussed as are their possible applications.

  16. INVESTIGATING THE OPTICAL COUNTERPART CANDIDATES OF FOUR INTEGRAL SOURCES LOCALIZED WITH CHANDRA

    SciTech Connect

    Oezbey Arabac Latin-Small-Letter-Dotless-I , Mehtap; Kalemci, Emrah; Tomsick, John A.; Bodaghee, Arash; Halpern, Jules; Chaty, Sylvain; Rodriguez, Jerome

    2012-12-10

    We report on the optical spectroscopic follow-up observations of the candidate counterparts to four INTEGRAL sources: IGR J04069+5042, IGR J06552-1146, IGR J21188+4901, and IGR J22014+6034. The candidate counterparts were determined with Chandra, and the optical observations were performed with 1.5 m RTT-150 telescope (TUeBITAK National Observatory, Antalya, Turkey) and 2.4 m Hiltner Telescope (MDM Observatory, Kitt Peak, Arizona). Our spectroscopic results show that one of the two candidates of IGR J04069+5042 and the one observed for IGR J06552-1146 could be active late-type stars in RS CVn systems. However, according to the likelihood analysis based on Chandra and INTEGRAL, two optically weaker sources in the INTEGRAL error circle of IGR J06552-1146 have higher probabilities to be the actual counterpart. The candidate counterparts of IGR J21188+4901 are classified as an active M-type star and a late-type star. Among the optical spectra of four candidates of IGR J22014+6034, two show H{alpha} emission lines, one is a late-type star, and the other is an M type. The likelihood analysis favors a candidate with no distinguishing features in the optical spectrum. Two of the candidates classified as M-type dwarfs, are similar to some IGR candidates claimed to be symbiotic stars. However, some of the prominent features of symbiotic systems are missing in our spectra, and their NIR colors are not consistent with those expected for giants. We consider the IR colors of all IGR candidates claimed to be symbiotic systems and find that low-resolution optical spectrum may not be enough for conclusive identification.

  17. 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

    2015-09-01

    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. PMID:26368410

  18. 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.

  19. 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.

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

    DOE PAGESBeta

    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

  1. In vivo imaging of epileptic foci in rats using a miniature probe integrating diffuse optical tomography and electroencephalographic source localization

    PubMed Central

    Yang, Hao; Zhang, Tao; Zhou, Junli; Carney, Paul R.; Jiang, Huabei

    2014-01-01

    SUMMARY Objective The goal of this work is to establish a new dual-modal brain mapping technique based on diffuse optical tomography (DOT) and electroencephalographic source localization (ESL) that can chronically/intracranially record optical/EEG data to precisely map seizures and localize the seizure onset zone and associated epileptic brain network. Methods The dual-modal imaging system was employed to image seizures in an experimental acute bicuculline methiodide rat model of focal epilepsy. Depth information derived from DOT was used as constraint in ESL to enhance the image reconstruction. Groups of animals were compared based on localization of seizure foci, either at different positions or at different depths. Results This novel imaging technique successfully localized the seizure onset zone in rat induced by bicuculline methiodide injected at a depth of 1mm, 2mm and 3mm, respectively. The results demonstrated that the incorporation of the depth information from DOT into the ESL image reconstruction resulted in more accurate and reliable ESL images. Although the ESL images showed a horizontal shift of the source localization, the DOT identified the seizure focus accurately. In one case, when the BMI was injected at a site outside the field of view (FOV) of the DOT/ESL interface, ESL gives false positive detection of the focus while DOT shows negative detection. Significance This study represents the first to identify seizure onset zone using implantable DOT. In addition, the combination of DOT/ESL has never been documented in neuroscience and epilepsy imaging. This technology will enable us to precisely measure the neural activity and hemodynamic response at exactly the same tissue site and at both cortical and sub cortical levels. PMID:25524046

  2. 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.

  3. 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.

  4. Study of local properties of fibre Bragg gratings by the method of optical space-domain reflectometry

    SciTech Connect

    Korolev, I G; Vasil'ev, Sergei A; Medvedkov, O I; Dianov, Evgenii M

    2003-08-31

    The method of optical space-domain reflectometry for measuring local spatial characteristics of fibre Bragg gratings (FBGs) is described in detail. It is demonstrated experimentally that, by using IR and UV radiation sources, this method provides good sensitivity ({approx}10{sup -4}) of measuring the modulation amplitude of the induced refractive index in the core of an optical fibre and a high spatial resolution ({approx}100 {mu}m and better). The factors affecting the accuracy of measurements as well as technical and methodological limitations of the method are considered. A comparative analysis of modern methods for studying the spatial properties of FBGs is performed and applications of these methods are considered. (special issue devoted to the memory of academician a m prokhorov)

  5. X-ray and Optical Properties of an Unbiased, Local ( z ≈ 0.03) AGN Sample Detected by Swift

    NASA Astrophysics Data System (ADS)

    Winter, Lisa M.; Mushotzky, R.; Reynolds, C.; Lewis, K.

    2009-01-01

    The Swift Burst Alert Telescope (BAT), while not focused on a Gamma-ray burst, conducts an all-sky survey in the 14 - 195 keV band. After the first 9 months, the BAT has detected a sample of 153 local (z 0.03) AGN at a flux limit of a few times 10-11 erg/s/cm-2 (Tueller et al. 2007). Since the AGN were detected at very high X-ray energies, they are an unbiased sample towards column densities below 1025 cm-2. We present the X-ray and optical properties of a sample of the BAT AGN, including an analysis of the 0.3-10 keV X-ray spectra (Winter et al. 2008) and optical spectra obtained from the literature, SDSS, and our own KPNO 2.1-m observations.

  6. A Bridge from Optical to Infrared Galaxies: Explaining Local Properties, Predicting Galaxy Counts and the Cosmic Background Radiation

    NASA Astrophysics Data System (ADS)

    Totani, T.; Takeuchi, T. T.

    2001-12-01

    A new model of infrared galaxy counts and the cosmic background radiation (CBR) is developed by extending a model for optical/near-infrared galaxies. Important new characteristics of this model are that mass scale dependence of dust extinction is introduced based on the size-luminosity relation of optical galaxies, and that the big grain dust temperature T dust is calculated based on a physical consideration for energy balance, rather than using the empirical relation between T dust and total infrared luminosity L IR found in local galaxies, which has been employed in most of previous works. Consequently, the local properties of infrared galaxies, i.e., optical/infrared luminosity ratios, L IR-T dust correlation, and infrared luminosity function are outputs predicted by the model, while these have been inputs in a number of previous models. Our model indeed reproduces these local properties reasonably well. Then we make predictions for faint infrared counts (in 15, 60, 90, 170, 450, and 850 μ m) and CBR by this model. We found considerably different results from most of previous works based on the empirical L IR-T dust relation; especially, it is shown that the dust temperature of starbursting primordial elliptical galaxies is expected to be very high (40--80K). This indicates that intense starbursts of forming elliptical galaxies should have occurred at z ~ 2--3, in contrast to the previous results that significant starbursts beyond z ~ 1 tend to overproduce the far-infrared (FIR) CBR detected by COBE/FIRAS. On the other hand, our model predicts that the mid-infrared (MIR) flux from warm/nonequilibrium dust is relatively weak in such galaxies making FIR CBR, and this effect reconciles the prima facie conflict between the upper limit on MIR CBR from TeV gamma-ray observations and the COBE\\ detections of FIR CBR. The authors thank the financial support by the Japan Society for Promotion of Science.

  7. 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.

  8. Custom-Built Optical Tweezers for Locally Probing the Viscoelastic Properties of Cancer Cells

    NASA Astrophysics Data System (ADS)

    Tavano, Federica; Bonin, Serena; Pinato, Giulietta; Stanta, Giorgio; Cojoc, Dan

    2011-07-01

    We report a home built optical tweezers setup to investigate the mechanism of the membrane tether formation from single cells in vitro. Using an optically trapped microbead as probe, we have determined the force-elongation curve during tether formation and extracted several parameters characterizing the viscoelastic behavior of the cell membrane: tether stiffness, force, and viscosity. Breast cancer MDA-MB-231 cells have been studied in two different conditions, at room and physiological temperatures, showing a strong temperature dependence of the visoelastic properties of the cell membrane. To get detailed inside information about the tether formation mechanism we have extended the analysis of the force-elongation curves fitting them with a Kelvin model. These preliminary results are part of a larger project of whose goal is to compare the viscoelastic properties of several types of cancer cell lines, characterized by different aggressiveness and metastatic potential.

  9. Optical meta-atom for localization of light with quantized energy

    PubMed Central

    Lannebère, Sylvain; Silveirinha, Mário G.

    2015-01-01

    The capacity to confine light into a small region of space is of paramount importance in many areas of modern science. Here we suggest a mechanism to store a quantized ‘bit' of light—with a very precise amount of energy—in an open core-shell plasmonic structure (‘meta-atom') with a nonlinear optical response. Notwithstanding the trapped light state is embedded in the radiation continuum, its lifetime is not limited by the radiation loss. Interestingly, it is shown that the interplay between the nonlinear response and volume plasmons enables breaking fundamental reciprocity restrictions, and coupling very efficiently an external light source to the meta-atom. The collision of an incident optical pulse with the meta-atom may be used to release the trapped light ‘bit'. PMID:26515977

  10. 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.

  11. Topographic localization of brain activation in diffuse optical imaging using spherical wavelets

    PubMed Central

    Abdelnour, F; Schmidt, B; Huppert, T J

    2009-01-01

    Diffuse optical imaging is a non-invasive technique that uses near-infrared light to measure changes in brain activity through an array of sensors placed on the surface of the head. Compared to functional MRI, optical imaging has the advantage of being portable while offering the ability to record functional changes in both oxy- and deoxy-hemoglobin within the brain at a high temporal resolution. However, the reconstruction of accurate spatial images of brain activity from optical measurements represents an ill-posed and underdetermined problem that requires regularization. These reconstructions benefit from incorporating prior information about the underlying spatial structure and function of the brain. In this work, we describe a novel image reconstruction approach which uses surface-based wavelets derived from structural MRI to incorporate high-resolution anatomical and structural prior information about the brain. This surface-based approach is used to approximate brain activation patterns through the reconstruction and presentation of topographical (two-dimensional) maps of brain activation directly onto the folded surface of the cortex. The set of wavelet coefficients is directly estimated by a truncated singular-value decomposition based pseudo-inversion of the wavelet projection of the optical forward model. We use a reconstruction metric based on Shannon entropy which quantifies the sparse loading of the wavelet coefficients and is used to determine the optimal truncation and regularization of this inverse model. In this work, examples of the performance of this model are illustrated for several cases of numerical simulation and experimental data with comparison to functional magnetic resonance imaging. PMID:19809125

  12. 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.

  13. Topographic localization of brain activation in diffuse optical imaging using spherical wavelets.

    PubMed

    Abdelnour, F; Schmidt, B; Huppert, T J

    2009-10-21

    Diffuse optical imaging is a non-invasive technique that uses near-infrared light to measure changes in brain activity through an array of sensors placed on the surface of the head. Compared to functional MRI, optical imaging has the advantage of being portable while offering the ability to record functional changes in both oxy- and deoxy-hemoglobin within the brain at a high temporal resolution. However, the reconstruction of accurate spatial images of brain activity from optical measurements represents an ill-posed and underdetermined problem that requires regularization. These reconstructions benefit from incorporating prior information about the underlying spatial structure and function of the brain. In this work, we describe a novel image reconstruction approach which uses surface-based wavelets derived from structural MRI to incorporate high-resolution anatomical and structural prior information about the brain. This surface-based approach is used to approximate brain activation patterns through the reconstruction and presentation of topographical (two-dimensional) maps of brain activation directly onto the folded surface of the cortex. The set of wavelet coefficients is directly estimated by a truncated singular-value decomposition based pseudo-inversion of the wavelet projection of the optical forward model. We use a reconstruction metric based on Shannon entropy which quantifies the sparse loading of the wavelet coefficients and is used to determine the optimal truncation and regularization of this inverse model. In this work, examples of the performance of this model are illustrated for several cases of numerical simulation and experimental data with comparison to functional magnetic resonance imaging. PMID:19809125

  14. Optical memory based on a biochemical structure

    NASA Astrophysics Data System (ADS)

    Baranov, Iu. A.; Gindilis, A. L.; Kiselev, B. S.; Koblov, A. N.; Mikaelian, A. L.

    1989-09-01

    A new type of optical memory with self-organized addressing is considered whose operation is based on bioelectrocatalysis and vibrational reactions. The principles of writing and reading are examined whereby addressing is realized by means of a local chemical signal representing a concentration wave propagating in data carrier space. Memory capacity and writing/reading rates in such memory devices are estimated.

  15. Optical fiber guided needle insertion to localize epidural space in porcine

    NASA Astrophysics Data System (ADS)

    Chang, Yin; Ting, Chien Kun; Tsou, Mei-Yung; Chen, Pin-Tarng; Chan, Kwok-Hon

    2010-02-01

    A novel optical method of guiding epidural catheter insertion is introduced due to high failure rate of traditional technique for epidural blocks. Experiments of ex-vivo and in-vivo in porcine were performed. In the ex-vivo study the optically reflective spectra of identified porcine tissues were obtained. By which wavelengths of 650 nm and 532 nm were selected to differentiate epidural space and ligamentum flavum. Then the typical stylet of an insertion needle set was replaced by a specially designed hollow stylet which contained optical fibers served for tissue illumination and receiving reflected light from tissue in the in-vivo experiment in pigs. The data was promising with mean magnitudes for 650 nm and 532 nm and their ratio at epidural space and ligamentum flavum were 3.565+/-0.194, 2.542+/-0.145, 0.958+/-0.172 and 3.842+/-0.191, 2.563+/-0.131, 1.228+/-0.244 respectively. Paired t test showed that significant differences occurred between epidural spaces and ligamentum flavum in both 650nm (p<0.001), 532nm (p=0.014) and their ratio (p <0.001). Two-way ANOVA for reflective lights of 650 and 532 nm indicates no significant difference at the different puncture sites for ligamentum flavum and epidural space (all p>0.05).

  16. 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

  17. Realization of a spin-wave multiplexer.

    PubMed

    Vogt, K; Fradin, F Y; Pearson, J E; Sebastian, T; Bader, S D; Hillebrands, B; Hoffmann, A; Schultheiss, H

    2014-01-01

    Recent developments in the field of spin dynamics--like the interaction of charge and heat currents with magnons, the quasi-particles of spin waves--opens the perspective for novel information processing concepts and potential applications purely based on magnons without the need of charge transport. The challenges related to the realization of advanced concepts are the spin-wave transport in two-dimensional structures and the transfer of existing demonstrators to the micro- or even nanoscale. Here we present the experimental realization of a microstructured spin-wave multiplexer as a fundamental building block of a magnon-based logic. Our concept relies on the generation of local Oersted fields to control the magnetization configuration as well as the spin-wave dispersion relation to steer the spin-wave propagation in a Y-shaped structure. Thus, the present work illustrates unique features of magnonic transport as well as their possible utilization for potential technical applications. PMID:24759754

  18. 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.

  19. Localized and propagating surface plasmon resonance based fiber optic sensor for the detection of tetracycline using molecular imprinting

    NASA Astrophysics Data System (ADS)

    Shrivastav, Anand M.; Mishra, Satyendra K.; Gupta, Banshi D.

    2015-03-01

    In the present study we report a novel approach for the fabrication of localized and propagating surface plasmon resonance based fiber optic sensor for the detection of tetracycline using molecular imprinting (MIP) technique. The sensor is fabricated by coating layers of silver film, silver nanoparticles and MIP film prepared using tetracycline molecule as template over an unclad core of the multimode optical fiber. Nanoparticles of sizes in the range 10-30 nm are synthesized by hydrothermal process. A polychromatic light source is used to launch the light from one end of the fiber and the absorption spectrum for a given concentration of the tetracycline solution around the probe is measured at the other end of the fiber using a spectrometer interfaced with a computer. The absorption spectra are recorded for the concentration range of tetracycline from 10-8 M to 10-5 M. A shift of 102 nm in peak absorbance wavelength is obtained for this concentration range. The sensor works in the promising concentration range of tetracycline found in foods etc. The sensor has various advantages such as high sensitivity, low cost, fast response and capability of online monitoring and remote sensing. Further, the sensitivity of the sensor is about double the sensor based on localized surface plasmon resonance and molecular imprinting.

  20. Self-contained diffuse optical imaging system for real-time detection and localization of vascular occlusions.

    PubMed

    Pollonini, Luca; Forseth, Kiefer J; Dacso, Clifford C; Parazynski, Scott E; Friedman, Jeffrey D

    2015-08-01

    Free flap surgery is a procedure where healthy tissue is transferred from a donor site to a recipient site of the body to fill a defect without maintaining the original blood supply to the flap. The anastomosis of the vascular network of the flap to the blood vessels adjacent to the recipient site has associated risks of arterial and/or venous occlusions that must be promptly detected to avoid temporary or permanent tissue damage. In this work, we present a skin-contact diffusion optical imaging (DOI) system able to continuously provide a three-dimensional representation of the flap oxygenation to promptly detect vascular occlusions potentially occurring in the flap. Multiple near-infrared LEDs and photodetectors were embedded into a self-contained optical sensor for prolonged monitoring of concentration changes of oxygenated (HbO) and deoxygenated hemoglobin (HbR) at multiple locations and depths. A time-efficient algorithm mapped measured oxygenation changes in a three-dimensional volume to allow surgeons and clinical personnel to detect and localize abnormal blood perfusion changes during or after surgery, in time for corrective intervention. The image reconstruction algorithm was validated using computerized flap models in which oxygenation was synthetically altered, whereas the optical system was preliminarily tested on a healthy forearm simulating a flap undergoing arterial and venous occlusions, proving the feasibility of implementing DOI in the form of a wearable patch for prolonged perfusion monitoring. PMID:26737630

  1. 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

  2. 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

    2016-01-01

    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

  3. Correlated, simultaneous, multiple-wavelength optical monitoring in vivo of localized cerebrocortical NADH and brain microvessel hemoglobin oxygen saturation.

    PubMed

    Rampil, I J; Litt, L; Mayevsky, A

    1992-07-01

    Current forms of brain monitoring, such as electroencephalography (EEG), have had limited clinical utility. The EEG records spontaneous cerebrocortical activity and thus is an indirect indicator of metabolic demand and, to a lesser extent, an indicator of mismatch of supply versus demand. Ischemia modulates EEG activity in ways that can usually be detected, but EEG patterns can be similarly modulated by many other factors, including temperature and pharmacologic manipulation. This in vivo study in physiologically monitored animals evaluated the use of correlated optical spectroscopy, performed with an instrument having a fiberoptic light-guide bundle in contact with the cerebral cortex, for the simultaneous monitoring of cerebrovascular oxygen availability and intracellular oxygen delivery. A highly specific monitor of cerebral intracellular oxygen supply, the cerebrocortical intramitochondrial NADH redox state, was monitored in vivo with a fluorescence technique. Absorption spectroscopy was used concurrently to monitor hemoglobin content (blood volume) and oxygen saturation in the microcirculation. Correlated changes in optical signals from cerebrocortical NADH and hemoglobin were studied in a swine model (n = 7) of nitrogen hypoxia. Measurements were made at four wavelengths with a time-division, multiplexed fluorometer/reflectometer. Because the NADH fluorescence signal at 450 nm is affected by local changes in blood volume, a "corrected" fluorescence signal is usually calculated. In previous studies, where only two wave lengths have been measured, attempts at correction were based on reflectance at the excitation wavelength (366 nm). We compared estimators of changes in microcirculatory blood volume using reflection at two wavelengths: 366 nm and 585 nm, the wavelengths for maximum and isobestic absorption. The results of the studies were as follows: (1) during transient hypoxia, NADH and local hemoglobin saturation signals changed in concert with arterial

  4. Optical Study of Exciton Localization Phenomena in Semimagnetic Semiconductors and Their Multiple Quantum Wells.

    NASA Astrophysics Data System (ADS)

    Zhang, Xi-Cheng

    1986-12-01

    The results of picosecond photomodulation and photoluminescence spectroscopies in novel II-VI semimagnetic semiconductors Cd(,1-x)Mn(,x)Te (x < 0.50) bulk and multiple quantum well (MQW) samples are presented. By studying excitonic emission near the bandgap of semiconductors, it is found that excitons can be confined or localized by alloy potential fluctuations, quantum well confinements, local strain of heterointerfaces and energy self-trapping. Steady-state photoluminescence in undoped CdTe/Cd(,1 -x)Mn(,x)Te MQW samples at low temperature shows intense excitonic emission where their radiative quantum efficiencies are two or three orders of magnitude larger than that of the high quality CdTe bulk samples. Time-resolved photoluminescence shows that the excitons have relatively short lifetime (500 picosecond). High quantum efficiency and short exciton lifetime suggest that the radiative recombination is a dominating factor in the excitonic-decay processes in the MQW samples. In general, excitonic emission energies in CdMnTe MQW samples are lower than the free exciton energies (typically 20-40 meV lower as noted from the reflectance spectra). The behavior of these emissions under an external magnetic field (up to 36 tesla) shows that excitons prefer to be localized at the heterointerfaces rather than at the center of the wells in MQW samples. The kinetics of the free and the heterointerface localized excitons in the Cd(,1-x)Mn(,x)Te/Cd(,1-y)Mn(,y)Te MQW samples have been studied by using a transient photoluminescence technique. Exciton lifetimes have been measured in several samples with various quantum well widths. The trapping time of the free exciton localized at the interface has been observed in the wide quantum well samples. The average energy loss rate of localized excitons has been calculated. The resonance excitation spectra of steady-state and transient luminescence show that the exciton spectra are spatially inhomogeneously broadened. An external magnetic

  5. Three-dimensional diffuse optical mammography with ultrasound localization in a human subject

    NASA Astrophysics Data System (ADS)

    Holboke, Monica J.; Tromberg, Bruce J.; Li, Xingde; Shah, Natasha; Fishkin, Joshua B.; Kidney, D.; Butler, J.; Chance, Britton; Yodh, Arjun G.

    2000-04-01

    We describe an approach that combines clinical ultrasound and photon migration techniques to enhance the sensitivity and information content of diffuse optical tomography. Measurements were performed on a postmenopausal woman with a single 1.8 X 0.9 cm malignant ductal carcinoma in situ approximately 7.4 mm beneath the skin surface (UCI IRB protocol 95-563). The ultrasound-derived information about tumor geometry enabled us to segment the breast tissue into tumor and background regions. Optical data was obtained with a multifrequency, multiwavelength hand-held frequency-domain photon migration backscattering probe. The optical properties of the tumor and background were then computed using the ultrasound-derived geometrical constraints. An iterative perturbative approach, using parallel processing, provided quantitative information about scattering and absorption simultaneously with the ability to incorporate and resolve complex boundary conditions and geometries. A three to four fold increase in the tumor absorption coefficient and nearly 50% reduction in scattering coefficient relative to background was observed ((lambda) equals 674, 782, 803, and 849 nm). Calculations of the mean physiological parameters reveal fourfold greater tumor total hemoglobin concentration [Hbtot] than normal breast (67 (mu) M vs 16 (mu) M) and tumor hemoglobin oxygen saturation (SOx) values of 63% (vs 73% and 68% in the region surrounding the tumor and the opposite normal tissue, respectively). Comparison of semi-infinite to heterogeneous models shows superior tumor/background contrast for the latter in both absorption and scattering. Sensitivity studies assessing the impact of tumor size and refractive index assumptions, as well as scan direction, demonstrate modest effects on recovered properties.

  6. 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.

  7. Porphyrin-doped solgel-lined structured optical fibers for local and remote sensing.

    PubMed

    Huyang, George; Canning, John; Åslund, Mattias L; Naqshbandi, Masood; Gibson, Brant; Petermann, Ingemar; Stocks, Danial; Crossley, Maxwell J

    2011-06-01

    We constructed a type of sensor by depositing a solgel layer within the interior holes of a silica-structured fiber and, subsequently, coating this with an acid-responsive porphyrin. Protonation of the porphyrin by an acidic gas (HCl in this case), is detected by a large change in the visible spectrum. Compared to previous work on a liquid-core sensor in a structured optical fiber, the signal-to-noise ratio of this gas sensor shows a reduced signal strength, but the detection rate is increased about fortyfold. PMID:21633420

  8. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope.

    PubMed

    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

  9. 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.

  10. 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

  11. Afocal optical flow sensor for reducing vertical height sensitivity in indoor robot localization and navigation.

    PubMed

    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

  12. 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

  13. On the Geometrical Optics Approach in the Theory of Freely-Localized Microwave Gas Breakdown

    NASA Astrophysics Data System (ADS)

    Shapiro, Michael; Schaub, Samuel; Hummelt, Jason; Temkin, Richard; Semenov, Vladimir

    2015-11-01

    Large filamentary arrays of high pressure gas microwave breakdown have been experimentally studied at MIT using a 110 GHz, 1.5 MW pulsed gyrotron. The experiments have been modeled by other groups using numerical codes. The plasma density distribution in the filaments can be as well analytically calculated using the geometrical optics approach neglecting plasma diffusion. The field outside the filament is a solution of an inverse electromagnetic problem. The solutions are found for the cylindrical and spherical filaments and for the multi-layered planar filaments with a finite plasma density at the boundaries. We present new results of this theory showing a variety of filaments with complex shapes. The solutions for plasma density distribution are found with a zero plasma density at the boundary of the filament. Therefore, to solve the inverse problem within the geometrical optics approximation, it can be assumed that there is no reflection from the filament. The results of this research are useful for modeling future MIT experiments.

  14. Some optical properties of metal in non-local potential theory

    NASA Astrophysics Data System (ADS)

    Chrzanowski, Janusz

    2007-04-01

    On the grounds of the non-local potential we can obtain a modified Schrödinger equation which allows on simple turn to the transform domain. Thereby the total energy of electron understood in terms of quasiparticle becomes an explicit function of the wave number. In result the response of the metal surface to the external electromagnetic radiation one can analyze in more general way.

  15. 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

  16. 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.

  17. Local Relationship between Global-Flash Multifocal Electroretinogram Optic Nerve Head Components and Visual Field Defects in Patients with Glaucoma

    PubMed Central

    Moon, Chan Hee; Han, Jungwoo; Ohn, Young-Hoon; Park, Tae Kwann

    2015-01-01

    Purpose. To investigate the local relationship between quantified global-flash multifocal electroretinogram (mfERG) optic nerve head component (ONHC) and visual field defects in patients with glaucoma. Methods. Thirty-nine patients with glaucoma and 30 normal controls were enrolled. The ONHC amplitude was measured from the baseline to the peak of the second positive deflection of the induced component. The ONHC amplitude was normalized by dividing ONHC amplitude by the average of seven largest ONHC amplitudes. The ONHC amplitude ratio map and ONHC deficiency map were constructed. The local relationship between the ONHC measurements and visual field defects was evaluated by calculating the overlap between the ONHC deficiency maps and visual field defect plots. Results. The mean ONHC amplitude measurements of patients with glaucoma (6.01 ± 1.91 nV/deg2) were significantly lower than those of the normal controls (10.29 ± 0.94 nV/deg2) (P < 0.001). The average overlap between the ONHC deficiency map and visual field defect plot was 71.4%. The highest overlap (75.0%) was between the ONHC ratios less than 0.5 and the total deviations less than 5%. Conclusions. The ONHC amplitude was reduced in patients with glaucoma compared to that in normal controls. Loss of the ONHC amplitude from the global-flash mfERG showed a high local agreement with visual field defects in patients with glaucoma. PMID:26697210

  18. All-Optical Sensing of the Components of the Internal Local Electric Field in Proteins

    PubMed Central

    Drobizhev, M.; Scott, J. N.; Callis, P. R.; Rebane, A.

    2014-01-01

    Here, we present a new all-optical method of interrogation of the internal electric field vector inside proteins. The method is based on experimental evaluation of the permanent dipole moment change upon excitation and the pure electronic transition frequency of a fluorophore embedded in a protein matrix. The permanent dipole moment change can be obtained from two-photon absorption measurements. In addition, permanent dipole moment change, tensor of polarizability change, and transition frequency for the free chromophore should be calculated quantum–mechanically. This allows obtaining the components of the electric field by considering the second-order Stark shift. We use the fluorescent protein mCherry as an example to demonstrate the applicability of the method. PMID:25419440

  19. All-Optical Sensing of the Components of the Internal Local Electric Field in Proteins.

    PubMed

    Drobizhev, M; Scott, J N; Callis, P R; Rebane, A

    2012-10-01

    Here, we present a new all-optical method of interrogation of the internal electric field vector inside proteins. The method is based on experimental evaluation of the permanent dipole moment change upon excitation and the pure electronic transition frequency of a fluorophore embedded in a protein matrix. The permanent dipole moment change can be obtained from two-photon absorption measurements. In addition, permanent dipole moment change, tensor of polarizability change, and transition frequency for the free chromophore should be calculated quantum-mechanically. This allows obtaining the components of the electric field by considering the second-order Stark shift. We use the fluorescent protein mCherry as an example to demonstrate the applicability of the method. PMID:25419440

  20. Gapless topological superconductors: Model Hamiltonian and realization

    NASA Astrophysics Data System (ADS)

    Baum, Yuval; Posske, Thore; Fulga, Ion Cosma; Trauzettel, Björn; Stern, Ady

    2015-07-01

    The existence of an excitation gap in the bulk spectrum is one of the most prominent fingerprints of topological phases of matter. In this paper, we propose a family of two-dimensional Hamiltonians that yield an unusual class D topological superconductor with a gapless bulk spectrum but well-localized Majorana edge states. We perform a numerical analysis for a representative model of this phase and suggest a concrete physical realization by analyzing the effect of magnetic impurities on the surface of a strong topological insulator.

  1. PCB with fully integrated optical interconnects

    NASA Astrophysics Data System (ADS)

    Langer, Gregor; Satzinger, Valentin; Schmidt, Volker; Schmid, Gerhard; Leeb, Walter R.

    2011-01-01

    The increasing demand for miniaturization and design flexibility of polymer optical waveguides integrated into electrical printed circuit boards (PCB) calls for new coupling and integration concepts. We report on a method that allows the coupling of optical waveguides to electro-optical components as well as the integration of an entire optical link into the PCB. The electro-optical devices such as lasers and photodiodes are assembled on the PCB and then embedded in an optically transparent material. A focused femtosecond laser beam stimulates a polymerization reaction based on a two-photon absorption effect in the optical material and locally increases the refractive index of the material. In this way waveguide cores can be realized and the embedded components can be connected optically. This approach does not only allow a precise alignment of the waveguide end faces to the components but also offers a truly 3-dimensional routing capability of the waveguides. Using this technology we were able to realize butt-coupling and mirror-coupling interface solutions in several demonstrators. We were also manufacturing demonstrator boards with fully integrated driver and preamplifier chips, which show very low power consumption of down to 10 mW for about 2.5 Gbit/s. Furthermore, demonstrators with interconnects at two different optical layers were realized.

  2. Optical bullets in (2+1)D photonic structures and their interaction with localized defects

    NASA Astrophysics Data System (ADS)

    Dohnal, Tomas

    2005-11-01

    This dissertation studies light propagation in Kerr-nonlinear two dimensional waveguides with a Bragg resonant, periodic structure in the propagation direction. The model describing evolution of the electric field envelopes is the system of 2D Nonlinear Coupled Mode Equations (2D CME). The periodic structure induces a range of frequencies (frequency gap) in which linear waves do not propagate. It is shown that, similarly to the ID case of a fiber grating, the 2D nonlinear system supports localized solitary wave solutions, referred to as 2D gap solitons, which have frequencies inside the linear gap and can travel at, any speed smaller than or equal to the speed of light in the corresponding homogeneous medium. Such solutions are constructed numerically via Newton's iteration. Convergence is obtained only near the upper edge of the gap. Gap solitons with a nonzero velocity are constructed by numerically following a bifurcation curve parameterized by the velocity v. It is shown that gap solitons are saddle points of the corresponding Hamiltonian functional and that no (constrained) local minima of the Hamiltonian exist. The linear stability problem is formulated and reasons for the failure of the standard Hamiltonian PDE approach for determining linear stability are discussed. In the second part of the dissertation interaction of 2D gap solitons with localized defects is studied and trapping of slow enough 2D gap solitons is demonstrated. This study builds on [JOSA B 19, 1635 (2002)], where such trapping of 1D gap solitons is considered. Analogously to this 1D problem trapping in the 2D model is explained as a resonant energy transfer into one or more defect modes existent for the particular defect. For special localized defects exact linear modes are found explicitly via the separation of variables. Numerical computation of linear defect modes is used for more general defects. Corresponding nonlinear modes are then constructed via Newton's iteration by following a

  3. Local probing of magnetic films by optical excitation of magnetostatic waves

    NASA Astrophysics Data System (ADS)

    Chernov, A. I.; Kozhaev, M. A.; Vetoshko, P. M.; Dodonov, D. V.; Prokopov, A. R.; Shumilov, A. G.; Shaposhnikov, A. N.; Berzhanskii, V. N.; Zvezdin, A. K.; Belotelov, V. I.

    2016-06-01

    Excitation of volume and surface magnetostatic spin waves in ferrite garnet films by circularly polarized laser pulses utilizing to the inverse magnetooptical Faraday effect has been studied experimentally. The region of excitation of the magnetostatic spin waves is determined by the diameter of the laser beam (˜10 μm). At the same time, the characteristic propagation length of the modes is 30 μm. A method of finding the local characteristics of a magnetic film, in particular, the cubic and uniaxial anisotropy constants, based on the analysis of the azimuthal-angle dependence of the spectrum of the magnetostatic spin waves has been proposed.

  4. 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

  5. Gauge fields, nonlinear realizations, supersymmetry

    NASA Astrophysics Data System (ADS)

    Ivanov, E. A.

    2016-07-01

    This is a brief survey of the all-years research activity in the Sector "Supersymmetry" (the former Markov Group) at the Bogoliubov Laboratory of Theoretical Physics. The focus is on the issues related to gauge fields, spontaneously broken symmetries in the nonlinear realizations approach, and diverse aspects of supersymmetry.

  6. 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. PMID:26161994

  7. 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.

  8. Accessing Extreme Spatiotemporal Localization of High-Power Laser Radiation through Transformation Optics and Scalar Wave Equations

    NASA Astrophysics Data System (ADS)

    Fedorov, V. Yu.; Chanal, M.; Grojo, D.; Tzortzakis, S.

    2016-07-01

    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.

  9. 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. PMID:27494473

  10. Local improvement of the signal-to-noise ratio for diffractive optical elements designed by unidirectional optimization methods

    NASA Astrophysics Data System (ADS)

    Meister, Martin; Winfield, Richard J.

    2002-12-01

    We present a straightforward method to design multilevel phase-only diffractive optical elements with a locally improved signal-to-noise ratio in the reconstruction. The method is generally applicable to all unidirectional design schemes, such as direct search, simulated annealing, or genetic optimization. As the shape and the location of the desired low noise areas are supplied by a bit map file the method allows for the design of basically any two-dimensional low noise area. The improvement in the signal-to-noise ratio that may be achieved is considerable but also entails reduced diffraction efficiency. The suggested method is applied to different beam-splitter design examples. All examples are calculated with the scalar diffraction approximation in the far field.

  11. The Optical Property of Core-Shell Nanosensors and Detection of Atrazine Based on Localized Surface Plasmon Resonance (LSPR) Sensing

    PubMed Central

    Yang, Shaobo; Wu, Tengfei; Zhao, Xinhua; Li, Xingfei; Tan, Wenbin

    2014-01-01

    Three different nanosensors with core-shell structures were fabricated by molecular self-assembly and evaporation techniques. Such closely packed nanoparticles exhibit fine optical properties which are useful for biochemical sensing. The refractive index sensitivity (RIS) of nanosensors was detected by varying the refractive index of the surrounding medium and the decay length of nanosensors was investigated using a layer-by-layer polyelectrolyte multilayer assembly. The results showed that the thickness of the Au shell plays an important role in determining the RIS and the decay length. A system based on localized surface plasmon resonances (LSPR) sensing was constructed in our study. The core-shell nanosensors can detect 10 ng/mL atrazine solutions and are suitable for pesticide residue detection. PMID:25057137

  12. The optical property of core-shell nanosensors and detection of atrazine based on localized surface plasmon resonance (LSPR) sensing.

    PubMed

    Yang, Shaobo; Wu, Tengfei; Zhao, Xinhua; Li, Xingfei; Tan, Wenbin

    2014-01-01

    Three different nanosensors with core-shell structures were fabricated by molecular self-assembly and evaporation techniques. Such closely packed nanoparticles exhibit fine optical properties which are useful for biochemical sensing. The refractive index sensitivity (RIS) of nanosensors was detected by varying the refractive index of the surrounding medium and the decay length of nanosensors was investigated using a layer-by-layer polyelectrolyte multilayer assembly. The results showed that the thickness of the Au shell plays an important role in determining the RIS and the decay length. A system based on localized surface plasmon resonances (LSPR) sensing was constructed in our study. The core-shell nanosensors can detect 10 ng/mL atrazine solutions and are suitable for pesticide residue detection. PMID:25057137

  13. 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. PMID:24562233

  14. Near-infrared optical absorption enhanced in black silicon via Ag nanoparticle-induced localized surface plasmon

    PubMed Central

    2014-01-01

    Due to the localized surface plasmon (LSP) effect induced by Ag nanoparticles inside black silicon, the optical absorption of black silicon is enhanced dramatically in near-infrared range (1,100 to 2,500 nm). The black silicon with Ag nanoparticles shows much higher absorption than black silicon fabricated by chemical etching or reactive ion etching over ultraviolet to near-infrared (UV-VIS-NIR, 250 to 2,500 nm). The maximum absorption even increased up to 93.6% in the NIR range (820 to 2,500 nm). The high absorption in NIR range makes LSP-enhanced black silicon a potential material used for NIR-sensitive optoelectronic device. PACS 78.67.Bf; 78.30.Fs; 78.40.-q; 42.70.Gi PMID:25285058

  15. Identification and localization of lamina cribrosa cells in the human optic nerve head.

    PubMed

    Tovar-Vidales, Tara; Wordinger, Robert J; Clark, Abbot F

    2016-06-01

    One of the central features of glaucoma is progressive cupping and excavation of the optic nerve head (ONH). Unmyelinated retinal ganglion cell (RGC) axons exit the eye through the ONH, which is supported by the lamina cribrosa (LC) consisting of plates of connective tissue with channels for bundles of RGC axons. The LC progressively remodels during glaucoma, but the cellular and molecular mechanisms responsible for this remodeling are poorly understood. Two major cell types have been isolated and cultured from the human ONH, which differ in their characteristics. Glial fibrillary acidic protein (GFAP) positive ONH astrocytes are the major cell type and are reactive in glaucoma. GFAP negative LC cells are the second major cell type isolated from the human ONH, and in contrast to ONH astrocytes, are α-smooth muscle actin (α-SMA) positive. Although a number of in vitro studies have been conducted with LC cells, to date there has been no direct evidence for these cells in situ in the human ONH. We used GFAP and α-SMA immunofluorescent staining of human eyes to clearly demonstrate the presence of not only ONH astrocytes within the human ONH, but also LC cells within the cribriform (e.g. laminar) plates/beams of the LC region. Both of these cell types likely play important roles in the homeostatic maintenance of the ONH and pathogenic changes that occur in primary open angle glaucoma (POAG). PMID:27167365

  16. Immunocytochemical localization of amines and GABA in the optic lobe of the butterfly, Papilio xuthus.

    PubMed

    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

  17. Cardiac-induced localized thoracic motion detected by a fiber optic sensing scheme.

    PubMed

    Allsop, Thomas; Lloyd, Glynn; Bhamber, Ranjeet S; Hadzievski, Ljupco; Halliday, Michael; Webb, David J; Bennion, Ian

    2014-01-01

    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. PMID:25393969

  18. 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.

  19. 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

  20. Noise-compensated homotopic non-local regularized reconstruction for rapid retinal optical coherence tomography image acquisitions

    PubMed Central

    2014-01-01

    Background Optical coherence tomography (OCT) is a minimally invasive imaging technique, which utilizes the spatial and temporal coherence properties of optical waves backscattered from biological material. Recent advances in tunable lasers and infrared camera technologies have enabled an increase in the OCT imaging speed by a factor of more than 100, which is important for retinal imaging where we wish to study fast physiological processes in the biological tissue. However, the high scanning rate causes proportional decrease of the detector exposure time, resulting in a reduction of the system signal-to-noise ratio (SNR). One approach to improving the image quality of OCT tomograms acquired at high speed is to compensate for the noise component in the images without compromising the sharpness of the image details. Methods In this study, we propose a novel reconstruction method for rapid OCT image acquisitions, based on a noise-compensated homotopic modified James-Stein non-local regularized optimization strategy. The performance of the algorithm was tested on a series of high resolution OCT images of the human retina acquired at different imaging rates. Results Quantitative analysis was used to evaluate the performance of the algorithm using two state-of-art denoising strategies. Results demonstrate significant SNR improvements when using our proposed approach when compared to other approaches. Conclusions A new reconstruction method based on a noise-compensated homotopic modified James-Stein non-local regularized optimization strategy was developed for the purpose of improving the quality of rapid OCT image acquisitions. Preliminary results show the proposed method shows considerable promise as a tool to improve the visualization and analysis of biological material using OCT. PMID:25319186

  1. Local SDSS galaxies in the Herschel Stripe 82 survey: a critical assessment of optically derived star formation rates

    NASA Astrophysics Data System (ADS)

    Rosario, D. J.; Mendel, J. T.; Ellison, S. L.; Lutz, D.; Trump, J. R.

    2016-04-01

    We study a set of 3319 galaxies in the redshift interval 0.04 < z < 0.15 with far-infrared (FIR) coverage from the Herschel Stripe 82 survey (HerS), and emission-line measurements, redshifts, stellar masses and star formation rates (SFRs) from the Sloan Digital Sky Survey (SDSS) (DR7) MPA/JHU data base. About 40 per cent of the sample are detected in the Herschel/SPIRE 250 μm band. Total infrared (TIR) luminosities derived from HerS and Wide-field Infrared Survey Explorer (WISE) photometry allow us to compare infrared and optical estimates of SFR with unprecedented statistics for diverse classes of galaxies. We find excellent agreement between TIR-derived and emission line-based SFRs for H II galaxies. Other classes, such as active galaxies and evolved galaxies, exhibit systematic discrepancies between optical and TIR SFRs. We demonstrate that these offsets are attributable primarily to survey biases and the large intrinsic uncertainties of the Dn4000- and colour-based optical calibrations used to estimate the SDSS SFRs of these galaxies. Using a classification scheme which expands upon popular emission-line methods, we demonstrate that emission-line galaxies with uncertain classifications include a population of massive, dusty, metal-rich star-forming systems that are frequently neglected in existing studies. We also study the capabilities of infrared selection of star-forming galaxies. FIR selection reveals a substantial population of galaxies dominated by cold dust which are missed by the long-wavelength WISE bands. Our results demonstrate that Herschel large-area surveys offer the means to construct large, relatively complete samples of local star-forming galaxies with accurate estimates of SFR that can be used to study the interplay between nuclear activity and star formation.

  2. 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.

  3. Near-field optical patterning and structuring based on local-field enhancement at the extremity of a metal tip.

    PubMed

    Royer, Pascal; Barchiesi, Dominique; Lerondel, Gilles; Bachelot, Renaud

    2004-04-15

    We present a particular approach and the associated results allowing the nanostructuration of a thin photosensitive polymer film. This approach based on a scanning near-field optical microscopy configuration uses the field-enhancement (FE) effect, a so-called lightning-rod effect appearing at the extremity of a metallic tip when illuminated with an incident light polarized along the tip axis. The local enhancement of the electromagnetic field straight below the tip's apex is observed directly through a photoisomerization reaction, inducing the growth of a topographical nanodot characterized in situ by atomic-force microscopy using the same probe. From a survey of the literature, we first review the different experimental approaches offered to nanostructure materials by near-field optical techniques. We describe more particularly the FE effect approach. An overview of the theoretical approach of this effect is then given before presenting some experimental results so as theoretical results using the finite-element method. These results show the influence on the nanostructuration of the polymer of a few experimental parameters such as the polarization state, the illumination mode and the tip's geometry. Finally, the potentiality of this technique for some applications in the field of lithography and high-density data storage is shown via the fabrication of nano-patterns. PMID:15306496

  4. Upstream vertical cavity surface-emitting lasers for fault monitoring and localization in WDM passive optical networks

    NASA Astrophysics Data System (ADS)

    Wong, Elaine; Zhao, Xiaoxue; Chang-Hasnain, Connie J.

    2008-04-01

    As wavelength division multiplexed passive optical networks (WDM-PONs) are expected to be first deployed to transport high capacity services to business customers, real-time knowledge of fiber/device faults and the location of such faults will be a necessity to guarantee reliability. Nonetheless, the added benefit of implementing fault monitoring capability should only incur minimal cost associated with upgrades to the network. In this work, we propose and experimentally demonstrate a fault monitoring and localization scheme based on a highly-sensitive and potentially low-cost monitor in conjunction with vertical cavity surface-emitting lasers (VCSELs). The VCSELs are used as upstream transmitters in the WDM-PON. The proposed scheme benefits from the high reflectivity of the top distributed Bragg reflector (DBR) mirror of optical injection-locked (OIL) VCSELs to reflect monitoring channels back to the central office for monitoring. Characterization of the fault monitor demonstrates high sensitivity, low bandwidth requirements, and potentially low output power. The added advantage of the proposed fault monitoring scheme incurs only a 0.5 dB penalty on the upstream transmissions on the existing infrastructure.

  5. Optical and physical characterization of a local evanescent array coupled biosensor: Use of evanescent field perturbations for multianalyte sensing

    PubMed Central

    Stephens, Matthew D.; Yuan, Guangwei; Lear, Kevin L.; Dandy, David S.

    2010-01-01

    The evanescent field surrounding the core of an optical waveguide is very sensitive to refractive index changes near the core. This sensitivity can be exploited to form the basis for a quantitative sensor with high specificity and sensitivity. Selective probe molecules may be attached to the surface of a waveguide core and the evanescent field locally monitored as target analytes are introduced to the system. In this study, probe/analyte regions were simulated using lithographically patterned organic films with thicknesses of 60 nm and 130 nm. The evanescent field strength was measured quantitatively using near field scanning optical microscopy (NSOM). The presence of the organic material on the waveguide caused up to a 70% change in the intensity of the evanescent field over the patterned region and the excitation of a weakly bound higher order mode. The waveguide core and surrounding cladding were numerically simulated using the beam propagation method and these predictions are in quantitative agreement with the experimental results obtained using NSOM. PMID:20436955

  6. Local oscillator free all optical OOK signal frequency up conversion enabled by injection locking of Fabry-Pérot laser

    NASA Astrophysics Data System (ADS)

    Han, Bing-chen; Yu, Jin-long; Wang, Wen-rui; Wang, Ju; Shi, Yun-long

    2014-08-01

    We demonstrate an all optical up-conversion system by injecting low bitrates baseband OOK signal directly into a conventional Fabry-Pérot laser diode (FP-LD). Radio frequency (RF) carrier is generated due to period-one (P1) oscillation state of nonlinear dynamics system (NDS) in the FP-LD with the injection of external optical signal. No extra high speed and expensive local oscillator is required for the up-conversion. Based on this approach, we experimentally achieved the up-conversion of 2 Gbps RZ-OOK baseband signal to 12 GHz and 14.28 GHz RF carriers, and 2.5 Gbps NRZ-OOK baseband signal to 10 GHz, 18.2 GHz and 20.88 GHz RF carriers respectively. The obtained 20.88 GHz RF carriers have a signal to side mode suppression ratio of 29 dB, and phase noise of -84.2 dBc/Hz@10 kHz.

  7. Non-local exchange correlation functionals impact on the structural, electronic and optical properties of III-V arsenides

    NASA Astrophysics Data System (ADS)

    Najwa Anua, N.; Ahmed, R.; Shaari, A.; Saeed, M. A.; Haq, Bakhtiar Ul; Goumri-Said, Souraya

    2013-10-01

    Exchange correlation (XC) energy functionals play a vital role in the efficiency of density functional theory (DFT) calculations, more soundly in the calculation of fundamental electronic energy bandgap. In the present DFT study of III-arsenides, we investigate the implications of XC-energy functional and corresponding potential on the structural, electronic and optical properties of XAs (X = B, Al, Ga, In). Firstly we report and discuss the optimized structural lattice parameters and the band gap calculations performed within different non-local XC functionals as implemented in the DFT-packages: WIEN2k, CASTEP and SIESTA. These packages are representative of the available code in ab initio studies. We employed the LDA, GGA-PBE, GGA-WC and mBJ-LDA using WIEN2k. In CASTEP, we employed the hybrid functional, sX-LDA. Furthermore LDA, GGA-PBE and meta-GGA were employed using SIESTA code. Our results point to GGA-WC as a more appropriate approximation for the calculations of structural parameters. However our electronic bandstructure calculations at the level of mBJ-LDA potential show considerable improvements over the other XC functionals, even the sX-LDA hybrid functional. We report also the optical properties within mBJ potential, which show a nice agreement with the experimental measurements in addition to other theoretical results.

  8. Fiber-optic system for monitoring fast photoactivation dynamics of optical highlighter fluorescent proteins

    PubMed Central

    Pei, Zhiguo; Qin, Lingsong; Zhang, Zhihong; Zeng, Shaoqun; Huang, Zhen-Li

    2011-01-01

    Characterizing the photoactivation performance of optical highlighter fluorescent proteins is crucial to the realization of photoactivation localization microscopy. In contrast to those fluorescence-based approaches that require complex data processing and calibration procedures, here we report a simple and quantitative alternative, which relies on the measurement of small absorption spectra changes over time with a fiber-optic system. Using Dronpa as a representative highlighter protein, we have investigated the capacity of this system in monitoring the fast photoactivation process. PMID:21833352

  9. Analysis of laser scribes at CIGS thin-film solar cells by localized electrical and optical measurements

    NASA Astrophysics Data System (ADS)

    Wehrmann, Anja; Puttnins, Stefan; Hartmann, Lars; Ehrhardt, Martin; Lorenz, Pierre; Zimmer, Klaus

    2012-09-01

    Laser patterning of thin-film solar cells is essential to perform external serial and integrated monolithic interconnections for module application and has recently received increasing attention. Current investigations show, however, that the efficiency of thin-film Cu(In,Ga)Se2 (CIGS) modules is reduced due to laser scribing also with ultrashort laser pulses. Hence, to investigate the reasons of the laser-induced material modifications, thin-film CIGS solar cells were laser-scribed with femto- and picosecond laser pulses using different scribing procedures and laser processing parameters. Besides standard electrical current voltage (I-V) measurements, additional electrical and optical analysis were performed such as laser beam-induced current (LBIC), dark lock-in thermography (DLIT), and electroluminescence (EL) measurements to characterize and localize electrical losses due to material removal/modifications at the scribes that effecting the electrical solar cell properties. Both localized as well as distributed shunts were found at laser scribe edges whereas the laser spot intensity distribution affecting the shunt formation. Already laser irradiation below the ablation threshold of the TCO film causes material modification inside the thin film solar cell stack resulting in shunt formation as a result of materials melting near the TCO/CIGS interface that probably induces the damage of the pn-junction.

  10. Effective Dirac equation for ultracold atoms in optical lattices: Role of the localization properties of the Wannier functions

    NASA Astrophysics Data System (ADS)

    Lopez-Gonzalez, Xabier; Sisti, Jacopo; Pettini, Giulio; Modugno, Michele

    2014-03-01

    We review the derivation of the effective Dirac equation for ultracold atoms in one-dimensional bichromatic optical lattices, following the proposal by Witthaut et al. [Phys. Rev. A 84, 033601 (2011), 10.1103/PhysRevA.84.033601]. We discuss how such a derivation—based on a suitable rotation of the Bloch basis and on a coarse-graining approximation—is affected by the choice of the Wannier functions entering the coarsening procedure. We show that in general the Wannier functions obtained by rotating the maximally localized Wannier functions for the original Bloch bands can be sufficiently localized for justifying the coarse-graining approximation. We also comment on the relation between the rotation needed to achieve the Dirac form and the standard Foldy-Wouthuysen transformation. Our results provide a solid ground for the interpretation of the experimental results by Salger et al. [Phys. Rev. Lett. 107, 240401 (2011), 10.1103/PhysRevLett.107.240401] in terms of an effective Dirac dynamics.

  11. 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

  12. Experimental realization of invisibility cloaking

    NASA Astrophysics Data System (ADS)

    Shchelokova, A. V.; Melchakova, I. V.; Slobozhanyuk, A. P.; Yankovskaya, E. A.; Simovski, C. R.; Belov, P. A.

    2015-02-01

    Advances in the studies of metamaterials have pushed the development of invisibility cloaks, which suppress scattering by objects within certain frequency ranges. During recent years, there has been a transition from a purely theoretical consideration of the cloaking effect to its practical implementation. This paper is an overview of the current state of the art in the area of invisibility cloaks. Special emphasis is put on experimental realizations of such devices.

  13. Demographics of galactic bulges in the local universe through optical windows

    NASA Astrophysics Data System (ADS)

    Kim, Keunho; Oh, Sree; Jeong, Hyunjin; Yi, Sukyoung

    2016-01-01

    We present our results of two-dimensional bulge-disk decompositions for 14,659 galaxies drawn from SDSS DR12 in order to examine properties of bulges residing in the local universe (0.005 < z < 0.05). We performed the decompositions in g and r-bands by utilizing GALFIT software. We have derived the color of bulges and found that bulge color is redder than galaxy color and most of bulges (B/T > 0.2) show almost constant (g-r) colors regardless of their size. We also investigated the scaling relations (Kormendy and Faber-Jackson relations), which ellipticals are generally known to follow, for all of our sample bulges. Specifically, we have found that low B/T (0.1

  14. High resolution magnetic resonance imaging of the anterior visual pathway in patients with optic neuropathies using fast spin echo and phased array local coils.

    PubMed Central

    Gass, A; Barker, G J; MacManus, D; Sanders, M; Riordan-Eva, P; Tofts, P S; Thorpe, J; McDonald, W I; Moseley, I F; Miller, D H

    1995-01-01

    High resolution MRI of the anterior visual pathways was evaluated using frequency selective fat suppressed fast spin echo (FSE) sequences in conjunction with phased array local coils in patients with optic neuropathies. Fifteen normal controls and 57 patients were examined. Coronal T2 weighted fat suppressed FSE images were obtained in 11 minutes with an in plane resolution of 0.39 x 0.39 mm. The optic nerve and its sheath containing CSF were clearly differentiated. Central retinal vessels were often visible. In demyelinating optic neuritis and in anterior ischaemic optic neuropathy high signal within the nerve was readily delineated. Meningiomas and gliomas involving the optic nerve were precisely visualised both in the orbit and intracranially. Extrinsic compression of the optic nerves was readily visualised in carotid artery ectasia and dysthyroid eye disease. Enlarged subarachnoid spaces around the optic nerves were demonstrated in benign intracranial hypertension. High resolution MRI of the anterior visual pathway represents an advance in the diagnosis and management of patients presenting with optic neuropathy. Images PMID:7745403

  15. 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

  16. Bloch oscillation, dynamical localization, and optical probing of electron gases in quantum-dot superlattices in high electric fields

    NASA Astrophysics Data System (ADS)

    Huang, Danhong; Lyo, S. K.; Gumbs, Godfrey

    2009-04-01

    In this paper, we present numerical results for steady-state and time-dependent currents as well as for a long-time average current in strong nonlinear dc and ac electric fields for an electron gas in a one-dimensional (1D) quantum-dot superlattice. A microscopic model is employed for the scattering of electrons by phonons and static impurities by means of the Boltzmann equation method. The dc results are favorably compared with recent exact analytic results based on a relaxation-time model for electron-phonon scattering. Our results demonstrate the different roles played by elastic and inelastic scattering on the damped Bloch oscillations as well as the nonlinear steady-state current and their opposite roles on the damped dynamical localization. We also find a suppression of dynamical localization by strong Bloch oscillations and features in the Esaki-Tsu peaks in the presence of an ac electric field when electron scattering is included. On the basis of a nonequilibrium electron distribution obtained from the Boltzmann equation, a self-consistent-field approach is employed to establish a general formalism for the optical response of current-driven electrons in both the linear and nonlinear regimes to a 1D quantum-dot superlattice. The dc-field dependences of both the peak energy and peak strength in the absorption spectrum for a 1D quantum-dot superlattice are calculated, from which we find: (1) both the peak energy and its strength are significantly reduced with increasing dc electric field; and (2) the peak energy and peak strength are anomalously enhanced by raising the temperature for the nonlinear transport of electrons when a strong dc electric field is applied.

  17. 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. PMID:26406688

  18. 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

  19. 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.

  20. Localized surface plasmon resonance of single silver nanoparticles studied by dark-field optical microscopy and spectroscopy

    PubMed Central

    Cao, Wei; Huang, Tao; Xu, Xiao-Hong Nancy; Elsayed-Ali, Hani E.

    2011-01-01

    Localized surface plasmon resonance (LSPR) of Ag nanoparticles (NPs) with different shapes and disk-shaped Ag NP pairs with varying interparticle distance is studied using dark-field optical microscopy and spectroscopy (DFOMS). Disk-, square-, and triangular-shaped Ag NPs were fabricated on indium tin oxide-coated glass substrates by electron beam lithography. The LSPR spectra collected from single Ag NPs within 5×5 arrays using DFOMS exhibited pronounced redshifts as the NP shape changed from disk to square and to triangular. The shape-dependent experimental LSPR spectra are in good agreement with simulations using the discrete dipole approximation model, although there are small deviations in the peak wavelengths for square- and triangular-shaped NPs. The LSPR spectra of disk-shaped Ag NP pairs with varying interparticle distances were acquired from five different locations across the pair axis. It was clearly observed that the LSPR wavelength redshifts as the interparticle distance decreases, indicating a strong interaction when two Ag NPs are close to each other. PMID:21383872

  1. The complete census of optically selected AGNs in the Coma supercluster: the dependence of AGN activity on the local environment

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Savorgnan, G.; Fumagalli, Mattia

    2011-10-01

    Aims: To investigate the dependence of the occurrence of active galactic nuclei (AGNs) on local galaxy density, we study the nuclear properties of ~5000 galaxies in the Coma supercluster whose density spans two orders of magnitude from the sparse filaments to the cores of rich clusters. Methods: We obtained optical spectra of the nuclei of 283 galaxies using the 1.5 m Cassini telescope of Bologna observatory. Among these galaxies, 177 belong to the Coma supercluster and are added to the 4785 spectra available from SDSS (DR7) to fill-in the incomplete coverage by SDSS of luminous galaxies. We perform a spectral classification of the nuclei of galaxies in this region (with a completeness of 98% at r ≤ 17.77), classifying the nuclear spectra in six classes: three of them (SEY, sAGN, LIN) refer to AGNs and the remaining three (HII, RET, PAS) refer to different stages of starburst activity. We perform this classification as recommended by Cid Fernandes and collaborators using the ratio of λ 6584 [NII] to Hα lines and the equivalent width of Hα (WHAN diagnostic), after correcting the last quantity by 1.3 Å for underlying absorption. Results: We find that 482 (10%) of 5027 galaxies host an AGN: their frequency strongly increases with increasing luminosity of the parent galaxies, such that 32% of galaxies with Log(Li/L⊙) ≥ 10.2 harbor an AGN at their interior. In addition to their presence in luminous galaxies, AGNs are also found in red galaxies with ⟨g - i⟩ ≃ 1.15 ± 0.15 mag. The majority of SEY and sAGN (strong AGNs) are associated with luminous late-type (or S0a) galaxies, while LIN (weak AGNs) and RET ("retired": nuclei that have experienced a starburst phase in the past and are now ionized by their hot evolved low-mass stars), are mostly found among E/S0as. The number density of AGNs, HII region-like, and retired galaxies is found to anti-correlate with the local density of galaxies, such that their frequency drops by a factor of two near the cluster

  2. Fabrication of fiber-optic localized surface plasmon resonance sensor and its application to detect antibody-antigen reaction of interferon-gamma

    NASA Astrophysics Data System (ADS)

    Jeong, Hyeon-Ho; Erdene, Norov; Lee, Seung-Ki; Jeong, Dae-Hong; Park, Jae-Hyoung

    2011-12-01

    A fiber-optic localized surface plasmon (FO LSPR) sensor was fabricated by gold nanoparticles (Au NPs) immobilized on the end-face of an optical fiber. When Au NPs were formed on the end-face of an optical fiber by chemical reaction, Au NPs aggregation occurred and the Au NPs were immobilized in various forms such as monomers, dimers, trimers, etc. The component ratio of the Au NPs on the end-face of the fabricated FO LSPR sensor was slightly changed whenever the sensors were fabricated in the same condition. Including this phenomenon, the FO LSPR sensor was fabricated with high sensitivity by controlling the density of Au NPs. Also, the fabricated sensors were measured for the resonance intensity for the different optical systems and analyzed for the effect on sensitivity. Finally, for application as a biosensor, the sensor was used for detecting the antibody-antigen reaction of interferon-gamma.

  3. Rashba realization: Raman with RF

    NASA Astrophysics Data System (ADS)

    Campbell, D. L.; Spielman, I. B.

    2016-03-01

    We theoretically explore a Rashba spin–orbit coupling scheme which operates entirely in the absolute ground state manifold of an alkali atom, thereby minimizing all inelastic processes. An energy gap between ground eigenstates of the proposed coupling can be continuously opened or closed by modifying laser polarizations. Our technique uses far-detuned ‘Raman’ laser coupling to create the Rashba potential, which has the benefit of low spontaneous emission rates. At these detunings, the Raman matrix elements that link m F magnetic sublevel quantum numbers separated by two are also suppressed. These matrix elements are necessary to produce the Rashba Hamiltonian within a single total angular momentum f manifold. However, the far-detuned Raman couplings can link the three XYZ states familiar to quantum chemistry, which possess the necessary connectivity to realize the Rashba potential. We show that these XYZ states are essentially the hyperfine spin eigenstates of {}87{Rb} dressed by a strong radio-frequency magnetic field.

  4. 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. PMID:26399220

  5. Realization of the topological Haldane model

    NASA Astrophysics Data System (ADS)

    Desbuquois, Rémi

    2015-03-01

    A topologically non-trivial band structure appears in a hexagonal lattice if time-reversal symmetry is broken, as suggested by F. D. M. Haldane. He further pointed out that, in combination with broken inversion symmetry, this gives rise to a phase diagram containing topologically distinct phases, yet without the necessity of a magnetic field. Studying the band structure of a hexagonal lattice with broken time reversal symmetry induced by complex valued next-nearest neighbor couplings, he showed that the boundaries of the topologically different phases are gap opening-and-closing transitions at the Dirac points. Whilst a realization of this model in a material was hardly conceivable, it provided the conceptual basis for other topological insulators and the quantum spin Hall effect. Prospects to realize the model with cold atoms emerged by advances in generating effective magnetic fields for neutral atoms and the idea to employ time-dependent fields to break time-reversal symmetry in a hexagonal lattice. Here we report on the implementation of the Haldane model in a periodically driven honeycomb optical lattice and the characterization of the topological Bloch bands using non-interacting fermionic atoms. Modulating the position of the lattice sites along a circular trajectory generates complex next-nearest-neighbor tunneling and a gap opens at the Dirac points, which we measure using momentum-resolved inter-band transitions. In analogy to a Hall conductance we observe a characteristic displacements of the atomic cloud under a constant force. By additionally breaking the inversion-symmetry, we identify the closing of the gap at an individual Dirac point, associated with the transition between the topologically distinct phases, obtaining good agreement with the calculated phase diagram. Whilst the physics of the non-interacting system is determined by the single-particle band structure, as studied in this work, the cold atom systems is also suited to explore the

  6. Low-threshold optical bistability with multilayer graphene-covering Otto configuration

    NASA Astrophysics Data System (ADS)

    Wang, Hengliang; Wu, Jipeng; Guo, Jun; Jiang, Leyong; Xiang, Yuanjiang; Wen, Shuangchun

    2016-06-01

    In this paper, we propose a modified Otto configuration to realize tunable and low-threshold optical bistability at terahertz frequencies by attaching multilayer graphene sheets to a nonlinear substrate interface. Our work demonstrates that the threshold of optical bistability can be markedly reduced (three orders of magnitude) by covering the nonlinear substrate with multilayer graphene sheets, due to strong local field enhancement with the excitation of surface plasmons. We present the influences of the Fermi energy of graphene, the incident angle, the thickness of air gap and the relaxation time of graphene on the hysteresis phenomenon and give a way to optimize the surface plasmon resonance, which will enable us to further lower the minimal power requirements for realizing optical bistability due to the strong interaction of light with graphene sheets. These results are promising for realization of terahertz optical switches, optical modulators and logical devices.

  7. Strong and Coherent Coupling between Localized and Propagating Phonon Polaritons.

    PubMed

    Gubbin, Christopher R; Martini, Francesco; Politi, Alberto; Maier, Stefan A; De Liberato, Simone

    2016-06-17

    Following the recent observation of localized phonon polaritons in user-defined silicon carbide nanoresonators, here we demonstrate strong and coherent coupling between those localized modes and propagating phonon polaritons bound to the surface of the nanoresonator's substrate. In order to obtain phase matching, the nanoresonators have been fabricated to serve the double function of hosting the localized modes, while also acting as a grating for the propagating ones. The coherent coupling between long lived, optically accessible localized modes, and low-loss propagative ones, opens the way to the design and realization of phonon-polariton based coherent circuits. PMID:27367398

  8. Strong and Coherent Coupling between Localized and Propagating Phonon Polaritons

    NASA Astrophysics Data System (ADS)

    Gubbin, Christopher R.; Martini, Francesco; Politi, Alberto; Maier, Stefan A.; De Liberato, Simone

    2016-06-01

    Following the recent observation of localized phonon polaritons in user-defined silicon carbide nanoresonators, here we demonstrate strong and coherent coupling between those localized modes and propagating phonon polaritons bound to the surface of the nanoresonator's substrate. In order to obtain phase matching, the nanoresonators have been fabricated to serve the double function of hosting the localized modes, while also acting as a grating for the propagating ones. The coherent coupling between long lived, optically accessible localized modes, and low-loss propagative ones, opens the way to the design and realization of phonon-polariton based coherent circuits.

  9. Hybrid plasmonic lattices with tunable magneto-optical activity.

    PubMed

    Kataja, Mikko; Pourjamal, Sara; Maccaferri, Nicolò; Vavassori, Paolo; Hakala, Tommi K; Huttunen, Mikko J; Törmä, Päivi; van Dijken, Sebastiaan

    2016-02-22

    We report on the optical and magneto-optical response of hybrid plasmonic lattices that consist of pure nickel and gold nanoparticles in a checkerboard arrangement. Diffractive far-field coupling between the individual emitters of the lattices results in the excitation of two orthogonal surface lattice resonance modes. Local analyses of the radiation fields indicate that both the nickel and gold nanoparticles contribute to these collective resonances and, thereby, to the magneto-optical activity of the hybrid arrays. The strong effect of noble metal nanoparticles on the magneto-optical response of hybrid lattices opens up new avenues for the realization of sensitive and tunable magneto-plasmonic nanostructures. PMID:26907022

  10. A High-Spatial-Resolution, Localized MODIS Aerosol Optical Depth Product for Use in Air Quality Exposure Assessment During Large Wildfire Smoke Events

    NASA Astrophysics Data System (ADS)

    McCarthy, M. C.; Raffuse, S. M.; DeWinter, J. L.; Craig, K. J.; Jumbam, L. K.; Fruin, S.; Lurmann, F.

    2011-12-01

    Aerosol optical depth (AOD) has potential use for determining the intra-urban variability of airborne particulate matter exposure during wildfire events; however, the standard Moderate Resolution Imaging Spectroradiometer (MODIS) AOD products have limitations for this application. Specifically, the 10x10 km resolution is too coarse for intra-urban population exposure assessments, the assumed aerosol optical properties are not representative of biomass burning aerosol, and the cloud masking algorithm misinterprets heavy smoke as clouds. We developed a localized MODIS AOD product at 1.5 and 2.5 km resolutions and tested the performance in northern California during the 2008 wildfires. The localized product's algorithm uses local biomass burning aerosol optical properties, local surface reflectance data, and a relaxed cloud filter. During the 2008 season, persistent heavy smoke was produced over northern California and the San Joaquin Valley for over two months. As California is both highly populated and covered with a relatively dense network of ground-based aerosol monitoring stations, this event provided an excellent opportunity to develop the AOD product and test its ability to predict aerosol concentrations on the ground to assess population exposure. We will present our methodology and discuss its potential for air quality and public health applications.

  11. 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.

  12. Statistical signatures of photon localization

    PubMed

    Chabanov; Stoytchev; Genack

    2000-04-20

    The realization that electron localization in disordered systems (Anderson localization) is ultimately a wave phenomenon has led to the suggestion that photons could be similarly localized by disorder. This conjecture attracted wide interest because the differences between photons and electrons--in their interactions, spin statistics, and methods of injection and detection--may open a new realm of optical and microwave phenomena, and allow a detailed study of the Anderson localization transition undisturbed by the Coulomb interaction. To date, claims of three-dimensional photon localization have been based on observations of the exponential decay of the electromagnetic wave as it propagates through the disordered medium. But these reports have come under close scrutiny because of the possibility that the decay observed may be due to residual absorption, and because absorption itself may suppress localization. Here we show that the extent of photon localization can be determined by a different approach--measurement of the relative size of fluctuations of certain transmission quantities. The variance of relative fluctuations accurately reflects the extent of localization, even in the presence of absorption. Using this approach, we demonstrate photon localization in both weakly and strongly scattering quasi-one-dimensional dielectric samples and in periodic metallic wire meshes containing metallic scatterers, while ruling it out in three-dimensional mixtures of aluminium spheres. PMID:10786786

  13. 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

  14. Experimental realization of an achromatic magnetic mirror based on metamaterials.

    PubMed

    Pisano, Giampaolo; Ade, Peter A R; Tucker, Carole

    2016-06-20

    Our work relates to the use of metamaterials engineered to realize a metasurface approaching the exotic properties of an ideal object not observed in nature, a "magnetic mirror." Previous realizations were based on resonant structures that implied narrow bandwidths and large losses. The working principle of our device is ideally frequency-independent, it does not involve resonances and it does not rely on a specific technology. The performance of our prototype, working at millimeter wavelengths, has never been achieved before and it is superior to any other device reported in the literature, both in the microwave and optical regions. The device inherently has large bandwidth (144%), low losses (<1%), and is almost independent of incidence angle and polarization state, and thus approaches the behavior of an ideal magnetic mirror. Applications of magnetic mirrors range from low-profile antennas, absorbers to optoelectronic devices. Our device can be realized using different technologies to operate in other spectral regions. PMID:27409104

  15. Rashba realization: Raman with RF

    PubMed Central

    Campbell, D L; Spielman, I B

    2016-01-01

    We theoretically explore a Rashba spin–orbit coupling scheme which operates entirely in the absolute ground state manifold of an alkali atom, thereby minimizing all inelastic processes. An energy gap between ground eigenstates of the proposed coupling can be continuously opened or closed by modifying laser polarizations. Our technique uses far-detuned ‘Raman’ laser coupling to create the Rashba potential, which has the benefit of low spontaneous emission rates. At these detunings, the Raman matrix elements that link mF magnetic sublevel quantum numbers separated by two are also suppressed. These matrix elements are necessary to produce the Rashba Hamiltonian within a single total angular momentum f manifold. However, the far-detuned Raman couplings can link the three XYZ states familiar to quantum chemistry, which possess the necessary connectivity to realize the Rashba potential. We show that these XYZ states are essentially the hyperfine spin eigenstates of 87Rb dressed by a strong radio-frequency magnetic field. PMID:27524933

  16. Realization of a cryogenic interface to an ultracold atomic chamber

    NASA Astrophysics Data System (ADS)

    Date, Aditya; Wang, Ke; Shaffer, Airlia; Patil, Yogesh Sharad; Schwab, Keith; Vengalattore, Mukund

    2016-05-01

    The control and manipulation of ultracold atoms in close proximity to cryogenic material surfaces opens up novel avenues for quantum sensing with cold atoms. However, integrating cryogenics with cold atomic systems presents the dual challenges of reducing thermal radiation load while allowing optimal optical access. Here, we present the realization of a unique interface between a cryogenic system and a room-temperature ultracold atomic chamber which allows for the optical trapping of cold atoms within microns of a sub-10 K cryogenic surface. Our interface serves as a platform for a cold-atoms based precision magnetic microscope for probing exotic condensed matter systems such as correlated electronic materials, as well as a platform for the realization of hybrid quantum systems. This work is supported by the DARPA QuASAR program through a grant from the ARO.

  17. Optical and spin properties of localized and free excitons in GaBi x As1‑x /GaAs multiple quantum wells

    NASA Astrophysics Data System (ADS)

    Balanta, M. A. G.; Kopaczek, J.; Orsi Gordo, V.; Santos, B. H. B.; Rodrigues, A. D.; Galeti, H. V. A.; Richards, R. D.; Bastiman, F.; David, J. P. R.; Kudrawiec, R.; Galvão Gobato, Y.

    2016-09-01

    Raman spectroscopy and magneto-photoluminescence measurements under high magnetic fields were used to investigate the optical and spin properties of GaBiAs/GaAs multiple quantum wells (MQWs). An anomalous negative diamagnetic energy shift was observed at higher temperatures and higher laser intensities, which was associated to a sign inversion of hole effective mass in these structures. In addition, an enhancement of the polarization degree with decreasing of laser intensity was observed (experimental condition where the emission is dominated by localized excitons). This effect was explained by changes of spin relaxation and exciton recombination times due to exciton localization by disorder.

  18. 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. PMID:27367051

  19. 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

  20. 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.

  1. 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.

  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). PMID:25321291

  3. Homogeneous Thermal Cloak with Constant Conductivity and Tunable Heat Localization

    PubMed Central

    Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei

    2013-01-01

    Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons. PMID:23549139

  4. Homogeneous thermal cloak with constant conductivity and tunable heat localization.

    PubMed

    Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei

    2013-01-01

    Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons. PMID:23549139

  5. Calculation of local optical properties in highly scattering media using a-priori structural information for application to simultaneous NIR-MR breast examination

    NASA Astrophysics Data System (ADS)

    Ntziachristos, Vasilis; Yodh, Arjun G.; Schnall, Mitchell D.; Ma, XuHui; Chance, Britton

    1998-12-01

    A single photon counting NIR imager designed to work simultaneously with an MRI scanner for concurrent NIR-MR mammography has recently been developed. The combination of imaging modalities aims in effectively investigating the competence of optical imaging as a stand along modality and as an MRI add-on in order to increase the sensitivity and specificity of the mammoraphic examination. In this work we focus on the second aim. We present the methodology developed to employ the MR anatomical information in order to simplify the forward problem and accurately calculate local tissue optical properties, by fitting the NIR data to this model. Derivation of local optical properties due to intrinsic or extrinsic may identify the existence of malignant and benign breast tissue NIR signatures. We have evaluated the performance of the solver with experimental measurements, also presented here, from models with known absorption perturbations. The average quantification error of absolute absorption of local lesions has been found to be less than 10% in simple models and algorithm convergence is always ensured.

  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. Optical chiral metamaterial based on the resonant behaviour of nanodiscs

    NASA Astrophysics Data System (ADS)

    Kordi, Mahdi; Mojtaba Mirsalehi, Mir

    2016-08-01

    Circular dichorism and optical activity have been achieved by chiral metamaterials in the optical spectrum, but for the case of negative index of refraction, remarkable achievements have not been obtained in this region so far. We employ nanoparticles to shift the resonant frequency of a chiral metamaterial based on twisted cross wires to optical domain. Our proposed structure provides giant optical activity, strong circular dichorism and also negative refractive index in the optical wavelengths. Optical activity in our structure has a rotary power similar to a gyrotropic crystal of quartz, but in a thickness which is four orders of magnitude smaller. The foundation of our method for realizing such an optical chiral metamaterial is based on creating a different coupling between longitudinal modes of localized surface plasmons for right and left circularly polarized incident waves.

  8. Realization of quantitative-grade fieldable snapshot imaging spectropolarimeter.

    PubMed

    Jones, Stephen; Iannarilli, Frank; Kebabian, Paul

    2004-12-27

    We discuss achievement of a long-standing technology goal: the first practical realization of a quantitative-grade, field-worthy snapshot imaging spectropolarimeter. The instrument employs Polarimetric Spectral Intensity Modulation (PSIM), a technique that enables full Stokes instantaneous "snapshot" spectropolarimetry with perfect channel registration. This is achieved with conventional single beam optics and a single focal plane array (FPA). Simultaneity and perfect registration are obtained by encoding the polarimetry onto the spectrum via a novel optical arrangement which enables sensing from moving platforms against dynamic scenes. PSIM is feasible across the electro-optical sensing range (UV-LWIR). We present measurement results from a prototype sensor that operates in the visible and near infrared regime (450-900 nm). We discuss in some detail the calibration and Stokes spectrum inversion algorithms that are presently achieving 0.5% polarimetric accuracy. PMID:19488307

  9. Realization of quantitative-grade fieldable snapshot imaging spectropolarimeter

    NASA Astrophysics Data System (ADS)

    Jones, Stephen H.; Iannarilli, Frank J.; Kebabian, Paul L.

    2004-12-01

    We discuss achievement of a long-standing technology goal: the first practical realization of a quantitative-grade, field-worthy snapshot imaging spectropolarimeter. The instrument employs Polarimetric Spectral Intensity Modulation (PSIM), a technique that enables full Stokes instantaneous "snapshot" spectropolarimetry with perfect channel registration. This is achieved with conventional single beam optics and a single focal plane array (FPA). Simultaneity and perfect registration are obtained by encoding the polarimetry onto the spectrum via a novel optical arrangement which enables sensing from moving platforms against dynamic scenes. PSIM is feasible across the electro-optical sensing range (UV-LWIR). We present measurement results from a prototype sensor that operates in the visible and near infrared regime (450-900 nm). We discuss in some detail the calibration and Stokes spectrum inversion algorithms that are presently achieving 0.5% polarimetric accuracy.

  10. High-Transmission Filters for Realizing Gray-Body Radiators

    NASA Astrophysics Data System (ADS)

    Ishii, J.; Yamada, Y.

    2015-08-01

    Calibration of infrared radiation thermometers at non-unity emissivity settings is a poorly solved problem for establishment of traceability to meet user needs, for instruments with both fixed and variable emissivity setting functions. A variable-temperature gray-body radiator having a constant value of emissivity independent of both wavelength and temperature can be a perfect tool for the calibration purpose. In this paper, two types of high-transmittance optical neutral density filters, one utilizing a rotating-sector optical chopper, and another of a wire-mesh type, are shown to perform well with a precise transmittance between 90 % and 100 % in the wide infrared wavelength range. These optical filters in combination with a blackbody cavity traceable to ITS-90 can realize reliable gray-body radiation. These methods are applied successfully to several models of infrared thermometers operated in the emissivity correction mode.

  11. Monitoring of Single-Cell Responses in the Optic Tectum of Adult Zebrafish with Dextran-Coupled Calcium Dyes Delivered via Local Electroporation

    PubMed Central

    Kassing, Vanessa

    2013-01-01

    The zebrafish (Danio rerio) has become one of the major animal models for in vivo examination of sensory and neuronal computation. Similar to Xenopus tadpoles neural activity in the optic tectum, the major region controlling visually guided behavior, can be examined in zebrafish larvae by optical imaging. Prerequisites of these approaches are usually the transparency of larvae up to a certain age and the use of two-photon microscopy. This principle of fluorescence excitation was necessary to suppress crosstalk between signals from individual neurons, which is a critical issue when using membrane-permeant dyes. This makes the equipment to study neuronal processing costly and limits the approach to the study of larvae. Thus there is lack of knowledge about the properties of neurons in the optic tectum of adult animals. We established a procedure to circumvent these problems, enabling in vivo calcium imaging in the optic tectum of adult zebrafish. Following local application of dextran-coupled dyes single-neuron activity of adult zebrafish can be monitored with conventional widefield microscopy, because dye labeling remains restricted to tens of neurons or less. Among the neurons characterized with our technique we found neurons that were selective for a certain pattern orientation as well as neurons that responded in a direction-selective way to visual motion. These findings are consistent with previous studies and indicate that the functional integrity of neuronal circuits in the optic tectum of adult zebrafish is preserved with our staining technique. Overall, our protocol for in vivo calcium imaging provides a useful approach to monitor visual responses of individual neurons in the optic tectum of adult zebrafish even when only widefield microscopy is available. This approach will help to obtain valuable insight into the principles of visual computation in adult vertebrates and thus complement previous work on developing visual circuits. PMID:23667529

  12. Local mechanisms for the separation of optic flow-field components in the land crab, Cardisoma guanhumi: a role for motion parallax?

    PubMed

    Johnson, Aaron P; Barnes, W Jon P; Macauley, Martin W S

    2004-01-01

    Although a number of global mechanisms have been proposed over the years that explain how crabs might separate the rotational and translational components of their optic flow field, there has been no evidence to date that local mechanisms such as motion parallax are used in this separation. We describe here a study that takes advantage of a recently developed suite of computer-generated visual stimuli that creates a three-dimensional world surrounding the crab in which we can simulate translational and rotational optic flow. We show that, while motion parallax is not the only mechanism used in flow-field separation, it does play a role in the recognition of translational optic flow fields in that, under conditions of low overall light intensity and low contrast ratio when crabs find the distinction between rotation and translation harder, smaller eye movements occur in response to translation when motion parallax cues are present than when they are absent. Thus, motion parallax is one of many cues that crabs use to separate rotational and translational optic flow by showing compensatory eye movements to only the former. PMID:15733345

  13. 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.

  14. Point Diffraction Interferometry to Measure Local Curvatures and Caustics of Noisy Wave Fronts: Application for Determining Optical Properties of Fish Lenses

    NASA Astrophysics Data System (ADS)

    Vallmitjana, S.; Ricart, I.; Bosch, S.; Gargallo, A.; Acosta, E.

    2015-02-01

    The study of caustics is important because they contain information about the image formation properties of optical systems. In this work we use the concept of caustic as a set of focal points, and we have developed a second order approach theory to determine local slopes and curvatures of a wavefront emerging from an optical system. The method is based on the use of a point diffraction interferometer, and the analysis of the interferograms allows us to compute the focal region. Experimental results obtained with a plano-convex lens demonstrate the accuracy of the combined theoretical-experimental method here developed. Application to noisy wavefronts such as those produced by biological samples, specifically in crystalline lenses of fish eyes, are also exposed.

  15. 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. PMID:21847236

  16. Electron Spectroscopy of Single Quantum Objects To Directly Correlate the Local Structure to Their Electronic Transport and Optical Properties.

    PubMed

    Senga, Ryosuke; Pichler, Thomas; Suenaga, Kazu

    2016-06-01

    Physical property of a single quantum object is governed by its precise atomic arrangement. The direct correlation of localized physical properties with the atomic structures has been therefore strongly desired but still limited in the theoretical studies. Here, we have successfully examined the localized electronic properties of individual carbon nanotubes by means of high-resolution electron energy-loss spectroscopy combined with high-resolution transmission electron microscopy. Well-separated sharp peaks at the carbon K(1s) absorption edge and in the valence-loss spectra are obtained from a single freestanding carbon nanotube with the local chiral index and unambiguously identified as the transitions between the van Hove singularities. The spectra features clearly vary upon the different areas even in the individual carbon nanotube. Variations in interband transitions, plasmonic behaviors, and unoccupied electronic structures are clearly attributed to the local irregular atomic arrangement such as topological defect and/or elastic bond stretching. PMID:27171894

  17. Realizing Fractional Chern Insulators in Dipolar Spin Systems

    NASA Astrophysics Data System (ADS)

    Yao, N. Y.; Gorshkov, A. V.; Laumann, C. R.; Läuchli, A. M.; Ye, J.; Lukin, M. D.

    2013-05-01

    Strongly correlated quantum systems can exhibit exotic behavior controlled by topology. We predict that the ν=1/2 fractional Chern insulator arises naturally in a two-dimensional array of driven, dipolar-interacting spins. As a specific implementation, we analyze how to prepare and detect synthetic gauge potentials for the rotational excitations of ultracold polar molecules trapped in a deep optical lattice. With the motion of the molecules pinned, under certain conditions, these rotational excitations form a fractional Chern insulating state. We present a detailed experimental blueprint for its realization and demonstrate that the implementation is consistent with near-term capabilities. Prospects for the realization of such phases in solid-state dipolar systems are discussed as are their possible applications.

  18. Enhanced optical output of InGaN/GaN near-ultraviolet light-emitting diodes by localized surface plasmon of colloidal silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Hong, Sang-Hyun; Kim, Jae-Joon; Kang, Jang-Won; Jung, Yen-Sook; Kim, Dong-Yu; Yim, Sang-Youp; Park, Seong-Ju

    2015-09-01

    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. 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. PMID:26335045

  20. Correlation and Characterization of 3D Morphological Dependent Localized Surface Plasmon Resonance Spectra of Single Silver Nanoparticles Using Dark-field Optical Microscopy and Spectroscopy and AFM

    PubMed Central

    Song, Yujun; Nallathamby, Prakash D.; Huang, Tao; Elsayed-Ali, Hani E.; Xu, Xiao-Hong Nancy

    2009-01-01

    We have developed a new and effective methodology to correlate optical and AFM images of single Ag nanoparticles (NPs), allowing us to study 3D-morphological dependent localized surface plasmon resonance (LSPR) spectra of individual Ag NPs. We fabricated arrays of distinctive microwindows on glass coverslips using photo-lithography method, and created well-isolated individual Ag NPs with a wide variety of shapes and morphologies on the glass coverslips using a modified nanosphere lithography method (NSL). Using distinctive geometries of microwindows, we located individual Ag NPs of interest in their optical and AFM images, enabling us to correlate and characterize the LSPR spectra and 3D morphologies of the same single NPs using dark-field optical microscopy and spectroscopy (DFOMS) and AFM, respectively. We found that LSPR spectra of single Ag NPs, with nearly equal volume [(8.6 ± 0.4) × 103 nm3], cross-section [(2.2 ± 0.2) × 102 nm3], and height (39.6 ± 3.6 nm), highly depend on their shapes, showing the red shift of peak wavelength to 629 nm (quasi trapezoidal cylindrical NP) from that of 506 nm (quasi circular cylindrical NP). LSPR spectra of single Ag NPs simulated using discrete dipole approximation (DDA) agree well with those measured experimentally when their shapes and morphologies can be accuractely described in both methods, but differ when they are not. Furthermore, we found location-dependent LSPR spectra on and around a single NP, offering a unique opportunity to characterize multi-mode plasmonic NPs at nanometer resolution for better understanding their plasmonic optical properties and for rational design of single NP optics. PMID:20190865

  1. 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

  2. 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. PMID:26421547

  3. 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

  4. 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

  5. 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

  6. Optical Flow-Based Tracking of Needles and Needle-Tip Localization Using Circular Hough Transform in Ultrasound Images.

    PubMed

    Ayvali, Elif; Desai, Jaydev P

    2015-08-01

    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

  7. Nanostructuring an erbium local environment inside sol-gel silica glasses: toward efficient erbium optical fiber lasers

    NASA Astrophysics Data System (ADS)

    Savelii, Inna; El Hamzaoui, Hicham; Bigot, Laurent; Bouwmans, Géraud; Fsaifes, Ihsan; Capoen, Bruno; Bouazaoui, Mohamed

    2016-02-01

    To extend the use of erbium- (Er-)/aluminum- (Al-) codoped optical fibers in hostile environments, the reduction of the Al amount has been identified as a serious way to harden them against harsh radiation. In this work, sol-gel monolithic Er3+-doped and Er3+/Al3+-codoped silica glasses were prepared from nanoporous silica xerogels soaked in a solution containing an Er salt together or not with an Al salt. After sintering, these glasses were used as the core material of microstructured optical fibers made by the stack-and-draw method. The influence of Al incorporation on the optical properties of Er3+-doped silica glasses and fibers is investigated. This approach enabled the preparation of silica glasses containing dispersed Er3+ ions with low Al content. The obtained fibers have been tested in an all-fibered cavity laser architecture. The Er3+/Al3+-codoped fiber laser presents a maximum efficiency of 27% at 1530 nm. We show that without Al doping, the laser exhibits lower performances that depend on Er content inside the doped fiber core. The effect of Er pair-induced quenching also has been investigated through nonsaturable absorption experiments, which clearly indicate that the fraction of Er ion pairs is significantly reduced in the Al-codoped fiber.

  8. Cloud scattering optical depth and local surface albedo in the Antarctic: Simultaneous retrieval using ground-based radiometry

    NASA Astrophysics Data System (ADS)

    Ricchiazzi, Paul; Gautier, Catherine; Lubin, Dan

    1995-10-01

    We have used solar irradiance measurements from a ground-based multichannel radiometer system deployed at Palmer Station, Antarctica (64°46'S, 64°04'W), during spring 1991 to simultaneously estimate cloud scattering optical depth and surface albedo. Irradiance measurements at 410 and 630 nm, in conjunction with a discrete ordinate radiative transfer (RT) model, enable this simultaneous retrieval by exploiting the wavelength dependence in Rayleigh scattering strength. The RT model is used in an inverse mode to find the values of surface albedo and cloud optical depth that match calculated and measured irradiances at both wavelengths. Under the homogeneous stratiform cloud cover for which the technique applies, surface albedo at 630 nm was consistently retrieved at above 0.9. For most homogeneous, overcast conditions, cloud optical depth (at 630 nm) is found to be in the range 20-50, with a most probable value of 25. This measurement and retrieval technique should be useful for compiling high-latitude cloud opacity and surface albedo climatologies of interest for global change and photobiology research.

  9. Experimental realization of a photonic Bell-state analyzer

    SciTech Connect

    Walther, Philip; Zeilinger, Anton

    2005-07-15

    Efficient teleportation is a crucial step for quantum computation and quantum networking. In the case of qubits, four different entangled Bell states have to be distinguished. We have realized a probabilistic, but in principle deterministic, Bell-state analyzer for two photonic quantum bits by the use of a nondestructive controlled-NOT gate based on entirely linear optical elements. This gate was capable of distinguishing between all of the Bell states with higher than 75% fidelity without any noise substraction due to utilizing quantum interference effects.

  10. Stochastic realization approach to the efficient simulation of phase screens.

    PubMed

    Beghi, Alessandro; Cenedese, Angelo; Masiero, Andrea

    2008-02-01

    The phase screen method is a well-established approach to take into account the effects of atmospheric turbulence in astronomical seeing. This is of key importance in designing adaptive optics for new-generation telescopes, in particular in view of applications such as exoplanet detection or long-exposure spectroscopy. We present an innovative approach to simulate turbulent phase that is based on stochastic realization theory. The method shows appealing properties in terms of both accuracy in reconstructing the structure function and compactness of the representation. PMID:18246185

  11. In-flight fiber optic acoustic emission sensor (FAESense) system for the real time detection, localization, and classification of damage in composite aircraft structures

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian

    2013-05-01

    Acoustic emission sensing is a leading structural health monitoring technique use for the early warning detection of structural damage associated with impacts, cracks, fracture, and delaminations in advanced materials. Current AE systems based on electronic PZT transducers suffer from various limitations that prevent its wide dynamic use in practical avionics and aerospace applications where weight, size and power are critical for operation. This paper describes progress towards the development of a wireless in-flight distributed fiber optic acoustic emission monitoring system (FAESense™) suitable for the onboard-unattended detection, localization, and classification of damage in avionics and aerospace structures. Fiber optic AE sensors offer significant advantages over its counterpart electronic AE sensors by using a high-density array of micron-size AE transducers distributed and multiplex over long lengths of a standard single mode optical fiber. Immediate SHM applications are found in commercial and military aircraft, helicopters, spacecraft, wind mil turbine blades, and in next generation weapon systems, as well as in the petrochemical and aerospace industries, civil structures, power utilities, and a wide spectrum of other applications.

  12. 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.

  13. Researchers Realize Major Breakthrough in Understanding Endometriosis

    MedlinePlus

    ... 16, 2014 Researchers Realize Major Breakthrough in Understanding Endometriosis Contact Jessica Meade nibibpress@mail.nih.gov 301- ... 10% of women, surprisingly little is known about endometriosis — a disorder that causes uterine tissue to grow ...

  14. 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.

  15. 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.

  16. Methods for investigating the local spatial anisotropy and the preferred orientation of cones in adaptive optics retinal images.

    PubMed

    Cooper, Robert F; Lombardo, Marco; Carroll, Joseph; Sloan, Kenneth R; Lombardo, Giuseppe

    2016-01-01

    The ability to noninvasively 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 and newly-developed (Fourier- and Radon-based) methods of measuring cone orientation in simulated and real images of the parafoveal cone mosaic. The proposed algorithms correlated well across both simulated and real mosaics, suggesting that each algorithm provides an accurate description of photoreceptor orientation. Despite 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 the cone coordinate reliability was excellent, the method previously described by Pum and colleagues 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

  17. Feasibility study of the automated detection and localization of underground tunnel excavation using Brillouin optical time domain reflectometer

    NASA Astrophysics Data System (ADS)

    Klar, Assaf; Linker, Raphael

    2009-05-01

    Cross-borders smuggling tunnels enable unmonitored movement of people, drugs and weapons and pose a very serious threat to homeland security. Recent advances in strain measurements using optical fibers allow the development of smart underground security fences that could detect the excavation of smuggling tunnels. This paper presents the first stages in the development of such a fence using Brillouin Optical Time Domain Reflectometry (BOTDR). In the simulation study, two different ground displacement models are used in order to evaluate the robustness of the system against imperfect modeling. In both cases, soil-fiber interaction is considered. Measurement errors, and surface disturbances (obtained from a field test) are also included in the calibration and validation stages of the system. The proposed detection system is based on wavelet decomposition of the BOTDR signal, followed by a neural network that is trained to recognize the tunnel signature in the wavelet coefficients. The results indicate that the proposed system is capable of detecting even small tunnel (0.5m diameter) as deep as 20 meter.

  18. Local Ensemble Transform Kalman Filter: a non stationary control law for complex adaptive optics systems on ELTs

    NASA Astrophysics Data System (ADS)

    Gray, Morgan; Petit, Cyril; Rodionov, Sergey; Bertino, Laurent; Bocquet, Marc; Fusco, Thierry

    2013-12-01

    We propose a new algorithm for an AO control law which allows to reduce the computation burden in the case of an Extremely Large Telescope and to deal with a non stationary behavior of the atmospheric turbulence. This approach uses Ensemble Transform Kalman Filter (ETKF) and localizations by domains decomposition: the assimilation is split into local domains on the pupil of the telescope and each of the update data assimilation for each domain is performed independently. This kind of assimilation enables parallel computation of much less data during the update stage. This is a Kalman Filter adaptation for large scale systems with a non stationary turbulence when the explicit storage and manipulation of extremely large covariance matrices are impossible. This distributed parallel environment implementation is highlighted and studied in the context of an ELT application. First simulation results are proposed to assess our theoretical analysis and to demonstrate the potentiality of this new approach for an AO control law on ELTs.

  19. In-situ Visualization and Two Dimensional Mapping of Local Electric Field at Probe Apex Using Scanning Electron Optical System

    NASA Astrophysics Data System (ADS)

    Fujita, Jun-ichi; Ikeda, Yuta; Suzuki, Ikumi

    2009-06-01

    We demonstrate an in-situ visualization of electric field distribution and the two-dimensional (2D) mapping of a local field by using a conventional scanning electron microscopy (SEM) system combined with a grid detector. The deflection of the primary electron that obeys Rutherford scattering projects a cross grid shape to a shadow constructed by concentric rings and radial spokes that appear to superimpose immediately behind the conventional SEM image. The correlation of the beam scanning position with the deflection position gives the true local field intensity, and thus, the 2D electric field distribution is obtained. The resulting 2D field distribution agrees well with the field element method (FEM) simulation.

  20. Phase conjugation used as a test of the local and nonlocal characteristics of optical nonlinearities in microemulsions.

    PubMed

    Freysz, E; Laffon, E; Ducasse, A

    1991-11-01

    We report what are to our knowledge the first degenerate four-wave mixing experiments in microemulsions using a cw argon laser. The static and dynamic behavior of the reflectivity of both induced gratings is quantitatively analyzed. The conjugated signal dependence on the angle between the pump and probe waves is used to separate the local electrostrictive and the nonlocal thermodiffusive nonlinear processes, which are both efficient in the studied microemulsion. PMID:19784095

  1. 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.

  2. Optical Coherence Tomography Noise Reduction Using Anisotropic Local Bivariate Gaussian Mixture Prior in 3D Complex Wavelet Domain

    PubMed Central

    Sonka, Milan; Abramoff, Michael D.

    2013-01-01

    In this paper, MMSE estimator is employed for noise-free 3D OCT data recovery in 3D complex wavelet domain. Since the proposed distribution for noise-free data plays a key role in the performance of MMSE estimator, a priori distribution for the pdf of noise-free 3D complex wavelet coefficients is proposed which is able to model the main statistical properties of wavelets. We model the coefficients with a mixture of two bivariate Gaussian pdfs with local parameters which are able to capture the heavy-tailed property and inter- and intrascale dependencies of coefficients. In addition, based on the special structure of OCT images, we use an anisotropic windowing procedure for local parameters estimation that results in visual quality improvement. On this base, several OCT despeckling algorithms are obtained based on using Gaussian/two-sided Rayleigh noise distribution and homomorphic/nonhomomorphic model. In order to evaluate the performance of the proposed algorithm, we use 156 selected ROIs from 650 × 512 × 128 OCT dataset in the presence of wet AMD pathology. Our simulations show that the best MMSE estimator using local bivariate mixture prior is for the nonhomomorphic model in the presence of Gaussian noise which results in an improvement of 7.8 ± 1.7 in CNR. PMID:24222760

  3. Periodic and aperiodic liquid crystal-polymer composite structures realized via spatial light modulator direct holography.

    PubMed

    Infusino, M; De Luca, A; Barna, V; Caputo, R; Umeton, C

    2012-10-01

    In this work we present the first realization and characterization of two-dimensional periodic and aperiodic POLICRYPS (Polymer Liquid Crystal Polymer Slices) structures, obtained by means of a single-beam holographic technique exploiting a high resolution spatial light modulator (SLM). A first investigation shows that the gratings, operating in the Raman Nath regime, exhibit a morphology and a electro-optical behavior that are typical of the POLICRYPS gratings realized by two-beam interference holography. PMID:23188278

  4. Realization rates of the National Energy Audit

    SciTech Connect

    Berry, L.G.; Gettings, M.B.

    1998-11-01

    Engineering estimates of savings resulting from installation of energy conservation measures in homes are often greater than the savings actually realized. A brief review of prior studies of realization rates prefaces this study of rates from an engineering audit tool, NEAT, (developed for the Department of Energy`s Low-Income Weatherization Assistance Program) used in a New York state utility`s low-income program. Estimates of metered and predicted savings are compared for 49 homes taken from a data base of homes that participated in the first year of the utility`s program. Average realization rates ranging from 57% to 69% result, depending on the data quality. Detailed examinations of two houses using an alternate engineering method, the DOE-2 computer program (considered an industry standard), seem to indicate that the low realization rates mainly result from factors other than inaccuracies in the audit`s internal algorithms. Causes of the low realization rates are examined, showing that the strongest single factor linked to the low rates in this study is the use of secondary heating fuels that supplement the primary heating fuel. This study, like the other similar studies, concludes that engineering estimates are valuable tools in determining ranked lists of cost-effective weatherization measures, but may not be accurate substitutes for measured results in evaluating program performance.

  5. Nonlinear optical vibrations of single-walled carbon nanotubes. 1. Energy exchange and localization of low-frequency oscillations

    NASA Astrophysics Data System (ADS)

    Smirnov, V. V.; Manevitch, L. I.; Strozzi, M.; Pellicano, F.

    2016-06-01

    We present the results of analytical study and molecular dynamics simulation of low energy nonlinear non-stationary dynamics of single-walled carbon nanotubes (CNTs). New phenomena of intense energy exchange between different parts of CNT and weak energy localization in the excited part of CNT are analytically predicted in the framework of the continuum shell theory. Their origin is clarified by means of the concept of Limiting Phase Trajectory, and the analytical results are confirmed by the molecular dynamics simulation of simply supported CNTs.

  6. 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.

  7. A novel method to couple light into an optical fiber avoiding fiber optic connectors

    NASA Astrophysics Data System (ADS)

    Maggi, Luca; Delrosso, Giovanni

    2008-04-01

    We present a new method for realizing optical connections to multi mode fiber, which eliminates the need for standard connectors. With such a device the fiber termination can be avoided, so that dramatically reducing the cost of installation of an optical network. Moreover the optical connection can be carry out by not specialized personnel. Its main application is in the new deployment of the local area networks (LAN) and the emerging market of the home area networks (HAN). The basic idea is to use advantageously the principle of bending losses for extracting signal from multimode fiber. Conversely the same effect can be used for inserting light into fiber without the need of connector or even without any controlled splicing and polishing operation. Studying the variation of losses versus bending radius, evaluating the reliability of a fiber under stress and considering the fabrication tolerances it's possible to determine the right position and angle for effectively inserting and extracting light. The focusing lenses have been implemented into a mechanical holder. Some prototypes have been realized by plastic molding technique. The optical study, the realization process and the first results are presented in this paper.

  8. Nanoglassified, optically-active monolayer films of gold nanoparticles for in situ orthogonal detection by localized surface plasmon resonance and surface-assisted laser desorption/ionization-MS.

    PubMed

    Chen, Chih-Yuan; Hinman, Samuel S; Duan, Jicheng; Cheng, Quan

    2014-12-16

    Localized surface plasmon resonance (LSPR) represents a sensitive and versatile method for detection of biomolecules in a label-free fashion, but identification of bound analytes can be challenging with LSPR alone, especially for samples in a complex medium. We report the fabrication of an optically active, plasmonic film of gold nanoparticles by using a self-assembly and calcination process, which offers orthogonal measurements enabling multifaceted characterization on the same surface with LSPR and surface-assisted laser desorption/ionization mass spectrometry. This proof-of-concept study involves plasmonic characterization of the fabricated nanofilm, real-time monitoring of vesicle-surface interactions toward formation of fluid lipid bilayer, and mass spectrometric analysis of peptides and cytochrome c digest. This multifunction-enabling surface material can yield complementary analytical information, providing new tools for comprehensive analysis of biomolecular samples. PMID:25417963

  9. Nanoglassified, Optically-Active Monolayer Films of Gold Nanoparticles for in Situ Orthogonal Detection by Localized Surface Plasmon Resonance and Surface-Assisted Laser Desorption/Ionization-MS

    PubMed Central

    2015-01-01

    Localized surface plasmon resonance (LSPR) represents a sensitive and versatile method for detection of biomolecules in a label-free fashion, but identification of bound analytes can be challenging with LSPR alone, especially for samples in a complex medium. We report the fabrication of an optically active, plasmonic film of gold nanoparticles by using a self-assembly and calcination process, which offers orthogonal measurements enabling multifaceted characterization on the same surface with LSPR and surface-assisted laser desorption/ionization mass spectrometry. This proof-of-concept study involves plasmonic characterization of the fabricated nanofilm, real-time monitoring of vesicle–surface interactions toward formation of fluid lipid bilayer, and mass spectrometric analysis of peptides and cytochrome c digest. This multifunction-enabling surface material can yield complementary analytical information, providing new tools for comprehensive analysis of biomolecular samples. PMID:25417963

  10. 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.

  11. 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.

  12. Consistent Realization of ITRS and ICRS

    NASA Astrophysics Data System (ADS)

    Seitz, M.; Steigenberger, P.; Artz, T.

    2012-12-01

    This paper deals with the consistent realization of the International Terrestrial Reference System (ITRS) and the International Celestial Reference System (ICRS). DGFI computes such a common realization for the first time by combining normal equations of the space geodetic techniques of Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), and Global Navigation Satellite Systems (GNSS). The results for the Celestial Reference Frame (CRF) are compared to a classical VLBI-only CRF solution. It turns out that the combination of EOP from the different space geodetic techniques impacts the CRF, in particular the VCS (VLBA Calibrator Survey) sources.

  13. Logical operations realized on the Ising chain of N qubits

    SciTech Connect

    Asano, Masanari; Tateda, Norihiro; Ishii, Chikara

    2004-08-01

    Multiqubit logical gates are proposed as implementations of logical operations on N qubits realized physically by the local manipulation of qubits before and after the one-time evolution of an Ising chain. This construction avoids complicated tuning of the interactions between qubits. The general rules of the action of multiqubit logical gates are derived by decomposing the process into the product of two-qubit logical operations. The formalism is demonstrated by the construction of a special type of multiqubit logical gate that is simulated by a quantum circuit composed of controlled-NOT gates.

  14. Subsurface diffuse optical tomography can localize absorber and fluorescent objects but recovered image sensitivity is nonlinear with depth

    NASA Astrophysics Data System (ADS)

    Kepshire, Dax S.; Davis, Scott C.; Dehghani, Hamid; Paulsen, Keith D.; Pogue, Brian W.

    2007-04-01

    Subsurface tomography with diffuse light has been investigated with a noncontact approach to characterize the performance of absorption and fluorescence imaging. Using both simulations and experiments, the reconstruction of local subsurface heterogeneity is demonstrated, but the recovery of target size and fluorophore concentration is not linear when changes in depth occur, whereas the mean position of the object for experimental fluorescent and absorber targets is accurate to within 0.5 and 1.45 mm when located within the first 10 mm below the surface. Improvements in the linearity of the response with depth appear to remain challenging and may ultimately limit the approach to detection rather than characterization applications. However, increases in tissue curvature and/or the addition of prior information are expected to improve the linearity of the response. The potential for this type of imaging technique to serve as a surgical guide is highlighted.

  15. Evidence for static localization in the lowest optically excited states of ruthenium(II) diimine complexes: a solvent- and time-dependent photoselection study at 77 K

    SciTech Connect

    Myrick, M.L.; Blakley, R.L.; DeArmond, M.K.; Arthur, M.L.

    1988-03-02

    The 77 K absorption, emission, steady-state excitation photoselection (SSExP), and time-resolved excitation photoselection (TRExP) results are reported for 11 (Ru(L)/sub 3/)(PF/sub 6/)/sub 2/ complexes with 2,2'-diimine ligands (L). The ligands are 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), 2,2'-bipyrazine (bpz), 2-(2-pyridyl)quinoline (pq), and 2,2'-biquinoline (biq). Complexes of the form (Ru(L)/sub 3/)/sup 2 +/ (L = bpy, phen, bpz, pq, and biq) were examined as well as mixed-ligand complexes of the form (Ru(bpy)/sub n/(L)/sub 3-n/)/sup 2 +/ (n = 1, 2) (L = phen, bpz, and pq). Data are also presented for the monomeric model complex, (Ru(bpy)(py)/sub 4/)/sup 2 +/ (py = pyridine). Data indicate that optical excitation leads to static localization of the optically excited electron. A model is developed that rationalizes the maximum value obtainable in the SSExP data. Solvent effects observed in the TRExP data are explained in terms of relative rates of spin-lattice relaxation associated with different solvents.

  16. 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.

  17. 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 ...

  18. Self - realization through through vedanta and yoga.

    PubMed

    Motilal, A J

    1983-07-01

    The seeker of ultimate truth needs the understanding of the practical side of Vedanta philosophy, the five Koshas or Sheaths beyond which the Atman, the Self remains. Through Vedanta and Yoga one can transcend these layers in a systematic manner to attain self realization - ultimate Reality. PMID:22557374

  19. Loop realizations of quantum affine algebras

    SciTech Connect

    Cautis, Sabin; Licata, Anthony

    2012-12-15

    We give a simplified description of quantum affine algebras in their loop presentation. This description is related to Drinfeld's new realization via halves of vertex operators. We also define an idempotent version of the quantum affine algebra which is suitable for categorification.

  20. Quantum dynamics of two quantum dots coupled through localized plasmons: An intuitive and accurate quantum optics approach using quasinormal modes

    NASA Astrophysics Data System (ADS)

    Ge, Rong-Chun; Hughes, Stephen

    2015-11-01

    We study the quantum dynamics of two quantum dots (QDs) or artificial atoms coupled through the fundamental localized plasmon of a gold nanorod resonator. We derive an intuitive and efficient time-local master equation, in which the effect of the metal nanorod is taken into consideration self-consistently using a quasinormal mode (QNM) expansion technique of the photon Green function. Our efficient QNM technique offers an alternative and more powerful approach over the standard Jaynes-Cummings model, where the radiative decay, nonradiative decay, and spectral reshaping effect of the electromagnetic environment is rigorously included in a clear and transparent way. We also show how one can use our approach to compliment the approximate Jaynes-Cummings model in certain spatial regimes where it is deemed to be valid. We then present a study of the quantum dynamics and photoluminescence spectra of the two plasmon-coupled QDs. We first explore the non-Markovian regime, which is found to be important only on the ultrashort time scale of the plasmon mode which is about 40 fs. For the field free evolution case of excited QDs near the nanorod, we demonstrate how spatially separated QDs can be effectively coupled through the plasmon resonance and we show how frequencies away from the plasmon resonance can be more effective for coherently coupling the QDs. Despite the strong inherent dissipation of gold nanoresonators, we show that qubit entanglements as large as 0.7 can be achieved from an initially separate state, which has been limited to less than 0.5 in previous work for weakly coupled reservoirs. We also study the superradiance and subradiance decay dynamics of the QD pair. Finally, we investigate the rich quantum dynamics of QDs that are incoherently pumped, and study the polarization dependent behavior of the emitted photoluminescence spectrum where a double-resonance structure is observed due to the strong photon exchange interactions. Our general quantum plasmonics

  1. A Study of Aerosol Optical and Chemical Properties from the Perspectives of Source Region, Local, and Synoptic Meteorology During Summer 2013 at a Southeast US Regionally Representative Site

    NASA Astrophysics Data System (ADS)

    Krintz, I. A.; Link, M. F.; Madison, B.; Morrow, H. A.; Sherman, J. P.; Zhou, Y.

    2014-12-01

    An intensive summer 2013 aerosol field campaign was conducted at the Appalachian Atmospheric Interdisciplinary Research facility at Appalachian State University (AppalAIR), coinciding with the SOAS campaign in the SE U.S. Measurements included lower tropospheric and column-averaged aerosol properties as part of the NOAA-ESRL and NASA AERONET, lidar-derived vertical profiles of aerosols and clouds, surface and vertical meteorology, and aerosol and organic precursor chemical composition. Clustered 120-hour HYSPLIT back-trajectories were used to determine the influence of source region on aerosol properties and composition. A synoptic-scale weather classification scheme (Sheridan 2000) was applied to bin the aerosol properties by synoptic weather type. Co-located near-surface T, P, and RH measurements and vertical profiles from 75 radiosonde launches were used to determine the influence of local meteorology on the aerosol properties. The anomalously cool, wet summer dampened and delayed the summer peak in aerosol scattering and absorption, relative to previous summers and limited the number of sunphotometer retrievals of column-averaged aerosol properties. Nevertheless, aerosol loading, composition, and several key optical properties such as absorption Angstrom exponent displayed distinct dependence on source region and meteorology. As an example, both light scattering and isoprene-derived SOA concentrations (Link et al, 2014) were highest for more pollution-influenced NE air masses, for which lower hemispheric backscatter fractions and absorption Angstrom exponents were observed. Aerosol loading was generally lower for SW and SE air masses, with the exception of extra-moist tropical weather types, which coincided with high aerosol optical depth and larger, hygroscopic, primarily scattering particles. Aerosol loading increased with local temperature and pressure and some other properties also displayed temperature dependence but the range of temperatures observed

  2. Underwater gas pipeline leakage source localization by distributed fiber-optic sensing based on particle swarm optimization tuning of the support vector machine.

    PubMed

    Huang, Yue; Wang, Qiang; Shi, Lilian; Yang, Qihua

    2016-01-10

    Accurate underwater gas pipeline leak localization requires particular attention due to the sensitivity of environmental conditions. Experiments were performed to analyze the localization performance of a distributed optical fiber sensing system based on the hybrid Sagnac and Mach-Zehnder interferometer. The traditional null frequency location method does not easily allow accurate location of the leakage points. To improve the positioning accuracy, the particle swarm optimization algorithm (PSO) tuning of the support vector machine (SVM) was used to predict the leakage points based on gathered leakage data. The PSO is able to optimize the SVM parameters. For the 10 km range chosen, the results show the PSO-SVM average absolute error of the leakage points predicted is 66 m. The prediction accuracy of leakage points is 98.25% by PSO tuning of the SVM processing. For 20 leakage test data points, the average absolute error of leakage point location is 124.8 m. The leakage position predicted by the PSO algorithm after optimization of the parameters is more accurate. PMID:26835758

  3. 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.

  4. Adaptive adjustment of unit tuning to sound localization cues in response to monaural occlusion in developing owl optic tectum.

    PubMed

    Mogdans, J; Knudsen, E I

    1992-09-01

    Bimodal units in the barn owl's optic tectum are tuned to the location of auditory and visual stimuli, and are systematically organized according to their spatial tuning to form mutually aligned maps of auditory and visual space. Map alignment results from the fact that, normally, units are tuned to the values of interaural level difference (ILD) and interaural time difference (ITD) produced by a sound source at the location of their visual receptive fields (VRFs). Monaural occlusion alters the correspondence of ILD and ITD values with locations in space. We investigated the effect that raising owls with a chronic monaural occlusion has on the tuning of tectal units to ILD and ITD. Owls were monaurally occluded beginning at 1 month of age. The effects of monaural occlusion were assessed 2-4 months later by comparing the ILD and ITD tuning of units in monaurally occluded owls with the ILD and ITD tuning of units with equivalent VRFs in normal owls. ILD and ITD tuning was shifted substantially and in the direction of the unoccluded ear (the adaptive direction) in owls raised with a monaural occlusion. In most tecta, the mapped representations of ILD and ITD were shifted systematically. In addition, in some tecta, monaural occlusion induced a change in the topography of the ILD map such that ILD tuning remained essentially constant at values near 0 dB over abnormally large portions of the tectum. Across all recording sites, the average shift in ILD tuning was 9 dB (n = 396) and the average shift in ITD tuning was 40 microseconds (n = 414). In four of five animals, the magnitude of the effect was not equivalent on the two sides of the brain, the adjustments being significantly larger and more systematic on the side ipsilateral to the occlusion. Such differences in the altered ILD and ITD maps on the two sides of the brain in individual animals indicate that, although a component of the adaptive adjustment might be due to regulation of the gain and phase response of the

  5. 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

  6. Electron-Optics in suspended Graphene

    NASA Astrophysics Data System (ADS)

    Makk, Peter; Rickhaus, Peter; Zihlmann, Simon; Hess, Samuel; Weiss, Markus; Schoenenberger, Christian; Maurand, Romain; Tovari, Endre; Liu, Ming-Hao; Richter, Klaus

    We realized electron optical elements in ballistic graphene by utilizing local electrostatic gating. But in contrast to conventional optics, in graphene gapless p-n interfaces can be formed showing a negative index of refraction and the effect of Klein tunneling. The devices were fabricated using high-mobility suspended monolayer graphene on LOR resists. We demonstrate that with this technique a ballistic p-n junction can be formed and in magnetic fields striking features appear that can be traced to the formation of ``snake states'' along the p-n interface. We also show that electrons in ballistic graphene can be guided by gate potentials as photons in an optical fiber, and that Klein filtering increases the guiding efficiency. We showed that we can fill the electrostatic guiding channel mode by mode. Similarly, we have shown that tunable p-n interfaces can act as beam splitters.

  7. 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.

  8. Photochromic point-diffraction interferometer for optical testing

    NASA Astrophysics Data System (ADS)

    Quintavalla, Martino; Pariani, Giorgio; Crimi, Giuseppe; Bianco, Andrea; Bertarelli, Chiara

    2012-09-01

    The principles for the realization of rewritable point-diffraction interferometers (PDIs) based on photochromic polyurethane films are described. Pinholes of variable sizes (diameter from 4 to 40 μm) have been optically written onto photochromic substrates converting locally the material from the colored to the uncolored form. The PDIs have been mounted in an interferometric setup and different reflective optics have been tested. By a controlled bleaching of the semi-transparent area around the pinhole, an optimal visibility in the interferograms is reached. Under this conditions several tests of reliability of the interferometer have been carried out.

  9. Realizing and optimizing an atomtronic SQUID

    NASA Astrophysics Data System (ADS)

    Mathey, Amy C.; Mathey, L.

    2016-05-01

    We demonstrate how a toroidal Bose–Einstein condensate with a movable barrier can be used to realize an atomtronic SQUID. The magnitude of the barrier height, which creates the analogue of an SNS junction, is of crucial importance, as well as its ramp-up and -down protocol. For too low of a barrier, the relaxation of the system is dynamically suppressed, due to the small rate of phase slips at the barrier. For a higher barrier, the phase coherence across the barrier is suppressed due to thermal fluctuations, which are included in our Truncated Wigner approach. Furthermore, we show that the ramp-up protocol of the barrier can be improved by ramping up its height first, and its velocity after that. This protocol can be further improved by optimizing the ramp-up and ramp-down time scales, which is of direct practical relevance for on-going experimental realizations.

  10. 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. PMID:27447253

  11. Algebraic geometry realization of quantum Hall soliton

    NASA Astrophysics Data System (ADS)

    Abounasr, R.; Ait Ben Haddou, M.; El Rhalami, A.; Saidi, E. H.

    2005-02-01

    Using the Iqbal-Netzike-Vafa dictionary giving the correspondence between the H2 homology of del Pezzo surfaces and p-branes, we develop a way to approach the system of brane bounds in M-theory on S1. We first review the structure of 10-dimensional quantum Hall soliton (QHS) from the view of M-theory on S1. Then, we show how the D0 dissolution in D2-brane is realized in M-theory language and derive the p-brane constraint equations used to define appropriately the QHS. Finally, we build an algebraic geometry realization of the QHS in type IIA superstring and show how to get its type IIB dual. Other aspects are also discussed.

  12. NIM Realization of the Gallium Triple Point

    NASA Astrophysics Data System (ADS)

    Xiaoke, Yan; Ping, Qiu; Yuning, Duan; Yongmei, Qu

    2003-09-01

    In the last three years (1999 to 2001), the gallium triple-point cell has been successfully developed, and much corresponding research has been carried out at the National Institute of Metrology (NIM), Beijing, China. This paper presents the cell design, apparatus and procedure for realizing the gallium triple point, and presents studies on the different freezing methods. The reproducibility is 0.03 mK, and the expanded uncertainty of realization of the gallium triple point is evaluated to be 0.17 mK (p=0.99, k=2.9). Also, the reproducibility of the gallium triple point was compared with that of the triple point of water.

  13. Experimental Realization of a Quantum Pentagonal Lattice

    PubMed Central

    Yamaguchi, Hironori; Okubo, Tsuyoshi; Kittaka, Shunichiro; Sakakibara, Toshiro; Araki, Koji; Iwase, Kenji; Amaya, Naoki; Ono, Toshio; Hosokoshi, Yuko

    2015-01-01

    Geometric frustration, in which competing interactions give rise to degenerate ground states, potentially induces various exotic quantum phenomena in magnetic materials. Minimal models comprising triangular units, such as triangular and Kagome lattices, have been investigated for decades to realize novel quantum phases, such as quantum spin liquid. A pentagon is the second-minimal elementary unit for geometric frustration. The realization of such systems is expected to provide a distinct platform for studying frustrated magnetism. Here, we present a spin-1/2 quantum pentagonal lattice in the new organic radical crystal α-2,6-Cl2-V [=α-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl]. Its unique molecular arrangement allows the formation of a partially corner-shared pentagonal lattice (PCPL). We find a clear 1/3 magnetization plateau and an anomalous change in magnetization in the vicinity of the saturation field, which originate from frustrated interactions in the PCPL. PMID:26468930

  14. Experimental Realization of a Quantum Pentagonal Lattice.

    PubMed

    Yamaguchi, Hironori; Okubo, Tsuyoshi; Kittaka, Shunichiro; Sakakibara, Toshiro; Araki, Koji; Iwase, Kenji; Amaya, Naoki; Ono, Toshio; Hosokoshi, Yuko

    2015-01-01

    Geometric frustration, in which competing interactions give rise to degenerate ground states, potentially induces various exotic quantum phenomena in magnetic materials. Minimal models comprising triangular units, such as triangular and Kagome lattices, have been investigated for decades to realize novel quantum phases, such as quantum spin liquid. A pentagon is the second-minimal elementary unit for geometric frustration. The realization of such systems is expected to provide a distinct platform for studying frustrated magnetism. Here, we present a spin-1/2 quantum pentagonal lattice in the new organic radical crystal α-2,6-Cl2-V [=α-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl]. Its unique molecular arrangement allows the formation of a partially corner-shared pentagonal lattice (PCPL). We find a clear 1/3 magnetization plateau and an anomalous change in magnetization in the vicinity of the saturation field, which originate from frustrated interactions in the PCPL. PMID:26468930

  15. Experimental Realization of a Quantum Pentagonal Lattice

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hironori; Okubo, Tsuyoshi; Kittaka, Shunichiro; Sakakibara, Toshiro; Araki, Koji; Iwase, Kenji; Amaya, Naoki; Ono, Toshio; Hosokoshi, Yuko

    2015-10-01

    Geometric frustration, in which competing interactions give rise to degenerate ground states, potentially induces various exotic quantum phenomena in magnetic materials. Minimal models comprising triangular units, such as triangular and Kagome lattices, have been investigated for decades to realize novel quantum phases, such as quantum spin liquid. A pentagon is the second-minimal elementary unit for geometric frustration. The realization of such systems is expected to provide a distinct platform for studying frustrated magnetism. Here, we present a spin-1/2 quantum pentagonal lattice in the new organic radical crystal α-2,6-Cl2-V [=α-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl]. Its unique molecular arrangement allows the formation of a partially corner-shared pentagonal lattice (PCPL). We find a clear 1/3 magnetization plateau and an anomalous change in magnetization in the vicinity of the saturation field, which originate from frustrated interactions in the PCPL.

  16. Exploring heterogeneous market hypothesis using realized volatility

    NASA Astrophysics Data System (ADS)

    Chin, Wen Cheong; Isa, Zaidi; Mohd Nor, Abu Hassan Shaari

    2013-04-01

    This study investigates the heterogeneous market hypothesis using high frequency data. The cascaded heterogeneous trading activities with different time durations are modelled by the heterogeneous autoregressive framework. The empirical study indicated the presence of long memory behaviour and predictability elements in the financial time series which supported heterogeneous market hypothesis. Besides the common sum-of-square intraday realized volatility, we also advocated two power variation realized volatilities in forecast evaluation and risk measurement in order to overcome the possible abrupt jumps during the credit crisis. Finally, the empirical results are used in determining the market risk using the value-at-risk approach. The findings of this study have implications for informationally market efficiency analysis, portfolio strategies and risk managements.

  17. N-body realizations of compound galaxies

    NASA Technical Reports Server (NTRS)

    Hernquist, Lars

    1993-01-01

    A prescription for constructing N-body models of galaxies consisting of more than one component is described. Spatial density profiles are realized exactly, but the phase space distribution is approximated using moments of the collisionless Boltzmann equation. While this approach is not fully rigorous, empirical tests suggest that it is adequate for studies of, e.g., interacting galaxies and the forced response of galaxies to imposed perturbations such as bars.

  18. Microwave Realization of the Gaussian Symplectic Ensemble

    NASA Astrophysics Data System (ADS)

    Rehemanjiang, A.; Allgaier, M.; Joyner, C. H.; Müller, S.; Sieber, M.; Kuhl, U.; Stöckmann, H.-J.

    2016-08-01

    Following an idea by Joyner et al. [Europhys. Lett. 107, 50004 (2014)], a microwave graph with an antiunitary symmetry T obeying T2=-1 is realized. The Kramers doublets expected for such systems are clearly identified and can be lifted by a perturbation which breaks the antiunitary symmetry. The observed spectral level spacings distribution of the Kramers doublets is in agreement with the predictions from the Gaussian symplectic ensemble expected for chaotic systems with such a symmetry.

  19. Microwave Realization of the Gaussian Symplectic Ensemble.

    PubMed

    Rehemanjiang, A; Allgaier, M; Joyner, C H; Müller, S; Sieber, M; Kuhl, U; Stöckmann, H-J

    2016-08-01

    Following an idea by Joyner et al. [Europhys. Lett. 107, 50004 (2014)], a microwave graph with an antiunitary symmetry T obeying T^{2}=-1 is realized. The Kramers doublets expected for such systems are clearly identified and can be lifted by a perturbation which breaks the antiunitary symmetry. The observed spectral level spacings distribution of the Kramers doublets is in agreement with the predictions from the Gaussian symplectic ensemble expected for chaotic systems with such a symmetry. PMID:27541466

  20. A first theoretical realization of honeycomb topological magnon insulator.

    PubMed

    Owerre, S A

    2016-09-28

    It has been recently shown that in the Heisenberg (anti)ferromagnet on the honeycomb lattice, the magnons (spin wave quasipacticles) realize a massless two-dimensional (2D) Dirac-like Hamiltonian. It was shown that the Dirac magnon Hamiltonian preserves time-reversal symmetry defined with the sublattice pseudo spins and the Dirac points are robust against magnon-magnon interactions. The Dirac points also occur at nonzero energy. In this paper, we propose a simple realization of nontrivial topology (magnon edge states) in this system. We show that the Dirac points are gapped when the inversion symmetry of the lattice is broken by introducing a next-nearest neighbour Dzyaloshinskii-Moriya (DM) interaction. Thus, the system realizes magnon edge states similar to the Haldane model for quantum anomalous Hall effect in electronic systems. However, in contrast to electronic spin current where dissipation can be very large due to Ohmic heating, noninteracting topological magnons can propagate for a long time without dissipation as magnons are uncharged particles. We observe the same magnon edge states for the XY model on the honeycomb lattice. Remarkably, in this case the model maps to interacting hardcore bosons on the honeycomb lattice. Quantum magnetic systems with nontrivial magnon edge states are called topological magnon insulators. They have been studied theoretically on the kagome lattice and recently observed experimentally on the kagome magnet Cu(1-3, bdc) with three magnon bulk bands. Our results for the honeycomb lattice suggests an experimental procedure to search for honeycomb topological magnon insulators within a class of 2D quantum magnets and ultracold atoms trapped in honeycomb optical lattices. In 3D lattices, Dirac and Weyl points were recently studied theoretically, however, the criteria that give rise to them were not well-understood. We argue that the low-energy Hamiltonian near the Weyl points should break time-reversal symmetry of the pseudo spins