WorldWideScience

Sample records for optical conductivity resonance

  1. Cross resonant optical antenna.

    Science.gov (United States)

    Biagioni, P; Huang, J S; Duò, L; Finazzi, M; Hecht, B

    2009-06-26

    We propose a novel cross resonant optical antenna consisting of two perpendicular nanosized gold dipole antennas with a common feed gap. We demonstrate that the cross antenna is able to convert propagating fields of any polarization state into correspondingly polarized, localized, and enhanced fields and vice versa. The cross antenna structure therefore opens the road towards the control of light-matter interactions based on polarized light as well as the analysis of polarized fields on the nanometer scale.

  2. Cross Resonant Optical Antenna

    Science.gov (United States)

    Biagioni, P.; Huang, J. S.; Duò, L.; Finazzi, M.; Hecht, B.

    2009-06-01

    We propose a novel cross resonant optical antenna consisting of two perpendicular nanosized gold dipole antennas with a common feed gap. We demonstrate that the cross antenna is able to convert propagating fields of any polarization state into correspondingly polarized, localized, and enhanced fields and vice versa. The cross antenna structure therefore opens the road towards the control of light-matter interactions based on polarized light as well as the analysis of polarized fields on the nanometer scale.

  3. Optical resonator theory

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jaeg Won; Cho, Sunh Oh; Jeong, Young Uk; Lee, Byung Cheol; Lee, Jong Min

    2000-10-01

    In this report we present a theoretical study of bare optical resonators having in mind to extend it to active resonators. To compute diffractional losses, phase shifts, intensity distributions and phases of radiation fields on mirrors, we coded a package of numerical procedures on bases of a pair of integral equations. Two numerical schemes, a matrix formalism and an iterative method, are programmed for finding numeric solutions to the pair of integral equations. The iterative method had been tried by Fox and Li, but it was not applicable to cases for high Fresnel numbers since the numerical errors involved propagate and accumulate uncontrollably. In this report, we implemented the matrix method to extend the computational limit further. A great deal of case studies are carried out with various configurations of stable and unstable resonators. Our results presented in this report show not only a good agreement with the results previously obtained by Fox and Li, but also a legitimacy of our numerical procedures in high Fresnel numbers.

  4. Loop coupled resonator optical waveguides.

    Science.gov (United States)

    Song, Junfeng; Luo, Lian-Wee; Luo, Xianshu; Zhou, Haifeng; Tu, Xiaoguang; Jia, Lianxi; Fang, Qing; Lo, Guo-Qiang

    2014-10-06

    We propose a novel coupled resonator optical waveguide (CROW) structure that is made up of a waveguide loop. We theoretically investigate the forbidden band and conduction band conditions in an infinite periodic lattice. We also discuss the reflection- and transmission- spectra, group delay in finite periodic structures. Light has a larger group delay at the band edge in a periodic structure. The flat band pass filter and flat-top group delay can be realized in a non-periodic structure. Scattering matrix method is used to calculate the effects of waveguide loss on the optical characteristics of these structures. We also introduce a tunable coupling loop waveguide to compensate for the fabrication variations since the coupling coefficient of the directional coupler in the loop waveguide is a critical factor in determining the characteristics of a loop CROW. The loop CROW structure is suitable for a wide range of applications such as band pass filters, high Q microcavity, and optical buffers and so on.

  5. Coupled-resonator optical waveguides

    DEFF Research Database (Denmark)

    Raza, Søren; Grgic, Jure; Pedersen, Jesper Goor

    2010-01-01

    Coupled-resonator optical waveguides hold potential for slow-light propagation of optical pulses. The dispersion properties may adequately be analyzed within the framework of coupled-mode theory. We extend the standard coupled-mode theory for such structures to also include complex-valued paramet...

  6. Optical antennas as nanoscale resonators

    CERN Document Server

    Agio, Mario

    2011-01-01

    Recent progress in nanotechnology has enabled us to fabricate subwavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interaction, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

  7. Optical antennas as nanoscale resonators.

    Science.gov (United States)

    Agio, Mario

    2012-02-07

    Recent progress in nanotechnology has enabled us to fabricate sub-wavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review the designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interactions, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

  8. Resonance modes in optical fibres

    Institute of Scientific and Technical Information of China (English)

    余寿绵; 余恬

    2002-01-01

    The weakly nonlinear boundary value problem of wave propagation in an optical fibre (for the transverse electric mode, for example) is formulated and a modified linear solution is obtained. It is shown that a self-consistent theory of fibre optics should be weakly nonlinear. The mode of critical refraction that does not exist in the linear theory is obtained, showing that it is a mode consisting of resonance modes. It is shown that the signal carriers in a long fibre are of resonance modes, not normal modes. Some experimental data are given for comparison with the theoretical predictions, and the agreement seems satisfactory.

  9. Optical conductivity of curved graphene.

    Science.gov (United States)

    Chaves, A J; Frederico, T; Oliveira, O; de Paula, W; Santos, M C

    2014-05-07

    We compute the optical conductivity for an out-of-plane deformation in graphene using an approach based on solutions of the Dirac equation in curved space. Different examples of periodic deformations along one direction translates into an enhancement of the optical conductivity peaks in the region of the far- and mid-infrared frequencies for periodicities ∼100 nm. The width and position of the peaks can be changed by dialling the parameters of the deformation profiles. The enhancement of the optical conductivity is due to intraband transitions and the translational invariance breaking in the geometrically deformed background. Furthermore, we derive an analytical solution of the Dirac equation in a curved space for a general deformation along one spatial direction. For this class of geometries, it is shown that curvature induces an extra phase in the electron wave function, which can also be explored to produce interference devices of the Aharonov-Bohm type.

  10. Advances in magnetic and optical resonance

    CERN Document Server

    Warren, Warren S

    1997-01-01

    Since 1965, Advances in Magnetic and Optical Resonance has provided researchers with timely expositions of fundamental new developments in the theory of, experimentation with, and application of magnetic and optical resonance.

  11. Distributed optical fiber surface plasmon resonance sensors

    Institute of Scientific and Technical Information of China (English)

    Zhenxin Cao; Lenan Wu; Dayong Li

    2006-01-01

    @@ The relationships of the resonant wavelength of optical fiber surface plasmon resonance (SPR) sensors to the modulation layer refractive index, thickness and the refractive index of the bulk medium are obtained by using theoretical calculation model of optical fiber SPR sensors under certain conditions, which indicates that resonant wavelength of the sensors is approximately linear with modulation layer thickness. Based on the linear relationship, multiple SPR sensors with different resonant wavelengths can be fabricated in a single optical fiber named as distributed optical fiber surface plasmon resonance sensors (DOFSPRSs).Experimental results are presented, showing that it is practical to fabricate more than one SPR sensors in a single optical fiber.

  12. Universal Zero Conductivity Condition for Optical Absorption

    CERN Document Server

    Guo, Yu; Jacob, Zubin

    2016-01-01

    Harnessing information and energy from light within a nanoscale mode volume is a fundamental challenge for nanophotonic applications ranging from solar photovoltaics to single photon detectors. Here, we show the existence of a universal condition in materials that sheds light on fundamental limits of electromagnetic to matter energy conversion (transduction). We show that the upper limit of absorption rate (transduction rate) in any nanoscale absorber converting light to matter degrees of freedom is revealed by the zero of optical conductivity at complex frequencies ($\\sigma(\\omega^\\prime + i\\omega^{\\prime\\prime})= 0$). We trace the origin of this universal zero conductivity condition to causality requirements on any passive linear response function and propose an experiment of absorption resonances using plasmonic nanoparticles to experimentally verify this universal zero conductivity condition. Our work is widely applicable to linear systems across the electromagnetic spectrum and allows for systematic opti...

  13. Detection of heavy metal ions in contaminated water by surface plasmon resonance based optical fibre sensor using conducting polymer and chitosan.

    Science.gov (United States)

    Verma, Roli; Gupta, Banshi D

    2015-01-01

    Optical fibre surface plasmon resonance (SPR) based sensor for the detection of heavy metal ions in the drinking water is designed. Silver (Ag) metal and indium tin oxide (ITO) are used for the fabrication of the SPR probe which is further modified with the coating of pyrrole and chitosan composite. The sensor works on the wavelength interrogation technique and is capable of detecting trace amounts of Cd(2+), Pb(2+), and Hg(2+) heavy metal ions in contaminated water. Four types of sensing probes are fabricated and characterised for heavy metal ions out of these pyrrole/chitosan/ITO/Ag coated probe is found to be highly sensitive among all other probes. Further, the cadmium ions bind strongly to the sensing surface than other ions and due to this the sensor is highly sensitive for Cd(2+) ions. The sensor's performance is best for the low concentrations of heavy metal ions and its sensitivity decreases with the increasing concentration of heavy metal ions.

  14. Optical Microspherical Resonators for Biomedical Sensing

    Directory of Open Access Journals (Sweden)

    Giancarlo C. Righini

    2011-01-01

    Full Text Available Optical resonators play an ubiquitous role in modern optics. A particular class of optical resonators is constituted by spherical dielectric structures, where optical rays are total internal reflected. Due to minimal reflection losses and to potentially very low material absorption, these guided modes, known as whispering gallery modes, can confer the resonator an exceptionally high quality factor Q, leading to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. These attractive characteristics make these miniaturized optical resonators especially suited as laser cavities and resonant filters, but also as very sensitive sensors. First, a brief analysis is presented of the characteristics of microspherical resonators, of their fabrication methods, and of the light coupling techniques. Then, we attempt to overview some of the recent advances in the development of microspherical biosensors, underlining a number of important applications in the biomedical field.

  15. Reconfigurable optical routers based on Coupled Resonator Induced Transparency resonances.

    Science.gov (United States)

    Mancinelli, M; Bettotti, P; Fedeli, J M; Pavesi, L

    2012-10-08

    The interferometric coupling of pairs of resonators in a resonator sequence generates coupled ring induced transparency (CRIT) resonances. These have quality factors an order of magnitude greater than those of single resonators. We show that it is possible to engineer CRIT resonances in tapered SCISSOR (Side Coupled Integrated Space Sequence of Resonator) to realize fast and efficient reconfigurable optical switches and routers handling several channels while keeping single channel addressing capabilities. Tapered SCISSORs are fabricated in silicon-on-insulator technology. Furthermore, tapered SCISSORs show multiple-channel switching behavior that can be exploited in DWDM applications.

  16. Saturating optical resonances in quantum dots

    Science.gov (United States)

    Nair, Selvakumar V.; Rustagi, K. C.

    Optical bistability in quantum dots, recently proposed by Chemla and Miller, is studied in a two-resonance model. We show that for such classical electromagnetic resonances the applicability of a two-resonance model is far more restrictive than for those in atoms.

  17. Optical resonance and two-level atoms

    CERN Document Server

    Allen, L

    1987-01-01

    ""Coherent and lucid…a valuable summary of a subject to which [the authors] have made significant contributions by their own research."" - Contemporary PhysicsOffering an admirably clear account of the basic principles behind all quantum optical resonance phenomena, and hailed as a valuable contribution to the literature of nonlinear optics, this distinguished work provides graduate students and research physicists probing fields such as laser physics, quantum optics, nonlinear optics, quantum electronics, and resonance optics an ideal introduction to the study of the interaction of electroma

  18. Polarimetric Properties of Optically Resonant Nanostructures

    Science.gov (United States)

    Theisen, Michael John

    Optically resonant nanostructures have been incorporated into a variety of devices used in a number of different fields. In this thesis, we explore optically resonant nanostructures in two forms. First we investigate a relatively new material, gallium implanted silicon (Si:Ga). We cover the fabrication process and experimentally find the optical properties as a function of both dose and wavelength. We then use the properties of this new material to create suspended arrays of Si:Ga nanowires, and determine their optical characteristics. In the second part of this thesis, we use more conventional materials and fabrication procedures to investigate the phase effects of guided mode resonators. We look at the spectral phase effects for a grating coupled silicon-on-insulator based guided mode resonator. We also look the angular phase effects of a surface plasmon polariton based guided mode resonator, comparing experimental results to theory calculated with rigorous coupled wave analysis for both cases. In addition, the guided mode resonance is modeled as a Fano resonance to gain insight into the functional form of the phase. Knowing the phase response of guided mode resonances may allow the creation of guided mode resonance based devices with higher sensitivity than traditional reflectance based devices.

  19. Resonant optical device with a microheater

    Energy Technology Data Exchange (ETDEWEB)

    Lentine, Anthony L.; DeRose, Christopher

    2017-04-04

    A resonant photonic device is provided. The device comprises an optical waveguiding element, such as an optical resonator, that includes a diode junction region, two signal terminals configured to apply a bias voltage across the junction region, and a heater laterally separated from the optical waveguiding element. A semiconductor electrical barrier element is juxtaposed to the heater. A metallic strip is electrically and thermally connected at one end to a signal terminal of the optical waveguiding element and thermally connected at another end to the barrier element.

  20. Optical resonance of metal-coated nanoshell

    Institute of Scientific and Technical Information of China (English)

    Diao Jia-Jie(刁佳杰); Chen Guang-De(陈光德); Xi Cong(席聪); Z Y Fan; Yuan Jin-She(苑进社)

    2003-01-01

    Metal-coated nanoshell, the nanoparticle consisting of a nanometre-scale dielectric core coated with a thin metallic shell, exhibits three distinct optical resonant forms, the sphere cavity resonance (SCR), plasmon resonance (PR), and concentric dielectric sphere resonance (CDSR). The SCR, PR and CDSR of the metal-coated nanoshell reveal a geometric tunability controlled by the core radius and by the ratio of the core radius to the total radius. Classical electrodynamics and Mie scattering theory are used to treat the resonant forms and the transition state between the resonant forms. Based on previous experimental research, we present a group of resonant equations for all the resonant forms, which depend on the geometric structure of the metal-coated nanoshell.

  1. Fermi resonance in optical microcavities

    Science.gov (United States)

    Yi, Chang-Hwan; Yu, Hyeon-Hye; Lee, Ji-Won; Kim, Chil-Min

    2015-04-01

    Fermi resonance is a phenomenon of quantum mechanical superposition, which most often occurs between normal and overtone modes in molecular systems that are nearly coincident in energy. We find that scarred resonances in deformed dielectric microcavities are the very phenomenon of Fermi resonance, that is, a pair of quasinormal modes interact with each other due to coupling and a pair of resonances are generated through an avoided resonance crossing. Then the quantum number difference of a pair of quasinormal modes, which is a consequence of quantum mechanical superposition, equals periodic orbits, whereby the resonances are localized on the periodic orbits. We derive the relation between the quantum number difference and the periodic orbits and confirm it in an elliptic, a rectangular, and a stadium-shaped dielectric microcavity.

  2. Resonance spectra of diabolo optical antenna arrays

    Science.gov (United States)

    Guo, Hong; Simpkins, Blake; Caldwell, Joshua D.; Guo, Junpeng

    2015-10-01

    A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

  3. Resonance spectra of diabolo optical antenna arrays

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hong; Guo, Junpeng, E-mail: guoj@uah.edu [Department of Electrical and Computer Engineering, University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, AL 35899 (United States); Simpkins, Blake; Caldwell, Joshua D. [Naval Research Laboratory, 4555 Overlook Ave., SW Washington, DC 20375 (United States)

    2015-10-15

    A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

  4. Method of shifting and fixing optical frequency of an optical resonator, and optical resonator made by same

    Science.gov (United States)

    Savchenkov, Anatoliy A. (Inventor); Strekalov, Dmitry V. (Inventor); Maleki, Lute (Inventor); Matsko, Andrey B. (Inventor); Iltchenko, Vladimir S. (Inventor); Martin, Jan M. (Inventor)

    2010-01-01

    A method of shifting and fixing an optical frequency of an optical resonator to a desired optical frequency, and an optical resonator made by such a method are provided. The method includes providing an optical resonator having a surface and a refractive index, and obtaining a coating composition having a predetermined concentration of a substance and having a refractive index that is substantially similar to the refractive index of the optical resonator. The coating composition inherently possesses a thickness when it is applied as a coating. The method further includes determining a coating ratio for the surface of the optical resonator and applying the coating composition onto a portion of the surface of the optical resonator based upon the determined coating ratio.

  5. Advances in magnetic and optical resonance

    CERN Document Server

    Warren, Warren S

    2013-01-01

    Advances in Magnetic and Optical Resonance contains three articles which review quite fundamentally different aspects of coherent spectroscopy. An enormous variety of effects can be observed when optical and spin resonances are coupled, usually by a combination of radio frequency and laser irradiation. The first article reviews these effects and pays particular attention to developing a theoretical framework which is as similar as possible for the optical and spin cases. Subsequent articles examine deuterium relaxation in molecular solids, and the spatiotemporal growth of multiple spin coheren

  6. Optical ballast and adaptive dynamic stable resonator

    Institute of Scientific and Technical Information of China (English)

    Zhang Guang-Yin; Jiao Zhi-Yong; Guo Shu-Guang; Zhang Xiao-Hua; Gu Xue-Wen; Yan Cai-Fan; Wu Ding-Er; Song Feng

    2004-01-01

    In this paper a new concept of ‘optical ballast' is put forward. Optical ballast is a kind of device that can be used to decrease the variation and fluctuation of the propagation characteristics of light beams caused by the disturbance of refractive index of the medium. To illustrate the idea clearly and concretely, a fully adaptive dynamic stable solid-state laser resonator is presented as application example of optical ballast.

  7. Characterization of optical whispering gallery mode resonance and applications

    Science.gov (United States)

    Quan, Haiyong

    The whispering-gallery mode microdisk or microsphere resonators have supercompact size, high energy storage, very narrow resonance bandwidth, and high sensitivity. These appealing properties have attracted much attention in the realization of microlasers, narrow filters, optical switching, biosensing, high resolution spectroscopy, and so on. In this dissertation, the optical and energy transport phenomena of whispering-gallery mode resonance and its potentials in some optical sensing applications will be characterized. A 2D theoretical analysis is first presented based on the method of separation of variables and by deriving several appropriate and reasonable boundary conditions to describe the electrical field distribution at resonance modes. This analytical model can precisely predict the intrinsic resonance frequencies of isolated whispering-gallery mode resonators. To consider the coupling of light-delivery waveguides with resonators and investigate the resonance phenomena of the resonator-waveguide system and/or device, simulations using a Finite Element Method solver of Maxwell's equations are conducted. The results indicate the influences of the geometric dimensions, refractive indices, gap distances, and excitation wavelengths on the main characteristics of the resonance modes such as the quality factor Q, the finesse, the mode intensity, and so on. Furthermore, the gap effects are detailedly studied by both theoretical analysis and simulation modeling. The optimal gap for the maximum coupling efficiency and the optimum gap for the best sensing application of the whispering gallery mode resonators are introduced and discussed based on simulation data and theoretical estimations. Three prospective applications of the whispering gallery mode-based sensors are introduced and proof-of-concept studies are demonstrated. The design schemes and fabrication process of the on-chip resonance device made of the Si3N4/SiO2 material system using nanofabrication

  8. Quantum resonance catastrophe for conductance through a periodically driven barrier

    Science.gov (United States)

    Thuberg, Daniel; Reyes, Sebastián A.; Eggert, Sebastian

    2016-05-01

    We consider the quantum conductance in a tight-binding chain with a locally applied potential which is oscillating in time. The steady state for such a driven impurity can be calculated exactly for any energy and applied potential using the Floquet formalism. The resulting transmission has a nontrivial, nonmonotonic behavior depending on incoming momentum, driving frequency, and the strength of the applied periodic potential. Hence there is an abundance of tuning possibilities, which allows finding the resonances of total reflection for any choice of incoming momentum and periodic potential. Remarkably, this implies that even for an arbitrarily small infinitesimal impurity potential it is always possible to find a resonance frequency at which there is a catastrophic breakdown of the transmission T =0 . The points of zero transmission are closely related to the phenomenon of Fano resonances at dynamically created bound states in the continuum. The results are relevant for a variety of one-dimensional systems where local AC driving is possible, such as quantum nanodot arrays, ultracold gases in optical lattices, photonic crystals, or molecular electronics.

  9. Velocity selective optical pumping resonance sign reversal

    Science.gov (United States)

    Krasteva, A.; Slavov, D.; Todorov, G.; Cartaleva, S.

    2013-03-01

    We report experimental and theoretical examinations of the peculiarities in Velocity Selective Optical Pumping (VSOP) resonance behavior at open and closed hyperfine transition spectra of Cs atoms (on the D2 line), confined in optical cell with thickness L = 6λ, where λ = 852 nm. For linear and circular polarizations of the irradiating light, open transitions exhibit reduced absorption (fluorescence) VSOP resonances whose contrast increases with atomic concentration and light intensity. However, in case of closed transition the situation is different, the enhanced absorption (fluorescence) VSOP resonance reverses its sign with the atomic concentration and light intensity. Theoretical analysis based on the density matrix formalism, taking into account the statistical tensors describing atomic population and longitudinal alignment, shows that the VSOP resonance sign reversal at the closed transition can be attributed to the efficiency reduction of population transfer by the spontaneous decay with atomic source temperature.

  10. Tunable Optical Filters Having Electro-optic Whispering-gallery-mode Resonators

    Science.gov (United States)

    Savchenkov, Anatoliy (Inventor); Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Maleki, Lutfollah (Inventor)

    2006-01-01

    Tunable optical filters using whispering-gallery-mode (WGM) optical resonators are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.

  11. Thermodynamics of the Optical Feshbach Resonance Effect

    CERN Document Server

    Blatt, S; Bloom, B J; Williams, J R; Thomsen, J W; Julienne, P S; Ye, J

    2011-01-01

    Using a narrow intercombination line in alkaline earth atoms to mitigate large inelastic losses, we explore the Optical Feshbach Resonance effect in an ultracold gas of bosonic $^{88}$Sr. A systematic measurement of several resonances allows precise determinations of the OFR strength and scaling law, in agreement with coupled-channels theory. Resonant enhancement of the complex scattering length leads to thermodynamic behavior mediated by elastic and inelastic collisions in an otherwise ideal gas. OFR could be used to control atomic interactions with high spatial and time resolution.

  12. Resonant superfluidity in an optical lattice

    Energy Technology Data Exchange (ETDEWEB)

    Titvinidze, Irakli; Hofstetter, Walter [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, 60438 Frankfurt am Main (Germany); Snoek, Michiel [Institute for Theoretical Physics, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)

    2010-07-01

    We study a system of ultracold fermionic Potassium ({sup 40}K) atoms in a three-dimensional optical lattice in the neighborhood of an s-wave Feshbach resonance. Close to resonance, the system is described by a multi-band Bose-Fermi Hubbard Hamiltonian. We derive an effective lowest-band Hamiltonian in which the effect of the higher band is incorporated by a self-consistent mean-field approximation. The resulting model is solved by means of Generalized Dynamical Mean-Field Theory. In addition to the BEC/BCS crossover we find on the BCS side of the resonance a phase transition to a fermionic Mott insulator at half filling, induced by the repulsive fermionic background scattering length. We also calculate the critical temperature of the BEC/BCS-state across the resonance and find it to be minimal at resonance.

  13. Optical resonances in multilayer structures

    NARCIS (Netherlands)

    Maksimovic, Milan

    2008-01-01

    Theoretical research in optics may be divided in two distinctive but well connected general directions. The first deals with developing new or improving existing mathematical models to describe relevant physics. The second aims to predict new phenomena or applications using established models and te

  14. Optical resonances in multilayer structures

    NARCIS (Netherlands)

    Maksimovic, Milan

    2008-01-01

    Theoretical research in optics may be divided in two distinctive but well connected general directions. The first deals with developing new or improving existing mathematical models to describe relevant physics. The second aims to predict new phenomena or applications using established models and

  15. Tuning of optical resonances of a microsphere with liquid crystal

    Science.gov (United States)

    Yilmaz, Hasan; Tamer, Mehmet Selman; Gürlü, Oguzhan; Serpengüzel, Ali

    2011-05-01

    Optical resonances are observed in the elastic light scattering form high refractive index glass microspheres placed on a single mode optical fiber coupler and in a liquid crystal. Placing the liquid crystal on the optical fiber coupler increases the non-resonant scattering, whereas placing the liquid crystal away from the optical coupler increases the resonant scattering. Optical resonances blue and red shift due to the placement and removal of the liquid crystal.

  16. Tuning of optical resonances of a microsphere with liquid crystal

    OpenAIRE

    Serpengüzel, Ali; Yılmaz, Huzeyfe; Tamer, Mehmet Selman; Gürlü, Oğuzhan

    2011-01-01

    Optical resonances are observed in the elastic light scattering form high refractive index glass microspheres placed on a single mode optical fiber coupler and in a liquid crystal. Placing the liquid crystal on the optical fiber coupler increases the non-resonant scattering, whereas placing the liquid crystal away from the optical coupler increases the resonant scattering. Optical resonances blue and red shift due to the placement and removal of the liquid crystal.

  17. Passive ring resonator micro-optical gyroscopes

    Science.gov (United States)

    Venediktov, V. Yu; Filatov, Yu V.; Shalymov, E. V.

    2016-05-01

    This paper reviews recent advances in passive micro-optical gyroscopes. In the last decade, most research effort in the area of micro-optical gyros has been concentrated on a configuration that takes advantage of a single-mode passive ring resonator, which is usually fabricated using integrated optical technologies. The dimensions of such micro-optical gyros are comparable to those of micromechanical gyroscopes (area of 10 to 100 mm2) and their sensitivity is considerably better than the sensitivity of the latter, approaching that of fibre-optic and laser gyros. Moreover, microoptical gyros can be made as a single integrated circuit, like the micromechanical gyros, but they have no movable parts, in contrast to their micromechanical counterparts. We also describe the development and investigation of micro-optical gyros produced in our studies.

  18. Resonating properties of passive spherical optical microcavities

    Institute of Scientific and Technical Information of China (English)

    Wen Li(李文); Ruopeng Wang(王若鹏)

    2004-01-01

    As an optically pumped device, the lasing characteristics of a spherical microcavity laser depend on the optical pumping processes. These characteristics can be described in term of the Q factor and the optical field distribution in a microsphere. We derived analytical expressions and carried out numerical calculation for Q factor and optical field. The Q factor is found to be oscillatory functions of the radius of a microsphere and the pumping wavelength, and the pumping efficiency for a resonating microsphere is much higher than that for an anti-resonating microsphere. Using tunable lasers as pumping sources is suggested in order to achieve a higher pumping efficiency. Numerical calculation on optical field distribution in spherical microcavities shows that a well focused Gaussian beam is a suitable incident wave for cavity quantum electrodynamics experiments in which strong confinement of optical field in the center of a microsphere is requested, but higher order spherical wave should be used instead for exciting whispering-gallery-mode (WGM) microsphere lasers, for the purpose of favoring optical energy transferring to WGM in optical microspheres.

  19. Monolithic resonant optical reflector laser diodes

    Science.gov (United States)

    Hirata, T.; Suehiro, M.; Maeda, M.; Hihara, M.; Hosomatsu, H.

    1991-10-01

    The first monolithic resonant optical reflector laser diode that has a waveguide directional coupler and two DBR reflectors integrated by compositional disordering of quantum-well heterostructures is described. A linewidth of 440 kHz was obtained, and this value is expected to be greatly decreased by reducing the propagation loss in the integrated waveguide.

  20. Resonance spectra of diabolo optical antenna arrays

    Directory of Open Access Journals (Sweden)

    Hong Guo

    2015-10-01

    Full Text Available A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

  1. Temperature Sensors Based on WGM Optical Resonators

    Science.gov (United States)

    Savchenkov, Anatoliy; Yu, Nan; Maleki, Lute; Itchenko, Vladimir; Matsko, Andrey; Strekalov, Dmitry

    2008-01-01

    A proposed technique for measuring temperature would exploit differences between the temperature dependences of the frequencies of two different electromagnetic modes of a whispering gallery-mode (WGM) optical resonator. An apparatus based on this technique was originally intended to be part of a control system for stabilizing a laser frequency in the face of temperature fluctuations. When suitably calibrated, apparatuses based on this technique could also serve as precise temperature sensors for purposes other than stabilization of lasers. A sensor according to the proposal would include (1) a transparent WGM dielectric resonator having at least two different sets of modes characterized by different thermo-optical constants and (2) optoelectronic instrumentation for measuring the difference between the temperature-dependent shifts of the resonance frequencies of the two sets of modes.

  2. Resonance Raman Optical Activity and Surface Enhanced Resonance Raman Optical Activity analysis of Cytochrome C

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim; White, Peter C.

    2007-01-01

    High quality Resonance Raman (RR) and resonance Raman Optical Activity (ROA) spectra of cytochrome c were obtained in order to perform full assignment of spectral features of the resonance ROA spectrum. The resonance ROA spectrum of cytochrome c revealed a distinct spectral signature pattern due...... to resonance enhanced skeletal porphyrin vibrations, more pronounced than any contribution from the protein back-bone. Combining the intrinsic resonance enhancement of cytochrome c with surface plasmon enhancement by colloidal silver particles, the Surface Enhanced Resonance Raman Scattering (SERRS) and Chiral...... Enhanced Raman Spectroscopy (ChERS) spectra of the protein were successfully obtained at very low concentration (as low as 1 µM). The assignment of spectral features was based on the information obtained from the RR and resonance ROA spectra. Excellent agreement between RR and SERRS spectra is reported...

  3. Magnetic resonance imaging of optic nerve

    Directory of Open Access Journals (Sweden)

    Foram Gala

    2015-01-01

    Full Text Available Optic nerves are the second pair of cranial nerves and are unique as they represent an extension of the central nervous system. Apart from clinical and ophthalmoscopic evaluation, imaging, especially magnetic resonance imaging (MRI, plays an important role in the complete evaluation of optic nerve and the entire visual pathway. In this pictorial essay, the authors describe segmental anatomy of the optic nerve and review the imaging findings of various conditions affecting the optic nerves. MRI allows excellent depiction of the intricate anatomy of optic nerves due to its excellent soft tissue contrast without exposure to ionizing radiation, better delineation of the entire visual pathway, and accurate evaluation of associated intracranial pathologies.

  4. Enhanced energy storage in chaotic optical resonators

    KAUST Repository

    Liu, Changxu

    2013-05-05

    Chaos is a phenomenon that occurs in many aspects of contemporary science. In classical dynamics, chaos is defined as a hypersensitivity to initial conditions. The presence of chaos is often unwanted, as it introduces unpredictability, which makes it difficult to predict or explain experimental results. Conversely, we demonstrate here how chaos can be used to enhance the ability of an optical resonator to store energy. We combine analytic theory with ab initio simulations and experiments in photonic-crystal resonators to show that a chaotic resonator can store six times more energy than its classical counterpart of the same volume. We explain the observed increase by considering the equipartition of energy among all degrees of freedom of the chaotic resonator (that is, the cavity modes) and discover a convergence of their lifetimes towards a single value. A compelling illustration of the theory is provided by enhanced absorption in deformed polystyrene microspheres. © 2013 Macmillan Publishers Limited. All rights reserved.

  5. Doubly Resonant Optical Periodic Structure.

    Science.gov (United States)

    Alagappan, G; Png, C E

    2016-02-08

    Periodic structures are well known in various branches of physics for their ability to provide a stopband. In this article, using optical periodic structures we showed that, when a second periodicity--very closed to the original periodicity is introduced, large number of states appears in the stopband corresponding to the first periodicity. In the limit where the two periods matches, we have a continuum of states, and the original stopband completely disappears. This intriguing phenomena is uncovered by noticing that, regardless of the proximities of the two periodicities, there is an array of spatial points where the dielectric functions corresponding to the two periodicities interfere destructively. These spatial points mimic photonic atoms by satisfying the standards equations of quantum harmonic oscillators, and exhibit lossless, atom-like dispersions.

  6. Coupled Optical Resonance Laser Lockin

    CERN Document Server

    Burd, Shaun

    2013-01-01

    We have demonstrated simultaneous laser frequency stabilization of a UV and IR laser, to the same spectroscopic sample, by monitoring only the absorption of the UV laser. For trapping and cooling Yb$^{+}$ ions, a frequency stabilized laser is required at 369.95nm to drive the $^{2}S_{1/2}$ $ \\rightarrow $ $ ^{2}P_{1/2}$ cooling transition. Since the cycle is not closed, a 935.18nm laser is needed to drive the $^{2}D_{3/2}$ $\\rightarrow$ $^{3}D_{[3/2]1/2}$ transition which is followed by rapid decay to the $^{2}S_{1/2}$ state. Our 369nm laser is locked to Yb$^{+}$ ions generated in a hollow cathode discharge lamp using saturated absorption spectroscopy. Without pumping, the metastable $^{2}D_{3/2}$ level is only sparsely populated and direct absorption of 935nm light is difficult to detect. A resonant 369nm laser is able to significantly populate the $^{2}D_{3/2}$ state due to the coupling between the levels. Fast re-pumping to the $^{2}S_{1/2}$ state, by 935nm light, can be detected by observing the change in...

  7. Time-dependent resonant magneto-optical rotation

    CERN Document Server

    Dziczek, Dariusz

    2015-01-01

    Results of a fairly straightforward experiment on resonant magneto-optical rotation by rubidium-87 atoms revealed strong time-dependence of the polarization plane of light emerging from atomic vapors following a sudden irradiation with a laser beam. The rotation of the plane appears as a not direct consequence of the influence of the magnetic field on atoms. Reported measurements conducted using a vapor cell without any buffer gas or an anti-relaxation wall coating show that transmitted light has initially the same (linear) polarization as the incident one. Rotation of the polarization plane caused by an axial magnetic field develops in time scales similar to the pace of establishing the optical pumping/relaxation equilibrium in the atomic ensemble. The traditional passive Faraday rotation picture providing working description for the resonant magneto-optical effects in steady-state conditions does not explain the observed sequence of evolution of the polarization. The picture has to be augmented with analysi...

  8. Extraordinary transmission in optical Helmholtz resonators.

    Science.gov (United States)

    Chevalier, Paul; Bouchon, Patrick; Sakat, Emilie; Pelouard, Jean-Luc; Pardo, Fabrice; Haïdar, Riad

    2015-06-15

    Optical Helmholtz resonators (OHRs) have been adapted from acoustics designs for light absorbing structures, exhibiting extreme light confinement. Here, extraordinary transmission of light is theoretically demonstrated through symmetric OHRs, comprising a cavity with two λ/500 narrow slits on either side. This device has appealing features to act as a spectral bandpass filter in the context of multispectral imaging, in particular its high angular tolerance because of the localized nature of the resonance. Besides, the cavity can be modeled as an inductor and the two slits can be modeled as capacitors, the whole design acting as a LC circuit thus preventing any harmonic features.

  9. Optical isolation via unidirectional resonant photon tunneling

    CERN Document Server

    Moccia, Massimo; Galdi, Vincenzo; Alu', Andrea; Engheta, Nader

    2013-01-01

    We show that tri-layer structures combining epsilon-negative and magneto-optical material layers can exhibit unidirectional resonant photon tunneling phenomena that can discriminate between circularly-polarized (CP) waves of given handedness impinging from opposite directions, or between CP waves with different handedness impinging from the same direction. This physical principle may be utilized to design compact optical isolators for CP waves. Within this framework, we derive simple analytical conditions and design formulae, and quantitatively assess the isolation performance, also taking into account the unavoidable imperfections and nonidealities.

  10. Passive optical resonator for OSQAR LSW experiment

    Science.gov (United States)

    Kunc, Š.; Messineo, G.; Schott, M.; Šulc, M.

    2016-11-01

    This paper treats the issue of locking a solid state laser, pumped by high power diodes (Verdi V5), to a twenty meter long optical resonator for OSQAR LSW - light shining through the wall, dark matter search experiment. In this paper the optical design and a possible locking scheme are presented. The environmental conditions in SM18 testing hall at CERN, where OSQAR experiment is based, are discussed. The main focus is put on the vibration analysis, cavity transversal modes behaviour, possible clipping in the anticryostat of LHC - Large Hadron Collider magnet bore and locking loop parameters required for future experimental testing. The expected finesse of resonator will be presented and discussed in the sense of OSQAR LSW; its impact on possible new exclusion limits is discussed.

  11. Rydberg optical Feshbach resonances in cold gases

    CERN Document Server

    Sándor, Nóra; Julienne, Paul S; Pupillo, Guido

    2016-01-01

    We propose a novel scheme to efficiently tune the scattering length of two colliding ground-state atoms by off-resonantly coupling the scattering-state to an excited Rydberg-molecular state using laser light. For the s-wave scattering of two colliding ${^{87}}\\mathrm{Rb}$ atoms, we demonstrate that the effective optical length and pole strength of this Rydberg optical Feshbach resonance can be tuned over several orders of magnitude, while incoherent processes and losses are minimised. Given the ubiquity of Rydberg molecular states, this technique should be generally applicable to homo-nuclear atomic pairs as well as to atomic mixtures with s-wave (or even p-wave) scattering.

  12. Ionic Coulomb Blockade and Resonant Conduction in Biological Ion Channels

    CERN Document Server

    Kaufman, I Kh; Eisenberg, R S

    2014-01-01

    The conduction and selectivity of calcium/sodium ion channels are described in terms of ionic Coulomb blockade, a phenomenon based on charge discreteness and an electrostatic model of an ion channel. This novel approach provides a unified explanation of numerous observed and modelled conductance and selectivity phenomena, including the anomalous mole fraction effect and discrete conduction bands. Ionic Coulomb blockade and resonant conduction are similar to electronic Coulomb blockade and resonant tunnelling in quantum dots. The model is equally applicable to other nanopores.

  13. Resonant Optical Absorption in Semiconductor Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    YU Li-Yuan; CAO Jun-Cheng

    2004-01-01

    @@ We have calculated the intraband photon absorption coefficients of hot two-dimensional electrons interacting with polar-optical phonon modes in quantum wells. The dependence of the photon absorption coefficients on the photon wavelength λ is obtained both by using the quantum mechanical theory and by the balance-equation theory. It is found that the photon absorption spectrum displays a local resonant maximum, corresponding to LO energy, and the absorption peak vanishes with increasing the electronic temperature.

  14. Optical microfiber coil resonator refractometric sensor.

    Science.gov (United States)

    Xu, Fei; Horak, Peter; Brambilla, Gilberto

    2007-06-11

    We present a novel refractometric sensor based on a coated all-coupling optical-fiber-nanowire microcoil resonator which is robust, compact, and comprises an intrinsic fluidic channel. We calculate the device sensitivity and find its dependence on the nanowire diameter and coating thickness. A sensitivity as high as 700 nm/RIU and a refractive index resolution as low as 10(-10) are predicted.

  15. Ammonia Optical Sensing by Microring Resonators

    Science.gov (United States)

    Passaro, Vittorio M. N.; Dell'Olio, Francesco; De Leonardis, Francesco

    2007-01-01

    A very compact (device area around 40 μm2) optical ammonia sensor based on a microring resonator is presented in this work. Silicon-on-insulator technology is used in sensor design and a dye doped polymer is adopted as sensing material. The sensor exhibits a very good linearity and a minimum detectable refractive index shift of sensing material as low as 8×10-5, with a detection limit around 4 ‰.

  16. Optical trapping apparatus, methods and applications using photonic crystal resonators

    Science.gov (United States)

    Erickson, David; Chen, Yih-Fan

    2015-06-16

    A plurality of photonic crystal resonator optical trapping apparatuses and a plurality optical trapping methods using the plurality of photonic crystal resonator optical trapping apparatuses include located and formed over a substrate a photonic waveguide that is coupled (i.e., either separately coupled or integrally coupled) with a photonic crystal resonator. In a particular embodiment, the photonic waveguide and the photonic crystal resonator comprise a monocrystalline silicon (or other) photonic material absent any chemical functionalization. In another particular embodiment, the photonic waveguide and the photonic crystal resonator comprise a silicon nitride material which when actuating the photonic crystal resonator optical trapping apparatus with a 1064 nanometer resonant photonic radiation wavelength (or other resonant photonic radiation wavelength in a range from about 700 to about 1200 nanometers) provides no appreciable heating of an aqueous sample fluid that is analyzed by the photonic crystal resonator optical trapping apparatus.

  17. Piezoelectric resonators with mechanical damping and resistance in current conduction

    Institute of Scientific and Technical Information of China (English)

    Yook-Kong; YONG; Mihir; S; PATEL

    2007-01-01

    A novel design method for high Q piezoelectric resonators was presented and proposed using the 3-D equations of linear piezoelectricity with quasi-electrostatic approximation which include losses attributed to mechanical damping in solid and resistance in current conduction. There is currently no finite element software for estimating the Q of a resonator without apriori assumptions of the resonator impedance or damping. There is a necessity for better and more realistic modeling of resonators and filters due to miniaturization and the rapid advances in frequency ranges in telecommunication.We presented new three-dimensional finite element models of quartz and barium titanate resonators with mechanical damping and resistance in current conduction. Lee, Liu and Ballato's 3-D equations of linear piezoelectricity with quasi-electro- static approximation which include losses attributed to mechanical damping in solid and resistance in current conduction were formulated in a weak form and implemented in COMSOL. The resulting finite element model could predict the Q and other electrical parameters for any piezoelectric resonator without apriori assumptions of damping or resistance. Forced and free vibration analyses were performed and the results for the Q and other electrical parameters were obtained. Comparisons of the Q and other electrical parameters obtained from the free vibration analysis with their corresponding values from the forced vibration analysis were found to be in excellent agreement. Hence, the frequency spectra obtained from the free vibration analysis could be used for designing high Q resonators. Results for quartz thickness shear AT-cut and SC-cut resonators and thickness stretch poled barium titanate resonators were presented. An unexpected benefit of the model was the prediction of resonator Q with energy losses via the mounting supports.

  18. Optical racetrack resonator transduction of nanomechanical cantilevers.

    Science.gov (United States)

    Sauer, V T K; Diao, Z; Freeman, M R; Hiebert, W K

    2014-02-07

    Optomechanical transduction has demonstrated its supremacy in probing nanomechanical displacements. In order to apply nano-optomechanical systems (NOMS) as force and mass sensors, knowledge about the transduction responsivity (i.e. the change in measured optical transmission with nanomechanical displacement) and its tradeoffs with system design is paramount. We compare the measured responsivities of NOMS devices with varying length, optomechanical coupling strength gom, and optical cavity properties. Cantilever beams 1.5 to 5 μm long are fabricated 70 to 160 nm from a racetrack resonator optical cavity and their thermomechanical (TM) noise signals are measured. We derive a generic expression for the transduction responsivity of the NOMS in terms of optical and mechanical system parameters such as finesse, optomechanical coupling constant, and interaction length. The form of the expression holds direct insight as to how these parameters affect the responsivity. With this expression, we obtain the optomechanical coupling constants using only measurements of the TM noise power spectra and optical cavity transmission slopes. All optical pump/probe operation is also demonstrated in our side-coupled cantilever-racetrack NOMS. Finally, to assess potential operation in a gas sensing environment, the TM noise signal of a device is measured at atmospheric pressure.

  19. Optically detected cyclotron resonance in a single GaAs/AlGaAs heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, Gregor

    2011-09-23

    Optically detected far-infrared cyclotron resonance (FIR-ODCR) in GaAs/AlGaAs HJs is interpreted in the frame of an exciton-dissociation mechanism. It is possible to explain the ODR mechanism by an exciton drag, mediated by ballistically propagating phonons. Furthermore, very narrow resonances are presented and realistic electron mobility values can be calculated. The exceptionally narrow ODCRs allow to measure conduction-band nonparabolicity effects and resolve satellite resonances, close to the main cyclotron resonance line.

  20. Resonant optical devices for IR lasers

    Science.gov (United States)

    Johnson, Eric G.; Li, Yuan; Raghu Srimathi, Indumathi; Woodward, Ryan H.; Poutous, Menelaos K.; Pung, Aaron J.; Richardson, Martin; Shah, Lawrence; Shori, Ramesh; Magnusson, Robert

    2013-03-01

    This paper highlights recent developments in resonant optical devices for infrared (IR) and mid-infrared (mid- IR) lasers. Sub-wavelength grating based resonant optical filters are introduced and their application in 2 μm thulium fiber laser and amplifier systems has been discussed. The paper focuses on applying such filtering techniques to 2.8 μm mid-IR fiber laser systems. A narrowband mid-IR Guided-Mode Resonance Filter (GMRF) was designed and fabricated using Hafnium(IV) Oxide film/quartz wafer material system. The fabricated GMRF was then integrated into an Erbium (Er)-doped Zr-Ba-La-Al-Na (ZBLAN) fluoride glass fiber laser as a wavelength selective feedback element. The laser operated at 2782 nm with a linewidth less than 2 nm demonstrating the viability of GMRF's for wavelength selection in the mid-IR. Furthermore, a GMRF of narrower linewidth based on Aluminum Oxide/quartz wafer material system is fabricated and tested in the same setup. The potentials and challenges with GMRFs will be discussed and summarized.

  1. Optical Conductivity of Anisotropic Quantum Dots in Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    GUO Kang-Xian; CHEN Chuan-Yu

    2005-01-01

    @@ Optical conductivity of anisotropic double-parabolic quantum dots is investigated with the memory-function approach, and the analytic expression for the optical conductivity is derived. With characteristic parameterspertaining to GaAs, the numerical results are presented. It is shown that: (1) the larger the optical phonon frequency ωLO, the stronger the peak intensity of the optical conductivity, and the more asymmetric the shape of the optical conductivity; (2) the magnetic field enhances the optical conductivity for levels l = 0 and l = 1, with or without electron-LO-phonon interactions; (3) the larger the quantum dot thickness lz, the smaller the optical conductivity σ(ω).

  2. Silicon single-crystal cryogenic optical resonator.

    Science.gov (United States)

    Wiens, Eugen; Chen, Qun-Feng; Ernsting, Ingo; Luckmann, Heiko; Rosowski, Ulrich; Nevsky, Alexander; Schiller, Stephan

    2014-06-01

    We report on the demonstration and characterization of a silicon optical resonator for laser frequency stabilization, operating in the deep cryogenic regime at temperatures as low as 1.5 K. Robust operation was achieved, with absolute frequency drift less than 20 Hz over 1 h. This stability allowed sensitive measurements of the resonator thermal expansion coefficient (α). We found that α=4.6×10(-13)  K(-1) at 1.6 K. At 16.8 K α vanishes, with a derivative equal to -6×10(-10)  K(-2). The temperature of the resonator was stabilized to a level below 10 μK for averaging times longer than 20 s. The sensitivity of the resonator frequency to a variation of the laser power was also studied. The corresponding sensitivities and the expected Brownian noise indicate that this system should enable frequency stabilization of lasers at the low-10(-17) level.

  3. Dynamic nonlinear thermal optical effects in coupled ring resonators

    Directory of Open Access Journals (Sweden)

    Chenguang Huang

    2012-09-01

    Full Text Available We investigate the dynamic nonlinear thermal optical effects in a photonic system of two coupled ring resonators. A bus waveguide is used to couple light in and out of one of the coupled resonators. Based on the coupling from the bus to the resonator, the coupling between the resonators and the intrinsic loss of each individual resonator, the system transmission spectrum can be classified by three different categories: coupled-resonator-induced absorption, coupled-resonator-induced transparency and over coupled resonance splitting. Dynamic thermal optical effects due to linear absorption have been analyzed for each category as a function of the input power. The heat power in each resonator determines the thermal dynamics in this coupled resonator system. Multiple “shark fins” and power competition between resonators can be foreseen. Also, the nonlinear absorption induced thermal effects have been discussed.

  4. Coupled-channels optical calculation of positron-hydrogen resonances

    Institute of Scientific and Technical Information of China (English)

    Yu Rong-Mei; Zhou Ya-Jun; Jiao Li-Guang; Cheng Yong-Jun

    2012-01-01

    An application of the coupled-channels optical method is given for the energy-dependent phenomena of positronhydrogen resonances below the n =2 excitation threshold.The equivalent local optical potential is used to account for the target polarization and positronium formation.The calculation includes 9 explicitly physical coupled channels.The lowest S-wave resonance energy position and new resonances are found.Angular dependence of the cross section in the resonance region are investigated.

  5. Ray and wave chaos in asymmetric resonant optical cavities

    CERN Document Server

    Nöckel, J U; Noeckel, Jens U.

    1998-01-01

    Optical resonators are essential components of lasers and other wavelength-sensitive optical devices. A resonator is characterized by a set of modes, each with a resonant frequency omega and resonance width Delta omega=1/tau, where tau is the lifetime of a photon in the mode. In a cylindrical or spherical dielectric resonator, extremely long-lived resonances are due to `whispering gallery' modes in which light circulates around the perimeter trapped by total internal reflection. These resonators emit light isotropically. Recently, a new category of asymmetric resonant cavities (ARCs) has been proposed in which substantial shape deformation leads to partially chaotic ray dynamics. This has been predicted to give rise to a universal, frequency-independent broadening of the whispering-gallery resonances, and highly anisotropic emission. Here we present solutions of the wave equation for ARCs which confirm many aspects of the earlier ray-optics model, but also reveal interesting frequency-dependent effects charac...

  6. Resonance-induced sensitivity enhancement method for conductivity sensors

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Shih, Chi-yuan (Inventor); Li, Wei (Inventor); Zheng, Siyang (Inventor)

    2009-01-01

    Methods and systems for improving the sensitivity of a variety of conductivity sensing devices, in particular capacitively-coupled contactless conductivity detectors. A parallel inductor is added to the conductivity sensor. The sensor with the parallel inductor is operated at a resonant frequency of the equivalent circuit model. At the resonant frequency, parasitic capacitances that are either in series or in parallel with the conductance (and possibly a series resistance) is substantially removed from the equivalent circuit, leaving a purely resistive impedance. An appreciably higher sensor sensitivity results. Experimental verification shows that sensitivity improvements of the order of 10,000-fold are possible. Examples of detecting particulates with high precision by application of the apparatus and methods of operation are described.

  7. Measurement of optical Feshbach resonances in an ideal gas.

    Science.gov (United States)

    Blatt, S; Nicholson, T L; Bloom, B J; Williams, J R; Thomsen, J W; Julienne, P S; Ye, J

    2011-08-12

    Using a narrow intercombination line in alkaline earth atoms to mitigate large inelastic losses, we explore the optical Feshbach resonance effect in an ultracold gas of bosonic (88)Sr. A systematic measurement of three resonances allows precise determinations of the optical Feshbach resonance strength and scaling law, in agreement with coupled-channel theory. Resonant enhancement of the complex scattering length leads to thermalization mediated by elastic and inelastic collisions in an otherwise ideal gas. Optical Feshbach resonance could be used to control atomic interactions with high spatial and temporal resolution.

  8. Synthetic gauge fields for light beams in optical resonators

    CERN Document Server

    Longhi, Stefano

    2015-01-01

    A method to realize artificial magnetic fields for light waves trapped in passive optical cavities with anamorphic optical elements is theoretically proposed. In particular, when a homogeneous magnetic field is realized, a highly-degenerate Landau level structure for the frequency spectrum of the transverse resonator modes is obtained, corresponding to a cyclotron motion of the optical cavity field. This can be probed by transient excitation of the passive optical resonator.

  9. Optical cavity resonator in an expanding universe

    Science.gov (United States)

    Kopeikin, Sergei M.

    2015-02-01

    We study the cosmological evolution of frequency of a standing electromagnetic wave in a resonant optical cavity placed to the expanding manifold described by the Robertson-Walker metric. Because of the Einstein principle of equivalence (EEP), one can find a local coordinate system (a local freely falling frame), in which spacetime is locally Minkowskian. However, due to the conformal nature of the Robertson-Walker metric the conventional transformation to the local inertial coordinates introduces ambiguity in the physical interpretation of the local time coordinate, . Therefore, contrary to a common-sense expectation, a straightforward implementation of EEP alone does not allow us to unambiguously decide whether atomic clocks based on quantum transitions of atoms, ticks at the same rate as the clocks based on electromagnetic modes of a cavity. To resolve this ambiguity we have to analyse the cavity rigidity and the oscillation of its electromagnetic modes in an expanding universe by employing the full machinery of the Maxwell equations irrespectively of the underlying theory of gravity. We proceed in this way and found out that the size of the cavity and the electromagnetic frequency experience an adiabatic drift in conformal (unphysical) coordinates as the universe expands in accordance with the Hubble law. We set up the oscillation equation for the resonant electromagnetic modes, solve it by the WKB approximation, and reduce the coordinate-dependent quantities to their counterparts measured by a local observer who counts time with atomic clock. The solution shows that there is a perfect mutual cancellation of the adiabatic drift of cavity's frequency by space transformation to local coordinates and the time counted by the clocks based on electromagnetic modes of cavity has the same rate as that of atomic clocks. We conclude that if general relativity is correct and the local expansion of space is isotropic there should be no cosmological drift of frequency of a

  10. Center mode of a doubly resonant optical periodic structure

    Science.gov (United States)

    Alagappan, G.; Png, C. E.

    2016-07-01

    An optical periodic structure with a single spatial resonance exhibits a stopband. When a second spatial resonance very close to the first one is added, the resulting doubly resonant structure exhibits a Gaussian enveloped, high quality factor transmission state right at the center of the original stopband. Using a slowly varying envelope approximation, we describe the optical characteristics of this transmission state analytically. The transmission state exists despite an optical structure of low refractive index contrast, and has potential applications in nano-optics, and photonics.

  11. Resonance frequency shift in a cavity with a thin conducting film near a conducting wall

    Energy Technology Data Exchange (ETDEWEB)

    Braggio, C. [Dipartimento di Fisica, Universita di Ferrara and INFN, Via del Paradiso 12, 44100 Ferrara (Italy)]. E-mail: caterina.braggio@lnl.infn.it; Bressi, G. [INFN, Sezione di Pavia, Via Bassi 6, 27100 Pavia (Italy); Carugno, G. [INFN, Sezione di Padova, Via F. Marzolo 8, 35131 Padova (Italy); Dodonov, A.V. [Departamento de Fisica, Universidade Federal de Sao Carlos, Via Washington Luiz, Km 235, Sao Carlos 13565-905, SP (Brazil); Dodonov, V.V. [Instituto de Fisica, Universidade de Brasilia, Caixa Postal 04455, 70910-900 Brasilia, DF (Brazil)]. E-mail: vdodonov@fis.unb.br; Galeazzi, G. [INFN, LNL, Viale dell' Universita 2, 35020 Legnaro (Italy); Ruoso, G. [INFN, LNL, Viale dell' Universita 2, 35020 Legnaro (Italy); Zanello, D. [INFN, Sezione di Roma, Piazzale A. Moro 2, 00185 Roma (Italy)

    2007-03-19

    We show that a very thin conducting film (whose thickness can be much smaller than the skin depth), placed nearby a wall of an electromagnetic cavity, can produce the same shift of the resonance frequency as a bulk conducting slab, provided the displacement of the film from the wall is much bigger than the skin depth. We derive a simple analytical formula for the frequency shift and compare it with exact numerical calculations and experimental data.

  12. Optical sensors of bulk refractive index using optical fiber resonators

    Science.gov (United States)

    Eryürek, M.; Karadag, Y.; Ghafoor, M.; Bavili, N.; Cicek, K.; Kiraz, A.

    2017-05-01

    Optical fiber resonator (OFR) sensor is presented for bulk liquid refractive index (RI) sensing. The sensing mechanism relies on the spectral shifts of whispering gallery modes (WGMs) of OFRs which are excited using a tapered fiber. OFR liquid RI sensor is fully characterized using water solutions of ethanol and ethylene glycol (EG). A good agreement is achieved between the analytical calculations and experimental results for both TE and TM polarizations. The detection limit for bulk RI is calculated to be between 2.7 - 4.7 × 10-5 refractive index unit (RIU). The OFR sensor provides a robust, easy-to-fabricate and sensitive liquid refractive index sensor which can be employed in lab-on-a-chip applications.

  13. Unstable optical resonator loss calculations using the prony method.

    Science.gov (United States)

    Siegman, A E; Miller, H Y

    1970-12-01

    The eigenvalues for all the significant low-order resonant modes of an unstable optical resonator with circular mirrors are computed using an eigenvalue method called the Prony method. A general equivalence relation is also given, by means of which one can obtain the design parameters for a single-ended unstable resonator of the type usually employed in practical lasers, from the calculated or tabulated values for an equivalent symmetric or double-ended unstable resonator.

  14. Demonstration of sharp multiple Fano resonances in optical metamaterials.

    Science.gov (United States)

    Moritake, Yuto; Kanamori, Yoshiaki; Hane, Kazuhiro

    2016-05-01

    We experimentally demonstrated multiple Fano resonances in optical metamaterials. By combination of two different sized asymmetric-double-bar (ADB) structures, triple Fano resonance was observed in the near-infrared region. In addition to Fano resonance due to anti-phase modes in isolated ADB structures, an anti-phase mode due to coupling among different sized ADBs was observed. Dependence of characteristics of resonances on size difference was also investigated. At specific conditions of size difference, quality factors of three Fano resonances were improved compared with ADB metamaterials consisting of one kind of ADBs. The results will help to realize applications using metamaterial resonators with multiple functionalities and high performance.

  15. Low-Loss Polymer-Based Ring Resonator for Resonant Integrated Optical Gyroscopes

    Directory of Open Access Journals (Sweden)

    Guang Qian

    2014-01-01

    Full Text Available Waveguide ring resonator is the sensing element of resonant integrated optical gyroscope (RIOG. This paper reports a polymer-based ring resonator with a low propagation loss of about 0.476 dB/cm for RIOG. The geometrical parameters of the waveguide and the coupler of the resonator were optimally designed. We also discussed the optical properties and gyroscope performance of the polymer resonator which shows a high quality factor of about 105. The polymer-based RIOG exhibits a limited sensitivity of less than 20 deg/h for the low and medium resolution navigation systems.

  16. Geometrically Protected Resonance Modes and Optical Fano Resonances

    CERN Document Server

    Regan, Emma C; Lopez, Josue J; Hsu, Chia Wei; Zhen, Bo; Joannopoulos, John D; Soljacic, Marin

    2015-01-01

    Traditionally, photonic crystal slabs can support resonances that are strongly confined to the slab but also couple to external radiation. However, when a photonic crystal slab is placed on a substrate, the resonance modes become less confined, and as the index contrast between slab and substrate decreases, they eventually disappear. Using the scale structure of the Dione Juno butterfly wing as an inspiration, we present a low-index zigzag surface structure that supports resonance modes even without index contrast with the substrate. The zigzag structure supports resonances that are contained away from the substrate; this geometrically protects the modes from coupling to the substrate. We experimentally verify the protected resonance property of the zigzag structure in the visible wavelength regime. Potential applications include substrate-independent structural color and light guiding.

  17. Optical cavity resonator in an expanding universe

    CERN Document Server

    Kopeikin, Sergei

    2014-01-01

    We study evolution of frequency of a standing electromagnetic (EM) wave in a resonant optical cavity placed to the expanding manifold described by the Robertson-Walker metric. One builds a local coordinate system in which spacetime is locally Minkowskian. However, due to the conformal nature of the Robertson-Walker metric the conventional transformation to the local inertial coordinates introduces ambiguity in the physical interpretation of the local time coordinate. Therefore, contrary to a common-sense expectation, a straightforward implementation of EEP alone does not allow us to decide whether atomic clocks ticks at the same rate as the clocks based on EM modes of a cavity. To resolve the ambiguity we analyzed the cavity rigidity and the oscillation of its EM modes in an expanding universe by employing the Maxwell equations. We found out that both the size of the cavity and the EM frequency experience an adiabatic drift in conformal coordinates as the universe expands. We set up the oscillation equation f...

  18. Optical wavelength conversion via optomechanical coupling in a silica resonator

    CERN Document Server

    Dong, Chunhua; Kuzyk, Mark C; Tian, Lin; Wang, Hailin

    2012-01-01

    We report the experimental demonstration of converting coherent optical fields between two different optical wavelengths by coupling two optical modes to a mechanical breathing mode in a silica resonator. The experiment is based on an itinerant approach, in which state-mapping from optical to mechanical and from mechanical to another optical state takes place simultaneously. In contrast to conventional nonlinear optical processes, optomechanical impedance matching as well as efficient optical input-output coupling, instead of phase-matching, plays a crucial role in optomechanics-based wavelength conversion.

  19. The role of the plasmon resonance for enhanced optical forces

    Science.gov (United States)

    Ploschner, Martin

    Optical manipulation of nanoscale objects is studied with particular emphasis on the role of plasmon resonance for enhancement of optical forces. The thesis provides an introduction to plasmon resonance and its role in confinement of light to a sub-diffraction volume. The strong light confinement and related enhancement of optical forces is then theoretically studied for a special case of nanoantenna supporting plasmon resonances. The calculation of optical forces, based on the Maxwell stress tensor approach, reveals relatively weak optical forces for incident powers that are used in typical realisations of trapping with nanoantenna. The optical forces are so weak that other non-optical effects should be considered to explain the observed trapping. These effects include heating induced convection, thermoporesis and chemical binding. The thesis also studies the optical effects of plasmon resonances for a fundamentally different application - size-based optical sorting of gold nanoparticles. Here, the plasmon resonances are not utilised for sub-diffraction light confinement but rather for their ability to increase the apparent cross-section of the particles for their respective resonant sizes. Exploiting these resonances, we realise sorting in a system of two counter-propagating evanescent waves, each at different wavelength that selectively guide gold nanoparticles of different sizes in opposite directions. The method is experimentally demonstrated for bidirectional sorting of gold nanoparticles of either 150 or 130 nm in diameter from those of 100 nm in diameter within a mixture. We conclude the thesis with a numerical study of the optimal beam-shape for optical sorting applications. The developed theoretical framework, based on the force optical eigenmode method, is able to find an illumination of the back-focal plane of the objective such that the force difference between nanoparticles of various sizes in the sample plane is maximised.

  20. Nonlinear and quantum optics with whispering gallery resonators

    Science.gov (United States)

    Strekalov, Dmitry V.; Marquardt, Christoph; Matsko, Andrey B.; Schwefel, Harald G. L.; Leuchs, Gerd

    2016-12-01

    Optical whispering gallery modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon has a rather general nature, equally applicable to sound and all other waves. It enables resonators of unique properties attractive both in science and engineering. Very high quality factors of optical WGM resonators persisting in a wide wavelength range spanning from radio frequencies to ultraviolet light, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.

  1. Optical wavelength conversion via optomechanical coupling in a silica resonator

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Chunhua; Fiore, Victor; Kuzyk, Mark C.; Wang, Hailin [Department of Physics, University of Oregon, Eugene, OR (United States); Tian, Lin [University of California, Merced, CA (United States)

    2015-01-01

    In an optomechanical resonator, an optically active mechanical mode can couple to any of the optical resonances via radiation pressure. This unique property can enable a remarkable phenomenon: conversion of optical fields via optomechanical coupling between vastly different wavelengths. Here we expand an earlier experimental study [Science 338, 1609 (2012)] on classical wavelength conversion of coherent optical fields by coupling two optical modes to a mechanical breathing mode in a silica resonator. Heterodyne detection of the converted optical fields shows that the wavelength conversion process is coherent and bidirectional. The conversion efficiency obtained features a distinct saturation behavior that arises from optomechanical impedance matching. A measurement of the coherent mechanical excitation involved in the wavelength conversion process also provides additional insight on the underlying optomechanical interactions. (copyright 2014 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Microwave-to-Optical Conversion in WGM Resonators

    Science.gov (United States)

    Savchenkov, Anatoliy; Strekalov, Dmitry; Yu, Nan; Matsko, Andrey; Maleki, Lute

    2008-01-01

    Microwave-to-optical frequency converters based on whispering-gallery-mode (WGM) resonators have been proposed as mixers for the input ends of microwave receivers in which, downstream of the input ends, signals would be processed photonically. A frequency converter as proposed (see figure) would exploit the nonlinearity of the electromagnetic response of a WGM resonator made of LiNbO3 or another suitable ferroelectric material. Up-conversion would take place by three-wave mixing in the resonator. The WGM resonator would be de - signed and fabricated to obtain (1) resonance at both the microwave and the optical operating frequencies and (2) phase matching among the input and output microwave and optical signals as described in the immediately preceding article. Because the resonator would be all dielectric there would be no metal electrodes signal losses would be very low and, consequently, the resonance quality factors (Q values) of the microwave and optical fields would be very large. The long lifetimes associated with the large Q values would enable attainment of high efficiency of nonlinear interaction with low saturation power. It is anticipated that efficiency would be especially well enhanced by the combination of optical and microwave resonances in operation at input signal frequencies between 90 and 300 GHz.

  3. Optical conductivity of ABA-stacked trilayer graphene

    Institute of Scientific and Technical Information of China (English)

    Zhu Guo-Bao; Zhang Peng

    2013-01-01

    The optical conductivity of a trilayer graphene is studied using the Kubo-Greenwood formula.We calculate the real part of the diagonal optical conductivity of an ABA-stacked trilayer graphene with different Fermi energies.The optical conductivity arises from interband matrix elements of the electric current operator involving the transitions from the occupied states to the unoccupied ones.We study the dependence of the real part of the diagonal optical conductivity on the photon energy,and the role of the transitions.

  4. Optical Conductivity of Graphene Sheet Including Electron-Phonon Interaction

    Institute of Scientific and Technical Information of China (English)

    Hamze Mousavi

    2012-01-01

    Using an expression of optical conductivity, based on the linear response theory, the Green's function technique and within the Holstein Hamiltonian model, the effect of electron-phonon interaction on the optical conductivity of graphene plane is studied. It is found that the electron-phonon coupling increases the optical conductivity of graphene sheet in the low frequency region due to decreasing quasiparticle weight of electron excitation while the optical conductivity reduces in the high frequency region. The latter is due to role of electrical field's frequency.

  5. Characterization of optical quantum circuits using resonant phase shifts

    CERN Document Server

    Poot, Menno

    2016-01-01

    We demonstrate that important information about linear optical circuits can be obtained through the phase shift induced by integrated optical resonators. As a proof of principle, the phase of an unbalanced Mach-Zehnder interferometer is determined. Then the method is applied to a complex optical circuit designed for linear optical quantum computation. In this controlled-NOT gate with qubit initialization and tomography stages, the relative phases are determined as well as the coupling ratios of its directional couplers.

  6. All-optical gates based on photonic crystal resonators

    Science.gov (United States)

    Moille, Grégory; De Rossi, Alfredo; Combrié, Sylvain

    2016-04-01

    We briefly review the technology of advanced nonlinear resonators for all-optical gating with a specific focus on the application of high-performance signal sampling and on the properties of III-V semiconductor photonic crystals

  7. An embedded optical nanowire loop resonator refractometric sensor.

    Science.gov (United States)

    Xu, Fei; Pruneri, Valerio; Finazzi, Vittoria; Brambilla, Gilberto

    2008-01-21

    A novel refractometric sensor based on an embedded optical nanowire loop resonator is presented. The device sensitivity has been studied in two typical configurations and its dependence on the nanowire diameter and coating thickness determined.

  8. Resonator chains of 2-D square dielectric optical microcavities

    NARCIS (Netherlands)

    Lohmeyer, Manfred

    2008-01-01

    Chains of coupled square dielectric cavities are investigated. Resonant transfer of optical power can be achieved along quite arbitrary, moderately long rectangular paths, even with individual standing-wave resonators of limited quality. We introduce an ab-initio coupled mode model that helps to int

  9. Optical combs with a crystalline whispering gallery mode resonator

    CERN Document Server

    Savchenkov, Anatoliy A; Ilchenko, Vladimir S; Solomatine, Iouri; Seidel, David; Maleki, Lute

    2008-01-01

    We report on the experimental demonstration of a tunable monolithic optical frequency comb generator. The device is based on the four-wave mixing in a crystalline calcium fluoride whispering gallery mode resonator. The frequency spacing of the comb is given by an integer number of the free spectral range of the resonator. We select the desired number by tuning the pumping laser frequency with respect to the corresponding resonator mode. We also observe interacting optical combs and high-frequency hyperparametric oscillation, depending on the experimental conditions. A potential application of the comb for generating narrowband frequency microwave signals is demonstrated.

  10. Ring resonator systems to perform optical communication enhancement using soliton

    CERN Document Server

    Amiri, Iraj Sadegh

    2014-01-01

    The title explain new technique of secured and high capacity optical communication signals generation by using the micro and nano ring resonators. The pulses are known as soliton pulses which are more secured due to having the properties of chaotic and dark soliton signals with ultra short bandwidth. They have high capacity due to the fact that ring resonators are able to generate pulses in the form of solitons in multiples and train form. These pulses generated by ring resonators are suitable in optical communication due to use the compact and integrated rings system, easy to control, flexibi

  11. HCMT models of optical microring-resonator circuits

    NARCIS (Netherlands)

    Lohmeyer, Manfred

    2010-01-01

    Circuits of dielectric integrated optical microring resonators are addressed through a two-dimensional hybrid analytical/numerical coupled mode theory (HCMT) model. Analytical modes of all straight and curved cores form templates for the optical fields of the entire circuits. Our variational techniq

  12. General Theoretical Model for Resonantly Enhanced Optical Modulators

    Institute of Scientific and Technical Information of China (English)

    Yuvaraja; S.; Visagathilagar; Arnan; Mitchell; Michael; W.; Austin

    2003-01-01

    1 IntroductionLiNbO3 optical modulators have become essential transmission devices for current and future wideband fibre-optic communications for both military and telecommunications applications. For many telecommunications applications, only a narrow bandwidth is required and thus resonantly enhancedMach-Zehndermodulators(RE-MZMs)have been developed to improve modulation efficiency at the expense of bandwidth.

  13. Photocurrent mapping of near-field optical antenna resonances.

    Science.gov (United States)

    Barnard, Edward S; Pala, Ragip A; Brongersma, Mark L

    2011-08-21

    An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data. Here, we demonstrate a photodetector platform that uses a silicon-on-insulator substrate to spectrally and spatially map the absolute values of enhanced fields near any type of optical antenna by transducing local electric fields into photocurrent. We are able to quantify the resonant optical and materials properties of nanoscale (∼50 nm) and wavelength-scale (∼1 µm) metallic antennas as well as high-refractive-index semiconductor antennas. The data agree well with light-scattering measurements, full-field simulations and intuitive resonator models.

  14. Nonlinear and Quantum Optics with Whispering Gallery Resonators

    CERN Document Server

    Strekalov, Dmitry V; Matsko, Andrey B; Schwefel, Harald G L; Leuchs, Gerd

    2016-01-01

    Optical Whispering Gallery Modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon was later realized to have a rather general nature, equally applicable to sound and all other waves, but in particular also to electromagnetic waves ranging from radio frequencies to ultraviolet light. Very high quality factors of optical WGM resonators persisting in a wide wavelength range, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.

  15. Resonance-enhanced optical forces between coupled photonic crystal slabs.

    Science.gov (United States)

    Liu, Victor; Povinelli, Michelle; Fan, Shanhui

    2009-11-23

    The behaviors of lateral and normal optical forces between coupled photonic crystal slabs are analyzed. We show that the optical force is periodic with displacement, resulting in stable and unstable equilibrium positions. Moreover, the forces are strongly enhanced by guided resonances of the coupled slabs. Such enhancement is particularly prominent near dark states of the system, and the enhancement effect is strongly dependent on the types of guided resonances involved. These structures lead to enhancement of light-induced pressure over larger areas, in a configuration that is directly accessible to externally incident, free-space optical beams.

  16. Plasmonic resonances in nanostructured transparent conducting oxide films

    CERN Document Server

    Kim, Jongbum; Emani, Naresh K; Boltasseva, Alexandra

    2012-01-01

    Transparent conducting oxides (TCO) are emerging as possible alternative constituent materials to replace noble metals such as silver and gold for low-loss plasmonic and metamaterial (MMs) applications in the near infrared (NIR) regime. The optical characteristics of TCOs have been studied to evaluate the functionalities and potential of these materials as metal substitutes in plasmonic and MM devices, even apart from their usual use as electrode materials. However, patterning TCOs at the nanoscale, which is necessary for plasmonic and MM devices, is not well-studied. This paper investigates nanopatterning processes for TCOs, especially the lift-off technique with electron-beam lithography, and the realization of plasmonic nanostructures with TCOs. By employing the developed nanopatterning process, we fabricate 2D-periodic arrays of TCO nanodisks and characterize the material's plasmonic properties to evaluate the performance of TCOs as metal substitutes. Light-induced collective oscillations of the free elec...

  17. Sign-Reversal Coupling in Coupled-Resonator Optical Waveguide

    CERN Document Server

    Gao, Zhen; Zhang, Youming; Zhang, Baile

    2016-01-01

    Coupled-resonator optical waveguides (CROWs), which play a significant role in modern photonics, achieve waveguiding through near-field coupling between tightly localized resonators. The coupling factor, a critical parameter in CROW theory, determines the coupling strength between two resonators and the waveguiding dispersion of a CROW. However, the original CROW theory proposed by Yariv et al. only demonstrated one value of coupling factor for a multipole resonance mode. Here, by imaging the tight-binding Bloch waves on a CROW consisting of designer-surface-plasmon resonators in the microwave regime, we demonstrate that the coupling factor in the CROW theory can reverse its sign for a multipole resonance mode. This determines two different waveguiding dispersion curves in the same frequency range, experimentally confirmed by matching Bloch wavevectors and frequencies in the CROW. Our study supplements and extends the original CROW theory, and may find novel use in functional photonic systems.

  18. Optical Twist Induced by Plasmonic Resonance

    Science.gov (United States)

    Chen, Jun; Wang, Neng; Cui, Liyong; Li, Xiao; Lin, Zhifang; Ng, Jack

    2016-06-01

    Harvesting light for optical torque is of significant importance, owing to its ability to rotate nano- or micro-objects. Nevertheless, applying a strong optical torque remains a challenging task: angular momentum must conserve but light is limited. A simple argument shows the tendency for two objects with strong mutual scattering or light exchange to exhibit a conspicuously enhanced optical torque without large extinction or absorption cross section. The torque on each object is almost equal but opposite, which we called optical twist. The effect is quite significant for plasmonic particle cluster, but can also be observed in structures with other morphologies. Such approach exhibits an unprecedentedly large torque to light extinction or absorption ratio, enabling limited light to exert a relatively large torque without severe heating. Our work contributes to the understanding of optical torque and introduces a novel way to manipulate the internal degrees of freedom of a structured particle cluster.

  19. Optical Torque from Enhanced Scattering by Multipolar Plasmonic Resonance

    CERN Document Server

    Lee, Yoonkyung E; Jin, Dafei; Fang, Nicholas

    2014-01-01

    We present a theoretical study of the optical angular momentum transfer from a circularly polarized plane wave to thin metal nanoparticles of different rotational symmetries. While absorption has been regarded as the predominant mechanism of torque generation on the nanoscale, we demonstrate numerically how the contribution from scattering can be enhanced by using multipolar plasmon resonance. The multipolar modes in non-circular particles can convert the angular momentum carried by the scattered field, thereby producing scattering-dominant optical torque, while a circularly symmetric particle cannot. Our results show that the optical torque induced by resonant scattering can contribute to 80% of the total optical torque in gold particles. This scattering-dominant torque generation is extremely mode-specific, and deserves to be distinguished from the absorption-dominant mechanism. Our findings might have applications in optical manipulation on the nanoscale as well as new designs in plasmonics and metamateria...

  20. Enhanced optical absorption and electric field resonance in diabolo metal bar optical antennas.

    Science.gov (United States)

    Pan, Zeyu; Guo, Junpeng

    2013-12-30

    Resonance behaviors of the fundamental resonance mode of diabolo metal bar optical antennas are investigated by using finite-difference time-domain (FDTD) numerical simulations and a dipole oscillator model. It is found that as the waist of the diabolo metal bar optical antenna is reduced, optical energy absorption cross section and near field enhancement at resonance increase significantly. Also reduction of the diabolo waist width causes red-shift of the resonant wavelengths in the spectra of absorption cross-section, scattering cross-section, and the near electric field. A dipole oscillator model including the self-inductance force is used to fit the FDTD numerical simulation results. The dipole oscillator model characterizes well the resonance behaviors of narrow waist diabolo metal bar optical antennas.

  1. Improving the Optical Quality Factor of the WGM Resonator

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey; Iltchenko, Vladimir

    2008-01-01

    Resonators usually are characterized with two partially dependent values: finesse (F) and quality factor (Q). The finesse of an empty Fabry-Perot (FP) resonator is defined solely by the quality of its mirrors and is calculated as F=piR(exp 1/2)/(1-R). The maximum up-to-date value of reflectivity R approximately equal to 1 - 1.6 x 10(exp -6) is achieved with dielectric mirrors. An FP resonator made with the mirrors has finesse F=1.9 x 10(exp 6). Further practical increase of the finesse of FP resonators is problematic because of the absorption and the scattering of light in the mirror material through fundamental limit on the reflection losses given by the internal material losses and by thermodynamic density fluctuations on the order of parts in 109. The quality factor of a resonator depends on both its finesse and its geometrical size. A one-dimensional FP resonator has Q=2 F L/lambda, where L is the distance between the mirrors and lambda is the wavelength. It is easy to see that the quality factor of the resonator is unlimited because L is unlimited. F and Q are equally important. In some cases, finesse is technically more valuable than the quality factor. For instance, buildup of the optical power inside the resonator, as well as the Purcell factor, is proportional to finesse. Sometimes, however, the quality factor is more valuable. For example, inverse threshold power of intracavity hyperparametric oscillation is proportional to Q(exp 2) and efficiency of parametric frequency mixing is proportional to Q(exp 3). Therefore, it is important to know both the maximally achievable finesse and quality factor values of a resonator. Whispering gallery mode (WGM) resonators are capable of achieving larger finesse compared to FP resonators. For instance, fused silica resonators with finesse 2.3 x 10(exp 6) and 2.8 x 10(exp 6) have been demonstrated. Crystalline WGM resonators reveal even larger finesse values, F=6.3 x 10(exp 6), because of low attenuation of light in the

  2. Optical cavity coupled surface plasmon resonance sensing for enhanced sensitivity

    Institute of Scientific and Technical Information of China (English)

    Zheng Zheng; Xin Zhao; Jinsong Zhu; Jim Diamond

    2008-01-01

    A surface plasmon resonance (SPR) sensing system based on the optical cavity enhanced detection tech-nique is experimentally demonstrated. A fiber-optic laser cavity is built with a SPR sensor inside. By measuring the laser output power when the cavity is biased near the threshold point, the sensitivity, defined as the dependence of the output optical intensity on the sample variations, can be increased by about one order of magnitude compared to that of the SPR sensor alone under the intensity interrogation scheme. This could facilitate ultra-high sensitivity SPR biosensing applications. Further system miniaturization is possible by using integrated optical components and waveguide SPR sensors.

  3. Optical chiral metamaterial based on the resonant behaviour of nanodiscs

    Science.gov (United States)

    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.

  4. Optical resonance problem in metamaterial arrays: a lattice dynamics approach

    Science.gov (United States)

    Liu, Wanguo

    2016-11-01

    A systematic dynamic theory is established to deal with the optical collective resonance in metamaterial arrays. As a reference model, we consider an infinite split ring resonator (SRR) array illuminated by a linearly polarized wave and introduce an N-degree-of-freedom forced oscillator equation to simplify the coupled-mode vibration problem. We derive a strict formula of resonance frequency (RF) and its adjustable range from the steady-state response. Unlike a single SRR possesses invariant RF, it successfully explains the mechanism of RF shift effect in the SRR array when the incident angle changes. Instead of full wave analysis, only one or two adjacent resonance modes can give an accurate response line shape. Our approach is applicable for metallic arrays with any N-particle cell at all incident angles and well matched with numerical results. It provides a versatile way to study the vibration dynamics in optical periodic many-body systems.

  5. Micro--structured crystalline resonators for optical frequency comb generation

    CERN Document Server

    Grudinin, Ivan S

    2014-01-01

    Optical frequency combs have recently been demonstrated in micro--resonators through nonlinear Kerr processes. Investigations in the past few years provided better understanding of micro--combs and showed that spectral span and mode locking are governed by cavity spectrum and dispersion. While various cavities provide unique advantages, dispersion engineering has been reported only for planar waveguides. In this Letter, we report a resonator design that combines dispersion control, mode crossing free spectrum, and ultra--high quality factor. We experimentally show that as the dispersion of a MgF2 resonator is flattened, the comb span increases reaching 700 nm with as low as 60 mW pump power at 1560 nm wavelength, corresponding to nearly 2000 lines separated by 46 GHz. The new resonator design may enable efficient low repetition rate coherent octave spanning frequency combs without the need for external broadening, ideal for applications in optical frequency synthesis, metrology, spectroscopy, and communicatio...

  6. Experimental study of resonance fiber optic gyroscope employing a dual-ring resonator

    Science.gov (United States)

    Fan, Yue; Wang, Wei

    2016-09-01

    A dual-ring resonator which is available to alter the full width at half maximum (FWHM) without altering the free spectrum range (FSR) for practice applications is analyzed theoretically and set up in practice. The parameters of the dual-ring resonator have been optimized in simulation, the resonance depth and the dynamic range are enhanced. The prototype is set up with single mode fiber of 8 meter and two 95 : 5 couplers for open loop experiment. The FWHM of the dual-ring resonator is demonstrated less than 1.5MHz and the fineness is calculated to be 37 during the frequency sweeping experiment. The frequency locking experiment with demodulation curve method has been accomplished, and the locking time achieves less than 40ms. All these provide a basic reference for optimizing the resonance fiber optic gyro based on dual-ring resonator.

  7. Optical Leaky-Wave Antenna Integrated in Ring Resonator

    CERN Document Server

    Guclu, Caner; Boyraz, Ozdal; Capolino, Filippo

    2014-01-01

    A leaky-wave antenna at optical frequencies is designed and integrated with a ring resonator at 1550 nm wavelength. The leaky wave is generated by using periodic perturbations in the integrated dielectric waveguide that excite the -1 spatial harmonic. The antenna consists of a dielectric waveguides with semiconductor corrugations, and it is compatible with CMOS fabrication technology. We show that integrating the leaky wave antenna in an optical ring resonator that is fed by directional couplers, we can improve the electronic control of the radiation through carrier injection into the semiconductor corrugations.

  8. Optical Kerr Frequency Comb Generation in Overmoded Resonators

    CERN Document Server

    Matsko, A B; Liang, W; Ilchenko, V S; Seidel, D; Maleki, L

    2012-01-01

    We show that scattering-based interaction among nearly degenerate optical modes is the key factor in low threshold generation of Kerr frequency combs in nonlinear optical resonators possessing small group velocity dispersion (GVD). The mode interaction is capable of producing drastic change in the local GVD, resulting in either a significant reduction or increase of the oscillation threshold. It is also responsible for the majority of observed combs in resonators characterized with large normal GVD. We present results of our numerical simulations as well as supporting experimental data.

  9. Capture into resonance and phase space dynamics in optical centrifuge

    CERN Document Server

    Armon, Tsafrir

    2016-01-01

    The process of capture of a molecular enesemble into rotational resonance in the optical centrifuge is investigated. The adiabaticity and phase space incompressibility are used to find the resonant capture probability in terms of two dimensionless parameters P1,P2 characterising the driving strength and the nonlinearity, and related to three characteristic time scales in the problem. The analysis is based on the transformation to action-angle variables and the single resonance approximation, yielding reduction of the three-dimensional rotation problem to one degree of freedom. The analytic results for capture probability are in a good agreement with simulations. The existing experiments satisfy the validity conditions of the theory.

  10. Applications of Optical Microcavity Resonators in Analytical Chemistry.

    Science.gov (United States)

    Wade, James H; Bailey, Ryan C

    2016-06-12

    Optical resonator sensors are an emerging class of analytical technologies that use recirculating light confined within a microcavity to sensitively measure the surrounding environment. Bolstered by advances in microfabrication, these devices can be configured for a wide variety of chemical or biomolecular sensing applications. We begin with a brief description of optical resonator sensor operation, followed by discussions regarding sensor design, including different geometries, choices of material systems, methods of sensor interrogation, and new approaches to sensor operation. Throughout, key developments are highlighted, including advancements in biosensing and other applications of optical sensors. We discuss the potential of alternative sensing mechanisms and hybrid sensing devices for more sensitive and rapid analyses. We conclude with our perspective on the future of optical microcavity sensors and their promise as versatile detection elements within analytical chemistry.

  11. Change of electrical conductivity of Ar welding arc under resonant absorption of laser radiation

    Science.gov (United States)

    Kozakov, R.; Emde, B.; Pipa, A. V.; Huse, M.; Uhrlandt, D.; Hermsdorf, J.; Wesling, V.

    2015-03-01

    Experimental investigations of the impact of resonant laser absorption by a tungsten inert gas welding arc in argon are presented. The intensity increase of the arc’s radiation between the laser entrance height and the anode are observed, as well as the variation of arc voltage due to the presence of the laser beam. High-speed camera recordings from different directions combined with absolutely calibrated spectroscopic measurements allow the reconstruction of the three-dimensional emission coefficient profiles without the assumption of axial symmetry. The obtained data are evaluated within the framework of local thermodynamic equilibrium. The local increase in the temperature and conductivity due to the influence of the laser is determined. Changes in the electrical conductivity obtained from the optical measurements coincide well with the measured voltage drop, and show significant redistribution of the current density profile near the anode in particular.

  12. Magnetic resonance imaging of luxury perfusion of the optic nerve head in anterior ischemic optic neuropathy.

    Science.gov (United States)

    Yovel, Oren S; Katz, Miriam; Leiba, Hana

    2012-09-01

    A 49-year-old woman with painless reduction in visual acuity in her left eye was found to have nonarteritic anterior ischemic optic neuropathy (NAION). Fluorescein angiography revealed optic disc capillary leakage consistent with "luxury perfusion." Contrast-enhanced FLAIR magnetic resonance imaging (MRI) showed marked enhancement of the left optic disc. Resolution of the optic disc edema and the MRI abnormalities followed a similar time course. This report appears unique in documenting the MRI findings of luxury perfusion in NAION.

  13. Spin microscope based on optically detected magnetic resonance

    Science.gov (United States)

    Berman, Gennady P.; Chernobrod, Boris M.

    2007-12-11

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  14. Squeezing Alters Frequency Tuning of WGM Optical Resonator

    Science.gov (United States)

    Mohageg, Makan; Maleki, Lute

    2010-01-01

    Mechanical squeezing has been found to alter the frequency tuning of a whispering-gallery-mode (WGM) optical resonator that has an elliptical shape and is made of lithium niobate. It may be possible to exploit this effect to design reconfigurable optical filters for optical communications and for scientific experiments involving quantum electrodynamics. Some background information is prerequisite to a meaningful description of the squeezing-induced alteration of frequency tuning: The spectrum of a WGM resonator is represented by a comblike plot of intensity versus frequency. Each peak of the comblike plot corresponds to an electromagnetic mode represented by an integer mode number, and the modes are grouped into sets represented by integer mode indices. Because lithium niobate is an electro-optically active material, the WGM resonator can be tuned (that is, the resonance frequencies can be shifted) by applying a suitable bias potential. The frequency shift of each mode is quantified by a tuning rate defined as the ratio between the frequency shift and the applied potential. In the absence of squeezing, all modes exhibit the same tuning rate. This concludes the background information. It has been demonstrated experimentally that when the resonator is squeezed along part of either of its two principal axes, tuning rates differ among the groups of modes represented by different indices (see figure). The differences in tuning rates could be utilized to configure the resonance spectrum to obtain a desired effect; for example, through a combination of squeezing and electrical biasing, two resonances represented by different mode indices could be set at a specified frequency difference something that could not be done through electrical biasing alone.

  15. Critical Coupling Between Optical Fibers and WGM Resonators

    Science.gov (United States)

    Matsko, Andrey; Maleki, Lute; Itchenko, Vladimir; Savchenkov, Anatoliy

    2009-01-01

    Two recipes for ensuring critical coupling between a single-mode optical fiber and a whispering-gallery-mode (WGM) optical resonator have been devised. The recipes provide for phase matching and aperture matching, both of which are necessary for efficient coupling. There is also a provision for suppressing intermodal coupling, which is detrimental because it drains energy from desired modes into undesired ones. According to one recipe, the tip of the single-mode optical fiber is either tapered in diameter or tapered in effective diameter by virtue of being cleaved at an oblique angle. The effective index of refraction and the phase velocity at a given position along the taper depend on the diameter (or effective diameter) and the index of refraction of the bulk fiber material. As the diameter (or effective diameter) decreases with decreasing distance from the tip, the effective index of refraction also decreases. Critical coupling and phase matching can be achieved by placing the optical fiber and the resonator in contact at the proper point along the taper. This recipe is subject to the limitation that the attainable effective index of refraction lies between the indices of refraction of the bulk fiber material and the atmosphere or vacuum to which the resonator and fiber are exposed. The other recipe involves a refinement of the previously developed technique of prism coupling, in which the light beam from the optical fiber is collimated and focused onto one surface of a prism that has an index of refraction greater than that of the resonator. Another surface of the prism is placed in contact with the resonator. The various components are arranged so that the collimated beam is focused at the prism/resonator contact spot. The recipe includes the following additional provisions:

  16. Slow light enhanced optical nonlinearity in a silicon photonic crystal coupled-resonator optical waveguide.

    Science.gov (United States)

    Matsuda, Nobuyuki; Kato, Takumi; Harada, Ken-Ichi; Takesue, Hiroki; Kuramochi, Eiichi; Taniyama, Hideaki; Notomi, Masaya

    2011-10-10

    We demonstrate highly enhanced optical nonlinearity in a coupled-resonator optical waveguide (CROW) in a four-wave mixing experiment. Using a CROW consisting of 200 coupled resonators based on width-modulated photonic crystal nanocavities in a line defect, we obtained an effective nonlinear constant exceeding 10,000 /W/m, thanks to slow light propagation combined with a strong spatial confinement of light achieved by the wavelength-sized cavities.

  17. Efficient single sideband microwave to optical conversion using an electro-optical whispering gallery mode resonator

    CERN Document Server

    Rueda, Alfredo; Collodo, Michele C; Vogl, Ulrich; Stiller, Birgit; Schunk, Gerhard; Strekalov, Dmitry V; Marquardt, Christoph; Fink, Johannes M; Painter, Oskar; Leuchs, Gerd; Schwefel, Harald G L

    2016-01-01

    Linking classical microwave electrical circuits to the optical telecommunication band is at the core of modern communication. Future quantum information networks will require coherent microwave-to-optical conversion to link electronic quantum processors and memories via low-loss optical telecommunication networks. Efficient conversion can be achieved with electro-optical modulators operating at the single microwave photon level. In the standard electro-optic modulation scheme this is impossible because both, up- and downconverted, sidebands are necessarily present. Here we demonstrate true single sideband up- or downconversion in a triply resonant whispering gallery mode resonator by explicitly addressing modes with asymmetric free spectral range. Compared to previous experiments, we show a three orders of magnitude improvement of the electro-optical conversion efficiency reaching 0.1% photon number conversion for a 10GHz microwave tone at 0.42mW of optical pump power. The presented scheme is fully compatible...

  18. Reflective Optical Limiter Based on Resonant Transmission

    CERN Document Server

    Makri, Eleana; Vitebskiy, Ilya

    2014-01-01

    Optical limiters transmit low-level radiation while blocking electromagnetic pulses with excessively high energy (energy limiters) or with excessively high peak intensity (power limiters). A typical optical limiter absorbs most of the high-level radiation which can cause its destruction via overheating. Here we introduce the novel concept of a reflective energy limiter which blocks electromagnetic pulses with excessively high total energy by reflecting them back to space, rather than absorbing them. The idea is to use a defect layer with temperature dependent loss tangent embedded in a low-loss photonic structure. The low energy pulses with central frequency close to that of the localized defect mode will pass through. But if the cumulative energy carried by the pulse exceeds certain level, the entire photonic structure reflects the incident light (and does not absorb it!) for a broad frequency window. The underlying physical mechanism is based on self-regulated impedance mismatch which increases dramatically...

  19. Hamiltonian optics formalism for microring resonator structures with varying ring resonances.

    Science.gov (United States)

    Sun, Xiaolan; Yang, Zhenshan; Liu, Xiaohong; Li, Chao; Dong, Yanhua; Xie, Libin; Sipe, J E

    2011-04-11

    We develop a Hamiltonian optics formalism to quantitatively analyze a recently proposed scheme for increasing the delay-time-bandwidth product for microring resonator structures with varying ring resonances [Yang and Sipe, Opt. Lett. 32, 918 (2007)]. This theory is formally compact, simple and physically intuitive. We compare this formalism with the more rigorous transfer matrix method, and conclude that the Hamiltonian optics formalism correctly gives the average dispersion, which essentially determines the group delay as well as the dispersive distortion for pulses in the ps regime or longer.

  20. Reconfigurable Optical Spectra from Perturbations on Elliptical Whispering Gallery Resonances

    Science.gov (United States)

    Mohageg, Makan; Maleki, Lute

    2008-01-01

    Elastic strain, electrical bias, and localized geometric deformations were applied to elliptical whispering-gallery-mode resonators fabricated with lithium niobate. The resultant perturbation of the mode spectrum is highly dependant on the modal indices, resulting in a discretely reconfigurable optical spectrum. Breaking of the spatial degeneracy of the whispering-gallery modes due to perturbation is also observed.

  1. Optical Phased Array Using Guided Resonance with Backside Reflectors

    Science.gov (United States)

    Horie, Yu (Inventor); Arbabi, Amir (Inventor); Faraon, Andrei (Inventor)

    2016-01-01

    Methods and systems for controlling the phase of electromagnetic waves are disclosed. A device can consist of a guided resonance grating layer, a spacer, and a reflector. A plurality of devices, arranged in a grid pattern, can control the phase of reflected electromagnetic phase, through refractive index control. Carrier injection, temperature control, and optical beams can be applied to control the refractive index.

  2. Demonstration of a refractometric sensor based on optical microfiber resonator

    OpenAIRE

    2008-01-01

    We experimentally demonstrated a refractometric sensor based on a coated optical microfiber coil resonator. It is robust, compact, and comprises an intrinsic fluidic channel. A sensitivity of about 40 nm/RIU (refractive index unit) has been measured, in agreement with predictions.

  3. Open-loop experiments of resonator micro-optic gyro

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-lin; ZHOU Ke-jiang

    2009-01-01

    An open-loop resonator micro-optic gyro (R-MOG) with a 6 cm-long waveguide-type ring resonator is set up using the phase modulation spectroscopy technique. In the experiment, according to the test parameters of the resonator, the shot-noise-limited sensitivity is estimated to be 1.07×10-4 rad/s. From the test demodulation signal, the gyro dynamic range of ±7.0×103 rad/s is obtained. Using different phase modulation frequencies, the open-loop gyro output signal is observed when the equivalent gyro rotation is applied to the aconstic-optical modulators (AOMs). The sensitivity of the R-MOG can be increased by some countermeasures against system noise.

  4. A modern Michelson-Morley experiment using ultrastable optical resonators

    Science.gov (United States)

    Peters, Achim

    2005-05-01

    This talk will describe a modern version of the classic Michelson-Morley experiment testing the isotropy of light propagation and thus the foundations of Special Relativity. The latest experimental setup employs of an assembly of orthogonal ultrastable optical resonators mounted inside a liquid Helium cryostat, which itself is actively rotated using a high performance air-supported turntable. The cavity resonance frequencies are continuously monitored using monolithic Nd:YAG lasers and analyzed for periodic modulations indicating violations of Lorentz-invariance. Compared to pervious experiments using cryogenic optical resonators (COREs), but relying solely on Earth's rotation, this new version is expected to lead to orders of magnitude improvement in sensitivity to Lorentz-Invariance violation. We present the initial results of this experimental effort at the δc(θ)/c ˜ 10-16 level for an direction dependent variation of the speed of light and discuss the potential for future improvements.

  5. Resonant state expansion applied to planar open optical systems

    CERN Document Server

    Doost, M B; Muljarov, E A

    2011-01-01

    The resonant state expansion (RSE), a novel perturbation theory of Brillouin-Wigner type developed in electrodynamics [Muljarov, Langbein, and Zimmermann, Europhys. Lett., 92, 50010(2010)], is applied to planar, effectively one-dimensional optical systems, such as layered dielectric slabs and Bragg reflector microcavities. It is demonstrated that the RSE converges with a power law in the basis size. Algorithms for error estimation and their reduction by extrapolation are presented and evaluated. Complex eigenfrequencies, electro-magnetic fields, and the Green's function of a selection of optical systems are calculated, as well as the observable transmission spectra. In particular we find that for a Bragg-mirror microcavity, which has sharp resonances in the spectrum, the transmission calculated using the resonant state expansion reproduces the result of the transfer/scattering matrix method.

  6. Electrical conductivity, ionic conductivity, optical absorption, and gas separation properties of ionically conductive polymer membranes embedded with Si microwire arrays

    OpenAIRE

    Spurgeon, Joshua M.; Walter, Michael G.; Zhou, Junfeng; Kohl, Paul A.; Lewis, Nathan S.

    2011-01-01

    The optical absorption, ionic conductivity, electronic conductivity, and gas separation properties have been evaluated for flexible composite films of ionically conductive polymers that contain partially embedded arrays of ordered, crystalline, p-type Si microwires. The cation exchange ionomer Nafion, and a recently developed anion exchange ionomer, poly(arylene ether sulfone) that contains quaternary ammonium groups (QAPSF), produced composite microwire array/ionomer membrane films that were...

  7. WGM-Resonator/Tapered-Waveguide White-Light Sensor Optics

    Science.gov (United States)

    Stekalov, Dmitry; Maleki, Lute; Matsko, Andrey; Savchenkov, Anatoliy; Iltchenko, Vladimir

    2007-01-01

    Theoretical and experimental investigations have demonstrated the feasibility of compact white-light sensor optics consisting of unitary combinations of (1) low-profile whispering-gallery-mode (WGM) resonators and (2) tapered rod optical waveguides. These sensors are highly wavelength-dispersive and are expected to be especially useful in biochemical applications for measuring absorption spectra of liquids. These sensor optics exploit the properties of a special class of non-diffracting light beams that are denoted Bessel beams because their amplitudes are proportional to Bessel functions of the radii from their central axes. High-order Bessel beams can have large values of angular momentum. In a sensor optic of this type, a low-profile WGM resonator that supports modes having large angular momenta is used to generate high-order Bessel beams. As used here, "low-profile" signifies that the WGM resonator is an integral part of the rod optical waveguide but has a radius slightly different from that of the adjacent part(s).

  8. Graphene photonics for resonator-enhanced electro-optic devices and all-optical interactions

    Science.gov (United States)

    Englund, Dirk R.; Gan, Xuetao

    2017-03-21

    Techniques for coupling light into graphene using a planar photonic crystal having a resonant cavity characterized by a mode volume and a quality factor and at least one graphene layer positioned in proximity to the planar photonic crystal to at least partially overlap with an evanescent field of the resonant cavity. At least one mode of the resonant cavity can couple into the graphene layer via evanescent coupling. The optical properties of the graphene layer can be controlled, and characteristics of the graphene-cavity system can be detected. Coupling light into graphene can include electro-optic modulation of light, photodetection, saturable absorption, bistability, and autocorrelation.

  9. Optical-optical double-resonant multiphoton ionization spectra of Rydberg states of nitrogen dioxide

    Institute of Scientific and Technical Information of China (English)

    Zhang Gui-Yin; Zhang Lian-Shui; Sun Bo; Han Xiao-Feng; Yu Wei

    2005-01-01

    The optical-optical double-resonant multiphoton ionization(OODR-MPI) technique has been applied to the study of the Rydberg states of nitrogen dioxide. The results show that ,althougy the OODR-MPI spectra of NO2 are composed of regular progression bands at different pump laser intensities, their ionization pathways are different.The NO2 mollecule is ionized through the (3+1+1)double-resonant process as the pump laser intensity is in a high value, or else it is through the (1+2+1)rpocess.The final resonant states in the two ionizing processes have been attributed to different Rydberg states.

  10. Graphene photonics for resonator-enhanced electro-optic devices and all-optical interactions

    Energy Technology Data Exchange (ETDEWEB)

    Englund, Dirk R.; Gan, Xuetao

    2017-03-21

    Techniques for coupling light into graphene using a planar photonic crystal having a resonant cavity characterized by a mode volume and a quality factor and at least one graphene layer positioned in proximity to the planar photonic crystal to at least partially overlap with an evanescent field of the resonant cavity. At least one mode of the resonant cavity can couple into the graphene layer via evanescent coupling. The optical properties of the graphene layer can be controlled, and characteristics of the graphene-cavity system can be detected. Coupling light into graphene can include electro-optic modulation of light, photodetection, saturable absorption, bistability, and autocorrelation.

  11. Chaos-assisted, broadband trapping of light in optical resonators

    CERN Document Server

    Liu, C; Molinari, D; Khan, Y; Ooi, B S; Krauss, T F; Fratalocchi, A

    2012-01-01

    Chaos is a phenomenon that occurs in many aspects of contemporary science. In classical dynamics, chaos is defined as a hypersensitivity to initial conditions. The presence of chaos is often unwanted, as it introduces unpredictability, which makes it difficult to predict or explain experimental results. Conversely, we demonstrate here how chaos can be used to enhance the ability of an optical resonator to store energy. We combine analytic theory with ab-initio simulations and experiments in photonic crystal resonators to show that a chaotic resonator can store six times more energy than its classical counterpart of the same volume. We explain the observed increase with the equipartition of energy among all degrees of freedom of the chaotic resonator, i.e. the cavity modes, which is evident from the convergence of their lifetime towards a single value. A compelling illustration of the theory is provided by demonstrating enhanced absorption in deformed polystyrene microspheres.

  12. A silicon single-crystal cryogenic optical resonator

    CERN Document Server

    Wiens, Eugen; Ernsting, Ingo; Luckmann, Heiko; Rosowski, Ulrich; Nevsky, Alexander; Schiller, Stephan

    2014-01-01

    We report on the demonstration and characterization of a silicon optical resonator for laser frequency stabilization, operating in the deep cryogenic regime at temperatures as low as 1.5 K. Robust operation was achieved, with absolute frequency drift less than 20 Hz over 1 hour. This stability allowed sensitive measurements of the resonator thermal expansion coefficient ($\\alpha$). We found $\\alpha=4.6\\times10^{-13}$ ${\\rm K^{-1}}$ at 1.6 K. At 16.8 K $\\alpha$ vanishes, with a derivative equal to $-6\\times10^{-10}$ ${\\rm K}^{-2}$. The temperature of the resonator was stabilized to a level below 10 $\\mu$K for averaging times longer than 20 s. The sensitivity of the resonator frequency to a variation of the laser power was also studied. The corresponding sensitivities and the expected Brownian noise indicate that this system should enable frequency stabilization of lasers at the low-$10^{-17}$ level.

  13. Silicon single-crystal cryogenic optical resonator: erratum

    Science.gov (United States)

    Wiens, Eugen; Chen, Qun-Feng; Ernsting, Ingo; Luckmann, Heiko; Rosowski, Ulrich; Nevsky, Alexander; Schiller, Stephan

    2015-01-01

    We report on the demonstration and characterization of a silicon optical resonator for laser frequency stabilization, operating in the deep cryogenic regime at temperatures as low as 1.5 K. Robust operation was achieved, with absolute frequency drift less than 20 Hz over 1 hour. This stability allowed sensitive measurements of the resonator thermal expansion coefficient ($\\alpha$). We found $\\alpha=4.6\\times10^{-13}$ ${\\rm K^{-1}}$ at 1.6 K. At 16.8 K $\\alpha$ vanishes, with a derivative equal to $-6\\times10^{-10}$ ${\\rm K}^{-2}$. The temperature of the resonator was stabilized to a level below 10 $\\mu$K for averaging times longer than 20 s. The sensitivity of the resonator frequency to a variation of the laser power was also studied. The corresponding sensitivities and the expected Brownian noise indicate that this system should enable frequency stabilization of lasers at the low-$10^{-17}$ level.

  14. Optical Feshbach Resonances: Field-Dressed Theory and Experimental Comparisons

    CERN Document Server

    Nicholson, T L; Bloom, B J; Williams, J R; Thomsen, J W; Ye, J; Julienne, P S

    2015-01-01

    Optical Feshbach resonances (OFRs) have generated significant experimental interest in recent years. These resonances are promising for many-body physics experiments, yet the practical application of OFRs has been limited. The theory of OFRs has been based on an approximate model that fails in important detuning regimes, and the incomplete theoretical understanding of this effect has hindered OFR experiments. We present the most complete theoretical treatment of OFRs to date, demonstrating important characteristics that must be considered in OFR experiments and comparing OFRs to the well studied case of magnetic Feshbach resonances. We also present a comprehensive treatment of the approximate OFR model, including a study of the range of validity for this model. Finally, we derive experimentally useful expressions that can be applied to real experimental data to extract important information about the resonance structure of colliding atoms.

  15. Thermal conductivities of some novel nonlinear optical materials.

    Science.gov (United States)

    Beasley, J D

    1994-02-20

    Results of thermal conductivity measurements are reported for several of the more recently developed nonlinear optical crystals. New or substantially revised values of thermal conductivity were obtained in six materials. Notable thermal conductivities measured were those for AgGaS(2) [0.014 W/(cm K) and 0.015 W/(cm K)], AgGaSe(2) [0.010 W/(cm K) and 0.011 W/(cm K)], beta barium borate [0.016 W/(cm K) and 0.012 W/(cm K)], and ZnGeP(2) [0.36 W/(cm K) and 0.35 W/(cm K)], with values quoted for directions respectively parallel and perpendicular to the optic axis for each material. These new data provide necessary input for the design of high-power optical frequency converters.

  16. Magnetic Metamaterials: A comparative study of resonator geometry and metal conductivity

    Science.gov (United States)

    Rangu, Shashank; Sreekar, Kamireddy; Reddy Annapureddy, Ravinithesh; Basak, Kausik; Bohra, Murtaza; Chowdhury, Dibakar Roy

    2016-10-01

    In this work, split ring resonators based metamaterials are studied for microwave, terahertz and infrared frequency regimes. Two different geometries, circular and rectangular split ring resonators based metamaterials are investigated numerically for different frequency regimes. Our study indicates that the effect of metal conductivity and resonator geometry shows very little impact on the fundamental resonance mode. However the higher order modes go through significant frequency tuning because of the change in resonator geometry. We have further shown that the metal conductivity is an important parameter for the metamaterials employed in infrared domains.

  17. Nonequilibrium optical conductivity: General theory and application to transient phases

    Science.gov (United States)

    Kennes, D. M.; Wilner, E. Y.; Reichman, D. R.; Millis, A. J.

    2017-08-01

    A nonequilibrium theory of optical conductivity of dirty-limit superconductors and commensurate charge density wave is presented. We discuss the current response to different experimentally relevant light-field probe pulses and show that a single frequency definition of the optical conductivity σ (ω )≡j (ω )/E (ω ) is difficult to interpret out of the adiabatic limit. We identify characteristic time-domain signatures distinguishing between superconducting, normal-metal, and charge density wave states. We also suggest a route to directly address the instantaneous superfluid stiffness of a superconductor by shaping the probe light field.

  18. Reversible quantum optical data storage based on resonant Raman optical field excited spin coherence.

    Science.gov (United States)

    Ham, Byoung S

    2008-09-01

    A method of reversible quantum optical data storage is presented using resonant Raman field excited spin coherence, where the spin coherence is stored in an inhomogeneously broadened spin ensemble. Unlike the photon echo method, in the present technique, a 2pi Raman optical rephasing pulse area is used and multimode (parallel) optical channels are available in which the multimode access gives a great benefit to quantum information processors such as quantum repeaters.

  19. Photocurrent mapping of near-field optical antenna resonances

    KAUST Repository

    Barnard, Edward S.

    2011-08-21

    An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data. Here, we demonstrate a photodetector platform that uses a silicon-on-insulator substrate to spectrally and spatially map the absolute values of enhanced fields near any type of optical antenna by transducing local electric fields into photocurrent. We are able to quantify the resonant optical and materials properties of nanoscale (∼50nm) and wavelength-scale (∼1μm) metallic antennas as well as high-refractive-index semiconductor antennas. The data agree well with light-scattering measurements, full-field simulations and intuitive resonator models. © 2011 Macmillan Publishers Limited. All rights reserved.

  20. Scalable nanofabrication of U-shaped nanowire resonators with tunable optical magnetism.

    Science.gov (United States)

    Zhou, Fan; Wang, Chen; Dong, Biqin; Chen, Xiangfan; Zhang, Zhen; Sun, Cheng

    2016-03-21

    Split ring resonators have been studied extensively in reconstituting the diminishing magnetism at high electromagnetic frequencies in nature. However, breakdown in the linear scaling of artificial magnetism is found to occur at the near-infrared frequency mainly due to the increasing contribution of self-inductance while reducing dimensions of the resonators. Although alternative designs have enabled artificial magnetism at optical frequencies, their sophisticated configurations and fabrication procedures do not lend themselves to easy implementation. Here, we report scalable nanofabrication of U-shaped nanowire resonators (UNWRs) using the high-throughput nanotransfer printing method. By providing ample area for conducting oscillating electric current, UNWRs overcome the saturation of the geometric scaling of the artificial magnetism. We experimentally demonstrated coarse and fine tuning of LC resonances over a wide wavelength range from 748 nm to 1600 nm. The added flexibility in transferring to other substrates makes UNWR a versatile building block for creating functional metamaterials in three dimensions.

  1. Spectral and angular characteristics of dielectric resonator metasurface at optical frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Longfang [School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA 5005 (Australia); Department of Electrical and Electronic Engineering, The University of Bristol, Bristol, BS8 1TH (United Kingdom); López-García, Martin; Oulton, Ruth; Klemm, Maciej [Department of Electrical and Electronic Engineering, The University of Bristol, Bristol, BS8 1TH (United Kingdom); Withayachumnankul, Withawat; Fumeaux, Christophe, E-mail: christophe.fumeaux@adelaide.edu.au [School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA 5005 (Australia); Shah, Charan M.; Mitchell, Arnan; Bhaskaran, Madhu; Sriram, Sharath [Functional Materials and Microsystems Research Group, School of Electrical and Computer Engineering, RMIT University, Melbourne VIC 3001 (Australia)

    2014-11-10

    The capability of manipulating light at subwavelength scale has fostered the applications of flat metasurfaces in various fields. Compared to metallic structure, metasurfaces made of high permittivity low-loss dielectric resonators hold the promise of high efficiency by avoiding high conductive losses of metals at optical frequencies. This letter investigates the spectral and angular characteristics of a dielectric resonator metasurface composed of periodic sub-arrays of resonators with a linearly varying phase response. The far-field response of the metasurface can be decomposed into the response of a single grating element (sub-array) and the grating arrangement response. The analysis also reveals that coupling between resonators has a non-negligible impact on the angular response. Over a wide wavelength range, the simulated and measured angular characteristics of the metasurface provide a definite illustration of how different grating diffraction orders can be selectively suppressed or enhanced through antenna sub-array design.

  2. Resonant bonding driven giant phonon anharmonicity and low thermal conductivity of phosphorene

    Science.gov (United States)

    Qin, Guangzhao; Zhang, Xiaoliang; Yue, Sheng-Ying; Qin, Zhenzhen; Wang, Huimin; Han, Yang; Hu, Ming

    2016-10-01

    Two-dimensional (2D) phosphorene, which possesses fascinating physical and chemical properties distinctively different from other 2D materials, calls for a fundamental understanding of thermal transport properties for its rapidly growing applications in nano- and optoelectronics and thermoelectrics. However, even the basic phonon property, for example, the exact value of the lattice thermal conductivity (κ ) of phosphorene reported in the literature, can differ unacceptably by one order of magnitude. More importantly, the fundamental physics underlying its unique properties such as strong phonon anharmonicity and unusual anisotropy remains largely unknown. In this paper, based on the analysis of electronic structure and lattice dynamics from first principles, we report that the giant phonon anharmonicity in phosphorene is associated with the soft transverse optical (TO) phonon modes and arises from the long-range interactions driven by the orbital governed resonant bonding. We also provide a microscopic picture connecting the anisotropic and low κ of phosphorene to the giant directional phonon anharmonicity and long-range interactions, which are further traced back to the asymmetric resonant orbital occupations of electrons and characteristics of the hinge-like structure. The unambiguously low κ of phosphorene obtained consistently by three independent ab initio methods confirms the phonon anharmonicity to a large extent and is expected to end the confusing huge deviations in previous studies. This work further pinpoints the necessity of including van der Waals interactions to accurately describe the interatomic interactions in phosphorene. We propose in 2D material that resonant bonding leads to low thermal conductivity, despite that it is originally found in three-dimensional (3D) thermoelectric and phase-change materials. Our study offers insights into phonon transport from the view of orbital states, which would be of great significance to the design of

  3. Optical sum-frequency generation in whispering gallery mode resonators

    CERN Document Server

    Strekalov, Dmitry V; Huang, Yu-Ping; Kumar, Prem

    2013-01-01

    We demonstrate sum-frequency generation in a nonlinear whispering gallery mode resonator between a telecom wavelength and the Rb D2 line, achieved through natural phase matching. Due to the strong optical field confinement and ultra high Q of the cavity, we achieve a 1000-fold enhancement in the conversion efficiency compared to existing waveguide-based devices. The experimental data are in agreement with the nonlinear dynamics and phase matching theory in the spherical geometry employed. The experimental and theoretical results point to a new platform to manipulate the color and quantum states of light waves toward applications such as atomic memory based quantum networking and logic operations with optical signals.

  4. Surface Plasmon Resonance Sensors Based on Polymer Optical Fiber

    Institute of Scientific and Technical Information of China (English)

    Rong-Sheng Zheng; Yong-Hua Lu; Zhi-Guo Xie; Jun Tao; Kai-Qun Lin; Hai Ming

    2008-01-01

    Surface Plasmon Resonance (SPR) is a powerful technique for directly sensing in biological studies, chemical detection and environmental pollution monitoring. In this paper, we present polymer optical fiber application in SPR sensors, including wavelength interrogation surface enhanced Raman scattering SPR sensor and surface enhanced Raman scattering (SERS) probe.Long-period fiber gratings are fabricated on single mode polymer optical fiber (POF) with 120 μm period and 50% duty cycle. The polarization characteristic of this kind of birefringent grating is studied. Theoretical analysis shows it will be advantageous in SPR sensing applications.

  5. Feedback-free optical cavity with self-resonating mechanism

    CERN Document Server

    Uesugi, Y; Honda, Y; Kosuge, A; Omori, T; Takahashi, T; Urakawa, J; Washio, M

    2015-01-01

    We demonstrated the operation of a high finesse optical cavity without utilizing an active feedback system to stabilize the resonance. The finesse of the cavity was measured to be $465,000 \\pm 3,000$, and the laser power stored in the cavity was $2.52 \\pm 0.13$ kW, which is about 187,000 times greater than the incident power to the cavity. The stored power was stabilized with a fluctuation of $1.7 \\%$, and we confirmed continuous cavity operation for more than two hours. This result relaxes the technical requirement of stabilizing of the optical resonant cavity and expands possibilities for various applications such as laser-Compton scattering.

  6. Resonant bowtie aperture nano-antenna for the control of optical nanocavities resonance

    CERN Document Server

    Baida, Fadi Issam

    2015-01-01

    Scanning Near-field Optical Microscopy (SNOM) has been successful in finely tuning the optical properties of photonic crystal (PC) nanocavities. The SNOM nanoprobes proposed so far allowed for either redshifting or blueshifting the resonance peak of the PC structures. In this Letter, we theoretically demonstrate the possibility of redshifting (up to +0.65nm) and blueshifting (up to $-5$~nm) PC cavity resonance with a single SNOM probe. This probe is obtained by opening a bowtie-aperture nano-antenna (BNA) at the apex of a metal-coated tip. This double-way PC tunability is the result of a competition between the effects of the BNA resonance (induced electric dipole leading to a redshift) and the metal-coated tip (induced magnetic dipole giving rise to a blueshift) onto the PC mode volume. The sign of the spectral shift is modified by simply controlling the tip-to-PC distance. This study opens the way to the full postproduction control of the resonance wavelength of high quality factor optical cavities.

  7. Frequency stabilization of the non resonant wave of a continuous-wave singly resonant optical parametric oscillator

    CERN Document Server

    Ly, Aliou; Bretenaker, Fabien

    2015-01-01

    We present an experimental technique allowing to stabilize the frequency of the non resonant wave in a singly resonant optical parametric oscillator (SRO) down to the kHz level, much below the pump frequency noise level. By comparing the frequency of the non resonant wave with a reference cavity, the pump frequency noise is imposed to the frequency of the resonant wave, and is thus subtracted from the frequency of the non resonant wave. This permits the non resonant wave obtained from such a SRO to be simultaneously powerful and frequency stable, which is usually impossible to obtain when the resonant wave frequency is stabilized.

  8. Singly-resonant optical parametric oscillator based on KTA crystal

    Indian Academy of Sciences (India)

    S Das; S Gangopadhyay; C Ghosh; G C Bhar

    2005-01-01

    Tunable mid-infra-red radiation by singly resonant optical parametric oscillation based on KTA crystal pumped by multi-axial Gaussian shape beam from Q-switched Nd:YAG laser has been demonstrated. Threshold energy of oscillation at different idler wavelengths for different cavity length has been demonstrated. Single pass conversion efficiency of incident pump energy to infra-red wavelength has also been measured.

  9. Triple-resonant Brillouin light scattering in magneto-optical cavities

    CERN Document Server

    Haigh, J A; Ramsay, A J; Ferguson, A J

    2016-01-01

    An enhancement in Brillouin light scattering of optical photons with magnons is demonstrated in magneto-optical whispering gallery mode resonators tuned to a triple resonance point. This occurs when both the input and output optical modes are resonant with those of the whispering gallery resonator, with a separation given by the ferromagnetic resonance (FMR) frequency. The identification and excitation of specific optical modes allows us to gain a clear understanding of the mode-matching conditions. A selection rule due to wavevector matching leads to an intrinsic single-sideband excitation. Strong suppression of one sideband is essential for one-to-one frequency mapping in coherent optical-to-microwave conversion.

  10. Resonance Frequency of Optical Microbubble Resonators: Direct Measurements and Mitigation of Fluctuations

    Science.gov (United States)

    Cosci, Alessandro; Berneschi, Simone; Giannetti, Ambra; Farnesi, Daniele; Cosi, Franco; Baldini, Francesco; Nunzi Conti, Gualtiero; Soria, Silvia; Barucci, Andrea; Righini, Giancarlo; Pelli, Stefano

    2016-01-01

    This work shows the improvements in the sensing capabilities and precision of an Optical Microbubble Resonator due to the introduction of an encaging poly(methyl methacrylate) (PMMA) box. A frequency fluctuation parameter σ was defined as a score of resonance stability and was evaluated in the presence and absence of the encaging system and in the case of air- or water-filling of the cavity. Furthermore, the noise interference introduced by the peristaltic and the syringe pumping system was studied. The measurements showed a reduction of σ in the presence of the encaging PMMA box and when the syringe pump was used as flowing system. PMID:27589761

  11. Surface plasmon resonance sensing detection of mercury and lead ions based on conducting polymer composite.

    Directory of Open Access Journals (Sweden)

    Mahnaz M Abdi

    Full Text Available A new sensing area for a sensor based on surface plasmon resonance (SPR was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU were obtained for PPy-CHI film due to a specific binding of chitosan with Pb(2+ and Hg(2+ ions. The Pb(2+ ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb(2+ compared to Hg(2+. The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.

  12. Electrostatic resonances and optical responses of cylindrical clusters

    Science.gov (United States)

    Choy, C. W.; Xiao, J. J.; Yu, K. W.

    2008-12-01

    We developed a Green function formalism (GFF) for computing the electrostatic resonance in clusters of cylindrical particles. In the GFF, we take advantage of a surface integral equation to avoid matching the complicated boundary conditions on the surfaces of the particles. Numerical solutions of the eigenvalue equation yield a pole spectrum in the spectral representation. The pole spectrum can in turn be used to compute the optical response of these particles. For two cylindrical particles, the results are in excellent agreement with the exact results from the multiple image method and the normal mode expansion method. The results of this work can be extended to investigate the enhanced nonlinear optical responses of metal-dielectric composites, as well as optical switching in plasmonic waveguides.

  13. Orbital order of spinless fermions near an optical Feshbach resonance

    Energy Technology Data Exchange (ETDEWEB)

    Hauke, Philipp [ICFO-Institut de Ciencies Fotoniques, Parc Mediterrani de la Tecnologia, E-08860 Castelldefels (Spain); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Zhao, Erhai [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Department of Physics and Astronomy, George Mason University, Fairfax, Virginia 22030 (United States); Goyal, Krittika; Deutsch, Ivan H. [Center for Quantum Information and Control (CQuIC), and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Liu, W. Vincent [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Lewenstein, Maciej [ICFO-Institut de Ciencies Fotoniques, Parc Mediterrani de la Tecnologia, E-08860 Castelldefels (Spain); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); ICREA-Institucio Catalana de Recerca i Estudis Avancats, Lluis Companys 23, E-08010 Barcelona (Spain)

    2011-11-15

    We study the quantum phases of a three-color Hubbard model that arises in the dynamics of the p-band orbitals of spinless fermions in an optical lattice. Strong, color-dependent interactions are induced by an optical Feshbach resonance. Starting from the microscopic scattering properties of ultracold atoms, we derive the orbital exchange constants at 1/3 filling on the cubic optical lattice. Using this, we compute the phase diagram in a Gutzwiller ansatz. We find phases with ''axial orbital order'' in which p{sub z} and p{sub x}+ip{sub y} (or p{sub x}-ip{sub y}) orbitals alternate.

  14. Magnetic resonance imaging in optic nerve lesions with multiple sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, Shigeyuki; Hirayama, Keizo; Kakisu, Yonetsugu; Adachi, Emiko (Chiba Univ. (Japan). School of Medicine)

    1990-12-01

    Magnetic resonance imaging (MRI) of the optic nerve was performed in 10 patients with multiple sclerosis (MS) using short inversion time inversion recovery (STIR) pulse sequences, and the results were compared with the visual evoked potentials (VEP). The 10 patients had optic neuritis in the chronic or remitting phase together with additional symptoms or signs allowing a diagnosis of clinically definite or probable MS. Sixteen optic nerves were clinically affected and 4 were unaffected. MRI was performed using a 0.5 tesla supeconducting unit, and multiple continuous 5 mm coronal and axial STIR images were obtained. A lesion was judged to be present if a focal or diffuse area of increased signal intensity was detectd in the optic nerve. In VEP, a delay in peak latency or no P 100 component was judged to be abnormal. With regard to the clinically affected optic nerves, MRI revealed a region of increased signal intensity in 14/16 (88%) and the VEP was abnormal in 16/16 (100%). In the clinically unaffected optic nerves, MRI revealed an increased signal intensity in 2/4 (50%). One of these nerves had an abnormal VEP and the other had a VEP latency at the upper limit of normal. The VEP was abnormal in 1/4 (25%). In the clinically affected optic nerves, the degree of loss of visual acuity was not associated with the longitudinal extent of the lesions shown by MRI. The mean length was 17.5 mm in optic nerves with a slight disturbance of visual acuity and 15.0 mm in nerves with severe visual loss. MRI using STIR pulse sequences was found to be almost as sensitive as VEP in detecting both clinically affected and unaffected optic nerve lesions in patients with MS, and was useful in visualizing the location or size of the lesions. (author).

  15. Optical Conductivity of Topological Surface States with Emergent Supersymmetry

    Science.gov (United States)

    Witczak-Krempa, William; Maciejko, Joseph

    2016-03-01

    Topological states of electrons present new avenues to explore the rich phenomenology of correlated quantum matter. Topological insulators (TIs) in particular offer an experimental setting to study novel quantum critical points (QCPs) of massless Dirac fermions, which exist on the sample's surface. Here, we obtain exact results for the zero- and finite-temperature optical conductivity at the semimetal-superconductor QCP for these topological surface states. This strongly interacting QCP is described by a scale invariant theory with emergent supersymmetry, which is a unique symmetry mixing bosons and fermions. We show that supersymmetry implies exact relations between the optical conductivity and two otherwise unrelated properties: the shear viscosity and the entanglement entropy. We discuss experimental considerations for the observation of these signatures in TIs.

  16. Ab initio electronic structure and optical conductivity of bismuth tellurohalides

    CERN Document Server

    Schwalbe, Sebastian; Starke, Ronald; Schober, Giulio A H; Kortus, Jens

    2016-01-01

    We investigate the electronic structure, dielectric and optical properties of bismuth tellurohalides BiTeX (X = I, Cl, Br) by means of all-electron density functional theory. In particular, we present the ab initio conductivities and dielectric tensors calculated over a wide frequency range, and compare our results with the recent measurements by Akrap et al. , Makhnev et al. , and Rusinov et al. . We show how the low-frequency branch of the optical conductivity can be used to identify characteristic intra- and interband transitions between the Rashba spin-split bands in all three bismuth tellurohalides. We further calculate the refractive indices and dielectric constants, which in turn are systematically compared to previous predictions and measurements. We expect that our quantitative analysis will contribute to the general assessment of bulk Rashba materials for their potential use in spintronics devices.

  17. Chemical shift selective magnetic resonance imaging of the optic nerve in patients with acute optic neuritis

    DEFF Research Database (Denmark)

    Larsson, H B; Thomsen, C; Frederiksen, J

    1988-01-01

    of the 16 patients, abnormalities were seen. In one patient with bilateral symptoms, signal hyperintensity and swelling of the right side of the chiasm were found. In another patient the optic nerve was found diffusely enlarged with only a marginally increased signal in the second echo. In the third patient......Optic neuritis is often the first manifestation of multiple sclerosis (MS). Sixteen patients with acute optic neuritis and one patient with benign intracranial hypertension (BIH) were investigated by magnetic resonance imaging, using a chemical shift selective double spin echo sequence. In 3...... an area of signal hyperintensity and swelling was seen in the left optic nerve. In the patient with BIH the subarachnoid space which surrounds the optic nerves was enlarged. Even using this refined pulse sequence, avoiding the major artefact in imaging the optic nerve, the chemical shift artefact, lesions...

  18. Self-resonant Coil for Contactless Electrical Conductivity Measurement under Pulsed Ultra-high Magnetic Fields

    CERN Document Server

    Nakamura, Daisuke; Takeyama, Shojiro

    2014-01-01

    In this study, we develop experimental apparatus for contactless electrical conductivity measurements under pulsed high magnetic fields over 100 T using a self-resonant-type high-frequency circuit. The resonant power spectra were numerically analyzed, and the conducted simulations showed that the apparatus is optimal for electrical conductivity measurements of materials with high electrical conductivity. The newly developed instruments were applied to a high-temperature cuprate superconductor La$_{2-x}$Sr$_x$CuO$_4$ to show conductivity changes in magnetic fields up to 102 T with a good signal-to-noise ratio. The upper critical field was determined with high accuracy.

  19. Demonstration of whispering-gallery-mode resonant enhancement of optical forces

    CERN Document Server

    Li, Yangcheng; Limberopoulos, Nicholaos I; Astratov, Vasily N

    2015-01-01

    We experimentally studied whispering-gallery modes(WGMs) and demonstrated resonance enhancement of optical forces evanescently exerted on dielectric microspheres. We showed that the resonant light pressure can be used for optical sorting of microparticles with extraordinary uniform resonant properties that is unachievable by conventional sorting techniques.

  20. On the fundamental mode of the optical resonator with toroidal mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Serednyakov, S.S.; Vinokurov, N.A. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1995-12-31

    The fundamental mode of the optical resonator with the toroidal mirrors is investigated. The losses in such resonator with the on-axis holes are low in compare with the case of spherical mirrors. The use of this type of optical resonator is briefly discussed.

  1. Radiation-induced optic neuropathy: A magnetic resonance imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Guy, J.; Mancuso, A.; Beck, R.; Moster, M.L.; Sedwick, L.A.; Quisling, R.G.; Rhoton, A.L. Jr.; Protzko, E.E.; Schiffman, J. (Univ. of Florida, Gainesville (USA))

    1991-03-01

    Optic neuropathy induced by radiation is an infrequent cause of delayed visual loss that may at times be difficult to differentiate from compression of the visual pathways by recurrent neoplasm. The authors describe six patients with this disorder who experienced loss of vision 6 to 36 months after neurological surgery and radiation therapy. Of the six patients in the series, two had a pituitary adenoma and one each had a metastatic melanoma, multiple myeloma, craniopharyngioma, and lymphoepithelioma. Visual acuity in the affected eyes ranged from 20/25 to no light perception. Magnetic resonance (MR) imaging showed sellar and parasellar recurrence of both pituitary adenomas, but the intrinsic lesions of the optic nerves and optic chiasm induced by radiation were enhanced after gadolinium-diethylenetriaminepenta-acetic acid (DTPA) administration and were clearly distinguishable from the suprasellar compression of tumor. Repeated MR imaging showed spontaneous resolution of gadolinium-DTPA enhancement of the optic nerve in a patient who was initially suspected of harboring recurrence of a metastatic malignant melanoma as the cause of visual loss. The authors found the presumptive diagnosis of radiation-induced optic neuropathy facilitated by MR imaging with gadolinium-DTPA. This neuro-imaging procedure may help avert exploratory surgery in some patients with recurrent neoplasm in whom the etiology of visual loss is uncertain.

  2. Statistics of chaotic resonances in an optical microcavity.

    Science.gov (United States)

    Wang, Li; Lippolis, Domenico; Li, Ze-Yang; Jiang, Xue-Feng; Gong, Qihuang; Xiao, Yun-Feng

    2016-04-01

    Distributions of eigenmodes are widely concerned in both bounded and open systems. In the realm of chaos, counting resonances can characterize the underlying dynamics (regular vs chaotic), and is often instrumental to identify classical-to-quantum correspondence. Here, we study, both theoretically and experimentally, the statistics of chaotic resonances in an optical microcavity with a mixed phase space of both regular and chaotic dynamics. Information on the number of chaotic modes is extracted by counting regular modes, which couple to the former via dynamical tunneling. The experimental data are in agreement with a known semiclassical prediction for the dependence of the number of chaotic resonances on the number of open channels, while they deviate significantly from a purely random-matrix-theory-based treatment, in general. We ascribe this result to the ballistic decay of the rays, which occurs within Ehrenfest time, and importantly, within the time scale of transient chaos. The present approach may provide a general tool for the statistical analysis of chaotic resonances in open systems.

  3. Oxide mediated spectral shifting in aluminum resonant optical antennas.

    Science.gov (United States)

    Schwab, Patrick M; Moosmann, Carola; Dopf, Katja; Eisler, Hans-Jürgen

    2015-10-01

    As a key feature among metals showing good plasmonic behavior, aluminum extends the spectrum of achievable plasmon resonances of optical antennas into the deep ultraviolet. Due to degradation, a native oxide layer gives rise to a metal-core/oxide-shell nanoparticle and influences the spectral resonance peak position. In this work, we examine the role of the underlying processes by applying numerical nanoantenna models that are experimentally not feasible. Finite-difference time-domain simulations are carried out for a large variety of elongated single-arm and two-arm gap nanoantennas. In a detailed analysis, which takes into account the varying surface-to-volume ratio, we show that the overall spectral shift toward longer wavelengths is mainly driven by the higher index surrounding material rather than by the decrease of the initial aluminum volume. In addition, we demonstrate experimentally that this shifting can be minimized by an all-inert fabrication and subsequent proof-of-concept encapsulation.

  4. Optical attenuation in ion-implanted silicon waveguide racetrack resonators.

    Science.gov (United States)

    Doylend, J K; Jessop, P E; Knights, A P

    2011-08-01

    The optical absorption at wavelengths near 1550 nm has been quantified as a function of annealing temperature in ion-implanted silicon-on-insulator racetrack resonators. The variation of the output characteristics of the bus waveguide versus the concentration of implantation-induced lattice disorder in the ring is used to develop a novel method for the determination of the coupling and round-trip loss of the resonator, independently. This experimental procedure has general applicability for the determination of these parameters. Significant propagation loss is found to persist following annealing at temperatures previously observed to remove the majority of ion implantation damage. It is suggested that these annealing characteristics are a consequence of an ion implantation range which is greater than the silicon waveguide layer thickness.

  5. Modeling of Self-Pumped Singly Resonant Optical Parametric Oscillator

    CERN Document Server

    Deng, Chengxian

    2016-01-01

    A model of the steady-state operating, self-pumped singly resonant optical parametric oscillator (SPSRO) has been developed. The characteristics of quasi three-level laser gain medium pumped longitudinally have been taken into account. The characteristics of standing wave cavity, reabsorption losses, focusing Gaussian beams of the pump laser, fundamental laser and signal wave have been considered in the analyses. Furthermore, The power characteristics of threshold and efficiency have been analyzed, employing a Yb3+-doped periodically poled lithium niobate co-doped with MgO (Yb3+:MgO:PPLN) as the medium of laser gain and second-order nonlinear crystal.

  6. Fluctuations and entropy in models of quantum optical resonance

    Science.gov (United States)

    Phoenix, S. J. D.; Knight, P. L.

    1988-09-01

    We use variances, entropy, and the Shannon entropy to analyse the fluctuations and quantum evolution of various simple models of quantum optical resonance. We discuss at length the properties of the single-mode radiation field coupled to a single two-level atom, and then extend our analysis to describe the micromaser in which a cavity mode is repeatedly pumped by a succession of atoms passing through the cavity. We also discuss the fluctuations in the single-mode laser theory of Scully and Lamb.

  7. Molecular system generation with strong resonance optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Kuntsevich, B.F.; Churakov, V.V.

    1977-03-01

    A study was made of molecular system generation modulated by three oscillating levels with a rotating structure with strong resonance optical pumping. Molecular behavior of the active medium is described by equations for the density matrix. The relationship between the amplification coefficient and pressure at various pumping intensities was examined. In approaching the assigned pumping field, an examination was made of how the generation field is affected by the volumetric density of the pumping energy, partial pressure of the buffer gas and frequency difference in the pumping channel.

  8. Magnetic resonance imaging of traumatic transection of the optic chiasm

    Energy Technology Data Exchange (ETDEWEB)

    De Nunzio, M.; McAuliffe, W.; Chakera, T.M.H. [Royal Perth Hospital, Perth, WA (Australia). Department of Diagnostic Radiology

    1997-05-01

    Traumatic lesions of the visual pathways are an uncommon, but well recognized complication of head injury. Optimal visualization of such lesions is probably best achieved using multiplanar magnetic resonance (MR) imaging. A case of complete sagittal transection of the optic chiasm using MR imaging is reported. This has been rarely documented in the literature. Computerized tomography demonstrated a basal skull fracture extending through the sphenoid sinus and into the floor of the pituitary fossa. However, MRI is advocated as the optimal imaging modality for the diagnosis of traumatic lesions of suprasellar structures, perhaps obviating the need for future investigations. 7 refs., 1 fig.

  9. Electrically conductive, optically transparent polymer/carbon nanotube composites

    Science.gov (United States)

    Connell, John W. (Inventor); Smith, Jr., Joseph G. (Inventor); Harrison, Joycelyn S. (Inventor); Park, Cheol (Inventor); Watson, Kent A. (Inventor); Ounaies, Zoubeida (Inventor)

    2011-01-01

    The present invention is directed to the effective dispersion of carbon nanotubes (CNTs) into polymer matrices. The nanocomposites are prepared using polymer matrices and exhibit a unique combination of properties, most notably, high retention of optical transparency in the visible range (i.e., 400-800 nm), electrical conductivity, and high thermal stability. By appropriate selection of the matrix resin, additional properties such as vacuum ultraviolet radiation resistance, atomic oxygen resistance, high glass transition (T.sub.g) temperatures, and excellent toughness can be attained. The resulting nanocomposites can be used to fabricate or formulate a variety of articles such as coatings on a variety of substrates, films, foams, fibers, threads, adhesives and fiber coated prepreg. The properties of the nanocomposites can be adjusted by selection of the polymer matrix and CNT to fabricate articles that possess high optical transparency and antistatic behavior.

  10. Slow light, induced dispersion, enhanced nonlinearity, and optical solitons in a resonator-array waveguide.

    Science.gov (United States)

    E Heebner, John; Boyd, Robert W; Park, Q-Han

    2002-03-01

    We describe an optical transmission line that consists of an array of wavelength-scale optical disk resonators coupled to an optical waveguide. Such a structure leads to exotic optical characteristics, including ultraslow group velocities of propagation, enhanced optical nonlinearities, and large dispersion with a controllable magnitude and sign. This device supports soliton propagation, which can be described by a generalized nonlinear Schrodinger equation.

  11. Adaptive optical design in surface plasma resonance sensor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; ZHONG Jin-gang

    2006-01-01

    A double-prism adaptive optical design in surface plasma resonance (SPR) sensor is proposed,which consists of two identical isosceles right-triangular prisms. One prism is used as a component of Kretschmann configuration,and the other is for regulation of the optical path. When double-prism structure is angle-scanned by an immovable incident ray,the output ray will be always parallel with the incident ray and just has a small displacement with the shift of output point.The output ray can be focused on a fixed photodetector by a convex lens.Thus it can be avoided that a prism and a photodetector rotate by θ and 2θ respectively in conventional angular scanning SPR sensor.This new design reduces the number of the movable components,makes the structure simple and compact,and makes the manipulation convenient.

  12. Resonant optical transducers for in-situ gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Bond, Tiziana C; Cole, Garrett; Goddard, Lynford

    2016-06-28

    Configurations for in-situ gas detection are provided, and include miniaturized photonic devices, low-optical-loss, guided-wave structures and state-selective adsorption coatings. High quality factor semiconductor resonators have been demonstrated in different configurations, such as micro-disks, micro-rings, micro-toroids, and photonic crystals with the properties of very narrow NIR transmission bands and sensitivity up to 10.sup.-9 (change in complex refractive index). The devices are therefore highly sensitive to changes in optical properties to the device parameters and can be tunable to the absorption of the chemical species of interest. Appropriate coatings applied to the device enhance state-specific molecular detection.

  13. The impact of optic nerve movement on optic nerve magnetic resonance diffusion parameters

    Directory of Open Access Journals (Sweden)

    Anand Moodley

    2014-04-01

    Full Text Available Background: Optic nerve diffusion imaging is a useful investigational tool of optic nerve microstructure, but is limited by eye-movement-induced optic nerve movement and artifacts from surrounding cerebrospinal fluid, fat, bone and air. Attempts at improving patient cooperation, thus voluntarily limiting eye movement during a standard diffusion imagingsequence, are usually futile. The aim of this study was to establish the impact of optic nerve movement on clinical diffusion parameters of the optic nerve.Method: Twenty-nine healthy volunteers with intact vision and intact conjugate gaze were recruited and subjected to magnetic resonance diffusion-weighted imaging (DWI and diffusion-tensor imaging (DTI of the optic nerves. Twenty right eyes had nerve tracking done using single-shot echo-planar imaging at 20 time points over 3 minutes. Optic nerve movement measurements were correlated with diffusion parameters of apparent diffusion coefficient (ADC, mean diffusivity (MD, fractional anisotropy (FA and anisotropic index(AI using Spearman’s rank correlation.Results: No significant correlations were noted between optic nerve movement parameters and ADC in the axial plane and MD of the optic nerve. Low to moderate negative correlations were noted between optic nerve movement parameters and AI and FA and positive correlation with ADC in the radial plane.Conclusion: Optic nerve movement documented during the timespan of standard diffusion sequences (DWI and DTI has a negative effect on the anisotropic diffusion parameters of the optic nerve. With greater eye movement, optic nerve diffusion appears less anisotropic owing to greater radial diffusion.

  14. Optical spectroscopy of single Si nanocylinders with magnetic and electric resonances

    DEFF Research Database (Denmark)

    Evlyukhin, A. B.; Eriksen, R. L.; Cheng, W.

    2014-01-01

    Resonant electromagnetic properties of nanoparticles fabricated from high-index semiconductor or dielectric materials are very promising for the realization of novel nanoantennas and metamaterials. In this paper we study optical resonances of Si nanocylinders located on a silica substrate...

  15. Tunable, continuous-wave single-resonant optical parametric oscillator with output coupling for resonant wave

    Science.gov (United States)

    Xiong-Hua, Zheng; Bao-Fu, Zhang; Zhong-Xing, Jiao; Biao, Wang

    2016-01-01

    We present a continuous-wave singly-resonant optical parametric oscillator with 1.5% output coupling of the resonant signal wave, based on an angle-polished MgO-doped periodically poled lithium niobate (MgO:PPLN), pumped by a commercial Nd:YVO4 laser at 1064 nm. The output-coupled optical parametric oscillator delivers a maximum total output power of 4.19 W with 42.8% extraction efficiency, across a tuning range of 1717 nm in the near- and mid-infrared region. This indicates improvements of 1.87 W in output power, 19.1% in extraction efficiency and 213 nm in tuning range extension in comparison with the optical parametric oscillator with no output coupling, while at the expense of increasing the oscillation threshold by a factor of ˜ 2. Moreover, it is confirmed that the finite output coupling also contributes to the reduction of the thermal effects in crystal. Project supported by the National Natural Science Foundation of China (Grant Nos. 61308056, 11204044, 11232015, and 11072271), the Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20120171110005 and 20130171130003), the Fundamental Research Funds for the Central Universities of China (Grant No. 14lgpy07), and the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory, China (Grant No. ZHD201203).

  16. Full investigation of the resonant frequency servo loop for resonator fiber-optic gyro.

    Science.gov (United States)

    Ma, Huilian; Lu, Xiao; Yao, Linzhi; Yu, Xuhui; Jin, Zhonghe

    2012-07-20

    Resonator fiber-optic gyro (RFOG) is a high-accuracy inertial rotation sensor based on the Sagnac effect. A high-accuracy resonant frequency servo loop is indispensable for a high-performance RFOG. It is composed of a frequency discriminator, a loop filter, and a laser actuator. Influences of the loop parameters are fully developed. Optimized loop parameters are obtained by considering the noise reduction and wide dynamic performance of the RFOG. As a result, with the integration time of 10 s, the accuracy of the resonant frequency loop is increased to 0.02 Hz (1σ). It is equivalent to a rotation rate of 0.067°/h, which is close to the shot noise limit for the RFOG, while a minimum rotation of ±0.05°/s has been carried out simultaneously. These are the best results reported to date, to the best of our knowledge, for an RFOG using the miniature semiconductor laser that benefits from the optimization of the resonant frequency servo-loop parameters.

  17. Theoretical analyses of resonant frequency shift in anomalous dispersion enhanced resonant optical gyroscopes

    Science.gov (United States)

    Lin, Jian; Liu, Jiaming; Zhang, Hao; Li, Wenxiu; Zhao, Lu; Jin, Junjie; Huang, Anping; Zhang, Xiaofu; Xiao, Zhisong

    2016-12-01

    Rigorous expressions of resonant frequency shift (RFS) in anomalous dispersion enhanced resonant optical gyroscopes (ADEROGs) are deduced without making approximation, which provides a precise theoretical guidance to achieve ultra-sensitive ADEROGs. A refractive index related modification factor is introduced when considering special theory of relativity (STR). We demonstrate that the RFS will not be ”infinitely large” by using critical anomalous dispersion (CAD) and negative modification does not exist, which make the mechanism of anomalous dispersion enhancement clear and coherent. Although step change of RFS will happen when the anomalous dispersion condition varies, the amplification of RFS is limited by attainable variation of refractive index in practice. Moreover, it is shown that the properties of anomalous dispersion will influence not only the amplification of RFS, but also the detection range of ADEROGs.

  18. Frequency-dependent conductivity contrast for tissue characterization using a dual-frequency range conductivity mapping magnetic resonance method.

    Science.gov (United States)

    Kim, Dong-Hyun; Chauhan, Munish; Kim, Min-Oh; Jeong, Woo Chul; Kim, Hyung Joong; Sersa, Igor; Kwon, Oh In; Woo, Eung Je

    2015-02-01

    Electrical conductivities of biological tissues show frequency-dependent behaviors, and these values at different frequencies may provide clinically useful diagnostic information. MR-based tissue property mapping techniques such as magnetic resonance electrical impedance tomography (MREIT) and magnetic resonance electrical property tomography (MREPT) are widely used and provide unique conductivity contrast information over different frequency ranges. Recently, a new method for data acquisition and reconstruction for low- and high-frequency conductivity images from a single MR scan was proposed. In this study, we applied this simultaneous dual-frequency range conductivity mapping MR method to evaluate its utility in a designed phantom and two in vivo animal disease models. Magnetic flux density and B(1)(+) phase map for dual-frequency conductivity images were acquired using a modified spin-echo pulse sequence. Low-frequency conductivity was reconstructed from MREIT data by the projected current density method, while high-frequency conductivity was reconstructed from MREPT data by B(1)(+) mapping. Two different conductivity phantoms comprising varying ion concentrations separated by insulating films with or without holes were used to study the contrast mechanism of the frequency-dependent conductivities related to ion concentration and mobility. Canine brain abscess and ischemia were used as in vivo models to evaluate the capability of the proposed method to identify new electrical properties-based contrast at two different frequencies. The simultaneous dual-frequency range conductivity mapping MR method provides unique contrast information related to the concentration and mobility of ions inside tissues. This method has potential to monitor dynamic changes of the state of disease.

  19. Origin invariance in vibrational resonance Raman optical activity

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, Luciano N., E-mail: lnvidal@utfpr.edu.br; Cappelli, Chiara, E-mail: chiara.cappelli@unipi.it [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 3, 56124 Pisa (Italy); Egidi, Franco [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Barone, Vincenzo [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy)

    2015-05-07

    A theoretical investigation on the origin dependence of the vibronic polarizabilities, isotropic and anisotropic rotational invariants, and scattering cross sections in Resonance Raman Optical Activity (RROA) spectroscopy is presented. Expressions showing the origin dependence of these polarizabilities were written in the resonance regime using the Franck-Condon (FC) and Herzberg-Teller (HT) approximations for the electronic transition moments. Differently from the far-from-resonance scattering regime, where the origin dependent terms cancel out when the rotational invariants are calculated, RROA spectrum can exhibit some origin dependence even for eigenfunctions of the electronic Hamiltonian. At the FC level, the RROA spectrum is completely origin invariant if the polarizabilities are calculated using a single excited state or for a set of degenerate states. Otherwise, some origin effects can be observed in the spectrum. At the HT level, RROA spectrum is origin dependent even when the polarizabilities are evaluated from a single excited state but the origin effect is expected to be small in this case. Numerical calculations performed for (S)-methyloxirane, (2R,3R)-dimethyloxirane, and (R)-4-F-2-azetidinone at both FC and HT levels using the velocity representation of the electric dipole and quadrupole transition moments confirm the predictions of the theory and show the extent of origin effects and the effectiveness of suggested ways to remove them.

  20. Robust design of an optical router based on a tapered side-coupled integrated spaced sequence of optical resonators.

    Science.gov (United States)

    Bettotti, P; Mancinelli, M; Guider, R; Masi, M; Vanacharla, M Rao; Pavesi, L

    2011-04-15

    A novel (to our knowledge) scheme of an optical router/switch element, composed of a tapered side-coupled integrated spaced sequence of optical resonators, is proposed. It is based on a modified design of the ring sequence in which the resonance conditions are set by the single ring resonance and by the coherent feedback of the sequence of rings. This double condition yields robustness against fabrication defects, dense routing capability, and high switching efficiency.

  1. Chiral Low Frequency Resonance on an Anisotropically Conductive Cylinder with a Thin Longitudinal Slot

    Science.gov (United States)

    2000-09-29

    electromagnetic waves by a Narrow anisotropically conductive strip," Radiotekh. Elektron ., vol. 44, no. 7, pp. 800-805, 1999. [3] A. N. Sivov, A. D...Chuprin, and A. D. Shatrov, "Low-frequency resonance in a hollow circular cylinder with perfect conductivity along helical lines," Radiotekh. Elektron

  2. Investigation of plasmon resonance tunneling through subwavelength hole arrays in highly doped conductive ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Nader, Nima, E-mail: nima.nader@nist.gov; Vangala, Shivashankar [Solid State Scientific Corporation, 12 Simon St., Nashua, New Hampshire 03060 (United States); Air Force Research Laboratory, Sensors Directorate, 2241 Avionics Circle, Wright Patterson AFB, Ohio 45433 (United States); Hendrickson, Joshua R.; Leedy, Kevin D.; Cleary, Justin W. [Air Force Research Laboratory, Sensors Directorate, 2241 Avionics Circle, Wright Patterson AFB, Ohio 45433 (United States); Look, David C. [Air Force Research Laboratory, Sensors Directorate, 2241 Avionics Circle, Wright Patterson AFB, Ohio 45433 (United States); Wyle Laboratories, Inc., 2601 Mission Point Blvd., Suite 300, Dayton, Ohio 45435 (United States); Semiconductor Research Center, Wright State University, Dayton, Ohio 45435 (United States); Guo, Junpeng [Department of Electrical and Computer Engineering, University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama 35899 (United States)

    2015-11-07

    Experimental results pertaining to plasmon resonance tunneling through a highly conductive zinc oxide (ZnO) layer with subwavelength hole-arrays is investigated in the mid-infrared regime. Gallium-doped ZnO layers are pulsed-laser deposited on a silicon wafer. The ZnO has metallic optical properties with a bulk plasma frequency of 214 THz, which is equivalent to a free space wavelength of 1.4 μm. Hole arrays with different periods and hole shapes are fabricated via a standard photolithography process. Resonant mode tunneling characteristics are experimentally studied for different incident angles and compared with surface plasmon theoretical calculations and finite-difference time-domain simulations. Transmission peaks, higher than the baseline predicted by diffraction theory, are observed in each of the samples at wavelengths that correspond to the excitation of surface plasmon modes.

  3. Origin of universal optical conductivity and optical stacking sequence identification in multilayer graphene.

    Science.gov (United States)

    Min, Hongki; MacDonald, A H

    2009-08-07

    We show that the origin of the universal optical conductivity in a normal N-layer graphene multilayer is an emergent chiral symmetry which guarantees that sigma(omega) = Nsigma_{uni} in both low and high-frequency limits. [sigma_{uni} = (pi/2)e;{2}/h]. We use this physics to relate intermediate frequency conductivity trends to qualitative characteristics of the multilayer stacking sequence.

  4. Origin of Universal Optical Conductivity and Optical Stacking Sequence Identification in Multilayer Graphene

    OpenAIRE

    Min, Hongki; MacDonald, A. H.

    2009-01-01

    We show that the origin of the universal optical conductivity in a normal $N$-layer graphene multilayer is an emergent chiral symmetry which guarantees that $\\sigma(\\omega)=N\\sigma_{uni}$ in both low and high frequency limits. [$\\sigma_{uni}=(\\pi/2) e^2/h$]. We use this physics to relate intermediate frequency conductivity trends to qualitative characteristics of the multilayer stacking sequence.

  5. Surface plasmon resonance microscopy: Achieving a quantitative optical response

    Science.gov (United States)

    Peterson, Alexander W.; Halter, Michael; Plant, Anne L.; Elliott, John T.

    2016-09-01

    Surface plasmon resonance (SPR) imaging allows real-time label-free imaging based on index of refraction and changes in index of refraction at an interface. Optical parameter analysis is achieved by application of the Fresnel model to SPR data typically taken by an instrument in a prism based figuration. We carry out SPR imaging on a microscope by launching light into a sample and collecting reflected light through a high numerical aperture microscope objective. The SPR microscope enables spatial resolution that approaches the diffraction limit and has a dynamic range that allows detection of subnanometer to submicrometer changes in thickness of biological material at a surface. However, unambiguous quantitative interpretation of SPR changes using the microscope system could not be achieved using the Fresnel model because of polarization dependent attenuation and optical aberration that occurs in the high numerical aperture objective. To overcome this problem, we demonstrate a model to correct for polarization diattenuation and optical aberrations in the SPR data and develop a procedure to calibrate reflectivity to index of refraction values. The calibration and correction strategy for quantitative analysis was validated by comparing the known indices of refraction of bulk materials with corrected SPR data interpreted with the Fresnel model. Subsequently, we applied our SPR microscopy method to evaluate the index of refraction for a series of polymer microspheres in aqueous media and validated the quality of the measurement with quantitative phase microscopy.

  6. Ultrafast optical modulation of magneto-optical terahertz effects occurring in a graphene-loaded resonant metasurface

    Science.gov (United States)

    Zanotto, S.; Lange, C.; Maag, T.; Pitanti, A.; Miseikis, V.; Coletti, C.; Degl'Innocenti, R.; Baldacci, L.; Huber, R.; Tredicucci, A.

    2016-09-01

    In this paper we investigate the effect of a static magnetic field and of optical pumping on the transmittance of a hybrid graphene-split ring resonator metasurface. A significant modulation of the transmitted spectra is obtained, both by optical pumping, and by a combination of optical pumping and magnetostatic biasing. The transmittance modulation features spectral fingerprints that are characteristic of a non-trivial interplay between the bare graphene response and the split ring resonance.

  7. Tuning the optical forces on- and off-resonance in microspherical photonics

    CERN Document Server

    Li, Yangcheng; Jofre, Ana; Astratov, Vasily N

    2015-01-01

    Light pressure effect has been discovered long ago and has been used as an optical method to manipulate microand nanoparticles. It is usually considered as a nonresonant effect determined by the transfer of the momentum of light. However, recently we have observed that large polystyrene microspheres of 15-20 {\\mu}m diameters supporting high quality whispering gallery resonances can be optically propelled in water at an extraordinary high velocity along tapered fibers under resonant conditions. In this work we compare on- and off-resonant optical forces in microspherical photonics by controlling the detuning between the laser emission line and whispering gallery resonances. Our approach involves manipulation with microspheres using conventional optical tweezers and their advanced spectroscopic characterization in fiber-integrated setups. We demonstrate dramatic difference in the optical forces exerted on microspheres in the on-resonant and off-resonant cases. This method can be used to study spectral propertie...

  8. White-Light Whispering Gallery Mode Optical Resonator System and Method

    Science.gov (United States)

    Matsko, Andrey B. (Inventor); Savchenkov, Anatoliy A. (Inventor); Maleki, Lute (Inventor)

    2009-01-01

    An optical resonator system and method that includes a whispering-gallery mode (WGM) optical resonator that is capable of resonating across a broad, continuous swath of frequencies is provided. The optical resonator of the system is shaped to support at least one whispering gallery mode and includes a top surface, a bottom surface, a side wall, and a first curved transition region extending between the side wall and the top surface. The system further includes a coupler having a coupling surface which is arranged to face the transition region of the optical resonator and in the vicinity thereof such that an evanescent field emitted from the coupler is capable of being coupled into the optical resonator through the first curved transition region

  9. SiO2 Waveguide Resonator Used in an Integrated Optical Gyroscope

    Institute of Scientific and Technical Information of China (English)

    YU Huai-Yong; ZHANG Chun-Xi; FENG Li-Shuang; ZHOU Zhen; HONG Ling-Fei

    2009-01-01

    An integrated optical waveguide resonator based on a SiO2 waveguide is proposed, fabricated and tested. The method of designing the resonator is also presented. The optimal spirting ratio of the coupler is gained by simulating the relationship between the splitting ratio of the key coupler in the resonator and the resonator's finesse w/th resonance depth. The calculated fundamental detection limit of this integrated optical wavegnide resonator is 1.6°/b. Finally, a micro-optical gyroscope system based on the integrated waveguide resonator is built, and the measured resonator's finesse F is close to 70 under fluctuating temperature. To the best of our knowledge, the present F is the best result to date. For the coupler splitting rate the experimental results have fixed errors with the simulation results caused by fabrication processes which can be easily eliminated, implying that the method of design is effective and applicable.

  10. Longitudinal optical and spin Hall conductivities of Rashba conducting strips coupled to ferromagnetic and antiferromagnetic layers

    Science.gov (United States)

    Riera, José A.

    2017-01-01

    A system composed of a conducting planar strip with Rashba spin-orbit coupling (RSOC), magnetically coupled to a layer of localized magnetic moments, at equilibrium, is studied within a microscopic Hamiltonian with numerical techniques at zero temperature in the clean limit. In particular, transport properties for the cases of ferromagnetic (FM) and antiferromagnetic (AFM) coupled layers are computed in linear response on strips of varying width. Some behaviors observed for these properties are consistent with the ones observed for the corresponding Rashba helical currents. The case of uncoupled Rashba strips is also studied for comparison. In the case of Rashba strips coupled to an AFM localized order, results for the longitudinal dc conductivity, for small strip widths, suggest the proximity to a metal-insulator transition. More interesting, in the proximity of this transition, and in general at intermediate values of the RSOC, a large spin Hall conductivity is observed that is two orders of magnitude larger than the one for the FM order for the same values of the RSOC and strip widths. There are clearly two different regimes for small and for large RSOC, which is also present in the behavior of Rashba helical currents. Different contributions to the optical and the spin Hall conductivities, according to a new classification of inter- or intraband origin proposed for planar strips in the clean limit, or coming from the hopping or spin-orbit terms of the Hamiltonian, are examined. Finally, the effects of different orientation of the coupled magnetic moments will be also studied.

  11. Chemical shift selective magnetic resonance imaging of the optic nerve in patients with acute optic neuritis

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, H.B.W.; Thomsen, C.; Frederiksen, J.; Henriksen, O.; Olesen, J.

    Optic neuritis is often the first manifestion of multiple sclerosis (MS). Sixteen patients with acute optic neuritis and one patient with benign intracranial hypertension (BIH) were investigated by magnetic resonance imaging, using a chemical shift selective double spin echo sequence. In 3 of the 16 patients, abnormalities were seen. In one patient with bilateral symptoms, signal hyperintensity and swelling of the right side of the chiasm were found. In another patient the optic nerve was found diffusely enlarged with only a marginally increased signal in the second echo. In the third patient an area of signal hyperintensity and swelling was seen in the left optic nerve. In the patient with BIH the subarachnoid space which surrounds the optic nerves was enlarged. Even using this refined pulse sequence, avoiding the major artefact in imaging the optic nerve, the chemical shift artefact, lesions were only shown in 3/16 (19%) of the patients with optic neuritis. Nevertheless, the presented chemical shift selective double spin echo sequence may be of great value for detection of retrobulbar lesions.

  12. Electrical conductivity of Jupiter's shallow interior and the formation of a resonant of a resonant planetary-ionospheric cavity

    Science.gov (United States)

    Sentman, D. D.

    1990-01-01

    The present consideration of hydrogenic atmospheric reactions on Jupiter, to a depth of 4000 km, notes the primary ion constituents at these depths to be both positive and negative ions of molecular hydrogen contributing less than 20 percent to total electrical conductivity by free electrons. An electrical surface defined by the boundary beneath which the interior is electrically conducting exists at depths which vary according to EM wave frequency, from 1100 km for 1 mHz to 3000 for 1 MHz. The presence of a lower electrical boundary within the shallow interior suggests that a planetary-ionosphere resonant cavity analogous to the earth-ionosphere cavity may exist.

  13. Resonant Doppler imaging with Fourier domain optical coherence tomography

    Science.gov (United States)

    Leitgeb, Rainer A.; Szklumowska, Anna; Pircher, Michael; Gotzinger, Erich; Fercher, Adolf F.

    2005-04-01

    Fourier Domain Optical Coherene Tomography (FD OCT) is a high speed imaging modality with increased sensitivity as compared to standard time domain (TD) OCT. The higher sensitivity is especially important, if strongly scattering tissue such as blood is investigated. Recently it could be shown that retinal blood flow can be assessed in-vivo by high speed FD OCT. However the detection bandwidth of color Doppler (CD) FDOCT is strongly limited due to blurring of the detected interference fringes during exposure. This leads to a loss of sensitivity for detection of fast changes in tissue. Using a moving mirror as a reference one can effectively increase the detection bandwidth for CD FDOCT and perform perfusion sectioning. The modality is called resonant CD FDOCT imaging. The principle of the method is presented and experimentally verified.

  14. Strongly driven nonlinear quantum optics in microring resonators

    CERN Document Server

    Vernon, Z

    2015-01-01

    We present a detailed analysis of strongly driven spontaneous four-wave mixing in a lossy integrated microring resonator side-coupled to a channel waveguide. A nonperturbative, analytic solution within the undepleted pump approximation is developed for a cw pump input of arbitrary intensity. In the strongly driven regime self- and cross-phase modulation, as well as multi-pair generation, lead to a rich variety of power-dependent effects; the results are markedly different than in the low power limit. The photon pair generation rate, single photon spectrum, and joint spectral intensity (JSI) distribution are calculated. Splitting of the generated single photon spectrum into a doublet structure associated with both pump detuning and cross-phase modulation is predicted, as well as substantial narrowing of the generated signal and idler bandwidths associated with the onset of optical parametric oscillation at intermediate powers. Both the correlated and uncorrelated contributions to the JSI are calculated, and fo...

  15. Brain metastasis detection by resonant Raman optical biopsy method

    Science.gov (United States)

    Zhou, Yan; Liu, Cheng-hui; Cheng, Gangge; Zhou, Lixin; Zhang, Chunyuan; Pu, Yang; Li, Zhongwu; Liu, Yulong; Li, Qingbo; Wang, Wei; Alfano, Robert R.

    2014-03-01

    Resonant Raman (RR) spectroscopy provides an effective way to enhance Raman signal from particular bonds associated with key molecules due to changes on a molecular level. In this study, RR is used for detection of human brain metastases of five kinds of primary organs of lung, breast, kidney, rectal and orbital in ex-vivo. The RR spectra of brain metastases cancerous tissues were measured and compared with those of normal brain tissues and the corresponding primary cancer tissues. The differences of five types of brain metastases tissues in key bio-components of carotene, tryptophan, lactate, alanine and methyl/methylene group were investigated. The SVM-KNN classifier was used to categorize a set of RR spectra data of brain metastasis of lung cancerous tissues from normal brain tissue, yielding diagnostic sensitivity and specificity at 100% and 75%, respectively. The RR spectroscopy may provide new moleculebased optical probe tools for diagnosis and classification of brain metastatic of cancers.

  16. Optomechanically induced stochastic resonance and chaos transfer between optical fields

    Science.gov (United States)

    Monifi, Faraz; Zhang, Jing; Özdemir, Şahin Kaya; Peng, Bo; Liu, Yu-Xi; Bo, Fang; Nori, Franco; Yang, Lan

    2016-06-01

    Chaotic dynamics has been reported in many physical systems and has affected almost every field of science. Chaos involves hypersensitivity to the initial conditions of a system and introduces unpredictability into its output. Thus, it is often unwanted. Interestingly, the very same features make chaos a powerful tool to suppress decoherence, achieve secure communication and replace background noise in stochastic resonance—a counterintuitive concept that a system's ability to transfer information can be coherently amplified by adding noise. Here, we report the first demonstration of chaos-induced stochastic resonance in an optomechanical system, as well as the optomechanically mediated chaos transfer between two optical fields such that they follow the same route to chaos. These results will contribute to the understanding of nonlinear phenomena and chaos in optomechanical systems, and may find applications in the chaotic transfer of information and for improving the detection of otherwise undetectable signals in optomechanical systems.

  17. Dynamic behavior and complexity of modulated optical micro ring resonator

    Institute of Scientific and Technical Information of China (English)

    Lei Yang; Wei Pan; Bin Luo; ShuiYing Xiang; Ning Jiang

    2011-01-01

    @@ The dynamic behavior of an optical micro ring resonator (OMRR) with an amplitude modulator positioned in the micro ring is investigated quantitatively by adopting a recently introduced quantifier, the permutation entropy (PE).The effects of modulation depth are focused on, and the roles of input power are considered.The two-dimensional (2D) maps of PE showing dependence on both modulation depth and input power are presented as well.PE values nearly increase with modulation depth.On the other hand, the optimal value of input power is achieved when the PE reaches its maximum.Thus, PE can successfully quantify the dynamics of modulated OMRR.Selecting the parameters in the region with high PE values would contribute to the complexity-enhanced OMRR-based chaotic communication systems.%The dynamic behavior of an optical micro ring resonator (OMRR) with an amplitude modulator positioned in the micro ring is investigated quantitatively by adopting a recently introduced quantifier, the permutation entropy (PE). The effects of modulation depth are focused on, and the roles of input power are considered. The two-dimensional (2D) maps of PE showing dependence on both modulation depth and input power are presented as well. PE values nearly increase with modulation depth. On the other hand, the optimal value of input power is achieved when the PE reaches its maximum. Thus, PE can successfully quantify the dynamics of modulated OMRR. Selecting the parameters in the region with high PE values would contribute to the complexity-enhanced OMRR-based chaotic communication systems.

  18. Optical resonators and quantum dots: An excursion into quantum optics, quantum information and photonics

    Science.gov (United States)

    Bianucci, Pablo

    Modern communications technology has encouraged an intimate connection between Semiconductor Physics and Optics, and this connection shows best in the combination of electron-confining structures with light-confining structures. Semiconductor quantum dots are systems engineered to trap electrons in a mesoscopic scale (the are composed of ≈ 10000 atoms), resulting in a behavior resembling that of atoms, but much richer. Optical microresonators are engineered to confine light, increasing its intensity and enabling a much stronger interaction with matter. Their combination opens a myriad of new directions, both in fundamental Physics and in possible applications. This dissertation explores both semiconductor quantum dots and microresonators, through experimental work done with semiconductor quantum dots and microsphere resonators spanning the fields of Quantum Optics, Quantum Information and Photonics; from quantum algorithms to polarization converters. Quantum Optics leads the way, allowing us to understand how to manipulate and measure quantum dots with light and to elucidate the interactions between them and microresonators. In the Quantum Information area, we present a detailed study of the feasibility of excitons in quantum dots to perform quantum computations, including an experimental demonstration of the single-qubit Deutsch-Jozsa algorithm performedin a single semiconductor quantum dot. Our studies in Photonics involve applications of microsphere resonators, which we have learned to fabricate and characterize. We present an elaborate description of the experimental techniques needed to study microspheres, including studies and proof of concept experiments on both ultra-sensitive microsphere sensors and whispering gallery mode polarization converters.

  19. Resonant Peak Splitting for Ballistic Conductance in Two-Dimensional Electron Gas Under Electromagnetic Modulation

    Institute of Scientific and Technical Information of China (English)

    WANG Ru-Zhi; YAN Xiao-Hong

    2000-01-01

    By developing a transfer-matrix method, the resonant peaks splitting of ballistic conductance are investigated into the two-dimensional electron gas system with both electric and magnetic modulations of nanoscale periods. It is found that there exists the n-fold resonant peak splitting for ballistic conductance through n perpendicular magnetic barriers to n electric barriers. With a combination of m magnetic barriers and n electric barriers by increasing the amplitude of electric field, the folds of the splitting would shift from m - 1 to n - 1.

  20. Design and optimization of optical modulators based on graphene-on-silicon nitride microring resonators

    CERN Document Server

    Wu, Zeru; Zhang, Tianyou; Shao, Zengkai; Wen, Yuanhui; Xu, Pengfei; Zhang, Yanfeng; Yu, Siyuan

    2016-01-01

    In order to overcome the challenge of obtaining high modulation depth due to weak graphene-light interaction, a graphene-on-silicon nitride (SiNx) microring resonator based on graphene's gate-tunable optical conductivity is proposed and studied. Geometrical parameters of graphene-on-SiNx waveguide are systematically analyzed and optimized, yielding a loss tunability of 0.04 dB/{\\mu}m and an effective index variation of 0.0022. We explicitly study the interaction between graphene and a 40-{\\mu}m-radius microring resonator, where electro-absorptive and electro-refractive modulation are both taken into account. By choosing appropriate graphene coverage and coupling coefficient, a high modulation depth of over 40 dB with large fabrication tolerance is obtained.

  1. Design and optimization of optical modulators based on graphene-on-silicon nitride microring resonators

    Science.gov (United States)

    Wu, Zeru; Chen, Yujie; Zhang, Tianyou; Shao, Zengkai; Wen, Yuanhui; Xu, Pengfei; Zhang, Yanfeng; Yu, Siyuan

    2017-04-01

    In order to overcome the challenge of obtaining high modulation depth due to weak graphene–light interaction, a graphene-on-silicon nitride (SiNx) microring resonator based on graphene’s gate-tunable optical conductivity is proposed and studied. Geometrical parameters of graphene-on-SiNx waveguide are systematically analyzed and optimized, yielding a loss tunability of 0.04 dB μm‑1 and an effective index variation of 0.0022. We explicitly study the interaction between graphene and a 40 μm-radius microring resonator, where electro-absorptive and electro-refractive modulation are both taken into account. By choosing appropriate graphene coverage and coupling coefficient, a high modulation depth of over 40 dB with large fabrication tolerance is obtained.

  2. Silicon resonant cavity enhanced photodetector arrays for optical interconnects

    Science.gov (United States)

    Emsley, Matthew Kent

    High bandwidth short distance communications standards are being developed based on parallel optical interconnect fiber arrays to meet the needs of increasing data rates of inter-chip communication in modern computer architecture. To ensure that this standard becomes an attractive option for computer systems, low cost components must be implemented on both the transmitting and receiving end of the fibers. To meet this low cost requirement silicon based receiver circuits are the most viable option, however, manufacturing high speed, high efficiency silicon photodetectors presents a technical challenge. Resonant cavity enhanced photodetectors have been shown to provide the required bandwidth-efficiency product but have remained a challenge to reproduce through commercially available fabrication techniques. In this work, commercially reproducible silicon wafers with a high reflectance buried distributed Bragg reflector (DBR) have been designed and fabricated. The substrates consist of a two-period, 90% reflecting, DBR fabricated using a double silicon-on-insulator (SOI) process. Resonant-cavity-enhanced (RCE) Si photodetectors have been fabricated with 40% quantum efficiency at 860 nm, a FWHM of 25 ps, and a 3dB bandwidth in excess of 10 GHz. Si RCE 12 x 1 photodetector arrays have been fabricated and packaged with silicon based amplifiers to demonstrate the feasibility of a low cost monolithic silicon photoreceiver array.

  3. Resonant optical absorption and defect control in Ta3N5 photoanodes

    NARCIS (Netherlands)

    Dabirian, A.; Van de Krol, R.

    2013-01-01

    In this study, we explore resonance-enhanced optical absorption in Ta3N5 photoanodes for water splitting. By using a reflecting Pt back-contact and appropriate Ta3N5 film thickness, the resonance frequency can be tuned to energies just above the bandgap, where the optical absorption is normally weak

  4. Optical bistability in a high-Q racetrack resonator based on small SU-8 ridge waveguides.

    Science.gov (United States)

    Jin, Li; Fu, Xin; Yang, Bo; Shi, Yaocheng; Dai, Daoxin

    2013-06-15

    A racetrack resonator with a high Q value (~34,000) is demonstrated experimentally based on small SU-8 optical ridge waveguides, which were fabricated with an improved etchless process. Optical bistability is observed in the present racetrack resonator even with a low input optical power (5.6-7.3 mW), which is attributed to the significant thermal nonlinear optical effect due to the high Q value and the large negative thermo-optical coefficient of SU-8. Theoretical modeling for the optical bistability is also given, and it agrees well with the experimental result.

  5. All-optical control of microfiber resonator by graphene's photothermal effect

    Science.gov (United States)

    Wang, Yadong; Gan, Xuetao; Zhao, Chenyang; Fang, Liang; Mao, Dong; Xu, Yiping; Zhang, Fanlu; Xi, Teli; Ren, Liyong; Zhao, Jianlin

    2016-04-01

    We demonstrate an efficient all-optical control of microfiber resonator assisted by graphene's photothermal effect. Wrapping graphene onto a microfiber resonator, the light-graphene interaction can be strongly enhanced via the resonantly circulating light, which enables a significant modulation of the resonance with a resonant wavelength shift rate of 71 pm/mW when pumped by a 1540 nm laser. The optically controlled resonator enables the implementation of low threshold optical bistability and switching with an extinction ratio exceeding 13 dB. The thin and compact structure promises a fast response speed of the control, with a rise (fall) time of 294.7 μs (212.2 μs) following the 10%-90% rule. The proposed device, with the advantages of compact structure, all-optical control, and low power acquirement, offers great potential in the miniaturization of active in-fiber photonic devices.

  6. A nonlinear plasmonic resonator for three-state all-optical switching

    KAUST Repository

    Amin, Muhammad

    2014-01-01

    A nonlinear plasmonic resonator design is proposed for three-state all-optical switching at frequencies including near infrared and lower red parts of the spectrum. The tri-stable response required for three-state operation is obtained by enhancing nonlinearities of a Kerr medium through multiple (higher order) plasmons excited on resonator\\'s metallic surfaces. Indeed, simulations demonstrate that exploitation of multiple plasmons equips the proposed resonator with a multi-band tri-stable response, which cannot be obtained using existing nonlinear plasmonic devices that make use of single mode Lorentzian resonances. Multi-band three-state optical switching that can be realized using the proposed resonator has potential applications in optical communications and computing. © 2014 Optical Society of America.

  7. Silicon resonant-cavity-enhanced photodetector arrays for optical interconnects

    Science.gov (United States)

    Emsley, Matthew K.; Dosunmu, Olufemi I.; Muller, Paul; Unlu, M. Selim; Leblebici, Yusuf

    2003-08-01

    High bandwidth short distance communications standards are being developed based on parallel optical interconnect fiber arrays to meet the needs of increasing data rates of inter-chip communication in modern computer architecture. To ensure that this standard becomes an attractive option for computer systems, low cost components must be implemented on both the transmitting and receiving end of the fibers. To meet this low cost requirement silicon based receiver circuits are the most viable option, however, manufacturing high speed, high efficiency silicon photodetectors presents a technical challenge. Resonant cavity enhanced (RCE) Si photodetectors have been shown to provide the required bandwidth-efficiency product and we have recently developed a method to reproduce them through commercially available fabrication techniques. In this work, commercially reproducible silicon wafers with a 90% reflectance buried distributed Bragg reflector (DBR) are used to create Si-RCE photodetector arrays for optical interconnects. The Si-RCE photodetectors have 40% quantum efficiency at 860 nm, a FWHM of 25 ps, and a 3dB bandwidth in excess of 10 GHz. We also demonstrate Si-RCE 12×1 photodetector arrays that have been fabricated and packaged with silicon based amplifiers to demonstrate the feasibility of a low cost monolithic silicon photoreceiver array.

  8. Fibre optic surface plasmon resonance sensor system designed for smartphones.

    Science.gov (United States)

    Bremer, Kort; Roth, Bernhard

    2015-06-29

    A fibre optic surface plasmon resonance (SPR) sensor system for smartphones is reported, for the first time. The sensor was fabricated by using an easy-to-implement silver coating technique and by polishing both ends of a 400 µm optical fibre to obtain 45° end-faces. For excitation and interrogation of the SPR sensor system the flash-light and camera at the back side of the smartphone were employed, respectively. Consequently, no external electrical components are required for the operation of the sensor system developed. In a first application example a refractive index sensor was realised. The performance of the SPR sensor system was demonstrated by using different volume concentrations of glycerol solution. A sensitivity of 5.96·10(-4) refractive index units (RIU)/pixel was obtained for a refractive index (RI) range from 1.33 to 1.36. In future implementations the reported sensor system could be integrated in a cover of a smartphone or used as a low-cost, portable point-of-care diagnostic platform. Consequently it offers the potential of monitoring a large variety of environmental or point-of-care parameters in combination with smartphones.

  9. Measurement of Optical Response of a Detuned Resonant Sideband Extraction Interferometer

    CERN Document Server

    Miyakawa, O; Adhikari, R; Evans, M; Abbott, B; Bork, R; Busby, D; Heefner, J; Ivanov, A; Smith, M; Taylor, R; Vass, S; Weinstein, A; Varvella, M; Kawamura, S; Kawazoe, F; Sakata, S; Mow-Lowry, C; Miyakawa, Osamu; Ward, Robert; Adhikari, Rana; Evans, Matthew; Abbott, Benjamin; Bork, Rolf; Busby, Daniel; Heefner, Jay; Ivanov, Alexander; Smith, Michael; Taylor, Robert; Vass, Stephen; Weinstein, Alan; Varvella, Monica; Kawamura, Seiji; Kawazoe, Fumiko; Sakata, Shihori; Mow-Lowry, Conor

    2006-01-01

    We report on the optical response of a suspended-mass detuned resonant sideband extraction (RSE) interferometer with power recycling. The purpose of the detuned RSE configuration is to manipulate and optimize the optical response of the interferometer to differential displacements (induced by gravitational waves) as a function of frequency, independently of other parameters of the interferometer. The design of our interferometer results in an optical gain with two peaks: an RSE optical resonance at around 4 kHz and a radiation pressure induced optical spring at around 41 Hz. We have developed a reliable procedure for acquiring lock and establishing the desired optical configuration. In this configuration, we have measured the optical response to differential displacement and found good agreement with predictions at both resonances and all other relevant frequencies. These results build confidence in both the theory and practical implementation of the more complex optical configuration being planned for Advanc...

  10. Simulation of optical soliton control in micro- and nanoring resonator systems

    CERN Document Server

    Daud, Suzairi; Ali, Jalil

    2015-01-01

    This book introduces optical soliton control in micro- and nanoring resonator systems. It describes how the ring resonator systems can be optimized as optical tweezers for photodetection by controlling the input power, ring radii and coupling coefficients of the systems. Numerous arrangements and configurations of micro and nanoring resonator systems are explained. The analytical formulation and optical transfer function for each model and the interaction of the optical signals in the systems are discussed. This book shows that the models designed are able to control the dynamical behaviour of generated signals.

  11. Laser-Machined Ultra-High-Q Microrod Resonators for Nonlinear Optics

    CERN Document Server

    Del'Haye, Pascal; Papp, Scott B

    2013-01-01

    Optical whispering-gallery microresonators are useful tools in microphotonics, and nonlinear optics at very low threshold powers. Here, we present details about the fabrication of ultra-high-Q whispering-gallery-mode resonators made by CO2-laser lathe machining of fused-quartz rods. The resonators can be fabricated in less than one minute and the obtained optical quality factors exceed Q = 10^9. Demonstrated resonator diameters are in the range between 170 {\\mu}m and 8 mm (free spectral ranges between 390 GHz and 8 GHz). Using these microresonators, a variety of optical nonlinearities are observed, including Raman scattering, Brillouin scattering and four-wave mixing.

  12. Dynamics mechanism of optical-optical double-resonant multiphoton ionization of nitrogen dioxide

    Institute of Scientific and Technical Information of China (English)

    Guiyin Zhang; Yidong Jin

    2007-01-01

    The optical-optical double-resonant multiphoton ionization (OODR-MPI) spectrum of NO2 molecule in the 460-605-nm wavelength region of the probe photon is presented. The mechanism of the OODR-MPI of NO2 molecule is analyzed. The results show that the resonant features can be assigned to the transitions from the first 3sσg Rydberg intermediate resonant state to the final npσu Rydberg series. The ionization pathway is NO2 (X2A1) 3hv1→ 3sσghv2→npσu hv2 or autoionization→NO2+ + e. It is found that the converging potential of the npσu Rydberg series and the quantum defect of np orbit about NO2 are (78803 ± 14) cm-1 and 0.652 ± 0.014, respectively. The bending vibration frequency of 5pσu state is determined also.

  13. Spin-current resonances in a magnetically inhomogeneous 2D conducting system

    Science.gov (United States)

    Charkina, O. V.; Kalinenko, A. N.; Kopeliovich, A. I.; Pyshkin, P. V.; Yanovsky, A. V.

    2016-10-01

    The high-frequency transport in a two-dimensional conducting ring having an inhomogeneous collinear magnetic structure has been considered in the hydrodynamic approximation. It is shown that the frequency dependence on the radial electric conductivity of the ring exhibits resonances corresponding to new hybrid oscillations in such systems. The oscillation frequencies are essentially dependent on the applied electromagnetic field and the spin state of the system.

  14. Conductivity mapping of nanoparticles by torsional resonance tunneling atomic force microscopy

    NARCIS (Netherlands)

    Prastani, C; Vetushka, A.; Fejfar, A.; Nanu, M.; Nanu, D.; Rath, J.K.; Schropp, R.E.I.

    2012-01-01

    In this paper, torsional resonance tunneling mode atomic force microscopy is used to study the conductivity of nanoparticles. SnS nanoparticles capped with trioctylphosphine oxide (TOPO) and with In2S3 shell are analyzed. This contactless technique allows carrying out measurements on nanoparticles w

  15. Temperature dependence of the cosphi conductance in Josephson tunnel junctions determined from plasma resonance experiments

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Sørensen, O. H.; Mygind, Jesper

    1978-01-01

    The microwave response at 9 GHz of Sn-O-Sn tunnel-junction current biased at zero dc voltage has been measured just below the critical temperature Tc of the Sn films. The temperature dependence of the cosφ conductance is determined from the resonant response at the junction plasma frequency fp...... of the experiment....

  16. Developments of Optical Resonators and Optical Recirculators for Compton X/γ Ray Machines

    Science.gov (United States)

    Martens, A.; , Mightylaser, Thomx Collaboration; Eurogammas Association

    2015-10-01

    Optical resonators and optical recirculators are key elements of Compton X/γ ray machines. With regard to their use in laser physics or in time-frequency metrology, these devices have to obey severe constraints when implemented in the vaccum of an electron accelerator. Our group has developed both types of devices. In this proceedings an original recirculator design, that was developed within the European proposal to the ELI-NP γ ray source call for tender, is described. This is an aberration free device which allows reciculating 32 times a short and high intensity laser pulse. It also allows synchronizing each of the 32 passes with the electron RF cavities within 100 fs. The second topic of these proceedings is a description of our R & D on optical resonators dedicated to laser-electron interactions. We have locked two different picosecond laser oscillators to the highest cavity finesse F=30000 ever reached in pulsed regime. We also designed and build a new kind of non-planar cavity, tetrahedron shape, providing circularly polarized eigen modes. This cavity was installed in the ATF accelerator of KEK and successfully used to produce a high gamma ray flux. Thanks to an original fibre amplifier, we succeed in stacking 100 kW of average power inside the cavity.

  17. Effect of electron-hole asymmetry on optical conductivity in 8-Pmmn borophene

    OpenAIRE

    Verma, Sonu; Mawrie, Alestin; Ghosh, Tarun Kanti

    2017-01-01

    We present a detail theoretical study of the Drude weight and optical conductivity of 8-$Pmmn$ borophene having tilted anisotropic Dirac cones. We provide exact analytical expressions of $xx$ and $yy$ components of the Drude weight as well as maximum optical conductivity. We also obtain exact analytical expressions of the minimum energy ($\\epsilon_1$) required to trigger the optical transitions and energy ($\\epsilon_2$) needed to attain maximum optical conductivity. We find that the Drude wei...

  18. Optical Conductivity of Impurity-Doped Parabolic Quantum Wells in an Applied Electric Field

    Institute of Scientific and Technical Information of China (English)

    GUO Kang-Xian; CHEN Chuan-Yu

    2005-01-01

    The optical conductivity of impurity-doped parabolic quantum wells in an applied electric field is investigated with the memory-function approach, and the analytic expression for the optical conductivity is derived. With characteristic parameters pertaining to GaAs/Ga1-xAlxAs parabolic quantum wells, the numerical results are presented.It is shown that, the smaller the well width, the larger the peak intensity of the optical conductivity, and the more asymmetric the shape of the optical conductivity; the optical conductivity is more sensitive to the electric field, the electric field enhances the optical conductivity; when the dimension of the quantum well increases, the optical conductivity increases until it reaches a maximum value, and then decreases.

  19. Single-photon all-optical switching using coupled microring resonators

    Indian Academy of Sciences (India)

    Wenge Yang; Amitabh Joshi; Min Xiao

    2007-08-01

    We study the nonlinear phase response of a microring resonator coupled to a bus waveguide and the use of this nonlinear phase shift to store information in the microring resonator and enhance the switching characteristics of a Mach–Zehnder interferometer (MZI). By introducing coupling between adjacent microring resonators, the switching characteristics of the MZI can be exponentially enhanced as a function of the number of microring resonators, when compared to the linear enhancement for uncoupled resonators. With only a few moderate-finesse microring resonators, the switching power can be reduced to attowatt level, allowing for photonic switching devices that operate at single-photon level in ordinary optical waveguides.

  20. Enhancement of the transverse magneto-optical Kerr effect via resonant tunneling in trilayers containing magneto-optical metals

    Science.gov (United States)

    Girón-Sedas, J. A.; Mejía-Salazar, J. R.; Moncada-Villa, E.; Porras-Montenegro, N.

    2016-07-01

    We propose a way to enhance the transverse magneto-optical Kerr effect, by the excitation of resonant tunneling modes, in subwavelength trilayer structures featuring a dielectric slab sandwiched between two magneto-optical metallic layers. Depending on the magneto-optical layer widths, the proposed system may exhibit an extraordinary transverse magneto-optical Kerr effect, which makes it very attractive for the design and engineering of thin-film magneto-optical-based devices for future photonic circuits or fiber optical-communication systems.

  1. The electronic conductance of polypyrrole (PPy molecular wires and emergence of Fano resonance phenomena

    Directory of Open Access Journals (Sweden)

    M Mardaani

    2012-06-01

    Full Text Available In this paper, we studied the electronic conductance of a polypyrrole polymer, which is embedded between two semi-infinite simple chains by using Green’s function technique in tight-binding approach. We first reduced the center polymer to a one dimensional chain with renormalized onsite and hopping energies by renormalization method. Then, we calculated the system conductivity as a function of incoming electron energy, polymer length and contact hopping terms. The results showed that by increasing polymer length and decreasing contact hopping energies, the conductance decreases in the gap regions. This means that for larger gaps, the electron tunneling happens with more difficulty. Moreover, at the resonance area, due to the existence of nitrogen atom in the polymer cyclic structure, the Fano resonance will emerge. Furthermore, the polymer can behave like a metallic chain by variation of the value of nitrogen on-site term.

  2. Resonant enhancement in nanostructured thermoelectric performance via electronic thermal conductivity engineering

    Science.gov (United States)

    Patil, Urvesh; Muralidharan, Bhaskaran

    2017-01-01

    The use of an asymmetric broadening in the transport distribution, a characteristic of resonant structures, is proposed as a route to engineer a decrease in electronic thermal conductivity thereby enhancing the electronic figure of merit in nanostructured thermoelectrics. Using toy models, we first demonstrate that a decrease in thermal conductivity resulting from such an asymmetric broadening may indeed lead to an electronic figure of merit well in excess of 1000 in an idealized situation and in excess of 10 in a realistic situation. We then substantiate with realistic resonant structures designed using graphene nano-ribbons by employing a tight binding framework with edge correction that match density functional theory calculations under the local density approximation. The calculated figure of merit exceeding 10 in such realistic structures further reinforces the concept and sets a promising direction to use nano-ribbon structures to engineer a favorable decrease in the electronic thermal conductivity.

  3. Coherent Fano resonances in a plasmonic nanocluster enhance optical four-wave mixing

    Science.gov (United States)

    Zhang, Yu; Wen, Fangfang; Zhen, Yu-Rong; Nordlander, Peter; Halas, Naomi J.

    2013-01-01

    Plasmonic nanoclusters, an ordered assembly of coupled metallic nanoparticles, support unique spectral features known as Fano resonances due to the coupling between their subradiant and superradiant plasmon modes. Within the Fano resonance, absorption is significantly enhanced, giving rise to highly localized, intense near fields with the potential to enhance nonlinear optical processes. Here, we report a structure supporting the coherent oscillation of two distinct Fano resonances within an individual plasmonic nanocluster. We show how this coherence enhances the optical four-wave mixing process in comparison with other double-resonant plasmonic clusters that lack this property. A model that explains the observed four-wave mixing features is proposed, which is generally applicable to any third-order process in plasmonic nanostructures. With a larger effective susceptibility χ(3) relative to existing nonlinear optical materials, this coherent double-resonant nanocluster offers a strategy for designing high-performance third-order nonlinear optical media. PMID:23690571

  4. Experimental demonstration of sharp Fano resonance in optical metamaterials composed of asymmetric double bars.

    Science.gov (United States)

    Moritake, Yuto; Kanamori, Yoshiaki; Hane, Kazuhiro

    2014-07-01

    We experimentally demonstrated Fano resonance in metamaterials composed of asymmetric double bars (ADBs) in the optical region. ADB metamaterials were fabricated by a lift-off method, and the optical spectra were measured. Around a wavelength of 1100 nm, measured optical spectra clearly showed sharp Fano resonance due to weak asymmetry of the ADB structures. The highest-quality factor (Q-factor) of the Fano resonance was 7.34. Calculated spectra showed the same tendency as the experimental spectra. Moreover, in a Fano resonant condition, out of phase of induced current flowing along each bar was revealed by electromagnetic field calculations. These antiphase currents decreased radiative loss of the Fano mode, resulting in a high Q-factor of the Fano resonance in ADB metamaterials. As the degree of asymmetry became small, the Q-factor decreased, and the Fano resonance disappeared because the effect of Joule loss became significant.

  5. Ultrafast all-optical switching using signal flow graph for PANDA resonator.

    Science.gov (United States)

    Bahadoran, Mahdi; Ali, Jalil; Yupapin, Preecha P

    2013-04-20

    In this paper, the bifurcation behavior of light in the PANDA ring resonator is investigated using the signal flow graph (SFG) method, where the optical transfer function for the through and drop ports of the PANDA Vernier system are derived. The optical nonlinear phenomena, such as bistability, Ikeda instability, and dynamics of light in the silicon-on-insulator (SOI) PANDA ring resonator with four couplers are studied. The transmission curves for bistability and instability as a function of the resonant mode numbers and coupling coefficients for the coupler are derived by the SFG method and simulated. The proposed system has an advantage as no optical pumping component is required. Simulated results show that closed-loop bistable switching can be generated and achieved by varying mode resonant numbers in the SOI-PANDA Vernier resonator, where a smooth and closed-loop bistable switching with low relative output/input power can be obtained and realized. The minimum through-port switching time of 1.1 ps for resonant mode numbers of 5;4;4 and minimum drop port switching time of 1.96 ps for resonant mode numbers of 9;7;7 of the PANDA Vernier resonator are achieved, which makes the PANDA Vernier resonator an operative component for optical applications, such as optical signal processing and a fast switching key in photonics integrated circuits.

  6. Resonant Photon-Assisted Structure of Conductance through a Quantum Wire

    Institute of Scientific and Technical Information of China (English)

    LIAO Wen-Hu; ZHOU Guang-Hui

    2005-01-01

    @@ We investigate theoretically the electron transport properties of a two-sublevel quantum wire irradiated by a strong laser field resonant with the quasiparticle transition at low temperatures. Using the method of theKeldysh equation of motion for nonequilibrium Green function, we examine the time-averaged conductance forthe system with photon polarization parallel and perpendicular to the tunnelling current direction, respectively.We demonstrate that, by analysing some numerical examples, a feature of absolute negative conductance appearsin the parallel case, while the conductance shows a symmetry distributed peaks in the perpendicular case.

  7. Electrical conductivity and electron-spin resonance in oxidatively stabilized polyacrylonitrile subjected to elevated temperature

    Science.gov (United States)

    Lerner, N. R.

    1981-01-01

    Electrical conductivity and electron spin resonance measurements are presented for oxidatively stabilized polyacrylonitrile (PAN) fibers subjected to heat treatment at temperatures ranging from 700 to 950 K. Conductivity measurements made at temperatures between 77 and 523 K reveal that PAN fibers heat treated in vacuum behave as semiconductors, with a room-temperature conductivity dominated by the contributions of impurity states, with an activation energy of 88 kcal/mole. A decrease in conductivity is observed upon air which is attributed to a decrease in the electron-phonon scattering time. ESR spectra indicate that conducting pathways having metallic properties are formed at temperatures as low as 715 K, although the contribution of these pathways to the room-temperature conductivity is extremely small next to the contribution of localized spin centers.

  8. Quantum kinetics of ultracold fermions coupled to an optical resonator

    Science.gov (United States)

    Piazza, Francesco; Strack, Philipp

    2014-10-01

    We study the far-from-equilibrium statistical mechanics of periodically driven fermionic atoms in a lossy optical resonator. We show that the interplay of the Fermi surface with cavity losses leads to subnatural cavity linewidth narrowing, squeezed light, and nonthermal quantum statistics of the atoms. Adapting the Keldysh approach, we set up and solve a quantum kinetic Boltzmann equation in a systematic 1/N expansion with N the number of atoms. In the strict thermodynamic limit N ,V→∞,N/V=const. we find that the atoms (fermions or bosons) remain immune against cavity-induced heating or cooling. At next-to-leading order in 1/N, we find a "one-way thermalization" of the atoms determined by cavity decay. In absence of an equilibrium fluctuation-dissipation relation, the long-time limit Δt →∞ does not commute with the thermodynamic limit N →∞, such that for the physically relevant case of large but finite N, the dynamics ultimately becomes strongly coupled, especially close to the superradiance phase transition.

  9. Reconstruction of apparent orthotropic conductivity tensor image using magnetic resonance electrical impedance tomography

    Energy Technology Data Exchange (ETDEWEB)

    Sajib, Saurav Z. K.; Kim, Ji Eun; Jeong, Woo Chul; Kim, Hyung Joong; Woo, Eung Je [Department of Biomedical Engineering, Kyung Hee University, Yongin, Gyeonggi (Korea, Republic of); Kwon, Oh In, E-mail: oikwon@konkuk.ac.kr [Department of Mathematics, Konkuk University, Seoul (Korea, Republic of)

    2015-03-14

    Magnetic resonance electrical impedance tomography visualizes current density and/or conductivity distributions inside an electrically conductive object. Injecting currents into the imaging object along at least two different directions, induced magnetic flux density data can be measured using a magnetic resonance imaging scanner. Without rotating the object inside the scanner, we can measure only one component of the magnetic flux density denoted as B{sub z}. Since the biological tissues such as skeletal muscle and brain white matter show strong anisotropic properties, the reconstruction of anisotropic conductivity tensor is indispensable for the accurate observations in the biological systems. In this paper, we propose a direct method to reconstruct an axial apparent orthotropic conductivity tensor by using multiple B{sub z} data subject to multiple injection currents. To investigate the anisotropic conductivity properties, we first recover the internal current density from the measured B{sub z} data. From the recovered internal current density and the curl-free condition of the electric field, we derive an over-determined matrix system for determining the internal absolute orthotropic conductivity tensor. The over-determined matrix system is designed to use a combination of two loops around each pixel. Numerical simulations and phantom experimental results demonstrate that the proposed algorithm stably determines the orthotropic conductivity tensor.

  10. Ultra-sharp plasmonic resonances from monopole optical nanoantenna phased arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shi-Qiang; Bruce Buchholz, D. [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, Illinois 60208-3108 (United States); Zhou, Wei [Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, Massachusetts 02138 (United States); Ketterson, John B. [Department of Physics, Northwestern University, 2145 Sheridan Rd., Evanston, Illinois 60208-3113 (United States); NU-NIMS Materials Innovation Center, 2220 Campus Dr., Evanston, Illinois 60208-3108 (United States); Ocola, Leonidas E. [Center for Nanoscale Materials, Argonne National Laboratory, 9700 S Cass Ave., Lemont, Illinois 60439 (United States); Sakoda, Kazuaki [NU-NIMS Materials Innovation Center, 2220 Campus Dr., Evanston, Illinois 60208-3108 (United States); National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Chang, Robert P. H., E-mail: r-chang@northwestern.edu [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, Illinois 60208-3108 (United States); NU-NIMS Materials Innovation Center, 2220 Campus Dr., Evanston, Illinois 60208-3108 (United States)

    2014-06-09

    Diffractively coupled plasmonic resonances possess both ultra-sharp linewidths and giant electric field enhancement around plasmonic nanostructures. They can be applied to create a new generation of sensors, detectors, and nano-optical devices. However, all current designs require stringent index-matching at the resonance condition that limits their applicability. Here, we propose and demonstrate that it is possible to relieve the index-matching requirement and to induce ultra-sharp plasmon resonances in an ordered vertically aligned optical nano-antenna phased array by transforming a dipole resonance to a monopole resonance with a mirror plane. Due to the mirror image effect, the monopole resonance not only retained the dipole features but also enhanced them. The engineered resonances strongly suppressed the radiative decay channel, resulting in a four-order of magnitude enhancement in local electric field and a Q-factor greater than 200.

  11. Enhanced linear and nonlinear optical phase response of AlGaAs microring resonators.

    Science.gov (United States)

    Heebner, John E; Lepeshkin, Nick N; Schweinsberg, Aaron; Wicks, G W; Boyd, Robert W; Grover, Rohit; Ho, P T

    2004-04-01

    We have constructed and characterized several optical microring resonators with scale sizes of the order of 10 microm. These devices are intended to serve as building blocks for engineerable linear and nonlinear photonic media. Light is guided vertically by an epitaxially grown structure and transversely by deeply etched air-clad sidewalls. We report on the spectral phase transfer characteristics of such resonators. We also report the observation of a pi-rad Kerr nonlinear phase shift accumulated in a single compact ring resonator evidenced by all-optical switching between output ports of a resonator-enhanced Mach-Zehnder interferometer.

  12. Multipolar third-harmonic generation driven by optically-induced magnetic resonances

    CERN Document Server

    Smirnova, Daria A; Smirnov, Lev A; Kivshar, Yuri S

    2016-01-01

    We analyze the third-harmonic generation from high-index dielectric nanoparticles and discuss the basic features and multipolar nature of the parametrically generated electromagnetic fields near the Mie-type optical resonances in silicon particles. By combining both analytical and numerical methods, we study the nonlinear scattering from simple nanoparticle geometries such as spheres and disks driven by the magnetic dipole resonance. We reveal the approaches for manipulating and directing the resonantly enhanced nonlinear emission with subwavelength all-dielectric structures that can be of a particular interest for a design of nonlinear optical antennas and engineering the magnetic optical nonlinear response at nanoscale.

  13. Extracting the complex optical conductivity of mono- and bilayer graphene by ellipsometry

    Science.gov (United States)

    Chang, You-Chia; Liu, Chang-Hua; Liu, Che-Hung; Zhong, Zhaohui; Norris, Theodore B.

    2014-06-01

    A method for analysis of spectroscopic ellipsometry data is demonstrated to extract the optical conductivity of mono- and bilayer chemical-vapor-deposited graphene. We model graphene as a truly two-dimensional (2D) material with a sheet conductivity, rather than a phenomenological effective refractive index as has been used in the literature. This technique measures both the real and imaginary part of the optical conductivity, which is important for graphene optoelectronics and metamaterials. Using this method, we obtain broadband measurements of the complex optical conductivity for mono- and bilayer graphene from ultraviolet to mid-infrared wavelengths. We also study how chemical doping with nitric acid modifies the complex optical conductivity.

  14. Blazed Grating Resonance Conditions and Diffraction Efficiency Optical Transfer Function

    KAUST Repository

    Stegenburgs, Edgars

    2017-01-08

    We introduce a general approach to study diffraction harmonics or resonances and resonance conditions for blazed reflecting gratings providing knowledge of fundamental diffraction pattern and qualitative understanding of predicting parameters for the most efficient diffraction.

  15. Athermalization of resonant optical devices via thermo-mechanical feedback

    Science.gov (United States)

    Rakich, Peter; Nielson, Gregory N.; Lentine, Anthony L.

    2016-01-19

    A passively athermal photonic system including a photonic circuit having a substrate and an optical cavity defined on the substrate, and passive temperature-responsive provisions for inducing strain in the optical cavity of the photonic circuit to compensate for a thermo-optic effect resulting from a temperature change in the optical cavity of the photonic circuit. Also disclosed is a method of passively compensating for a temperature dependent thermo-optic effect resulting on an optical cavity of a photonic circuit including the step of passively inducing strain in the optical cavity as a function of a temperature change of the optical cavity thereby producing an elasto-optic effect in the optical cavity to compensate for the thermo-optic effect resulting on an optical cavity due to the temperature change.

  16. Review on Optical and Electrical Properties of Conducting Polymers

    Directory of Open Access Journals (Sweden)

    Manisha Bajpai

    2016-01-01

    Full Text Available We reviewed optical and electrical properties of conjugated polymers. The charge transport models to describe the hole and electron transport mechanism are also included in the electrical properties of conjugated polymers. The effect of optical and electrical properties after doping is also indexed in this paper.

  17. Anisotropic optical response of optically opaque elastomers with conductive fillers as revealed by terahertz polarization spectroscopy

    Science.gov (United States)

    Okano, Makoto; Watanabe, Shinichi

    2016-12-01

    Elastomers are one of the most important materials in modern society because of the inherent viscoelastic properties due to their cross-linked polymer chains. Their vibration-absorbing and adhesive properties are especially useful and thus utilized in various applications, for example, tires in automobiles and bicycles, seismic dampers in buildings, and seals in a space shuttle. Thus, the nondestructive inspection of their internal states such as the internal deformation is essential in safety. Generally, industrial elastomers include various kinds of additives, such as carbon blacks for reinforcing them. The additives make most of them opaque in a wide spectral range from visible to mid-infrared, resulting in that the nondestructive inspection of the internal deformation is quite difficult. Here, we demonstrate transmission terahertz polarization spectroscopy as a powerful technique for investigating the internal optical anisotropy in optically opaque elastomers with conductive additives, which are transparent only in the terahertz frequency region. The internal deformation can be probed through the polarization changes inside the material due to the anisotropic dielectric response of the conductive additives. Our study about the polarization-dependent terahertz response of elastomers with conductive additives provides novel knowledge for in situ, nondestructive evaluation of their internal deformation.

  18. Solid state optical refrigeration using stark manifold resonances in crystals

    Energy Technology Data Exchange (ETDEWEB)

    Seletskiy, Denis V.; Epstein, Richard; Hehlen, Markus P.; Sheik-Bahae, Mansoor

    2017-02-21

    A method and device for cooling electronics is disclosed. The device includes a doped crystal configured to resonate at a Stark manifold resonance capable of cooling the crystal to a temperature of from about 110K to about 170K. The crystal host resonates in response to input from an excitation laser tuned to exploit the Stark manifold resonance corresponding to the cooling of the crystal.

  19. Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies

    CERN Document Server

    Tadesse, Semere Ayalew

    2014-01-01

    Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acousto-optic coupling in nanophotonic devices. Here we demonstrate microwave frequency surface acoustic wave transducers co-integrated with nanophotonic resonators on piezoelectric aluminum nitride substrates. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength is achieved. The phase and modal matching conditions in this scheme are investigated for efficient modulation. The new acousto-optic platform can lead to novel optical devices based on nonlinear Brillouin processes and provides a direct...

  20. Design of all-optical memory cell using EIT and lasing without inversion phenomena in optical micro ring resonators

    Science.gov (United States)

    Pasyar, N.; Yadipour, R.; Baghban, H.

    2017-07-01

    The proposed design of the optical memory unit cell contains dual micro ring resonators in which the effect of lasing without inversion (LWI) in three-level nano particles doped over the optical resonators or integrators as the gain segment is used for loss compensation. Also, an on/off phase shifter based on electromagnetically induced transparency (EIT) in three-level quantum dots (QDs) has been used for data reading at requested time. Device minimizing for integrated purposes and high speed data storage are the main advantages of the optical integrator based memory.

  1. Discontinuous conduction mode analysis of phase-modulated series resonant converter

    Indian Academy of Sciences (India)

    UTSAB KUNDU; PARTHASARATHI SENSARMA

    2017-08-01

    This paper proposes an analytical approach to derive voltage gain for phase-modulated dc–dc series resonant converter (SRC) operating in discontinuous conduction mode (DCM). The conventional fundamental harmonic approximation technique is extended for a non-ideal series resonant tank to clarify the limitations of SRC operating in continuous conduction mode (CCM). The DCM analysis is described in a normalized form defining appropriate base quantities. The converter is analysed both in time and frequency domain to derive a non-linear algebraic function of diode rectifier extinction angle. The root of this function is numericallydetermined using MATLAB and used to predict the dc bus voltage. Analytical derivation of critical load resistance is discussed, which indicates the CCM–DCM boundary condition. Experimental results are presented to validate the analysis

  2. Analytic Theory of Titans Schumann Resonance: Constraints on Ionospheric Conductivity and Buried Water Ocean

    Science.gov (United States)

    Beghin, Christian; Randriamboarison, Orelien; Hamelin, Michel; Karkoschka, Erich; Sotin, Christophe; Whitten, Robert C.; Berthelier, Jean-Jacques; Grard, Rejean; Simoes, Fernando

    2013-01-01

    This study presents an approximate model for the atypical Schumann resonance in Titan's atmosphere that accounts for the observations of electromagnetic waves and the measurements of atmospheric conductivity performed with the Huygens Atmospheric Structure and Permittivity, Wave and Altimetry (HASI-PWA) instrumentation during the descent of the Huygens Probe through Titan's atmosphere in January 2005. After many years of thorough analyses of the collected data, several arguments enable us to claim that the Extremely Low Frequency (ELF) wave observed at around 36 Hz displays all the characteristics of the second harmonic of a Schumann resonance. On Earth, this phenomenon is well known to be triggered by lightning activity. Given the lack of evidence of any thunderstorm activity on Titan, we proposed in early works a model based on an alternative powering mechanism involving the electric current sheets induced in Titan's ionosphere by the Saturn's magnetospheric plasma flow. The present study is a further step in improving the initial model and corroborating our preliminary assessments. We first develop an analytic theory of the guided modes that appear to be the most suitable for sustaining Schumann resonances in Titan's atmosphere. We then introduce the characteristics of the Huygens electric field measurements in the equations, in order to constrain the physical parameters of the resonating cavity. The latter is assumed to be made of different structures distributed between an upper boundary, presumably made of a succession of thin ionized layers of stratospheric aerosols spread up to 150 km and a lower quasi-perfect conductive surface hidden beneath the non-conductive ground. The inner reflecting boundary is proposed to be a buried water-ammonia ocean lying at a likely depth of 55-80 km below a dielectric icy crust. Such estimate is found to comply with models suggesting that the internal heat could be transferred upwards by thermal conduction of the crust, while

  3. Configuration resonance in scattering scanning near-field optical microscopy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A theoretical model is proposed in order to study the configuration resonance in s-SNOM. The electromagnetic coupling between the sample and the probe tip is described with the quasi-electrostatic field theory. This method permits us to analyze the configurational resonance evoked by the interaction between the probe tip and the sample in s-SNOM intuitively.The resonant conditions for a certain system are presented in an explicit form. On the condition of considering the actual size of the sample dipoles and the probe dipole, we discuss the possibility of realizing the configurational resonance for various material samples. The numerical results indicate that the polarizability of the dielectric probe tip is too small to arouse this resonance, whereas, with the surface plasmon resonance emerging on the metallic nanoparticles, the enhanced polarizability of the metallic probe tip ensures the requirements of fulfilling the resonance.

  4. Observation of Robust Quantum Resonance Peaks in an Atom Optics Kicked Rotor with Amplitude Noise

    CERN Document Server

    Sadgrove, M; Mullins, T; Parkins, S; Leonhardt, R; Sadgrove, Mark; Hilliard, Andrew; Mullins, Terry; Parkins, Scott; Leonhardt, Rainer

    2004-01-01

    The effect of pulse train noise on the energy peaks at quantum resonance seen in the Atom Optics Kicked Rotor is investigated experimentally. Quantum resonance peaks in the late time energy of the atoms were found to be completely robust against noise applied to the kicking amplitude but even small levels of noise on the kicking period lead to destruction of the quantum resonance peak. The robustness of low energy levels to either side of the resonance peak to amplitude noise and their comparative susceptibility to period noise is explained in terms of a recurrence of classically stable dynamics which occurs near quantum resonance.

  5. Out-of-plane resonances in terahertz photonic crystal slabs modulated by optical pumping.

    Science.gov (United States)

    Shi, Yulei; Zhou, Qing-Li; Liu, Wei; Zhang, Cunlin

    2011-10-10

    This paper describes detailed optical-pump-terahertz-probe studies of two-dimensional photonic crystal slabs for propagation perpendicular to the slabs. When the slabs are excited by an 800 nm pump pulse and the effect of shielding by photocarriers is removed, we find that the decaying tail in the transmitted terahertz radiation is strikingly enhanced. The photocarriers weaken guided resonances, but they also greatly enhance the excitation efficiency of guided resonances and the ability of the guided resonances to transfer energy back to the radiation field. This increases the resonance-assisted contribution to transmitted field. The photoinduced resonant extremes agree well with the Fano model.

  6. Thermo-optically tunable switching in an electro-microtube ring resonator

    Science.gov (United States)

    Zeng, Jing; Zhu, Tao; Deng, Ming

    2015-07-01

    We propose a tunable optical switching based on thermo-optic nonlinear effect in an electro-microtube ring resonator (EMRR) made by a capillary embedded with a heating wire. The significant modes shift in the EMRR for nonlinear switching are attributed to a huge joule heat generated by the heating wire, leading to the resonant wavelength shifts over 0.9nm when using 250mA current. In our viewpoints, with such a significant performance, the EMRR may be practically applied to switching, optical filter, sensing and optical network process.

  7. Optical bistability effect in plasmonic racetrack resonator with high extinction ratio.

    Science.gov (United States)

    Wang, Xiaolei; Jiang, Houqiang; Chen, Junxue; Wang, Pei; Lu, Yonghua; Ming, Hai

    2011-09-26

    In this paper, optical bistability effect in an ultracompact plasmonic racetrack resonator with nonlinear optical Kerr medium is investigated both analytically and numerically. The properties of optical bistability and pump threshold are studied at 1.55 µm with various detuning parameters by an analytical model. The transmission switch from the upper branch to the lower branch with a pulse is also demonstrated by a finite-difference time-domain method. An extinction ratio of 97.8% and a switching time of 0.38 ps can be achieved with proper detuning parameter. Such a plasmonic resonator design provides a promising realization for highly effective optical modulators and switch.

  8. Magneto-optic transmittance modulation observed in a hybrid graphene–split ring resonator terahertz metasurface

    Energy Technology Data Exchange (ETDEWEB)

    Zanotto, Simone; Pitanti, Alessandro [NEST, Istituto Nanoscienze–CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa (Italy); Lange, Christoph; Maag, Thomas; Huber, Rupert [Department of Physics, University of Regensburg, 93040 Regensburg (Germany); Miseikis, Vaidotas; Coletti, Camilla [CNI@NEST, Istituto Italiano di Tecnologia, P.za S. Silvestro 12, 56127 Pisa (Italy); Degl' Innocenti, Riccardo [Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Baldacci, Lorenzo [Scuola Superiore Sant' Anna, Institute of Life Sciences, P.za Martiri della Libertà 33, 56127 Pisa (Italy); Tredicucci, Alessandro [NEST, Istituto Nanoscienze-CNR and Dipartimento di Fisica “E. Fermi,” Università di Pisa, L.go Pontecorvo 3, 56127 Pisa (Italy)

    2015-09-21

    By placing a material in close vicinity of a resonant optical element, its intrinsic optical response can be tuned, possibly to a wide extent. Here, we show that a graphene monolayer, spaced a few tenths of nanometers from a split ring resonator metasurface, exhibits a magneto-optical response which is strongly influenced by the presence of the metasurface itself. This hybrid system holds promises in view of thin optical modulators, polarization rotators, and nonreciprocal devices, in the technologically relevant terahertz spectral range. Moreover, it could be chosen as the playground for investigating the cavity electrodynamics of Dirac fermions in the quantum regime.

  9. Frequency dependent optical conductivity of strained graphene at T=0 from an effective quantum field theory

    Science.gov (United States)

    Zhang, Shi-Jiang; Pan, Hui; Wang, Hai-Long

    2017-04-01

    An effective quantum field theory (EQFT) graphene sheet with arbitrary one dimensional strain field is derived from a microscopic effective low energy Hamiltonian. The geometric meaning of the strain-induced complex gauge field is clarified. The optical conductivity is also investigated, and a frequency dependent optical conductivity is obtained. The actual value of interband optical conductivity along the deformed direction is C0 + C1/ω2 in spite of the particular strain fields at T=0.

  10. Sub-natural width resonances in Cs vapor confined in micrometric thickness optical cell

    Science.gov (United States)

    Cartaleva, S.; Krasteva, A.; Sargsyan, A.; Sarkisyan, D.; Slavov, D.; Vartanyan, T.

    2013-03-01

    We present here the behavior of Electromagnetically Induced Transparency (EIT), Velocity Selective Optical Pumping (VSOP) resonances and Velocity Selective Excitation (VSE) resonances observed in Cs vapor confined in а micrometric optical cell (MC) with thickness L = 6λ, λ = 852nm. For comparison of behavior of VSE resonance another conventional optical cell with thickness L=2.5 cm is used. Cells are irradiated in orthogonal to their windows directions by probe beam scanned on the Fg = 4 → Fe= 3, 4, 5 set of transitions and pump beam fixed at the Fg = 3 → Fe = 4 transition, on the D2 line of Cs. The enhanced absorption (fluorescence) narrow VSOP resonance at the closed transition transforms into reduced absorption (fluorescence) one with small increase of atomic concentration or light intensity. A striking difference appears between the VSE resonance broadening in L = 6λ and conventional L = 2.5cm cells.

  11. Laterally vibrating resonator based elasto-optic modulation in aluminum nitride

    Science.gov (United States)

    Ghosh, Siddhartha; Piazza, Gianluca

    2016-06-01

    An integrated strain-based optical modulator driven by a piezoelectric laterally vibrating resonator is demonstrated. The composite structure consists of an acoustic Lamb wave resonator, in which a photonic racetrack resonator is internally embedded to enable overlap of the guided optical mode with the induced strain field. Both types of resonators are defined in an aluminum nitride (AlN) thin film, which rests upon a layer of silicon dioxide in order to simultaneously define optical waveguides, and the structure is released from a silicon substrate. Lateral vibrations produced by the acoustic resonator are transferred through a partially etched layer of AlN, producing a change in the effective index of the guided wave through the interaction of the strain components with the AlN elasto-optic (p) coefficients. Optical modulation through the elasto-optic effect is demonstrated at electromechanically actuated frequencies of 173 MHz and 843 MHz. This device geometry further enables the development of MEMS-based optical modulators in addition to studying elasto-optic interactions in suspended piezoelectric thin films.

  12. Laterally vibrating resonator based elasto-optic modulation in aluminum nitride

    Directory of Open Access Journals (Sweden)

    Siddhartha Ghosh

    2016-06-01

    Full Text Available An integrated strain-based optical modulator driven by a piezoelectric laterally vibrating resonator is demonstrated. The composite structure consists of an acoustic Lamb wave resonator, in which a photonic racetrack resonator is internally embedded to enable overlap of the guided optical mode with the induced strain field. Both types of resonators are defined in an aluminum nitride (AlN thin film, which rests upon a layer of silicon dioxide in order to simultaneously define optical waveguides, and the structure is released from a silicon substrate. Lateral vibrations produced by the acoustic resonator are transferred through a partially etched layer of AlN, producing a change in the effective index of the guided wave through the interaction of the strain components with the AlN elasto-optic (p coefficients. Optical modulation through the elasto-optic effect is demonstrated at electromechanically actuated frequencies of 173 MHz and 843 MHz. This device geometry further enables the development of MEMS-based optical modulators in addition to studying elasto-optic interactions in suspended piezoelectric thin films.

  13. Coupled-resonator optical waveguides: Q-factor and disorder influence

    DEFF Research Database (Denmark)

    Grgic, Jure; Campaioli, Enrico; Raza, Søren;

    2011-01-01

    Coupled resonator optical waveguides (CROW) can significantly reduce light propagation pulse velocity due to pronounced dispersion properties. A number of interesting applications have been proposed to benefit from such slow-light propagation. Unfortunately, the inevitable presence of disorder, i...

  14. Subwavelength imaging and control of ultrafast optical near-field under resonant- and off-resonant excitation of bowtie nanostructures

    Science.gov (United States)

    Ji, Boyu; Qin, Jiang; Tao, Haiyan; Hao, Zuoqiang; Lin, Jingquan

    2016-09-01

    We demonstrate subwavelength imaging and control of localized near-field distribution under resonant and off-resonant excitation of identical gold bowtie nanostructures through photoemission electron microscopy. Control of the near-field distribution was realized by polarization rotation of single femtosecond laser pulse and variation of the phase delay of two orthogonally polarized femtosecond laser pulses. We show that the localized optical near-field distribution can be well controlled either among the corners of the nano-prisms in the bowtie for resonant excitation or the edges for off-resonant excitation. A better visualization of the PEEM image is achieved for resonant excitation than in the case of off-resonant excitation. The experimental results of the optical near-field distribution control are well reproduced by finite-difference time-domain simulations and understood by linear combination of electric charge distribution of the bowtie by s- and p- polarized light illumination. In addition, a shift of the near-field excitation position with inverted or unchanged phase, alternatively an un-shift of the excitation position but only with inverted phase of the near-field, can be realized by rotating the polarization angle of a single pulse and coherent control of two orthogonally polarized fs laser pulses.

  15. Optical reflectance, optical refractive index and optical conductivity measurements of nonlinear optics for L-aspartic acid nickel chloride single crystal

    Science.gov (United States)

    Anbazhagan, G.; Joseph, P. S.; Shankar, G.

    2013-03-01

    Single crystals of L-aspartic acid nickel chloride (LANC) were grown by the slow evaporation technique at room temperature. The grown crystals were subjected to Powder X-ray diffraction studies to confirm the crystal structure. The modes of vibration of different molecular groups present in LANC have been identified by FTIR spectral analysis. Optical transferency of the grown crystal was investigated by UV-Vis-NIR spectrum. The lower optical cut off wavelength for this crystal is observed at 240 nm and energy band gap 5.179 eV. The optical reflectance and optical refractive index studies have been carried out in this crystal. Finally, the optical conductivity and electrical conductivity studies have been carried out on LANC single crystal.

  16. Enhanced all-optical switching by use of a nonlinear fiber ring resonator.

    Science.gov (United States)

    Heebner, J E; Boyd, R W

    1999-06-15

    We predict dramatically reduced switching thresholds for nonlinear optical devices incorporating fiber ring resonators. The circulating power in such a resonator is much larger than the incident power; also, the phase of the transmitted light varies rapidly with the single-pass phase shift. The combined action of these effects leads to a finesse-squared reduction in the switching threshold, allowing for photonic switching devices that operate at milliwatt power levels in ordinary optical fibers.

  17. Multi-hole Optical Fiber Surface Plasmon Resonance Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Guan Chunying; Wang Yang; Yuan Libo, E-mail: cyguan@163.com [College of Science, Harbin Engineering University, Harbin 150001 (China)

    2011-02-01

    A microstructured-fiber containing six large air holes is proposed to construct the surface plasmon resonance (SPR) sensor. The finite element method is used to analyze characteristics of the surface plasmon resonance sensor. The effects of the thickness of metal films, pitch between air holes, diameter of air hole, and refractive index of liquid on the resonance wavelength are elucidated. The results show that the resonance wavelength is sensitive to the thickness of metal film and refractive index of liquid, while the resonance wavelength doesn't change basically when the pitch between air holes and diameter of air holes vary. The proposed surface plasmon resonance sensor exhibits high sensitivity up to 10{sup -4}.

  18. Continuous spectrum of modes for optical micro-sphere resonators

    Science.gov (United States)

    Nooramin, Amir Saman; Shahabadi, Mahmoud

    2016-09-01

    This paper presents an improved modal analysis for the spherical dielectric resonator. This is commonly carried out by assuming an outgoing spherical Hankel function for the region surrounding the dielectric sphere. It will be shown that this assumption is incomplete and cannot lead to the entire spectrum of resonance frequencies. Following an analytical formulation, we prove that, like cylindrical resonators, the only choice for the outer region of the dielectric sphere can be a proper linear combination of an inward and an outward traveling wave. Starting from this formulation, we determine the complete spectrum of the resonance frequencies and the associated mode fields. In this analysis, the continuous spectrum of resonance frequencies is introduced and the properties of radiation modes are studied in detail. The proposed analytical formulation is thereafter employed to calculate the quality factor of the resonator due to radiation and dielectric loss.

  19. Ultrahigh Q whispering gallery mode electro-optic resonators on a silicon photonic chip.

    Science.gov (United States)

    Soltani, Mohammad; Ilchenko, Vladimir; Matsko, Andrey; Savchenkov, Anatoliy; Schlafer, John; Ryan, Colm; Maleki, Lute

    2016-09-15

    Crystalline whispering gallery mode (WGM) electro-optic resonators made of LiNbO3 and LiTaO3 are critical for a wide range of applications in nonlinear and quantum optics, as well as RF photonics, due to their remarkably ultrahigh Q(>108) and large electro-optic coefficient. Achieving efficient coupling of these resonators to planar on-chip optical waveguides is essential for any high-yield and robust practical applications. However, it has been very challenging to demonstrate such coupling while preserving the ultrahigh Q properties of the resonators. Here, we show how the silicon photonic platform can overcome this long-standing challenge. Silicon waveguides with appropriate designs enable efficient and strong coupling to these WGM electro-optic resonators. We discuss various integration architectures of these resonators onto a silicon chip and experimentally demonstrate critical coupling of a planar Si waveguide and an ultrahigh QLiTaO3 resonator (Q∼108). Our results show a promising path for widespread and practical applications of these resonators on a silicon photonic platform.

  20. Two-dimensional imaging of optical emission in a multicusp-ECR microwave resonant cavity

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, C.B.; Brake, M.L. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering

    1996-02-01

    Optical emission of the electron-cyclotron resonant (ECR) region of a multicusp microwave resonant cavity plasma source has been imaged onto a two-dimensional charge-coupled device (CCD) camera. The technique provides a real-time diagnostic of the plasma emission around the ECR region within a wavelength region defined by low-bandpass filters.

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

    Science.gov (United States)

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

    2015-01-01

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

  2. Thermal self-frequency locking of doubly-resonant optical parametric oscillator

    DEFF Research Database (Denmark)

    Hansen, P.L.; Buchhave, Preben

    1997-01-01

    The increase in the circulating signal and idler fields that occurs in a high-Q doubly resonant optical parametric oscillator (OPO) as it approaches resonance results in a small increase in the crystal temperature owing to absorption of the generated fields. The temperature change affects...

  3. Field representation for optical defect resonances in multilayer microcavities using quasi-normal modes

    NARCIS (Netherlands)

    Maksimovic, Milan; Lohmeyer, Manfred; van Groesen, Embrecht W.C.

    2008-01-01

    Quasi-normal modes are used to characterize transmission resonances in 1D optical defect cavities and the related field approximations. We specialize to resonances inside the bandgap of the periodic multilayer mirrors that enclose the defect cavities. Using a template with the most relevant QNMs a

  4. All-optical Photonic Oscillator with High-Q Whispering Gallery Mode Resonators

    Science.gov (United States)

    Savchenkov, Anatoliy A.; Matsko, Andrey B.; Strekalov, Dmitry; Mohageg, Makan; Iltchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We demonstrated low threshold optical photonic hyper-parametric oscillator in a high-Q 10(exp 10) CaF2 whispering gallery mode resonator which generates stable 8.5 GHz signal. The oscillations result from the resonantly enhanced four wave mixing occurring due to Kerr nonlinearity of the material.

  5. ¿/4 Resonance of an Optical Monopole Antenna Probed by Single Molecule Fluorescence

    NARCIS (Netherlands)

    Taminiau, Tim H.; Moerland, R.J.; Segerink, Franciscus B.; Kuipers, L.; van Hulst, N.F.

    2007-01-01

    We present a resonant optical nanoantenna positioned at the end of a metal-coated glass fiber near-field probe. Antenna resonances, excitation conditions, and field localization are directly probed in the near field by single fluorescent molecules and compared to finite integration technique

  6. Optimum design of a polymer electro-optic microring resonator switch

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Novel transfer functions are presented for a polymer electro-optic microring resonator switches. The resonating process of the light in the microring is simulated using the formulas. Then the optimization of the structural parameters is performed,and the characteristics are analyzed, such as the resonance time, output spectrum, operation voltage, insertion loss and crosstalk were analyzed. The simulation results show that the designed device exhibits favorable switching functions.

  7. Optical monitoring of thin film electro-polymerization on surface of ITO-coated lossy-mode resonance sensor

    Science.gov (United States)

    Sobaszek, Michał; Dominik, Magdalena; Burnat, Dariusz; Bogdanowicz, Robert; Stranak, Viteszlav; Sezemsky, Petr; Śmietana, Mateusz

    2017-04-01

    This work presents an optical fiber sensors based on lossy-mode resonance (LMR) phenomenon supported by indium tin oxide (ITO) thin overlay for investigation of electro-polymerization effect on ITO's surface. The ITO overlays were deposited on core of polymer-clad silica (PCS) fibers using reactive magnetron sputtering (RMS) method. Since ITO is electrically conductive and electrochemically active it can be used as a working electrode in 3-electrode cyclic voltammetry setup. For fixed potential applied to the electrode current flow decrease with time what corresponds to polymer layer formation on the ITO surface. Since LMR phenomenon depends on optical properties in proximity of the ITO surface, polymer layer formation can be monitored optically in real time. The electrodeposition process has been performed with Isatin which is a strong endogenous neurochemical regulator in humans as it is a metabolic derivative of adrenaline. It was found that optical detection of Isatin is possible in the proposed configuration.

  8. Optically thin hybrid cavity for terahertz photo-conductive detectors

    Science.gov (United States)

    Thompson, R. J.; Siday, T.; Glass, S.; Luk, T. S.; Reno, J. L.; Brener, I.; Mitrofanov, O.

    2017-01-01

    The efficiency of photoconductive (PC) devices, including terahertz detectors, is constrained by the bulk optical constants of PC materials. Here, we show that optical absorption in a PC layer can be modified substantially within a hybrid cavity containing nanoantennas and a Distributed Bragg Reflector. We find that a hybrid cavity, consisting of a GaAs PC layer of just 50 nm, can be used to absorb >75% of incident photons by trapping the light within the cavity. We provide an intuitive model, which describes the dependence of the optimum operation wavelength on the cavity thickness. We also find that the nanoantenna size is a critical parameter, small variations of which lead to both wavelength shifting and reduced absorption in the cavity, suggesting that impedance matching is key for achieving efficient absorption in the optically thin hybrid cavities.

  9. Linear addition algebra of optical nonlinearities in transparent conductive oxides

    CERN Document Server

    Kinsey, N; Clerici, M; Kim, J; Carnemolla, E; Shaltout, A; Kaipurath, R; Faccio, D; Shalaev, V M; Ferrera, M; Boltasseva, A

    2016-01-01

    The fields of nanophotonics and metamaterials have revolutionized the way we think of optical space ({\\epsilon},{\\mu}), enabling us to engineer the refractive index almost at will to confine light to the smallest of volumes as well as to manipulate optical signals with extremely small footprints and energy requirements. More recently, significant efforts have been devoted to the search for suitable materials for dynamic control, and so far, all-optical methods have primarily relied on either interband or intraband excitations. Here, we show that aluminum doped zinc oxide (AZO) supports a hybrid nonlinearity that exhibits a large and ultrafast response with controllable sign. We demonstrate that these two opposite material responses are independent and can be algebraically added together via two-color excitation, resulting in an increase in device bandwidth and unprecedented tuning capabilities. This peculiar behavior of AZO places it as a key material for next-generation ultrafast tunable nanophotonics and me...

  10. Ramp-preserving denoising for conductivity image reconstruction in magnetic resonance electrical impedance tomography.

    Science.gov (United States)

    Lee, Chang-Ock; Jeon, Kiwan; Ahn, Seonmin; Kim, Hyung Joong; Woo, Eung Je

    2011-07-01

    In magnetic resonance electrical impedance tomography, among several conductivity image reconstruction algorithms, the harmonic B(z) algorithm has been successfully applied to B(z) data from phantoms and animals. The algorithm is, however, sensitive to measurement noise in B(z) data. Especially, in in vivo animal and human experiments where injection current amplitudes are limited within a few milliampere at most, measured B(z) data tend to have a low SNR. In addition, magnetic resonance (MR) signal void in outer layers of bones and gas-filled organs, for example, produces salt-pepper noise in the MR phase and, consequently, B(z) images. The B(z) images typically present areas of sloped transitions, which can be assimilated to ramps. Conductivity contrasts change ramp slopes in B(z) images and it is critical to preserve positions of those ramps to correctly recover edges in conductivity images. In this paper, we propose a ramp-preserving denoising method utilizing a structure tensor. Using an eigenvalue analysis, we identified local regions of salt-pepper noise. Outside the identified local regions, we applied an anisotropic smoothing to reduce noise while preserving their ramp structures. Inside the local regions of salt-pepper noise, we used an isotropic smoothing. After validating the proposed denoising method through numerical simulations, we applied it to in vivo animal imaging experiments. Both numerical simulation and experimental results show significant improvements in the quality of reconstructed conductivity images. © 2011 IEEE

  11. Modelling a singly resonant, intracavity ring optical parametric oscillator

    DEFF Research Database (Denmark)

    Buchhave, Preben; Tidemand-Lichtenberg, Peter; Wei, Hou;

    2003-01-01

    We study theoretically and experimentally the dynamics of a single-frequency, unidirectional ring laser with an intracavity nonlinear singly resonant OPO-crystal in a coupled resonator. We find for a range of operating conditions good agreement between model results and measurements of the laser ...

  12. Magneto-optical conductivity in graphene including electron-phonon coupling

    Science.gov (United States)

    Pound, Adam; Carbotte, J. P.; Nicol, E. J.

    2012-03-01

    We show how coupling to an Einstein phonon ωE affects the absorption peaks seen in the optical conductivity of graphene under a magnetic field B. The energies and widths of the various lines are shifted, and additional peaks arise in the spectrum. Some of these peaks are Holstein sidebands, resulting from the transfer of spectral weight in each Landau level (LL) into phonon-assisted peaks in the spectral function. Other additional absorption peaks result from transitions involving split LLs, which occur when a LL falls sufficiently close to a peak in the self-energy. We establish the selection rules for the additional transitions and characterize the additional absorption peaks. For finite chemical potential, spectral weight is asymmetrically distributed about the Dirac point; we discuss how this causes an asymmetry in the transitions due to left- and right-handed circularly polarized light and therefore oscillatory behavior in the imaginary part of the off-diagonal Hall conductivity. We also find that the semiclassical cyclotron resonance region is renormalized by an effective-mass factor but is not directly affected by the additional transitions. Last, we discuss how the additional transitions can manifest in broadened, rather than split, absorption peaks due to large scattering rates seen in experiment.

  13. Integration of conductive reduced graphene oxide into microstructured optical fibres for optoelectronics applications.

    Science.gov (United States)

    Ruan, Yinlan; Ding, Liyun; Duan, Jingjing; Ebendorff-Heidepriem, Heike; Monro, Tanya M

    2016-02-22

    Integration of conductive materials into optical fibres can largely expand functions of fibre devices including surface plasmon resonator/metamaterial, modulators/detectors, or biosensors. Some early attempts have been made to incorporate metals such as tin into fibres during the fibre drawing process. Due to the restricted range of materials that have compatible melting temperatures with that of silica glass, the methods to incorporate metals along the length of the fibres are very challenging. Moreover, metals are nontransparent with strong light absorption, which causes high fibre loss. This article demonstrates a novel but simple method for creating transparent conductive reduced graphene oxide film onto microstructured silica fibres for potential optoelectronic applications. The strongly confined evanescent field of the suspended core fibres with only 2 μW average power was creatively used to transform graphene oxide into reduced graphene oxide with negligible additional loss. Existence of reduced graphene oxide was confirmed by their characteristic Raman signals, shifting of their fluorescence peaks as well as largely decreased resistance of the bulk GO film after laser beam exposure.

  14. Resonant Optical Gradient Force Interaction for Nano-Imaging and-Spectroscopy

    Science.gov (United States)

    2016-07-19

    perspective for further resonant enhancement and control of optical forces. 1. Introduction The combination of scanning probemicroscopywith optics... relatively small force variation between 23 fN to 25 fN across the resonance is due to the large broadband offset as a result of  1 2, which is a...ismuchweaker than the case of R6Gbut exhibits a larger relative spectral variation across the resonance from0.2 fN to 1 fN (for z= 2 nm). Irrespective

  15. Study of an integrated-optical slow light ring-resonator for sensing applications

    NARCIS (Netherlands)

    Uranus, H.P.; Dijkstra, M.; Hoekman, M.; Hoekstra, H.J.W.M.

    2008-01-01

    Integrated-optical (IO) micro-ring, -disk, and -sphere resonators have been long considered as a good candidate to enhance optical sensor performance. To the best of our knowledge, none of previous reported works has explicitly attributed such (expected) enhancement to slow-light phenomenon, i.e. a

  16. Stochastic resonance in periodic potentials realization in a dissipative optical lattice

    CERN Document Server

    Schiavoni, M; Sánchez-Palencia, L; Renzoni, F; Grynberg, G; Schiavoni, Michele; Carminati, Francois-Regis; Sanchez-Palencia, Laurent; Renzoni, Ferruccio; Proxy, Gilbert Grynberg; ccsd-00000107, ccsd

    2002-01-01

    We have observed the phenomenon of stochastic resonance on the Brillouin propagation modes of a dissipative optical lattice. Such a mode has been excited by applying a moving potential modulation with phase velocity equal to the velocity of the mode. Its amplitude has been characterized by the center-of-mass (CM) velocity of the atomic cloud. At Brillouin resonance, we studied the CM-velocity as a function of the optical pumping rate at a given depth of the potential wells. We have observed a resonant dependence of the CM velocity on the optical pumping rate, corresponding to the noise strength. This corresponds to the experimental observation of stochastic resonance in a periodic potential in the low-damping regime.

  17. Transparent conducting oxides for electro-optical plasmonic modulators

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Boltasseva, Alexandra; Lavrinenko, Andrei V.

    2015-01-01

    ), or optical materials with metal-like behavior,have recently attracted a lot of attention due to thepromise they hold to enable low-loss, tunable, CMOScompatibledevices for photonic technologies. In this review,we provide a systematic overview of various compactoptical modulator designs that utilize a class...... and their working characteristics, suchas their extinction ratio, compactness, bandwidth, andlosses, is performed identifying the most promising designs....

  18. Stopping and storing light pulses within a fiber optic ring resonator

    Institute of Scientific and Technical Information of China (English)

    F.H.Suhailin; J.Ali; P.P.Yupapin; Y.Fujii; H.Ahmad; S.W.Harun

    2009-01-01

    A simple all optical system for stopping and storing light pulses is demonstrated.The system consists of an erbium-doped fiber amplifier(EDFA),a semiconductor optical amplifier(SOA),and a fiber ring resonator.The results show that the multisoliton generation with a free spectrum range of 2.4 nm and a pulse spectral width of 0.96 nm is achieved.The memory time of 15 min and the maximum soliton output power of 5.94 dBm are noted,respectively.This means that light pulses can be trapped,i.e.,stopped optically within the fiber ring resonator.

  19. Enhanced Faraday Rotation via Resonant Tunnelling in Tri-Layers Containing Magneto-Optical Metals

    CERN Document Server

    Moccia, Massimo; Galdi, Vincenzo; Alu', Andrea; Engheta, Nader

    2013-01-01

    We study resonant tunnelling effects that can occur in tri-layer structures featuring a dielectric layer sandwiched between two magneto-optical-metal layers. We show that the resonance splitting associated with these phenomena can be exploited to enhance Faraday rotation at optical frequencies. Our results indicate that, in the presence of realistic loss levels, a tri-layer structure of sub-wavelength thickness is capable of yielding sensible (~10{\\deg}) Faraday rotation with transmittance levels that are an order of magnitude larger than those attainable with a standalone slab of magneto-optical metal of same thickness.

  20. Harmonic detection of magnetic resonance for sensitivity improvement of optical atomic magnetometers

    Science.gov (United States)

    Ranjbaran, M.; Tehranchi, M. M.; Hamidi, S. M.; Khalkhali, S. M. H.

    2017-02-01

    Highly sensitive atomic magnetometers use optically detected magnetic resonance of atomic spins to measure extremely weak magnetic field changes. The magnetometer sensitivity is directly proportional to the ratio of intensity to line-shape of the resonance signal. To obtain narrower resonance signal, we implemented harmonic detection of magnetic resonance method in Mx configuration. The nonlinear spin polarization dynamics in detection of the higher harmonics were employed in phenomenological Bloch equations. The measured and simulated harmonic components of the resonance signals in frequency domain yielded significantly narrower line-width accompanying much improved sensitivity. Our results confirm the sensitivity improvement by a factor of two in optical atomic magnetometer via second harmonic signal which can open a new insight in the weak magnetic field measurement system design.

  1. Microring-resonator-based four-port optical router for photonic networks-on-chip.

    Science.gov (United States)

    Ji, Ruiqiang; Yang, Lin; Zhang, Lei; Tian, Yonghui; Ding, Jianfeng; Chen, Hongtao; Lu, Yangyang; Zhou, Ping; Zhu, Weiwei

    2011-09-26

    We design and fabricate a four-port optical router, which is composed of eight microring-resonator-based switching elements, four optical waveguides and six waveguide crossings. The extinction ratio is about 13 dB for the through port and larger than 30 dB for the drop port. The crosstalk of the measured optical links is less than -13 dB. The average tuning power consumption is about 10.37 mW and the tuning efficiency is 5.398 mW/nm. The routing functionality and optical signal integrity are verified by transmitting a 12.5 Gb/s PRBS optical signal.

  2. Reconfigurable non-blocking four-port optical router based on microring resonators.

    Science.gov (United States)

    Yang, Lin; Jia, Hao; Zhao, Yunchou; Chen, Qiaoshan

    2015-03-15

    A reconfigurable non-blocking four-port optical router with the least optical switches is demonstrated. The device is based on microring resonators tuned through thermo-optic effect. The optical signal-to-noise ratio of the device at its nine routing states is about 15 dB. A 25 Gbps data transmission has been performed on its whole 12 optical links, and 8-channel wavelength division multiplexing data transmission has been implemented to expand its communication capacity. The energy efficiency of the device is 23 fJ/bit, and the response time of the device is about 25 μs.

  3. Magnetic resonance electrical impedance tomography for measuring electrical conductivity during electroporation.

    Science.gov (United States)

    Kranjc, M; Bajd, F; Serša, I; Miklavčič, D

    2014-06-01

    The electroporation effect on tissue can be assessed by measurement of electrical properties of the tissue undergoing electroporation. The most prominent techniques for measuring electrical properties of electroporated tissues have been voltage-current measurement of applied pulses and electrical impedance tomography (EIT). However, the electrical conductivity of tissue assessed by means of voltage-current measurement was lacking in information on tissue heterogeneity, while EIT requires numerous additional electrodes and produces results with low spatial resolution and high noise. Magnetic resonance EIT (MREIT) is similar to EIT, as it is also used for reconstruction of conductivity images, though voltage and current measurements are not limited to the boundaries in MREIT, hence it yields conductivity images with better spatial resolution. The aim of this study was to investigate and demonstrate the feasibility of the MREIT technique for assessment of conductivity images of tissues undergoing electroporation. Two objects were investigated: agar phantoms and ex vivo liver tissue. As expected, no significant change of electrical conductivity was detected in agar phantoms exposed to pulses of all used amplitudes, while a considerable increase of conductivity was measured in liver tissue exposed to pulses of different amplitudes.

  4. Magnetic resonance electrical impedance tomography (MREIT): conductivity and current density imaging

    Science.gov (United States)

    Seo, Jin Keun; Kwon, Ohin; Woo, Eung Je

    2005-01-01

    This paper reviews the latest impedance imaging technique called Magnetic Resonance Electrical Impedance Tomography (MREIT) providing information on electrical conductivity and current density distributions inside an electrically conducting domain such as the human body. The motivation for this research is explained by discussing conductivity changes related with physiological and pathological events, electromagnetic source imaging and electromagnetic stimulations. We briefly summarize the related technique of Electrical Impedance Tomography (EIT) that deals with cross-sectional image reconstructions of conductivity distributions from boundary measurements of current-voltage data. Noting that EIT suffers from the ill-posed nature of the corresponding inverse problem, we introduce MREIT as a new conductivity imaging modality providing images with better spatial resolution and accuracy. MREIT utilizes internal information on the induced magnetic field in addition to the boundary current-voltage measurements to produce three-dimensional images of conductivity and current density distributions. Mathematical theory, algorithms, and experimental methods of current MREIT research are described. With numerous potential applications in mind, future research directions in MREIT are proposed.

  5. Conduction electron spin resonance in Mg 1 - x Al x B2

    Science.gov (United States)

    Likodimos, V.; Koutandos, S.; Pissas, M.; Papavassiliou, G.; Prassides, K.

    2003-01-01

    Conduction electron spin resonance is employed to study the interplay of the electronic and structural properties in the normal state of Mg 1 - x Al x B2 alloys as a function of Al-doping for 0 <= x <= 1. The x-dependence of the spin susceptibility reveals considerable reduction of the total density of states N(EF) with increasing Al concentration, complying with theoretical predictions for a predominant filling effect of the hole σ bands by electron doping. The CESR linewidth exhibits significant broadening, especially prominent in the high-Al-content region, indicative of the presence of enhanced structural disorder, consistent with the presence of compositional fluctuations.

  6. Enhanced optical tuning of modified-geometry resonators clad in blue phase liquid crystals.

    Science.gov (United States)

    Ptasinski, Joanna; Khoo, Iam-Choon; Fainman, Yeshaiahu

    2014-09-15

    Active optical tuning of silicon racetrack resonators clad in dye-doped blue phase liquid crystals (BPLCs) is experimentally demonstrated. An adiabatic racetrack resonator geometry that allows for enhanced tuning is presented and analyzed. The resonance shift of an unmodified geometry racetrack is Δλ=0.7 nm, while an adiabatic racetrack achieves a Δλ=1.23 nm resonance shift because of a greater mode overlap with the cladding. The calculated refractive index change of the BPLC is Δn=0.0041 for both geometries.

  7. Twisted split-ring-resonator photonic metamaterial with huge optical activity

    CERN Document Server

    Decker, M; Soukoulis, C M; Linden, S; Wegener, M

    2010-01-01

    Coupled split-ring-resonator metamaterials have previously been shown to exhibit large coupling effects, which are a prerequisite for obtaining large effective optical activity. By a suitable lateral arrangement of these building blocks, we completely eliminate linear birefringence and obtain pure optical activity and connected circular optical dichroism. Experiments at around 100-THz frequency and corresponding modeling are in good agreement. Rotation angles of about 30 degrees for 205nm sample thickness are derived.

  8. Loading Dynamics and Characteristics of a Far Off-Resonance Optical Dipole Trap

    Science.gov (United States)

    Mickelson, P. G.; Martinez, Y. N.; Nagel, S. B.; Traverso, A. J.; Killian, T. C.

    2007-10-01

    We implement an optical dipole trap in a crossed beam configuration for experiments with ultracold strontium. Strontium atoms cooled to nearly 1 μK are loaded into the optical dipole trap from a magneto-optical trap operating on the 689 nm intercombination line. Loading dynamics and characteristics of the far off-resonance dipole trap are explored as part of our group's study of ultracold collisions in strontium.

  9. Resonant mixing of optical orbital and spin angular momentum by using chiral silicon nanosphere clusters.

    Science.gov (United States)

    Al-Jarro, Ahmed; Biris, Claudiu G; Panoiu, Nicolae C

    2016-04-01

    We present an in-depth analysis of the resonant intermixing between optical orbital and spin angular momentum of Laguerre-Gaussian (LG) beams, mediated by chiral clusters made of silicon nanospheres. In particular, we establish a relationship between the spin and orbital quantum numbers characterizing the LG beam and the order q of the rotation symmetry group q of the cluster of nanospheres for which resonantly enhanced coupling between the two components of the optical angular momentum is observed. Thus, similar to the case of diffraction grating-mediated transfer of linear momentum between optical beams, we demonstrate that clusters of nanospheres that are invariant to specific rotation transformations can efficiently transfer optical angular momentum between LG beams with different quantum numbers. We also discuss the conditions in which the resonant interaction between LG beams and a chiral cluster of nanospheres leads to the generation of superchiral light.

  10. Resonant optical control of the spin of a single Cr atom in a quantum dot

    Science.gov (United States)

    Lafuente-Sampietro, A.; Utsumi, H.; Boukari, H.; Kuroda, S.; Besombes, L.

    2017-01-01

    A Cr atom in a semiconductor host carries a localized spin with an intrinsic large spin to strain coupling, which is particularly promising for the development of hybrid spin-mechanical systems and coherent mechanical spin driving. We demonstrate here that the spin of an individual Cr atom inserted in a semiconductor quantum dot can be controlled optically. We first show that a Cr spin can be prepared by resonant optical pumping. Monitoring the time dependence of the intensity of the resonant fluorescence of the quantum dot during this process permits us to probe the dynamics of the optical initialization of the Cr spin. Using this initialization and readout technique we measured a Cr spin relaxation time at T =5 K in the microsecond range. We finally demonstrate that, under a resonant single-mode laser field, the energy of any spin state of an individual Cr atom can be independently tuned by using the optical Stark effect.

  11. Optical fiber strain sensor using fiber resonator based on frequency comb Vernier spectroscopy

    DEFF Research Database (Denmark)

    Zhang, Liang; Lu, Ping; Chen, Li;

    2012-01-01

    A novel (to our best knowledge) optical fiber strain sensor using a fiber ring resonator based on frequency comb Vernier spectroscopy is proposed and demonstrated. A passively mode-locked optical fiber laser is employed to generate a phased-locked frequency comb. Strain applied to the optical fiber...... be proportionally improved by increasing the length of the optical fiber ring resonator....... of the fiber ring resonator can be measured with the transmission spectrum. A good linearity is obtained between displacement and the inverse of wavelength spacing with an R2 of 0.9989, and high sensitivities better than 40  pm/με within the range of 0 to 10  με are achieved. The sensitivity can...

  12. Optical sensors from electrohydrodynamic jetted polymer fiber resonators

    DEFF Research Database (Denmark)

    Laye, Fabrice; Kraemmer, Sarah; Castillo, Alejandro;

    2016-01-01

    Electrohydrodynamic jetting is used to manufacture dye-doped polymer fiber resonators. We present comb-like laser emission from different polymer/dye combinations and report the use of these structures as sensitive detection of ethanol and methanol....

  13. Polymeric microring resonator based electro-optic modulator

    NARCIS (Netherlands)

    Leinse, Arne

    2005-01-01

    This thesis will describe the design, realization and characterization of an EO polymeric MR resonator, which was fabricated in the framework of a MESA+ Strategic Research Orientation TeraHertz and an IST project NAIS.

  14. Molecular-Resonance Fiber Optic Gas Sensors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aspen systems proposes to develop an innovative and smart sensors to continuously monitor ambient air compositions by utilizing a resonating tunable micro-cavity...

  15. A scheme to expand the delay-bandwidth product in the resonator-based delay lines by optical OFDM technique

    DEFF Research Database (Denmark)

    Zhu, Jiangbo; Tao, Li; Zhang, Ziran

    2013-01-01

    We propose a novel scheme to expand the inherent limit in the product of the optical delay and the transmission bandwidth in resonator-based delay lines, with the optical orthogonal frequency division multiplexing (OOFDM) technique. The optical group delay properties of a single ring resonator we...

  16. Optical sensors from electrohydrodynamic jetted polymer fiber resonators

    DEFF Research Database (Denmark)

    Laye, Fabrice; Kraemmer, Sarah; Castillo, Alejandro

    2016-01-01

    Electrohydrodynamic jetting is used to manufacture dye-doped polymer fiber resonators. We present comb-like laser emission from different polymer/dye combinations and report the use of these structures as sensitive detection of ethanol and methanol.......Electrohydrodynamic jetting is used to manufacture dye-doped polymer fiber resonators. We present comb-like laser emission from different polymer/dye combinations and report the use of these structures as sensitive detection of ethanol and methanol....

  17. Optical rogue waves in whispering-gallery-mode resonators

    Science.gov (United States)

    Coillet, Aurélien; Dudley, John; Genty, Goëry; Larger, Laurent; Chembo, Yanne K.

    2014-01-01

    We report a theoretical study showing that rogue waves can emerge in whispering-gallery-mode resonators as the result of the chaotic interplay between Kerr nonlinearity and anomalous group-velocity dispersion. The nonlinear dynamics of the propagation of light in a whispering-gallery-mode resonator is investigated using the Lugiato-Lefever equation, and we give evidence of a range of parameters where rare and extreme events associated with non-Gaussian statistics of the field maxima are observed.

  18. Optical Rogue Waves in Whispering-Gallery-Mode Resonators

    CERN Document Server

    Coillet, Aurélien; Genty, Goery; Larger, Laurent; Chembo, Yanne K

    2014-01-01

    We report a theoretical study showing that rogue waves can emerge in whispering gallery mode resonators as the result of the chaotic interplay between Kerr nonlinearity and anomalous group-velocity dispersion. The nonlinear dynamics of the propagation of light in a whispering gallery-mode resonator is investigated using the Lugiato-Lefever equation, and we evidence a range of parameters where rare and extreme events associated with a non-gaussian statistics of the field maxima are observed.

  19. Controllable Optical Switch in a One-Dimensional Resonator Waveguide Coupled to a Whispering-Gallery Resonator

    Institute of Scientific and Technical Information of China (English)

    LANG Jia-Hong

    2011-01-01

    Single photon transport properties in a one-dimensional array of coupled microcavities waveguide coupled to a whispering-gallery resonator interacting with a A-type system are theoretically investigated.The calculations reveal that the transport properties of single photons with arbitrary energy can be controlled by varying the Rabi frequency and detuning the control optical field.This phenomenon can be used for controllable optical switching.Single photon transport properties in a onedimensional waveguide coupled to a two-level[1-10] or multi-level[11-17] system have been studied theoretically and experimentally for their potential applications in quantum information and all-optical devices.A coupled cavity array is considered as a one-dimensional waveguide and the single photon transport properties in such a system coupled to a two-level and multi-level system have been studied.%Single photon transport properties in a one-dimensional array of coupled microcavities waveguide coupled to a whispering-gallery resonator interacting with a A-type system are theoretically investigated. The calculations reveal that the transport properties of single photons with arbitrary energy can be controlled by varying the Rabi frequency and detuning the control optical field. This phenomenon can be used for controllable optical switching.

  20. Family of graphene-assisted resonant surface optical excitations for terahertz devices

    Science.gov (United States)

    Lin, I-Tan; Liu, Jia-Ming; Tsai, Hsin-Cheng; Wu, Kaung-Hsiung; Syu, Jheng-Yuan; Su, Ching-Yuan

    2016-01-01

    The majority of the proposed graphene-based THz devices consist of a metamaterial that can optically interact with graphene. This coupled graphene-metamaterial system gives rise to a family of resonant modes such as the surface plasmon polariton (SPP) modes of graphene, the geometrically induced SPPs, also known as the spoof SPP modes, and the Fabry-Perot (FP) modes. In the literature, these modes are usually considered separately as if each could only exist in one structure. By contrast, in this paper, we show that even in a simple metamaterial structure such as a one-dimensional (1D) metallic slit grating, these modes all exist and can potentially interact with each other. A graphene SPP-based THz device is also fabricated and measured. Despite the high scattering rate, the effective SPP resonances can still be observed and show a consistent trend between the effective frequency and the grating period, as predicted by the theory. We also find that the excitation of the graphene SPP mode is most efficient in the terahertz spectral region due to the Drude conductivity of graphene in this spectral region. PMID:27739504

  1. The spectral shift between near- and far-field resonances of optical nano-antennas.

    Science.gov (United States)

    Menzel, Christoph; Hebestreit, Erik; Mühlig, Stefan; Rockstuhl, Carsten; Burger, Sven; Lederer, Falk; Pertsch, Thomas

    2014-04-21

    Within the past several years a tremendous progress regarding optical nano-antennas could be witnessed. It is one purpose of optical nano-antennas to resonantly enhance light-matter interactions at the nanoscale, e.g. the interaction of an external illumination with molecules. In this specific, but in almost all schemes that take advantage of resonantly enhanced electromagnetic fields in the vicinity of nano-antennas, the precise knowledge of the spectral position of resonances is of paramount importance to fully exploit their beneficial effects. Thus far, however, many nano-antennas were only optimized with respect to their far-field characteristics, i.e. in terms of their scattering or extinction cross sections. Although being an emerging feature in many numerical simulations, it was only recently fully appreciated that there exists a subtle but very important difference in the spectral position of resonances in the near-and the far-field. With the purpose to quantify this shift, Zuloaga et al. suggested a Lorentzian model to estimate the resonance shift. Here, we devise on fully analytical grounds a strategy to predict the resonance in the near-field directly from that in the far-field and disclose that the issue is involved and multifaceted, in general. We outline the limitations of our theory if more sophisticated optical nano-antennas are considered where higher order multipolar contributions and higher order antenna resonances become increasingly important. Both aspects are highlighted by numerically studying relevant nano-antennas.

  2. Ultrafast broadband tuning of resonant optical nanostructures using phase change materials

    CERN Document Server

    Rudé, Miquel; Cetin, Arif E; Miller, Timothy A; Carrilero, Albert; Wall, Simon; de Abajo, F Javier García; Altug, Hatice; Pruneri, Valerio

    2015-01-01

    The phenomenon of extraordinary optical transmission {EOT} through arrays of nanoholes patterned in a metallic film has emerged as a promising tool for a wide range of applications, including photovoltaics, nonlinear optics, and sensing. Designs and methods enabling the dynamic tuning of the optical resonances of these structures are essential to build efficient optical devices, including modulators, switches, filters, and biosensors. However, the efficient combination of EOT and dynamic tuning remains a challenge, mainly because of the lack of materials that can induce modulation over a broad spectral range at high speeds. Here, we demonstrate tuneable resonance wavelength shifts as large as 385 nm - an order of magnitude higher than previously reported - through the combination of phase change materials {PCMs}, which exhibit dramatic variations in optical properties upon transitions between amorphous and crystalline phases, with properly designed subwavelength nanohole metallic arrays. We further find throu...

  3. Alternative approach of conducting phase-modulated all-optical logic gates

    Science.gov (United States)

    Chakraborty, Bikash; Mukhopadhyay, Sourangshu

    2009-03-01

    It is well established that optical devices and components are more advantageous than their electronic counterparts because of inherent parallelism in optics. Basically electronics are found to be very unsuitable in high speed (above gigahertz) data processing systems whereas tremendous operational speed (in the range of terahertz) can be achieved with the help of optics. The parallelism of optics and the properties of low loss transmission make optics a powerful technology for digital computing and processing and in long-range communications. Again it is well established that logic gates are the basic building blocks of any computing or data processing system. Therefore, any optical data processor needs suitable optically run logic gates. A method of conducting phase-modulated all-optical logic gates is proposed. Here we will exploit the advantages of phase modulation not only in processing but also in encoding as well decoding also.

  4. Transmission line resonance technique for eccentric core optical fibers

    Science.gov (United States)

    Georgantzos, E.; Boucouvalas, A. C.

    2016-12-01

    In several cases optical fibers in telecommunications have cores of non circular geometry. Fibre optic deformations appear in optical fibres for many reasons. Optical fibre core ellipticity for example where the fibre optic core is not perfectly circular due to fibre optic manufacturing tolerances, is measured and often is a problem. Optical fibre core eccentricity, where the fibre core is not on the axis of the fibre, but it is offset by a small length. This is another issue and very important for ensuring performance low loss splices and connector losses. Both of ellipticity and eccentricity are specified in accordance to international standards for fibre optic manufacturing telecommunications grade fibres. The present paper studies ellipticity and core eccentricity specifically and presents a new method for analysing their effect. We present an extension of the transmission line technique as a means of studying such fibers and deriving necessary parameters. Conformal mapping on the other hand is a simple mathematical tool by which we can generate sets of orthogonal two-dimensional coordinate systems. Shortly a conformal map of Cartesian two-dimensional space is defined by any analytical function W(z) where z, w, are: z = x + jy, W = θ + j φ The function deriving by the conformal mapping transformation h(θ ,φ )=| ∂w/∂z | = 1/|∂z/∂w|, can be used in order to define ∇A → and ∇×A → where A → is the magnetic or electric field in the derived orthogonal coordinate system. Useful conformal maps for fiber optics applications should have the property that the equation θ(x, y) = constant, is forming closed curves in a Cartesian two-dimensional space (x,y). If θ(x, y) = constant represents a set of co-eccentric circles, we obtain the normal case of conventional fibers with circular cores. If θ(x, y) = constant represents a set of eclipses, we are have the formation of elliptic core optical fibers. If θ(x, y) = constant represents a set of

  5. Soliton models in resonant and nonresonant optical fibers

    Indian Academy of Sciences (India)

    K Porsezian

    2001-11-01

    In this review, considering the important linear and nonlinear optical effects like group velocity dispersion, higher order dispersion, Kerr nonlinearity, self-steepening, stimulated Raman scattering, birefringence, self-induced transparency and various inhomogeneous effects in fibers, the completely integrable concept and bright, dark and self-induced transparency soliton models in nonlinear fiber optics are discussed. Considering the above important optical effects, the different completely integrable soliton models in the form of nonlinear Schrödinger (NLS), NLS-MaxwellBloch (MB) type equations reported in the literature are discussed. Finally, solitons in stimulated Raman scattering (SRS) system is briefly discussed.

  6. A subwavelength plasmonic metamolecule exhibiting magnetic-based optical Fano resonance

    Science.gov (United States)

    Shafiei, Farbod; Monticone, Francesco; Le, Khai Q.; Liu, Xing-Xiang; Hartsfield, Thomas; Alù, Andrea; Li, Xiaoqin

    2013-02-01

    The lack of symmetry between electric and magnetic charges, a fundamental consequence of the small value of the fine-structure constant, is directly related to the weakness of magnetic effects in optical materials. Properly tailored plasmonic nanoclusters have been proposed recently to induce artificial optical magnetism based on the principle that magnetic effects are indistinguishable from specific forms of spatial dispersion of permittivity at optical frequencies. In a different context, plasmonic Fano resonances have generated a great deal of interest, particularly for use in sensing applications that benefit from sharp spectral features and extreme field localization. In the absence of natural magnetism, optical Fano resonances have so far been based on purely electric effects. In this Letter, we demonstrate that a subwavelength plasmonic metamolecule consisting of four closely spaced gold nanoparticles supports a strong magnetic response coupled to a broad electric resonance. Small structural asymmetries in the assembled nanoring enable the interaction between electric and magnetic modes, leading to the first observation of a magnetic-based Fano scattering resonance at optical frequencies. Our findings are supported by excellent agreement with simulations and analytical calculations, and represent an important step towards the quest for artificial magnetism and negative refractive index metamaterials at optical frequencies.

  7. All optical NAND gate based on nonlinear photonic crystal ring resonator

    Directory of Open Access Journals (Sweden)

    Somaye Serajmohammadi

    2016-06-01

    Full Text Available In this paper we proposed a new design for all optical NAND gate. By combining nonlinear Kerr effect with photonic crystal ring resonators, we designed an all optical NAND gate. A typical NAND gate is a logic device with one bias and two logic input and one output ports. It has four different combinations for its logic input ports. The output port of the NAND gate is OFF, when both logic ports are ON, otherwise the output port will be ON. The switching power threshold obtained for this structure equals to 1.5 kW/μm2. For designing the proposed optical logic gate we employed one resonant ring whose resonant wavelength is at 1554 nm. The functionality of the proposed NAND gate depends on the operation of this resonant ring. When the power intensity of optical waves is less than the switching threshold the ring will couple optical waves into drop waveguide otherwise the optical waves will propagate on the bus waveguide.

  8. Spin-dependent electrical conduction in a pentacene Schottky diode explored by electrically detected magnetic resonance

    Science.gov (United States)

    Fukuda, Kunito; Asakawa, Naoki

    2017-02-01

    Reported is the observation of dark spin-dependent electrical conduction in a Schottky barrier diode with pentacene (PSBD) using electrically detected magnetic resonance at room temperature. It is suggested that spin-dependent conduction exists in pentacene thin films, which is explored by examining the anisotropic linewidth of the EDMR signal and current density-voltage (J-V) measurements. The EDMR spectrum can be decomposed to Gaussian and Lorentzian components. The dependency of the two signals on the applied voltage was consistent with the current density-voltage (J-V) of the PSBD rather than that of the electron-only device of Al/pentacene/Al, indicating that the spin-dependent conduction is due to bipolaron formation associated with hole polaronic hopping processes. The applied-voltage dependence of the ratio of intensity of the Gaussian line to the Lorentzian may infer that increasing current density should make conducting paths more dispersive, thereby resulting in an increased fraction of the Gaussian line due to the higher dispersive g-factor.

  9. Non-intrusive tunable resonant microwave cavity for optical detected magnetic resonance of NV centres in nanodiamonds

    Science.gov (United States)

    Le Floch, Jean-Michel; Bradac, Carlo; Volz, Thomas; Tobar, Michael E.; Castelletto, Stefania

    2013-12-01

    Optically detected magnetic resonance (ODMR) in nanodiamond nitrogen-vacancy (NV) centres is usually achieved by applying a microwave field delivered by micron-size wires, strips or antennas directly positioned in very close proximity (~ μm) of the nanodiamond crystals. The microwave field couples evanescently with the ground state spin transition of the NV centre (2.87 GHz at zero magnetic field), which results in a reduction of the centre photoluminescence. We propose an alternative approach based on the construction of a dielectric resonator. We show that such a resonator allows for the efficient detection of NV spins in nanodiamonds without the constraints associated to the laborious positioning of the microwave antenna next to the nanodiamonds, providing therefore improved flexibility. The resonator is based on a tunable Transverse Electric Mode in a dielectric-loaded cavity, and we demonstrate that the resonator can detect single NV centre spins in nanodiamonds using less microwave power than alternative techniques in a non-intrusive manner. This method can achieve higher precision measurement of ODMR of paramagnetic defects spin transition in the micro to millimetre-wave frequency domain. Our approach would permit the tracking of NV centres in biological solutions rather than simply on the surface, which is desirable in light of the recently proposed applications of using nanodiamonds containing NV centres for spin labelling in biological systems with single spin and single particle resolution.

  10. Optical properties of surface plasmon resonances of coupled metallic nanorods.

    Science.gov (United States)

    Smythe, Elizabeth J; Cubukcu, Ertugrul; Capasso, Federico

    2007-06-11

    We present a systematic study of optical antenna arrays, in which the effects of coupling between the antennas, as well as of the antenna length, on the reflection spectra are investigated and compared. Such arrays can be fabricated on the facet of a fiber, and we propose a photonic device, a plasmonic optical antenna fiber probe, that can potentially be used for in-situ chemical and biological detection and surface-enhanced Raman scattering.

  11. Random polarization dynamics in a resonant optical medium

    CERN Document Server

    Newhall, Katherine A; Kramer, Peter R; Kovacic, Gregor; Gabitov, Ildar R

    2013-01-01

    Random optical-pulse polarization switching along an active optical medium in the $\\Lambda$-configuration with spatially disordered occupation numbers of its lower energy sub-level pair is described using the idealized integrable Maxwell-Bloch model. Analytical results describing the light polarization-switching statistics for the single self-induced transparency pulse are compared with statistics obtained from direct Monte-Carlo numerical simulations.

  12. Fiber Optic Surface Plasmon Resonance-Based Biosensor Technique: Fabrication, Advancement, and Application.

    Science.gov (United States)

    Liang, Gaoling; Luo, Zewei; Liu, Kunping; Wang, Yimin; Dai, Jianxiong; Duan, Yixiang

    2016-05-03

    Fiber optic-based biosensors with surface plasmon resonance (SPR) technology are advanced label-free optical biosensing methods. They have brought tremendous progress in the sensing of various chemical and biological species. This review summarizes four sensing configurations (prism, grating, waveguide, and fiber optic) with two ways, attenuated total reflection (ATR) and diffraction, to excite the surface plasmons. Meanwhile, the designs of different probes (U-bent, tapered, and other probes) are also described. Finally, four major types of biosensors, immunosensor, DNA biosensor, enzyme biosensor, and living cell biosensor, are discussed in detail for their sensing principles and applications. Future prospects of fiber optic-based SPR sensor technology are discussed.

  13. A Novel Analysis Approach for Ring-resonator Performance as Optical Filter

    Institute of Scientific and Technical Information of China (English)

    XU Jing-bo

    2008-01-01

    A novel attempt has been made in this paper for a different approach for determination of ring resonator transmittance with the help of delay line signal processing techniques and Totally Coded Method (TCM). A generalized approach for determination of transfer function in Z-domain of optical waveguide based ring resonator is introduced. Delay line signal processing technique is used to develop the signal flow graph of different ring resonator architectures, and a rule is implemented to determine its overall transmittance. The parameters describing the performance of optical filter can be directly estimated from the frequency response plot. A waveguide based double ring resonator (DRR) architecture is proposed, and its frequency response analysis is carried out.

  14. Symposium KK, Resonant Optics in Dielectric and Metallic Structures: Fundamentals and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Larouche, Stephane [Duke Univ., Durham, NC (United States); Caldwell, Joshua [Naval Research Lab. (NRL), Washington, DC (United States)

    2016-09-06

    Symposium KK focused on the design, fabrication, characterization of novel nanoscale optical resonators and alternative materials for sub-diffraction scale resonant particles. Contributions discussed all aspects of this field, and the organizers had more than 130 contributing participants to this session alone, spanning North America, Europe, Asia and Australia. Participants discussed cutting edge research results focused on the structure, physical and optical properties, and ultrafast dynamic response of nanoscale resonators such as plasmonic and dielectric nanoparticles. A strong focus on state-of-the-art characterization and fabrication approaches, as well as presentations on novel materials for sub-diffraction resonators took place. As expected, the sessions provided strong interdisciplinary interactions and lively debate among presenters and participants.

  15. Ultrafast optical control using the Kerr nonlinearity in hydrogenated amorphous silicon microcylindrical resonators

    Science.gov (United States)

    Vukovic, N.; Healy, N.; Suhailin, F. H.; Mehta, P.; Day, T. D.; Badding, J. V.; Peacock, A. C.

    2013-10-01

    Microresonators are ideal systems for probing nonlinear phenomena at low thresholds due to their small mode volumes and high quality (Q) factors. As such, they have found use both for fundamental studies of light-matter interactions as well as for applications in areas ranging from telecommunications to medicine. In particular, semiconductor-based resonators with large Kerr nonlinearities have great potential for high speed, low power all-optical processing. Here we present experiments to characterize the size of the Kerr induced resonance wavelength shifting in a hydrogenated amorphous silicon resonator and demonstrate its potential for ultrafast all-optical modulation and switching. Large wavelength shifts are observed for low pump powers due to the high nonlinearity of the amorphous silicon material and the strong mode confinement in the microcylindrical resonator. The threshold energy for switching is less than a picojoule, representing a significant step towards advantageous low power silicon-based photonic technologies.

  16. Experimental Investigation on a Fibre-Optic Hydrophone with a Cylindrical Helmholtz Resonator

    Institute of Scientific and Technical Information of China (English)

    WANG Ze-Feng; HUNG Yong-Ming; MENG Zhou; NI Ming

    2008-01-01

    A novel mechanical anti-aliasing filtering fibre-optic hydrophone with a cylindrical Helmholtz resonator is constructed and tested.The experimental results show that the hydrophone has a function of low-pass filtering.The low frequency acoustic sensitivity is about -160 dB (1 rad/μPa),and the response curve has a resonance determined by the Helmholtz resonator.Theoretical and experimental results both show that the resonant frequency moves towards high frequency with the increasing orifice diameters.The sensitivity attenuation of high frequency is larger than 10 dB.This new fibre-optic hydrophone is a prototype device for a c/ass of sensors used to eliminate the aliasing in future sonar systems.

  17. Highly-efficient thermally-tuned resonant optical filters.

    Science.gov (United States)

    Cunningham, John E; Shubin, Ivan; Zheng, Xuezhe; Pinguet, Thierry; Mekis, Attila; Luo, Ying; Thacker, Hiren; Li, Guoliang; Yao, Jin; Raj, Kannan; Krishnamoorthy, Ashok V

    2010-08-30

    We demonstrate spectral tunability for microphotonic add-drop filters manufactured as ring resonators in a commercial 130 nm SOI CMOS technology. The filters are provisioned with integrated heaters built in CMOS for thermal tuning. Their thermal impedance has been dramatically increased by the selective removal of the SOI handler substrate under the device footprint using a bulk silicon micromachining process. An overall ~20x increase in the tuning efficiency has been demonstrated with a 100 µm radius ring as compared to a pre-micromachined device. A total of 3.9 mW of applied tuning power shifts the filter resonant peak across one free spectral node of the device. The Q-factor of the resonator remains unchanged after the co-integration process and hence this device geometry proves to be fully CMOS compatible. Additionally, after the cointegration process our result of 2π shift with 3.9 mW power is among the best tuning performances for this class of devices. Finally, we examine scaling the tuning efficiency versus device footprint to develop a different performance criterion for an easier comparison to evaluate thermal tuning. Our criterion is defined as the unit of power to shift the device resonance by a full 2π phase shift.

  18. Optical refractometric sensors based on embedded nanowire microcoil resonators

    OpenAIRE

    2007-01-01

    We present a novel, robust, and compact refractometric sensor based on a high Q factor embedded nanowire microcoil resonator with an intrinsic fluidic channel. Ideally, sensitivities as high as 1000 nm/RIU and a refractive index resolution of 10 can be achieved.

  19. Spatial confinement of acoustic and optical waves in stubbed slab structure as optomechanical resonator

    Energy Technology Data Exchange (ETDEWEB)

    Li, Changsheng, E-mail: lcs135@163.com; Huang, Dan; Guo, Jierong

    2015-02-20

    We theoretically demonstrate that acoustic waves and optical waves can be spatially confined in the same micro-cavity by specially designed stubbed slab structure. The proposed structure presents both phononic and photonic band gaps from finite element calculation. The creation of cavity mode inside the band gap region provides strong localization of phonon and photon in the defect region. The practical parameters to inject cavity and work experimentally at telecommunication range are discussed. This structure can be precisely fabricated, hold promises to enhance acousto-optical interactions and design new applications as optomechanical resonator. - Highlights: • A resonator simultaneously supports acoustic and optical modes. • Strong spatial confinement and slow group velocity. • Potential to work as active optomechanical resonator.

  20. Optical Fiber Sensor Based on Localized Surface Plasmon Resonance Using Silver Nanoparticles Photodeposited on the Optical Fiber End

    Science.gov (United States)

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

    2014-01-01

    This paper reports the implementation of an optical fiber sensor to measure the refractive index in aqueous media based on localized surface plasmon resonance (LSPR). We have used a novel technique known as photodeposition to immobilize silver nanoparticles on the optical fiber end. This technique has a simple instrumentation, involves laser light via an optical fiber and silver nanoparticles suspended in an aqueous medium. The optical sensor was assembled using a tungsten lamp as white light, a spectrometer, and an optical fiber with silver nanoparticles. The response of this sensor is such that the LSPR peak wavelength is linearly shifted to longer wavelengths as the refractive index is increased, showing a sensitivity of 67.6 nm/RIU. Experimental results are presented. PMID:25302813

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

    Science.gov (United States)

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

    2014-10-09

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

  2. Optical Fiber Sensor Based on Localized Surface Plasmon Resonance Using Silver Nanoparticles Photodeposited on the Optical Fiber End

    Directory of Open Access Journals (Sweden)

    J. Gabriel Ortega-Mendoza

    2014-10-01

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

  3. Dipolariton formation in quantum dot molecules strongly coupled to optical resonators

    CERN Document Server

    Domínguez, Marlon S; Ramírez, Hanz Y

    2016-01-01

    In this theoretical work, we study a double quantum dot interacting strongly with a microcavity, while undergoing resonant tunneling. Effects of interdot tunneling on the light-matter hybridized states are determined, and tunability of their brightness degrees and associated dipole moments is demonstrated. These results predict dipolariton generation in artificial molecules coupled to optical resonators, and provide a promising scenario for control of emission efficiency and coherence times of exciton polaritons.

  4. Optically detected magnetic resonance studies on {pi}-conjugate polymers and novel carbon allotropes

    Energy Technology Data Exchange (ETDEWEB)

    Partee, J.

    1999-02-12

    This report describes the following: introduction to photoluminescence detected magnetic resonance (PLDMR); introduction to {pi}-conjugated systems; PLDMR measurements on poly(p-phenylene)-type ladder polymers; PLMDR measurements on poly(p-phenylene ethylene); and PLDMR measurements on C{sub 70}, polythiophene, poly(p-phenylene vinylene) and Dan-40. Appendices to this report describe: Operation of ODMR (optically detected magnetic resonance) spectrometer; ODMR system parameters; and Special purpose circuitry.

  5. Three-Wave Resonant Interactions in Self-Defocusing Optical Media

    Institute of Scientific and Technical Information of China (English)

    崔维娜; 黄国翔; 孙春柳

    2003-01-01

    A three-wave resonant interaction for nonlinear excitations created from a continuous-wave background is shown to be possible in an isotropic optical medium with a self-defocusing cubic nonlinearity. Under suitable phasematching conditions the nonlinear envelope equations for the resonant interaction are derived by using a method of multiple-scales. Some explicit three-wave solitary wave and lump solutions are discussed.

  6. Ultralow loss, high Q, four port resonant couplers for quantum optics and photonics.

    Science.gov (United States)

    Rokhsari, H; Vahala, K J

    2004-06-25

    We demonstrate a low-loss, optical four port resonant coupler (add-drop geometry), using ultrahigh Q (>10(8)) toroidal microcavities. Different regimes of operation are investigated by variation of coupling between resonator and fiber taper waveguides. As a result, waveguide-to-waveguide power transfer efficiency of 93% (0.3 dB loss) and nonresonant insertion loss of 0.02% (photonic networks.

  7. Optical Conductivity of Small Polarons in Sm1-xSrxTiO3 Epitaxial Films

    Science.gov (United States)

    Flaherty, William; Hauser, Adam; Law, Strange; Jackson, Clayton; Raghavan, Santosh; Isaac, Brandon; Freeze, Chris; Allen, S. James; Stemmer, Susanne

    2015-03-01

    We present our findings in the optical conductivity in a doping-controlled metal-to-Mott-insulator transition. These samples, grown using hybrid MBE, span the transition from the Mott insulator SmTiO3 to metallic, lightly-doped SrTiO3. Zhou and Goodenough have studied a wide range of rare earth titanates and found that SmTiO3 has thermally activated transport. We measure the optical conductivity to determine the conduction mechanism. Using FTIR spectroscopy, we extract the optical conductivity in the 0.06-2.5 eV range. If conduction in Sm1-xSrxTiO3 is due to small polarons, it will have a distinct Gaussian optical conductivity feature, related to the DC transport, as described by David Emin. Alternatively, conduction could be due to variable-range hopping between defects. Furthermore, the combination of DC and optical conductivity can test the prediction of Yee and Balents that the metal-to-insulator transition is first-order with percolative phase separation between metallic and localized regions. Such a sample would have a distinct Drude tail plus polaron contributions to its conductivity. Extreme Electron Concentration Oxide Devices, Supported by ONR N00014-12-0976.

  8. Nanoscale Plasmonic and Optical Modulators Based on Transparent Conducting Oxides

    CERN Document Server

    Lu, Zhaolin; Shi, Kaifeng

    2012-01-01

    Recent experiments showed that unity-order index change in a transparent conducting oxide (TCO) can be achieved in a metal-oxide-semiconductor (MOS) structure by accumulation charge. However, the ultrathin (~5nm) accumulation layer and inherent absorption of TCOs impede the practical applications of this effect. Herein, we propose and explore a novel waveguide, namely "TCO-slot waveguide", which combines both the tunable property of a TCO and field enhancement of a slot waveguide. In particular, light absorption can be sharply enhanced when the slot dielectric constant is tuned close to zero. Based on TCO-slot waveguides, efficient electro-absorption modulation can be achieved within 200 nm with small insertion loss.

  9. A magneto-optical isolator based on series-coupled race-track resonators

    Science.gov (United States)

    Qi, Wei; Jin, Yichang; Yu, Hui; Jiang, Xiaoqing

    2015-01-01

    In this paper, we propose a novel kind of magneto-optical (MO) isolators based on series-coupled race-track resonators. The perturbation theory is used to calculate the non-reciprocal phase shift (NRPS) induced by the MO effect. The numerical result indicates that the isolation is greatly enhanced by the box-like spectra of series-coupled resonators. Optical isolation ratio for the first, second, and third order devices are 7.8, 21, and 36.2 dB, respectively.

  10. A simplified hollow-core microstructured optical fibre laser with microring resonators and strong radial emission

    Science.gov (United States)

    Li, Zhi-Li; Liu, Yan-Ge; Yan, Min; Zhou, Wen-Yuan; Ying, Cui-Feng; Ye, Qing; Tian, Jian-Guo

    2014-08-01

    A simplified hollow-core microstructured optical fibre (SHMOF) laser with microring resonators and strong radial emission is demonstrated. We propose that a submicron thickness silica ring embedded in the SHMOF can act as a microring resonator, with the advantages of being both compact and solid. Furthermore, the microfluidics can be easily controlled with a side pumping scheme. We also obtained a highly stable and tunable laser. The attractive possibility of developing microfluidic dye lasers within single SHMOFs presents opportunities for integrated optics applications and biomedical analysis.

  11. Far-off-resonant coupling between a semiconductor quantum dot and an optical cavity

    DEFF Research Database (Denmark)

    Lund, Anders Mølbjerg; Settnes, Mikkel; Nielsen, Per Kær

    2014-01-01

    We present an investigation of the far-off-resonant coupling between a semiconductor quantum dot and a cavity. We show that the enhanced coupling observed in experiments is explained by Coulomb interactions with wetting layer carriers. © 2014 Optical Society of America.......We present an investigation of the far-off-resonant coupling between a semiconductor quantum dot and a cavity. We show that the enhanced coupling observed in experiments is explained by Coulomb interactions with wetting layer carriers. © 2014 Optical Society of America....

  12. Forty-Four Pass Fibre Optic Loop for Improving the Sensitivity of Surface Plasmon Resonance Sensors

    CERN Document Server

    Su, Chin B

    2007-01-01

    A forty-four pass fibre optic surface plasmon resonance sensor that enhances detection sensitivity according to the number of passes is demonstrated for the first time. The technique employs a fibre optic recirculation loop that passes the detection spot forty- four times, thus enhancing sensitivity by a factor of forty-four. Presently, the total number of passes is limited by the onset of lasing action of the recirculation loop. This technique offers a significant sensitivity improvement for various types of plasmon resonance sensors that may be used in chemical and biomolecule detections.

  13. Conductive shield for ultra-low-field magnetic resonance imaging: Theory and measurements of eddy currents

    Science.gov (United States)

    Zevenhoven, Koos C. J.; Busch, Sarah; Hatridge, Michael; Öisjöen, Fredrik; Ilmoniemi, Risto J.; Clarke, John

    2014-03-01

    Eddy currents induced by applied magnetic-field pulses have been a common issue in ultra-low-field magnetic resonance imaging. In particular, a relatively large prepolarizing field—applied before each signal acquisition sequence to increase the signal—induces currents in the walls of the surrounding conductive shielded room. The magnetic-field transient generated by the eddy currents may cause severe image distortions and signal loss, especially with the large prepolarizing coils designed for in vivo imaging. We derive a theory of eddy currents in thin conducting structures and enclosures to provide intuitive understanding and efficient computations. We present detailed measurements of the eddy-current patterns and their time evolution in a previous-generation shielded room. The analysis led to the design and construction of a new shielded room with symmetrically placed 1.6-mm-thick aluminum sheets that were weakly coupled electrically. The currents flowing around the entire room were heavily damped, resulting in a decay time constant of about 6 ms for both the measured and computed field transients. The measured eddy-current vector maps were in excellent agreement with predictions based on the theory, suggesting that both the experimental methods and the theory were successful and could be applied to a wide variety of thin conducting structures.

  14. Conductive shield for ultra-low-field magnetic resonance imaging: Theory and measurements of eddy currents.

    Science.gov (United States)

    Zevenhoven, Koos C J; Busch, Sarah; Hatridge, Michael; Oisjöen, Fredrik; Ilmoniemi, Risto J; Clarke, John

    2014-03-14

    Eddy currents induced by applied magnetic-field pulses have been a common issue in ultra-low-field magnetic resonance imaging. In particular, a relatively large prepolarizing field-applied before each signal acquisition sequence to increase the signal-induces currents in the walls of the surrounding conductive shielded room. The magnetic-field transient generated by the eddy currents may cause severe image distortions and signal loss, especially with the large prepolarizing coils designed for in vivo imaging. We derive a theory of eddy currents in thin conducting structures and enclosures to provide intuitive understanding and efficient computations. We present detailed measurements of the eddy-current patterns and their time evolution in a previous-generation shielded room. The analysis led to the design and construction of a new shielded room with symmetrically placed 1.6-mm-thick aluminum sheets that were weakly coupled electrically. The currents flowing around the entire room were heavily damped, resulting in a decay time constant of about 6 ms for both the measured and computed field transients. The measured eddy-current vector maps were in excellent agreement with predictions based on the theory, suggesting that both the experimental methods and the theory were successful and could be applied to a wide variety of thin conducting structures.

  15. The longitudinal optical conductivity in bilayer graphene and other two-dimensional systems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.H., E-mail: chyang@nuist.edu.cn [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Ao, Z.M., E-mail: zhimin.ao@uts.edu.au [Centre for Clean Energy Technology, School of Chemistry and Forensic Science, University of Technology, Sydney ,PO Box 123, Broadway, Sydney, NSW 2007 (Australia); Wei, X.F. [West Anhui University, Luan 237012 (China); Jiang, J.J. [Department of Physics, Sanjing College, Nanjing 210012 (China)

    2015-01-15

    The longitudinal optical conductivity in bilayer graphene is calculated using the dielectric function by defining the density operator theoretically, while the effect of the broadening width determined by the scattering sources on the optical conductivity is also investigated. Some features, such as chirality, energy dispersion and density of state (DOS) in bilayer graphene, are similar to those in monolayer graphene and a traditional two-dimensional electron gas (2DEG). Therefore, in this paper, the bilayer graphene optical conductivity is compared with the results in these two systems. The analytical and numerical results show that the optical conductivity per graphene layer is almost a constant and close to e{sup 2}/(4ℏ), which agrees with the experimental results.

  16. Interpretation of anomalous normal state optical conductivity of K3C60 fullerides

    Indian Academy of Sciences (India)

    K K Choudhary

    2013-02-01

    The observed frequency dependent optical response of alkali–metal-doped fulleride superconductors (c ≈ 19 K) has been theoretically analysed. The calculations of the optical conductivity, (), have been made within the two-component schemes: one is the coherent Drude carriers (electrons) responsible for superconductivity and the other is incoherent motion of carriers from one atom to other atom of C60 molecule to a pairing between Drude carriers. The approach accounts for the anomalies reported (frequency dependence of optical conductivity) in the optical measurements for the normal state. The model has only one free parameter, the relaxation rate. The frequency dependent relaxation rates are expressed in terms of memory functions. The coherent Drude carriers form a sharp peak at zero frequency and a long tail at higher frequencies, i.e. in the infrared region. However, the hopping of carriers from one atom to the other (incoherent motion of doped electrons) yields a peak value in the optical conductivity centred at mid-infrared region. It is found that both the Drude and hopping carriers will contribute to the optical process of conduction in the K3C60 and shows similar results on optical conductivity in the mid-infrared as well as infrared frequency regions as those revealed from experiments.

  17. Dynamics of all-optically switched micropillar resonances

    CERN Document Server

    Thyrrestrup, Henri; Ctistis, Georgios; Claudon, Julien; Vos, Willem L

    2014-01-01

    Here we do frequency and time resolved switching of a single GaAs/AlGa micropillar cavity with a pillar diameter of 6 mu using a ultrafast pump-probe setup. The switching is achieved by two-photon excitation of free carriers by an femtosecond pump pulse. We observe a simultaneously frequency shift of the first two transverse micropillar modes and obtain high resolution frequency traces of the two resonances in time. A difference in the the maximum switching magnitude of 12% point is caused by spatial inhomogeneous excitation of carriers in the pillar. The relaxation dynamic of the two resonances show a strongly non-exponential decay. We interpret the non-exponential dynamics in term of a second order decay model for the spontaneous recombination of electron and hole for the free carriers and a slow free carrier trapping time of ~300 ps.

  18. All-optical tunable microfiber knot resonator with graphene-assisted sandwich structure.

    Science.gov (United States)

    Meng, Yinghao; Deng, Lin; Liu, Zilong; Xiao, Huifu; Guo, Xiaonan; Liao, Miaomiao; Guo, Anqi; Ying, Tonghe; Tian, Yonghui

    2017-07-24

    We demonstrate an all-optical tunable microfiber knot resonator (MFKR) by direct light-graphene interaction using external vertical incidence pump laser. The 1530 nm CW pump source is employed to irradiate the sample, which can achieve the performance modulation of MFKR including transmission loss, extinction ratio, and resonant wavelength by the saturable absorption, photo-thermal, and optical Kerr effects, respectively. Compared with the MFKR with only the bottom graphene film, the tunable ranges of transmission loss and extinction ratio are increased by 69 and 125 times, respectively, which can induce a remarkable amplitude tuning. The resonant wavelength of MFKR occurs a red-shift under the irradiation of the pump light, and the red-shift range can exceed one free spectral range (FSR), which means the resonant wavelength could be tuned in the full wavelength range of the transparent window of optical fiber. It is promising for the device to be applied as an all-optical modulator, tunable optical filter, etc.

  19. Vertically-coupled Whispering Gallery Mode Resonator Optical Waveguide, and Methods

    Science.gov (United States)

    Matsko, Andrey B. (Inventor); Savchenkov, Anatolly A. (Inventor); Matleki, Lute (Inventor)

    2007-01-01

    A vertically-coupled whispering gallery mode (WGM) resonator optical waveguide, a method of reducing a group velocity of light, and a method of making a waveguide are provided. The vertically-coupled WGM waveguide comprises a cylindrical rod portion having a round cross-section and an outer surface. First and second ring-shaped resonators are formed on the outer surface of the cylindrical rod portion and are spaced from each other along a longitudinal direction of the cylindrical rod. The first and second ringshaped resonators are capable of being coupled to each other by way an evanescent field formed in an interior of the cylindrical rod portion.

  20. All-optical 10 Gb/s AND logic gate in a silicon microring resonator

    DEFF Research Database (Denmark)

    Xiong, Meng; Lei, Lei; Ding, Yunhong

    2013-01-01

    An all-optical AND logic gate in a single silicon microring resonator is experimentally demonstrated at 10 Gb/s with 50% RZ-OOK signals. By setting the wavelengths of two intensity-modulated input pumps on the resonances of the microring resonator, field-enhanced four-wave mixing with a total inp...... power of only 8.5 dBm takes place in the ring, resulting in the generation of an idler whose intensity follows the logic operation between the pumps. Clear and open eye diagrams with a bit-error- ratio below 10−9 are achieved....

  1. A relation between electromagnetically induced absorption resonances and nonlinear magneto-optics in Lambda-systems

    CERN Document Server

    Budker, D

    2003-01-01

    Recent work on Lambda-resonances in alkali metal vapors (E. Mikhailov, I. Novikova, Yu. V. Rostovtsev, and G. R. Welch, quant-ph/0309171, and references therein) has revealed a novel type of electromagnetically induced absorption resonance that occurs in three-level systems under specific conditions normally associated with electromagnetically induced transparency. In this note, we show that these resonances have a direct analog in nonlinear magneto-optics, and support this conclusion with a calculation for a J=1->J'=0 system interacting with a single nearly circularly polarized light field in the presence of a weak longitudinal magnetic field.

  2. Mechanical control of a microrod-resonator optical frequency comb

    CERN Document Server

    Papp, Scott B; Diddams, Scott A

    2012-01-01

    Robust control and stabilization of optical frequency combs enables an extraordinary range of scientific and technological applications, including frequency metrology at extreme levels of precision, novel spectroscopy of quantum gases and of molecules from visible wavelengths to the far infrared, searches for exoplanets, and photonic waveform synthesis. Here we report on the stabilization of a microresonator-based optical comb (microcomb) by way of mechanical actuation. This represents an important step in the development of microcomb technology, which offers a pathway toward fully-integrated comb systems. Residual fluctuations of our 32.6 GHz microcomb line spacing reach a record stability level of $5\\times10^{-15}$ for 1 s averaging, thereby highlighting the potential of microcombs to support modern optical frequency standards. Furthermore, measurements of the line spacing with respect to an independent frequency reference reveal the effective stabilization of different spectral slices of the comb with a $&...

  3. Atomic-Scale Confinement of Resonant Optical Fields

    Science.gov (United States)

    Kern, Johannes; Großmann, Swen; Tarakina, Nadezda V.; Häckel, Tim; Emmerling, Monika; Kamp, Martin; Huang, Jer-Shing; Biagioni, Paolo; Prangsma, Jord C.; Hecht, Bert

    2012-11-01

    In the presence of matter there is no fundamental limit preventing confinement of visible light even down to atomic scales. Achieving such confinement and the corresponding intensity enhancement inevitably requires simultaneous control over atomic-scale details of material structures and over the optical modes that such structures support. By means of self-assembly we have obtained side-by-side aligned gold nanorod dimers with robust atomically-defined gaps reaching below 0.5 nm. The existence of atomically-confined light fields in these gaps is demonstrated by observing extreme Coulomb splitting of corresponding symmetric and anti-symmetric dimer eigenmodes of more than 800 meV in white-light scattering experiments. Our results open new perspectives for atomically-resolved spectroscopic imaging, deeply nonlinear optics, ultra-sensing, cavity optomechanics as well as for the realization of novel quantum-optical devices.

  4. Rb optical resonance inside a random porous medium

    CERN Document Server

    Villalba, S; Laliotis, A; Lenci, L; Barreiro, S; Lezama, A

    2012-01-01

    We studied absorption and fluorescence of Rb atoms confined to the interstitial cavities of a random porous glass. Due to the diffusive light propagation in the porous sample, resonant light absorption is almost entirely compensated by atomic fluorescence at low atomic densities. For higher densities, radiation trapping increases the probability of non-radiative decay via atom-wall collisions. A simple connection of the fluorescence/absorption yield to the sample porosity is given.

  5. Eigenmodes of misaligned unstable optical resonators with circular mirrors.

    Science.gov (United States)

    Bowers, M S

    1992-03-20

    It is shown numerically that the diffractive transverse (Fox-Li) eigenmodes supported by an unstable cavity with tilted end mirrors can be computed by expanding these modes in terms of the fully aligned (aberration-free) eigenmodes of the same cavity. Circular mirror resonators are considered in which the aligned cavity eigenmodes can be decomposed into different azimuthal components. The biorthogonality property of the aligned cavity eigenmodes is used to obtain the coefficients in the modal expansion of the misaligned modes. Results are given for two different resonators: a conventional hard-edge unstable cavity with a small tilt of the output coupler and one that uses a graded reflectivity output mirror with a small tilt of the primary mirror. It is shown that the series expansion of the misaligned modes in terms of the aligned modes converges, and the converged eigenvalues are virtually identical to those computed by using the Prony method. Symmetry considerations and other new insights into the effects of a mirror tilt on the modes of a resonator are also discussed.

  6. Integrated optical gyroscope using active long-range surface plasmon-polariton waveguide resonator.

    Science.gov (United States)

    Zhang, Tong; Qian, Guang; Wang, Yang-Yang; Xue, Xiao-Jun; Shan, Feng; Li, Ruo-Zhou; Wu, Jing-Yuan; Zhang, Xiao-Yang

    2014-01-24

    Optical gyroscopes with high sensitivity are important rotation sensors for inertial navigation systems. Here, we present the concept of integrated resonant optical gyroscope constructed by active long-range surface plasmon-polariton (LRSPP) waveguide resonator. In this gyroscope, LRSPP waveguide doped gain medium is pumped to compensate the propagation loss, which has lower pump noise than that of conventional optical waveguide. Peculiar properties of single-polarization of LRSPP waveguide have been found to significantly reduce the polarization error. The metal layer of LRSPP waveguide is electro-optical multiplexed for suppression of reciprocal noises. It shows a limited sensitivity of ~10(-4) deg/h, and a maximum zero drift which is 4 orders of magnitude lower than that constructed by conventional single-mode waveguide.

  7. Reconfigurable electro-optical directed-logic circuit using carrier-depletion micro-ring resonators.

    Science.gov (United States)

    Qiu, Ciyuan; Gao, Weilu; Soref, Richard; Robinson, Jacob T; Xu, Qianfan

    2014-12-15

    Here we demonstrate a reconfigurable electro-optical directed-logic circuit based on a regular array of integrated optical switches. Each 1×1 optical switch consists of a micro-ring resonator with an embedded lateral p-n junction and a micro-heater. We achieve high-speed on-off switching by applying electrical logic signals to the p-n junction. We can configure the operation mode of each switch by thermal tuning the resonance wavelength. The result is an integrated optical circuit that can be reconfigured to perform any combinational logic operation. As a proof-of-principle, we fabricated a multi-spectral directed-logic circuit based on a fourfold array of switches and showed that this circuit can be reconfigured to perform arbitrary two-input logic functions with speeds up to 3  GB/s.

  8. Vertical optical ring resonators fully integrated with nanophotonic waveguides on silicon-on-insulator substrates

    CERN Document Server

    Madani, Abbas; Stolarek, David; Zimmermann, Lars; Ma, Libo; Schmidt, Oliver G

    2015-01-01

    We demonstrate full integration of vertical optical ring resonators with silicon nanophotonic waveguides on silicon-on-insulator substrates to accomplish a significant step towards 3D photonic integration. The on-chip integration is realized by rolling up 2D differentially strained TiO2 nanomembranes into 3D microtube cavities on a nanophotonic microchip. The integration configuration allows for out of plane optical coupling between the in-plane nanowaveguides and the vertical microtube cavities as a compact and mechanically stable optical unit, which could enable refined vertical light transfer in 3D stacks of multiple photonic layers. In this vertical transmission scheme, resonant filtering of optical signals at telecommunication wavelengths is demonstrated based on subwavelength thick walled microcavities. Moreover, an array of microtube cavities is prepared and each microtube cavity is integrated with multiple waveguides which opens up interesting perspectives towards parallel and multi-routing through a ...

  9. Tunable Fano resonance and magneto-optical response in magnetoplasmonic structure fabricated by pure ferromagnetic metals

    Science.gov (United States)

    Chen, Leyi; Gao, Jinlong; Xia, Wenbin; Zhang, Shaoyin; Tang, Shaolong; Zhang, Weiyi; Li, Daoyong; Wu, Xiaoshan; Du, Youwei

    2016-06-01

    The developments in nanophotonics demand more efficient and delicate control of light. It has recently been proposed to achieve this goal by combining plasmonics and magneto-optics in so-called magnetoplasmonic nanostructures. However, significant challenges still remain because of the difficulty in the design of spectrally tunable systems exhibiting novel plasmonic and magneto-optical responses simultaneously. Here we report a magnetoplasmonic structure which consists of a two-dimensional nickel nanodisk array on top of a cobalt film substrate. We demonstrate that a tunable Fano resonance can be generated in this system with properly designed geometric parameters. Furthermore, the magneto-optical Kerr responses in this system can be manipulated due to the concerted actions of free electrons in the resonance. Our results reveal the possibility of fabricating large-area magnetoplasmonic structures by a simple, mass-producible method, and tuning the plasmonic and magneto-optical responses simultaneously.

  10. Monolayer graphene as dissipative membrane in an optical resonator

    CERN Document Server

    Meyer, Hendrik M; Köhl, Michael

    2016-01-01

    We experimentally demonstrate coupling of an atomically thin, free-standing graphene membrane to an optical cavity. By changing the position of the membrane along the standing-wave field of the cavity we tailor the dissipative coupling between the membrane and the cavity, and we show that the dissipative coupling can outweigh the dispersive coupling. Such a system, for which controlled dissipation prevails dispersion, will prove useful for novel laser-cooling schemes in optomechanics. In addition, we have determined the continuous-wave optical damage threshold of free-standing monolayer graphene of 1.8(4)~MW/cm$^2$ at 780nm.

  11. Monolayer graphene as dissipative membrane in an optical resonator

    Science.gov (United States)

    Meyer, Hendrik M.; Breyer, Moritz; Köhl, Michael

    2016-12-01

    We experimentally demonstrate coupling of an atomically thin, free-standing graphene membrane to an optical cavity. By changing the position of the membrane along the standing-wave field of the cavity, we tailor the dissipative coupling between the membrane and the cavity, and we show that the dissipative coupling can outweigh the dispersive coupling. Such a system, for which controlled dissipation prevails dispersion, will prove useful for novel laser-cooling schemes in optomechanics. In addition, we have determined the continuous-wave optical damage threshold of free-standing monolayer graphene of 1.8(4) MW/cm^2 at 780 nm.

  12. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance

    Science.gov (United States)

    Moritake, Y.; Kanamori, Y.; Hane, K.

    2016-09-01

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers.

  13. Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance.

    Science.gov (United States)

    Moritake, Y; Kanamori, Y; Hane, K

    2016-09-13

    We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers.

  14. Optical Switching in Silicon Nanowaveguide Ring Resonators Based on Kerr Effect and TPA Effect

    Institute of Scientific and Technical Information of China (English)

    LI Chun-Fei; DOU Na

    2009-01-01

    We analyze theoretically the 1 × 2 low-power all-optical switching in silicon nanowaveguide ring resonators (RR) based on the Kerr effect and two-photon absorption (TPA), and give a comparison between both the all-optical switches. The calculation shows that the switching power of the TPA-RR switch is 3 orders smaller than that of the Kerr-RR switch. The switching time for both the switches is about 100ps.

  15. Improving Acousto-Optical Interaction by Mechanical Resonators on a Surface

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    The finite element method is employed to model surface acoustic waves generated by high aspect ratio electrodes and their interaction with an optical wave in a waveguide. With a periodic model it is first shown that these electrodes act as a mechanical resonator, which introduces several confined...... types of surface acoustic waves compared to using a conventional interdigital transducer with thin electrodes. Thus, this indicates a way to improve acousto-optical interaction for integrated modulators....

  16. Optical trapping via guided resonance modes in a Slot-Suzuki-phase photonic crystal lattice.

    Science.gov (United States)

    Ma, Jing; Martínez, Luis Javier; Povinelli, Michelle L

    2012-03-12

    A novel photonic crystal lattice is proposed for trapping a two-dimensional array of particles. The lattice is created by introducing a rectangular slot in each unit cell of the Suzuki-Phase lattice to enhance the light confinement of guided resonance modes. Large quality factors on the order of 10⁵ are predicted in the lattice. A significant decrease of the optical power required for optical trapping can be achieved compared to our previous design.

  17. Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

    KAUST Repository

    Li, Yuan

    2014-12-03

    We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply bandlike transport.

  18. Mechanism of resonant perfect optical absorption in dielectric film supporting metallic grating structures.

    Science.gov (United States)

    Chen, Xiumei; Yan, Xiaopeng; Li, Ping; Mou, Yongni; Wang, Wenqiang; Guan, Zhiqiang; Xu, Hongxing

    2016-08-22

    The mechanism of resonant perfect optical absorbers is quantitatively revealed by the coupled mode method for the air/grating/dielectric film/air four region system. The sufficient and necessary conditions of the perfect optical absorption are derived from the interface scattering coefficients analyses. The coupling of the Fabry-Perot modes in the grating slits and non-zero order quasi waveguide modes in the dielectric film play a key role for the perfect optical absorption when the light is incident from the grating side. The analytical sufficient and necessary conditions of the perfect optical absorption provide an efficient tool towards geometry design for the perfect optical absorption at the specific wavelengths. The advantages of a widely tunable perfect optical absorption wavelength, a high Q factor and the confined energy loss on metal surfaces make the air/grating/film/air structures promising for applications in sensing, modulation and detection.

  19. Static conductivity imaging using variational gradient Bz algorithm in magnetic resonance electrical impedance tomography.

    Science.gov (United States)

    Park, Chunjae; Park, Eun-Jae; Woo, Eung Je; Kwon, Ohin; Seo, Jin Keun

    2004-02-01

    A new image reconstruction algorithm is proposed to visualize static conductivity images of a subject in magnetic resonance electrical impedance tomography (MREIT). Injecting electrical current into the subject through surface electrodes, we can measure the induced internal magnetic flux density B = (Bx, By, Bz) using an MRI scanner. In this paper, we assume that only the z-component Bz is measurable due to a practical limitation of the measurement technique in MREIT. Under this circumstance, a constructive MREIT imaging technique called the harmonic Bz algorithm was recently developed to produce high-resolution conductivity images. The algorithm is based on the relation between inverted delta2Bz and the conductivity requiring the computation of inverted delta2Bz. Since twice differentiations of noisy Bz data tend to amplify the noise, the performance of the harmonic Bz algorithm is deteriorated when the signal-to-noise ratio in measured Bz data is not high enough. Therefore, it is highly desirable to develop a new algorithm reducing the number of differentiations. In this work, we propose the variational gradient Bz algorithm where Bz is differentiated only once. Numerical simulations with added random noise confirmed its ability to reconstruct static conductivity images in MREIT. We also found that it outperforms the harmonic Bz algorithm in terms of noise tolerance. From a careful analysis of the performance of the variational gradient Bz algorithm, we suggest several methods to further improve the image quality including a better choice of basis functions, regularization technique and multilevel approach. The proposed variational framework utilizing only Bz will lead to different versions of improved algorithms.

  20. Plasmon resonance enhanced optical transmission and magneto-optical Faraday effects in nanohole arrays blocked by metal antenna

    Science.gov (United States)

    Lei, Chengxin; Tang, Zhixiong; Wang, Sihao; Li, Daoyong; Chen, Leyi; Tang, Shaolong; Du, Youwei

    2017-07-01

    The properties of the optical and magneto-optical effects of an improved plasmonic nanohole arrays blocked by gold mushroom caps are investigated by using the finite difference time domain (FDTD) method. It is most noteworthy that the strongly enhanced Faraday rotation along with high transmittance has been achieved simultaneously by optimizing the parameters of nanostructure in a broad spectrum spanning visible to near-infrared frequencies, which is very important in practical application for designing novel optical and magneto-optical devices. In our designed structure, we obtained two extraordinary optical transmission (EOT) resonant peaks along with enhanced Faraday rotation and two peaks of the figure of merit (FOM). By optimizing the geometrical parameters of the structure, we can obtain an almost 10-fold enhancement of Faraday rotation with a corresponding transmittance 50%, and the FOM of 0.752 at the same wavelength. As expected, the optical and magneto-optical effects sensitively depends on the geometrical parameters of our structure, which can be simply tailored by the height of pillar, the diameter of mushroom cap, and the period of the structure, and so on. The physical mechanism of these physical phenomena in the paper has been explained in detail. These research findings are of great theoretical significance in developing the novel magneto-optical devices in the future.

  1. Role of PbO in EPR, optical properties and DC conductivity of vanadyl-doped alkali lead borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Gahlot, P.S. [Department of Physics, Maharshi Dayanand University, Rohtak 124001 (India); Seth, V.P. [Department of Physics, Maharshi Dayanand University, Rohtak 124001 (India); Agarwal, A. [Department of Applied Physics, Guru Jambheshwar University, Hisar 25001 (India)]. E-mail: aagju@yahoo.com; Sanghi, S. [Department of Applied Physics, Guru Jambheshwar University, Hisar 25001 (India); Chand, P. [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Goyal, D.R. [Department of Physics, Maharshi Dayanand University, Rohtak 124001 (India)

    2005-01-31

    Glasses with composition xM{sub 2}O (0.30-x) PbO 0.70 B{sub 2}O{sub 3} (M=Li, K) containing 2.0mol% of V{sub 2}O{sub 5} have been prepared in the range 0.00=resonance (EPR), optical properties and DC conductivity of these glasses have been studied. Spin Hamiltonian parameters (SHPs), dipolar hyperfine parameter, P and Fermi contact interaction parameter, K and molecular orbital coefficients ({alpha}2 and {gamma}2) have been calculated. In these glasses there is an increase in the tetragonality of the V{sup 4+}O{sub 6} complex and the 3dxy orbit expands with an increase in the M{sub 2}O:PbO ratio. Values of the theoretical optical basicity, {lambda}{sub th}, have also been reported. Optical band gap increases with decrease in PbO content. For x>0.02, the DC conductivity of these glasses increases and activation energy decreases.

  2. Plasmon resonance optical tuning based on photosensitive composite structures

    DEFF Research Database (Denmark)

    Gilardi, Giovanni; Xiao, Sanshui; Mortensen, N. Asger

    2014-01-01

    This paper reports a numerical investigation of a periodic metallic structure sandwiched between two quartz plates. The volume comprised between the quartz plates and the metallic structure is infiltrated by a mixture of azo-dye-doped liquid crystal. The exposure to a low power visible light beam...... modifies the azo dye molecular configuration, thus allowing the wavelength shift of the resonance of the system. The wavelength shift depends on the geometry of the periodic structure and it also depends on the intensity of the visible light beam....

  3. Optically tunable Fano resonance in a grating-based Fabry-Perot cavity-coupled microring resonator on a silicon chip.

    Science.gov (United States)

    Zhang, Weifeng; Li, Wangzhe; Yao, Jianping

    2016-06-01

    A grating-based Fabry-Perot (FP) cavity-coupled microring resonator on a silicon chip is reported to demonstrate an all-optically tunable Fano resonance. In the device, an add-drop microring resonator (MRR) is employed, and one of the two bus waveguides is replaced by an FP cavity consisting of two sidewall Bragg gratings. By choosing the parameters of the gratings, the resonant mode of the FP cavity is coupled to one of the resonant modes of the MRR. Due to the coupling between the resonant modes, a Fano resonance with an asymmetric line shape resulted. Measurement results show a Fano resonance with an extinction ratio of 22.54 dB, and a slope rate of 250.4 dB/nm is achieved. A further study of the effect of the coupling on the Fano resonance is performed numerically and experimentally. Thanks to the strong light-confinement capacity of the MRR and the FP cavity, a strong two-photon absorption induced nonlinear thermal-optic effect resulted, which is used to tune the Fano resonance optically.

  4. Drude Weight,Optical Conductivity of Two-Dimensional Hubbard Model at Half Filling

    Institute of Scientific and Technical Information of China (English)

    XU Lei; ZHANG Jun

    2008-01-01

    We study the Drude weight D and optical conductivity of the two-dimensional (2D) Hubbard model at half filling with staggered magnetic flux (SMF).When SMF being introduced,the hopping integrals are modulated by the magnetic flux.The optical sum rule,which is related to the mean kinetic energy of band electrons,is evaluated for this 2D Hubbard Hamiltonian.Our present result gives the dependence of the kinetic energy,D and the optical conductivity on SMF and U.At half filling D vanishes exponentially with system size.We also find in the frequency dependence of the optical conductivity,there is &function peak at ω≈2|m|U and the incoherent excitations begin to present themselves extended to a higher energy region.

  5. Stochastic Pulse Switching in a Degenerate Resonant Optical Medium

    CERN Document Server

    Atkins, Ethan P; Kovacic, Gregor; Gabitov, Ildar R

    2012-01-01

    Using the idealized integrable Maxwell-Bloch model, we describe random optical-pulse polarization switching along an active optical medium in the Lambda-configuration with disordered occupation numbers of its lower energy sub-level pair. The description combines complete integrability and stochastic dynamics. For the single-soliton pulse, we derive the statistics of the electric-field polarization ellipse at a given point along the medium in closed form. If the average initial population difference of the two lower sub-levels vanishes, we show that the pulse polarization will switch intermittently between the two circular polarizations as it travels along the medium. If this difference does not vanish, the pulse will eventually forever remain in the circular polarization determined by which sub-level is more occupied on average. We also derive the exact expressions for the statistics of the polarization-switching dynamics, such as the probability distribution of the distance between two consecutive switches a...

  6. Traumatic transection of the optic chiasm: Magnetic resonance evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R.; Goyal, M.; Sharma, A.; Dada, V.K.; Berry, M. [All India Institute of Medical Sciences, New Delhi (India). Departments of Radiodiagnosis and Ophthalmology

    1998-02-01

    Disruption of the optic chiasm is a rare complication of head trauma. Non-contrast Computed tomography of the head showed basi-frontal contusion but no evidence of haematoma. We present the findings on MRI of this entity in a 40-year-old patient presenting with bitemporal hemianopia. Complete chismal transection was confirmed on T1-weighted axial, coronal and sagittal images. Copyright (1998) Blackwell Science Pty Ltd 10 refs., 1 fig.

  7. Double-way spectral tunability for the control of optical nanocavity resonance.

    Science.gov (United States)

    Baida, Fadi I; Grosjean, Thierry

    2015-12-08

    Scanning Near-field Optical Microscopy (SNOM) has been successful in finely tuning the optical properties of photonic crystal (PC) nanocavities. The SNOM nanoprobes proposed so far allowed for either redshifting or blueshifting the resonance peak of the PC structures. In this paper, we theoretically demonstrate the possibility of a redshifting (up to +0.65 nm) and a blueshifting (up to -5 nm) the PC cavity resonance wavelength with a single perturbation element. As an example, a fiber bowtie-aperture nano-antenna (BNA) engraved at the apex of a SNOM tip is proposed to play this role. The double-way tunability is the result of a competition between an induced electric dipole (BNA at resonance) leading to a redshift and an induced magnetic dipole (the tip metalcoating) giving rise to a blueshift of the resonance wavelength. We demonstrate that the sign of the spectral shift can be simply controlled through the tip-to-cavity distance. This study opens the way to the full postproduction control of the resonance wavelength of high quality-factor optical cavities.

  8. Linear all-optical signal processing using silicon micro-ring resonators

    DEFF Research Database (Denmark)

    Ding, Yunhong; Ou, Haiyan; Xu, Jing

    2016-01-01

    Silicon micro-ring resonators (MRRs) are compact and versatile devices whose periodic frequency response can be exploited for a wide range of applications. In this paper, we review our recent work on linear all-optical signal processing applications using silicon MRRs as passive filters. We focus...

  9. Electro-Optical Multichannel Spectrometer for Transient Resonance Raman and Absorption Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Karina Benthin; Wilbrandt, Robert Walter; Pagsberg, Palle Bjørn

    1979-01-01

    An optical multichannel system is described, used for time‐dependent absorption measurements in the gas phase and the liquid phase and for resonance Raman spectroscopy of short‐lived transient species in the liquid phase in pulse radiolysis. It consists of either an image converter streak unit or...

  10. Normalization of quasinormal modes in leaky optical cavities and plasmonic resonators

    CERN Document Server

    Kristensen, Philip Trøst; Hughes, Stephen

    2015-01-01

    We discuss three formally different formulas for normalization of quasinormal modes currently in use for modeling optical cavities and plasmonic resonators and show that they are complementary and provide the same result. Regardless of the formula used for normalization, one can use the norm to define an effective mode volume for use in Purcell factor calculations.

  11. Ultra-pure RF tone from a micro-ring resonator based optical frequency comb source

    CERN Document Server

    Pasquazi, Alessia; Little, Brent E; Chu, Sai T; Moss, David J; Morandotti, Roberto

    2014-01-01

    We demonstrate a novel mode locked ultrafast laser, based on an integrated high-Q micr-oring resonator. Our scheme exhibits stable operation of two slightly shifted spectral optical comb replicas. It generates a highly monochromatic radiofrequency modulation of 60MHz on a 200GHz output pulse train, with a linewidth < 10kHz

  12. Protein detection on biotin-derivatized polyallylamine by optical microring resonators

    NARCIS (Netherlands)

    Ullien, D.; Harmsma, P.J.; Abdulla, S.M.C.; De Boer, B.M.; Bosma, D.; Sudhölter, E.J.R.; De Smet, L.C.P.M.; Jager, W.F.

    2014-01-01

    Silicon optical microring resonators (MRRs) are sensitive devices that can be used for biosensing. We present a novel biosensing platform based on the application of polyelectrolyte (PE) layers on such MRRs. The top PE layer was covalently labeled with biotin to ensure binding sites for antibodies v

  13. HLA typing in acute optic neuritis. Relation to multiple sclerosis and magnetic resonance imaging findings

    DEFF Research Database (Denmark)

    Frederiksen, J.L.; Madsen, H.O.; Ryder, L.P.

    1997-01-01

    OBJECTIVE: To study the association of brain magnetic resonance imaging (MRI) findings and HLA findings to clarify the relationship between monosymptomatic optic neuritis (ON) and ON as part of clinically definite multiple sclerosis (CDMS). DESIGN: Population-based cohort of patients with ON refe...

  14. Calculation of optical absorption and resonance Raman correlators using time-dependent recursion relationships

    DEFF Research Database (Denmark)

    Svendsen, Christian; Mortensen, O. Sonnich; Henriksen, Niels Engholm

    1996-01-01

    Time-dependent recursion relationships are derived for optical absorption and resonance Raman correlators in the multidimensional harmonic case using a second-quantization formalism. Furthermore, a procedure is given for the calculation of correlators involving a general analytic coordinate depen...... dependence of the transition dipole moment....

  15. Design of a ring resonator-based optical beam forming network for phased array receive antennas

    NARCIS (Netherlands)

    Klooster, van 't J.W.; Roeloffzen, C.G.H.; Meijerink, A.; Zhuang, L.; Marpaung, D.A.I.; Etten, van W.C.; Heideman, R.G.; Leinse, A.; Schippers, H.; Verpoorte, J.; Wintels, M.

    2008-01-01

    A novel squint-free ring resonator-based optical beam forming network (OBFN) for phased array antennas (PAA) is proposed. It is intended to provide broadband connectivity to airborne platforms via geostationary satellites. In this paper, we present the design of the OBFN and its control system. Our

  16. Optimization of an integrated-optical ring-resonator slow-light-based sensor

    NARCIS (Netherlands)

    Uranus, H.P.; Hoekman, M.; Dijkstra, M.; Hoekstra, H.J.W.M.; stoffer, R.

    2008-01-01

    A 3-D, vectorial, and multimodal model that incorporates realistic losses was developed to study the performance of Si3N4 based integrated-optical ring-resonator slow-light-based refractometric sensor. Efficient optimization of the coupler gap and tolerance analysis were also performed using the mod

  17. Folded Fabry-Perot quasi-optical ring resonator diplexer Theory and experiment

    Science.gov (United States)

    Pickett, H. M.; Chiou, A. E. T.

    1983-01-01

    Performance of folded Fabry-Perot quasi-optical ring resonator diplexers with different geometries of reflecting surfaces is investigated both theoretically and experimentally. Design of optimum surface geometry for minimum diffraction, together with the figure of merit indicating improvement in performance, are given.

  18. Modeling of mode-locked coupled-resonator optical waveguide lasers

    DEFF Research Database (Denmark)

    Agger, Christian; Skovgård, Troels Suhr; Gregersen, Niels;

    2010-01-01

    Coupled-resonator optical waveguides made from coupled high-Q photonic crystal nanocavities are investigated for use as cavities in mode-locked lasers. Such devices show great potential in slowing down light and can serve to reduce the cavity length of a mode-locked laser. An explicit expression...

  19. Tunable surface plasmon resonance and enhanced electrical conductivity of In doped ZnO colloidal nanocrystals

    Science.gov (United States)

    Ghosh, Sirshendu; Saha, Manas; de, S. K.

    2014-05-01

    We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The dopant induced shape evolution changes the hexagonal pyramid structured ZnO to a platelet like structure upon 8% In doping. The introduction of trivalent In3+ into the ZnO lattice and consequent substitution of divalent Zn2+ generates free electrons in the conduction band which produces a plasmonic resonance in the infrared region. The electron concentration controls plasmon frequency as well as the band gap of host ZnO. The variation of the band gap and the modification of the conduction band have been explained by the Burstein-Moss effect and Mie's theory respectively. The In dopant changes the defect chemistry of pure ZnO nanocrystals which has been studied by photoluminescence and other spectroscopic measurements. The nanocrystals are highly stable in the organic medium and can be deposited as a crack free thin film on different substrates. Careful ligand exchange and thermal annealing of the spin cast film lead to a good conductive film (720 Ω per square to 120 Ω per square) with stable inherent plasmonic absorption in the infrared and 90% transmittance in the visible region. A temperature induced metal-semiconductor transition was found for doped ZnO nanocrystals. The transition temperature shifts to a lower temperature with increase of the doping concentration.We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The

  20. Picosecond all-optical switching in hydrogenated amorphous silicon microring resonators

    CERN Document Server

    Pelc, Jason S; Vo, Sonny; Santori, Charles; Fattal, David A; Beausoleil, Raymond G

    2014-01-01

    We utilize cross-phase modulation to observe all-optical switching in microring resonators fabricated with hydrogenated amorphous silicon (a-Si:H). Using 2.7-ps pulses from a mode-locked fiber laser in the telecom C-band, we observe optical switching of a cw telecom-band probe with full-width at half-maximum switching times of 14.8 ps, using approximately 720 fJ of energy deposited in the microring. In comparison with telecom-band optical switching in crystalline silicon microrings, a-Si:H exhibits substantially higher switching speeds due to reduced impact of free-carrier processes.

  1. Low-Threshold Optical Parametric Oscillations in a Whispering Gallery Mode Resonator

    DEFF Research Database (Denmark)

    Fürst, J. U.; Strekalov, D. V.; Elser, D.;

    2010-01-01

    efficient optical frequency conversion. Our analysis of the phase-matching conditions for optical parametric down-conversion (PDC) in a spherical WGM resonator shows their direct relation to the sum rules for photons' angular momenta and predicts a very low parametric oscillation threshold. We realized...... such an optical parametric oscillator (OPO) based on naturally phase-matched PDC in lithium niobate. We demonstrated a single-mode, strongly nondegenerate OPO with a threshold of 6.7  μW and linewidth under 10 MHz. This work demonstrates the remarkable capabilities of WGM-based OPOs....

  2. Optically detected magnetic resonance study of a type-II GaAs/AlAs multiple quantum well

    Science.gov (United States)

    van Kesteren, H. W.; Cosman, E. C.; Greidanus, F. J. A. M.; Dawson, P.; Moore, K. J.; Foxon, C. T.

    1988-07-01

    In a type-II GaAs/AlAs multiple quantum well three optically detected magnetic resonance lines and two level anticrossings were observed. Two of the resonance lines and the two level anticrossings are in agreement with the electronic level scheme of the heavy-hole exciton. The third resonance line is in accordance with a magnetic spin resonance of an unbound electron. These optically detected magnetic resonance measurements open up the possibility to obtain detailed information about the excitons in and the band structure of type-II quantum wells.

  3. 2D aquifer characterization and improved prediction of hydraulic conductivity using surface Nuclear Magnetic Resonance

    Science.gov (United States)

    Dlugosch, Raphael; Günther, Thomas; Müller-Petke, Mike; Yaramanci, Ugur

    2014-05-01

    We present recent studies on the characterization of shallow aquifers using Nuclear Magnetic Resonance (NMR). NMR can help to gather detailed information about the water content and pore size related NMR relaxation time, of porous and water saturated material. The field application of surface NMR uses large wire loops placed at the surface of the Earth allows imaging the subsurface down to around hundred meters. First, a sophisticated inversion scheme is presented to simultaneously determine the two-dimensional (2D) distribution of the water content and the NMR relaxation time (T2*) in the subsurface from a surface NMR survey. The outstanding features of the new inversion scheme are its robustness to noisy data and the potential to distinguish aquifers of different lithology due to their specific NMR relaxation time. The successful application of the inversion scheme is demonstrated on two field cases both characterized by channel structures in the glacial sediments of Northern Germany. Second, we revise the prediction of hydraulic conductivity from NMR measurements for coarse-grained and unconsolidated sediments, commonly found in shallow aquifers. The presented Kozeny-Godefroy model replaces the empirical factors in known relations with physical, structural, and intrinsic NMR parameters. It additionally accounts for bulk water relaxation and is not limited to fast diffusion conditions. This improves the prediction of the hydraulic conductivity for clay-free sediments with grain sizes larger than medium sand. The model is validated by laboratory measurements on glass beads and sand samples. Combining the new inversion scheme and petrophysical model allows 2D imaging of the hydraulic conductivity in the subsurface from a surface NMR survey.

  4. Conductivity and current density image reconstruction using harmonic Bz algorithm in magnetic resonance electrical impedance tomography.

    Science.gov (United States)

    Oh, Suk Hoon; Lee, Byung Il; Woo, Eung Je; Lee, Soo Yeol; Cho, Min Hyoung; Kwon, Ohin; Seo, Jin Keun

    2003-10-07

    Magnetic resonance electrical impedance tomography (MREIT) is to provide cross-sectional images of the conductivity distribution sigma of a subject. While injecting current into the subject, we measure one component Bz of the induced magnetic flux density B = (Bx, By, Bz) using an MRI scanner. Based on the relation between (inverted delta)2 Bz and inverted delta sigma, the harmonic Bz algorithm reconstructs an image of sigma using the measured Bz data from multiple imaging slices. After we obtain sigma, we can reconstruct images of current density distributions for any given current injection method. Following the description of the harmonic Bz algorithm, this paper presents reconstructed conductivity and current density images from computer simulations and phantom experiments using four recessed electrodes injecting six different currents of 26 mA. For experimental results, we used a three-dimensional saline phantom with two polyacrylamide objects inside. We used our 0.3 T (tesla) experimental MRI scanner to measure the induced Bz. Using the harmonic Bz algorithm, we could reconstruct conductivity and current density images with 82 x 82 pixels. The pixel size was 0.6 x 0.6 mm2. The relative L2 errors of the reconstructed images were between 13.8 and 21.5% when the signal-to-noise ratio (SNR) of the corresponding MR magnitude images was about 30. The results suggest that in vitro and in vivo experimental studies with animal subjects are feasible. Further studies are requested to reduce the amount of injection current down to less than 1 mA for human subjects.

  5. Testing Lorentz Invariance Using an Odd-Parity Asymmetric Optical Resonator

    CERN Document Server

    Baynes, Fred; Tobar, Michael

    2011-01-01

    We present the first experimental test of Lorentz invariance using the frequency difference between counter-propagating modes in an asymmetric odd-parity optical resonator. This type of test is $\\sim10^{4}$ more sensitive to odd-parity and isotropic (scalar) violations of Lorentz invariance than equivalent conventional even-parity experiments due to the asymmetry of the optical resonator. The disadvantages of odd parity resonators have been negated by the use of counter-propagating modes, delivering a high level of immunity to environmental fluctuations. With a non-rotating experiment our result limits the isotropic Lorentz violating parameter $\\tilde{\\kappa}_{tr}$ to 3.4 $\\pm$ 6.2 x $10^{-9}$, the best reported constraint from direct measurements. Using this technique the bounds on odd-parity and scalar violations of Lorentz invariance can be improved by many orders of magnitude.

  6. Tailoring optical resonant cavity modes in SnO2 microstructures through doping and shape engineering

    Science.gov (United States)

    García-Tecedor, M.; Maestre, D.; Cremades, A.; Piqueras, J.

    2017-10-01

    Optical resonances are effectively tailored by engineering size, morphology and doping in tin oxide microstructures. The use of Cr shifts the light confinement to the near-infrared region, as compared to the undoped microstructures, while achieving good Q and F factors. Other issues, such as appropriate thickness to width ratio, allow the selection of Fabry–Pérot or Whispering Gallery modes, or the appearance of a combination of both kinds of resonances in the same microstructure. Morphology variability would contribute with flexibility in the design of systems for different applications, while combining the observed waveguiding behavior with the optical resonances in the same material is an advantage for applications based in a monolithic design. Refraction index of Cr doped tin oxide has been obtained.

  7. Photonic crystal waveguides intersection for resonant quantum dot optical spectroscopy detection.

    Science.gov (United States)

    Song, Xiaohong; Declair, Stefan; Meier, Torsten; Zrenner, Artur; Förstner, Jens

    2012-06-18

    Using a finite-difference time-domain method, we theoretically investigate the optical spectra of crossing perpendicular photonic crystal waveguides with quantum dots embedded in the central rod. The waveguides are designed so that the light mainly propagates along one direction and the cross talk is greatly reduced in the transverse direction. It is shown that when a quantum dot (QD) is resonant with the cavity, strong coupling can be observed via both the transmission and crosstalk spectrum. If the cavity is far off-resonant from the QD, both the cavity mode and the QD signal can be detected in the transverse direction since the laser field is greatly suppressed in this direction. This structure could have strong implications for resonant excitation and in-plane detection of QD optical spectroscopy.

  8. Resonance-inclined optical nuclear spin polarization of liquids in diamond structures

    CERN Document Server

    Chen, Qiong; Jelezko, Fedor; Retzker, Alex; Plenio, Martin B

    2015-01-01

    Dynamic nuclear polarization (DNP) of molecules in a solution at room temperature has potential to revolutionize nuclear magnetic resonance spectroscopy and imaging. The prevalent methods for achieving DNP in solutions are typically most effective in the regime of small interaction correlation times between the electron and nuclear spins, limiting the size of accessible molecules. To solve this limitation, we design a mechanism for DNP in the liquid phase that is applicable for large interaction correlation times. Importantly, while this mechanism makes use of a resonance condition similar to solid-state DNP, the polarization transfer is robust to a relatively large detuning from the resonance due to molecular motion. We combine this scheme with optically polarized nitrogen vacancy (NV) center spins in nanodiamonds to design a setup that employs optical pumping and is therefore not limited by room temperature electron thermal polarisation. We illustrate numerically the effectiveness of the model in a flow cel...

  9. Elliptical polarization of near-resonant linearly polarized probe light in optically pumped alkali metal vapor.

    Science.gov (United States)

    Li, Yingying; Wang, Zhiguo; Jin, Shilong; Yuan, Jie; Luo, Hui

    2017-02-20

    Optically pumped alkali metal atoms currently provide a sensitive solution for magnetic microscopic measurements. As the most practicable plan, Faraday rotation of linearly polarized light is extensively used in spin polarization measurements of alkali metal atoms. In some cases, near-resonant Faraday rotation is applied to improve the sensitivity. However, the near-resonant linearly polarized probe light is elliptically polarized after passing through optically pumped alkali metal vapor. The ellipticity of transmitted near-resonant probe light is numerically calculated and experimentally measured. In addition, we also analyze the negative impact of elliptical polarization on Faraday rotation measurements. From our theoretical estimate and experimental results, the elliptical polarization forms an inevitable error in spin polarization measurements.

  10. Optical model calculation for the unresolved/resolved resonance region of Fe-56

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Toshihiko [Kyushu Univ., Fukuoka (Japan); Froehner, F.H.

    1997-03-01

    We have studied optical model fits to total neutron cross sections of structural materials using the accurate data base for {sup 56}Fe existing in the resolved and unresolved resonance region. Averages over resolved resonances were calculated with Lorentzian weighting in Reich-Moore (reduced R matrix) approximation. Starting from the best available optical potentials we found that adjustment of the real and imaginary well depths does not work satisfactorily with the conventional weak linear energy dependence of the well depths. If, however, the linear dependences are modified towards low energies, the average total cross sections can be fitted quite well, from the resolved resonance region up to 20 MeV and higher. (author)

  11. Graphene coated fiber optic surface plasmon resonance biosensor for the DNA hybridization detection: Simulation analysis

    Science.gov (United States)

    Shushama, Kamrun Nahar; Rana, Md. Masud; Inum, Reefat; Hossain, Md. Biplob

    2017-01-01

    In this paper, a graphene coated optical fiber surface plasmon resonance (SPR) biosensor is presented for the detection of DNA Hybridization. For the proposed sensor, a four layer model (fiber core /metal /sensing layer /sample) where a sheet of graphene (biomolecular recognition elements (BRE)) acting as a sensing layer is coated around the gold film because graphene enhances the sensitivity of fiber optic SPR biosensor. Numerical analysis shows the variation of resonance wavelength and spectrum of transmitted power for mismatched DNA strands and for complementary DNA strands. For mismatched DNA strands variation is negligible whereas for complementary DNA strands is considerably countable. Proposed sensor successfully distinguishes hybridization and single nucleotide polymorphisms (SNP) by observing the variation level of resonance wavelength and spectrum of transmitted power.

  12. Photonic crystal dumbbell resonators in silicon and aluminum nitride integrated optical circuits

    CERN Document Server

    Pernice, W H P; Tang, H X

    2014-01-01

    Tight confinement of light in photonic cavities provides an efficient template for the realization of high optical intensity with strong field gradients. Here we present such a nanoscale resonator device based on a one-dimensional photonic crystal slot cavity. Our design allows for realizing highly localized optical modes with theoretically predicted Q factors in excess of 106. The design is demonstrated experimentally both in a high-contrast refractive index system (silicon), as well as in medium refractive index contrast devices made from aluminum nitride. We achieve extinction ratio of 21dB in critically coupled resonators using an on-chip readout platform with loaded Q factors up to 33,000. Our approach holds promise for realizing ultra-small opto-mechanical resonators for high-frequency operation and sensing applications.

  13. Ultra-cold mechanical resonators coupled to atoms in an optical lattice

    CERN Document Server

    Geraci, Andrew A

    2009-01-01

    We propose an experiment utilizing an array of cooled micro-cantilevers coupled to a sample of ultra-cold atoms trapped near a micro-fabricated surface. The cantilevers allow individual lattice site addressing for atomic state control and readout, and potentially may be useful in optical lattice quantum computation schemes. Assuming resonators can be cooled to their vibrational ground state, the implementation of a two-qubit controlled-NOT gate with atomic internal states and the motional states of the resonator is described. We also consider a protocol for entangling two or more cantilevers on the atom chip with different resonance frequencies, using the trapped atoms as an intermediary. Although similar experiments could be carried out with magnetic microchip traps, the optical confinement scheme we consider may exhibit reduced near-field magnetic noise and decoherence. Prospects for using this novel system for tests of quantum mechanics at macroscopic scales or quantum information processing are discussed.

  14. Alternative method for design and optimization of the ring resonator used in micro-optic gyro.

    Science.gov (United States)

    Wang, Kunbo; Feng, Lishuang; Wang, Junjie; Lei, Ming

    2013-03-01

    The ring resonator is one of the key elements in the micro-optic gyro system, but there is not a uniform method for designing the parameters of a ring resonator, especially for its size. In this paper, an alternative method is presented for designing the ring resonator used in micro-optic gyro. Maximization of the resonator output is proposed to be the principle in design and optimization for the first time to our knowledge. The scale factor accuracy and the full range of the gyro system are taken into account to obtain the optimum diameter of the ring. A theoretical optimal diameter of 0.25 m is achieved for SiO(2) waveguide resonator with a dynamic range of ±500°/s by analyzing the influence of resonator parameters on the output in detail, and the corresponding sensitivity of the gyro is less than 1.28°/h, which can meet the demands of a tactical inertia system.

  15. UV-Vis Ratiometric Resonance Synchronous Spectroscopy for Determination of Nanoparticle and Molecular Optical Cross Sections.

    Science.gov (United States)

    Nettles, Charles B; Zhou, Yadong; Zou, Shengli; Zhang, Dongmao

    2016-03-01

    Demonstrated herein is a UV-vis Ratiometric Resonance Synchronous Spectroscopic (R2S2, pronounced as "R-two-S-two" for simplicity) technique where the R2S2 spectrum is obtained by dividing the resonance synchronous spectrum of a NP-containing solution by the solvent resonance synchronous spectrum. Combined with conventional UV-vis measurements, this R2S2 method enables experimental quantification of the absolute optical cross sections for a wide range of molecular and nanoparticle (NP) materials that range optically from pure photon absorbers or scatterers to simultaneous photon absorbers and scatterers, simultaneous photon absorbers and emitters, and all the way to simultaneous photon absorbers, scatterers, and emitters in the UV-vis wavelength region. Example applications of this R2S2 method were demonstrated for quantifying the Rayleigh scattering cross sections of solvents including water and toluene, absorption and resonance light scattering cross sections for plasmonic gold nanoparticles, and absorption, scattering, and on-resonance fluorescence cross sections for semiconductor quantum dots (Qdots). On-resonance fluorescence quantum yields were quantified for the model molecular fluorophore Eosin Y and fluorescent Qdots CdSe and CdSe/ZnS. The insights and methodology presented in this work should be of broad significance in physical and biological science research that involves photon/matter interactions.

  16. Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

    Science.gov (United States)

    Ma, Pei; Wang, Yves T.; Gu, Shi; Watanabe, Michiko; Jenkins, Michael W.; Rollins, Andrew M.

    2014-07-01

    Optical mapping (OM) of cardiac electrical activity conventionally collects information from a three-dimensional (3-D) surface as a two-dimensional (2-D) projection map. When applied to measurements of the embryonic heart, this method ignores the substantial and complex curvature of the heart surface, resulting in significant errors when calculating conduction velocity, an important electrophysiological parameter. Optical coherence tomography (OCT) is capable of imaging the 3-D structure of the embryonic heart and accurately characterizing the surface topology. We demonstrate an integrated OCT/OM imaging system capable of simultaneous conduction mapping and 3-D structural imaging. From these multimodal data, we obtained 3-D activation maps and corrected conduction velocity maps of early embryonic quail hearts. 3-D correction eliminates underestimation bias in 2-D conduction velocity measurements, therefore enabling more accurate measurements with less experimental variability. The integrated system will also open the door to correlate the structure and electrophysiology, thereby improving our understanding of heart development.

  17. Efficient Method to Extract Coupling Ratio and Round-trip Loss Parameters of Optical Waveguide Ring Resonator

    Institute of Scientific and Technical Information of China (English)

    HAN Xiu-you; PANG Fu-fei; FANG Zu-jie; ZHAO Ming-shan

    2008-01-01

    Based on the measurement of the contrast ratios of the transmission spectra from the throughput and drop ports of ring resonator, an efficient method is proposed to extract the coupling ratio and round-trip loss of the integrated optical waveguide ring resonator. The parameters of a racetrack resonator prepared by ion-exchange technique in K9 optical glass substrate are examined, which demonstrates the validity of this method. The accuracy and applicable range of this method are also discussed.

  18. Optical resonance on LIPSS sensed by polarized light

    Science.gov (United States)

    Silvennoinen, Martti; HasoÅ, Stanislav; Silvennoinen, Raimo

    2013-12-01

    Non-symmetric and directional reflectivity from three dimensional (3D) laser induced periodic surface structures (LIPSS) is considered. LIPSS structures were patterned in stainless steel (W720) by using linear and elliptical polarized laser beams from a femtosecond (fs) laser. The short and long periodic ripples and possible other type artifact remaining has decreasing influences to relative reflectivity variation between 5% and 65% in the wavelength range from 200nm to 800nm. The studies of patterned W720LIPSS structures indicated, besides of increased surface area, that decrease of reflectivity is affected by light scattering from ultra-structures of LIPSS and produces resonance type differences in spectral reflectivity when either TM or TE polarized probing beam interacts with micro- and ultrastructure of LIPSS.

  19. All-optical clock recovery of NRZ-DPSK signals using optical resonator-type filters

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Seoane, Jorge; Ji, Hua

    2009-01-01

    It is shown how introducing a limited rise time to the driving signal enables all-optical clock recovery of NRZ-DPSK signals generated using a phase modulator. A Fabry-Perot filter is used to generate the optical clock.......It is shown how introducing a limited rise time to the driving signal enables all-optical clock recovery of NRZ-DPSK signals generated using a phase modulator. A Fabry-Perot filter is used to generate the optical clock....

  20. Directed assembly of hybrid nanostructures using optically resonant nanotweezers

    Energy Technology Data Exchange (ETDEWEB)

    Erickson, David [Cornell Univ., Ithaca, NY (United States)

    2015-09-09

    This represents the final report for this project. Over the course of the project we have made significant progress in photonically driven nano-assembly including: (1) demonstrating the first direct optical tweezer based manipulation of proteins, (2) the ability to apply optical angular torques to microtubuals and other rod-shaped microparticles, (3) direct assembly of hybrid nanostructures comprising of polymeric nanoparticles and carbon nanotubes and, (4) the ability to drive biological reactions (specifically protein aggregation) that are thermodynamically unfavorable by applying localized optical work. These advancements are described in the list of papers provided in section 2.0 of the below. Summary details are provided in prior year annual reports. We have two additional papers which will be submitted shortly based on the work done under this award. An updated publication list will be provided to the program manager when those are accepted. In this report, we report on a new advancement made in the final project year, which uses the nanotweezer technology to perform direct measurements of particle-surface interactions. Briefly, these measurements are important for characterizing the stability and behavior of colloidal and nanoparticle suspensions and current techniques are limited in their ability to measure piconewton scale interaction forces on sub-micrometer particles due to signal detection limits and thermal noise. In this project year we developed a new technique called “Nanophotonic Force Microscopy” which uses the localized region of exponentially decaying, near-field, light to confine small particles close to a surface. From the statistical distribution of the light intensity scattered by the particle the technique maps out the potential well of the trap and directly quantify the repulsive force between the nanoparticle and the surface. The major advantage of the technique is that it can measure forces and energy wells below the thermal noise

  1. Phase-sensitive microwave optical double resonance in an N system

    Science.gov (United States)

    Preethi, T. M.; Manukumara, M.; Asha, K.; Vijay, J.; Roshi, D. A.; Narayanan, A.

    2011-08-01

    An experimental investigation of a Microwave Optical Double Resonance (MODR) phenomenon is carried out in a four level N system of 85Rb atoms, at room temperature. This N system consists of a closed three level Λ subsystem irradiated with two optical fields and one microwave field. The MODR response is investigated in a separate probe field which drives a resonant transition from one of the ground states of the Λ system to a fourth level. We find that, under two-photon resonance condition for the optical fields, the MODR becomes a function of the relative phase between the beat frequency envelop of the optical fields and the microwave field. The variation in MODR is shown to be correlated with the phase-sensitive variation of the EIT phenomenon seen in such microwave-connected closed Λ systems. We envisage that this phase-sensitive variation in the MODR, can be utilized for a phase-sensitive manipulation of non-linear optical phenomena in N systems.

  2. Nanoparticle detection using fano-resonance photonic crystal on optical fiber-tip

    Science.gov (United States)

    Yang, Daquan; Yuan, Wei; Ji, Yuefeng

    2016-10-01

    Recently, Fano-resonance photonic crystals (PhC) have been employed within a wide variety of nanophotonic structures for different applications, including imaging, filtering, switching, sensing, and so on. In this paper, we propose a convenient and compact fiber-optic sensor based on optical fiber-tips integrated with Fano-resonance pillar-array PhC. The quality factor 1.04×104 and refractive index sensitivity of 226 nm per refractive index unit (RIU) have been demonstrated. In addition, the proposed Fiber-PhC integrated senor structure can be used for nanoparticle detection by checking the reflection spectrum shift with a narrow line-width. Using this method, we demonstrate that the detection of polystyrene nanoparticles with dimensions down to 50 nm in radius can be achieved. Thus, we believe that the design and results presented here are promising and enable the implementation of simple but functional fiber-optic sensors and devices.

  3. Optically detected electron paramagnetic resonance by microwave modulated magnetic circular dichroism

    Science.gov (United States)

    Börger, Birgit; Bingham, Stephen J.; Gutschank, Jörg; Schweika, Marc Oliver; Suter, Dieter; Thomson, Andrew J.

    1999-11-01

    Electron paramagnetic resonance (EPR) can be detected optically, with a laser beam propagating perpendicular to the static magnetic field. As in conventional EPR, excitation uses a resonant microwave field. The detection process can be interpreted as coherent Raman scattering or as a modulation of the laser beam by the circular dichroism of the sample oscillating at the microwave frequency. The latter model suggests that the signal should show the same dependence on the optical wavelength as the MCD signal. We check this for two different samples [cytochrome c-551, a metalloprotein, and ruby (Cr3+:Al2O3)]. In both cases, the observed wavelength dependence is almost identical to that of the MCD signal. A quantitative estimate of the amplitude of the optically detected EPR signal from the MCD also shows good agreement with the experimental results.

  4. Resonances in coated long period fiber gratings and cladding removed multimode optical fibers: a comparative study.

    Science.gov (United States)

    Del Villar, Ignacio; Zamarreño, Carlos R; Hernaez, Miguel; Arregui, Francisco J; Matias, Ignacio R

    2010-09-13

    Two optical fiber devices have been coated in parallel: a long period fiber grating (LPFG) and a cladding-removed multimode optical fiber (CRMOF). The progressive coating of the LPFG by means of the layer-by-layer electrostatic-self-assembly, permits to observe a resonance wavelength shift of the attenuation bands in the transmission spectrum. The cause of this wavelength shift is the reorganization of the cladding mode effective indices. The cause of this modal reorganization can be understood with the results observed in the CRMOF coated in parallel. A lossy-mode-resonance (LMR) is generated in the same wavelength range of the LPFG attenuation bands analyzed. Moreover, the thickness range where the wavelength shift of the LPFG attenuation bands occurs coincides exactly with the thickness range where the LMR can be visualized in the transmission spectrum. These phenomena are analyzed theoretically and corroborated experimentally. The advantages and disadvantages of both optical fiber devices are explained.

  5. Origin of optical losses in gallium arsenide disk whispering gallery resonators

    CERN Document Server

    Parrain, David; Wang, Guillaume; Guha, Biswarup; Santos, Eduardo Gil; Lemaitre, Aristide; Senellart, Pascale; Leo, Giuseppe; Ducci, Sara; Favero, Ivan

    2015-01-01

    Whispering gallery modes in GaAs disk resonators reach half a million of optical quality factor. These high Qs remain still well below the ultimate design limit set by bending losses. Here we investigate the origin of residual optical dissipation in these devices. A Transmission Electron Microscope analysis is combined with an improved Volume Current Method to precisely quantify optical scattering losses by roughness and waviness of the structures, and gauge their importance relative to intrinsic material and radiation losses. The analysis also provides a qualitative description of the surface reconstruction layer, whose optical absorption is then revealed by comparing spectroscopy experiments in air and in different liquids. Other linear and nonlinear optical loss channels in the disks are evaluated likewise. Routes are given to further improve the performances of these miniature GaAs cavities.

  6. Optimization of optical filter using triple coupler ring resonators structure based on polyimide substrate

    Science.gov (United States)

    Mahmudin, D.; Estu, T. T.; Fathnan, A. A.; Maulana, Y. Y.; Daud, P.; Sugandhi, G.; Wijayanto, Y. N.

    2016-11-01

    Optical filter is very important components in WDM network. MRR is a basic structure to design the optical filter because of easy to design for improving its performance. This paper discusses an innovative structure of the MRR, which is Triple Coupler Ring Resonators (TCRR) for optical filter applications. Values of width between bus and ring and values of radius of the ring in the structure TCRR were analyzed and optimized for several variations for obtaining coupling coefficient values. Therefore, wide Free Spectral Range (FSR) and high crosstalk suppression bandwidth can be obtained. As results, at the optimized width of gap of 100 nm and the optimized radiation of 8 μm, FSR of 2.85 THz and crosstalk suppression bandwidth of 60 GHz were achieved. Based on the results, this structure can be used for filtering optical signals in optical fiber communication.

  7. Effective electro-optical modulation with high extinction ratio by a graphene-silicon microring resonator

    DEFF Research Database (Denmark)

    Ding, Yunhong; Zhu, Xiaolong; Xiao, Sanshui

    2015-01-01

    comprehensively study the interaction between graphene and a microring resonator, and its influence on the optical modulation depth. We demonstrate graphene-silicon microring devices showing a high modulation depth of 12.5 dB with a relatively low bias voltage of 8.8 V. On-off electro-optical switching......Graphene opens up for novel optoelectronic applications thanks to its high carrier mobility, ultra-large absorption bandwidth, and extremely fast material response. In particular, the opportunity to control optoelectronic properties through tuning of the Fermi level enables electro-optical...... modulation, optical-optical switching, and other optoelectronics applications. However, achieving a high modulation depth remains a challenge because of the modest graphene-light interaction in the graphene-silicon devices, typically, utilizing only a monolayer or few layers of graphene. Here, we...

  8. Tunable optical analog to electromagnetically induced transparency in graphene-ring resonators system

    Science.gov (United States)

    Wang, Yonghua; Xue, Chenyang; Zhang, Zengxing; Zheng, Hua; Zhang, Wendong; Yan, Shubin

    2016-12-01

    The analogue of electromagnetically induced transparency in optical ways has shown great potential in optical delay and quantum-information technology due to its flexible design and easy implementation. The chief drawback for these devices is the bad tunability. Here we demonstrate a tunable optical transparency system formed by graphene-silicon microrings which could control the transparent window by electro-optical means. The device consists of cascaded coupled ring resonators and a graphene/graphene capacitor which integrated on one of the rings. By tuning the Fermi level of the graphene sheets, we can modulate the round-trip ring loss so that the transparency window can be dynamically tuned. The results provide a new method for the manipulation and transmission of light in highly integrated optical circuits and quantum information storage devices.

  9. Diagnostic implication of magnetic resonance imaging using STIR sequences in optic neuritis

    Energy Technology Data Exchange (ETDEWEB)

    Igarashi, Yasuo; Hashimoto, Masato; Ohyachi, Hiroaki; Nakamura, Yasushi; Ohguro, Hiroshi; Ohtsuka, Kenji; Nakagawa, Takashi (Sapporo Medical Coll. (Japan))

    1994-10-01

    We evaluated 23 patients with optic neuritis by magnetic resonance imaging (MRI) using STIR sequences. The series comprised 5 cases of multiple sclerosis and 18 of unknown etiology. Abnormal high-intensity area was observed in the optic nerve in at least one slice. The slices showing a high signal intensity averaged 3.4 in number. The abnormal finding was most frequent at 15 mm posterior to the eyeglobe in papillitis and retrobulbar optic neuritis. The incidence of abnormal finding was more frequent in papillitis than in retrobulbar neuritis. The high-intensity signal in the optic nerve was not correlated with the latency of major positivity of pattern-reversal VEPs and was rather associated with the clinical course and outcome of optic neuritis. (author).

  10. Highly tunable ultra-narrow-resonances with optical nano-antenna phased arrays in the infrared

    CERN Document Server

    Li, Shi-Qiang; Guo, Peijun; Buchholz, D Bruce; Qiu, Ziwei; Ketterson, John B; Ocola, Leonidas E; Sakoda, Kazuaki; Chang, Robert P H

    2014-01-01

    We report our recent development in pursuing high Quality-Factor (high-Q factor) plasmonic resonances, with vertically aligned two dimensional (2-D) periodic nanorod arrays. The 2-D vertically aligned nano-antenna array can have high-Q resonances varying arbitrarily from near infrared to terahertz regime, as the antenna resonances of the nanorod are highly tunable through material properties, the length of the nanorod, and the orthogonal polarization direction with respect to the lattice surface,. The high-Q in combination with the small optical mode volume gives a very high Purcell factor, which could potentially be applied to various enhanced nonlinear photonics or optoelectronic devices. The 'hot spots' around the nanorods can be easily harvested as no index-matching is necessary. The resonances maintain their high-Q factor with the change of the environmental refractive index, which is of great interest for molecular sensing.

  11. Leaky Modes of Waveguides as a Classical Optics Analogy of Quantum Resonances

    Directory of Open Access Journals (Sweden)

    Sara Cruz y Cruz

    2015-01-01

    Full Text Available A classical optics waveguide structure is proposed to simulate resonances of short range one-dimensional potentials in quantum mechanics. The analogy is based on the well-known resemblance between the guided and radiation modes of a waveguide with the bound and scattering states of a quantum well. As resonances are scattering states that spend some time in the zone of influence of the scatterer, we associate them with the leaky modes of a waveguide, the latter characterized by suffering attenuation in the direction of propagation but increasing exponentially in the transverse directions. The resemblance is complete because resonances (leaky modes can be interpreted as bound states (guided modes with definite lifetime (longitudinal shift. As an immediate application we calculate the leaky modes (resonances associated with a dielectric homogeneous slab (square well potential and show that these modes are attenuated as they propagate.

  12. Characterization of rock thermal conductivity by high-resolution optical scanning

    Science.gov (United States)

    Popov, Y.A.; Pribnow, D.F.C.; Sass, J.H.; Williams, C.F.; Burkhardt, H.

    1999-01-01

    We compared thress laboratory methods for thermal conductivity measurements: divided-bar, line-source and optical scanning. These methods are widely used in geothermal and petrophysical studies, particularly as applied to research on cores from deep scientific boreholes. The relatively new optical scanning method has recently been perfected and applied to geophysical problems. A comparison among these methods for determining the thermal conductivity tensor for anisotropic rocks is based on a representative collection of 80 crystalline rock samples from the KTB continental deep borehole (Germany). Despite substantial thermal inhomogeneity of rock thermal conductivity (up to 40-50% variation) and high anisotropy (with ratios of principal values attaining 2 and more), the results of measurements agree very well among the different methods. The discrepancy for measurements along the foliation is negligible (conductivity normal to the foliation reveals somewhat larger differences (3-4%). Optical scanning allowed us to characterize the thermal inhomogeneity of rocks and to identify a three-dimensional anisotropy in thermal conductivity of some gneiss samples. The merits of optical scanning include minor random errors (1.6%), the ability to record the variation of thermal conductivity along the sample, the ability to sample deeply using a slow scanning rate, freedom from constraints for sample size and shape, and quality of mechanical treatment of the sample surface, a contactless mode of measurement, high speed of operation, and the ability to measure on a cylindrical sample surface. More traditional methods remain superior for characterizing bulk conductivity at elevated temperature.Three laboratory methods including divided-bar, line-source and optical scanning are widely applied in geothermal and petrophysical studies. In this study, these three methods were compared for determining the thermal conductivity tensor for anisotropic rocks. For this study, a

  13. Blocking Phonon Transport by Structural Resonances in Alloy-Based Nanophononic Metamaterials Leads to Ultralow Thermal Conductivity

    Science.gov (United States)

    Xiong, Shiyun; Sääskilahti, Kimmo; Kosevich, Yuriy A.; Han, Haoxue; Donadio, Davide; Volz, Sebastian

    2016-07-01

    Understanding the design rules to obtain materials that enable a tight control of phonon transport over a broad range of frequencies would aid major developments in thermoelectric energy harvesting, heat management in microelectronics, and information and communication technology. Using atomistic simulations we show that the metamaterials approach relying on localized resonances is very promising to engineer heat transport at the nanoscale. Combining designed resonant structures to alloying can lead to extremely low thermal conductivity in silicon nanowires. The hybridization between resonant phonons and propagating modes greatly reduces the group velocities and the phonon mean free paths in the low frequency acoustic range below 4 THz. Concurrently, alloy scattering hinders the propagation of high frequency thermal phonons. Our calculations establish a rationale between the size, shape, and period of the resonant structures, and the thermal conductivity of the nanowire, and demonstrate that this approach is even effective to block phonon transport in wavelengths much longer than the size and period of the surface resonant structures. A further consequence of using resonant structures is that they are not expected to scatter electrons, which is beneficial for thermoelectric applications.

  14. Blocking Phonon Transport by Structural Resonances in Alloy-Based Nanophononic Metamaterials Leads to Ultralow Thermal Conductivity.

    Science.gov (United States)

    Xiong, Shiyun; Sääskilahti, Kimmo; Kosevich, Yuriy A; Han, Haoxue; Donadio, Davide; Volz, Sebastian

    2016-07-01

    Understanding the design rules to obtain materials that enable a tight control of phonon transport over a broad range of frequencies would aid major developments in thermoelectric energy harvesting, heat management in microelectronics, and information and communication technology. Using atomistic simulations we show that the metamaterials approach relying on localized resonances is very promising to engineer heat transport at the nanoscale. Combining designed resonant structures to alloying can lead to extremely low thermal conductivity in silicon nanowires. The hybridization between resonant phonons and propagating modes greatly reduces the group velocities and the phonon mean free paths in the low frequency acoustic range below 4 THz. Concurrently, alloy scattering hinders the propagation of high frequency thermal phonons. Our calculations establish a rationale between the size, shape, and period of the resonant structures, and the thermal conductivity of the nanowire, and demonstrate that this approach is even effective to block phonon transport in wavelengths much longer than the size and period of the surface resonant structures. A further consequence of using resonant structures is that they are not expected to scatter electrons, which is beneficial for thermoelectric applications.

  15. Drag detection and identification by whispering gallery mode optical resonance based sensor

    Science.gov (United States)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas

    2013-06-01

    Experimental data on optical resonance spectra of whispering gallery modes of dielectric microspheres in antibiotic solutions under varied in wide range concentration are represented. Optical resonance was demonstrated could be detected at a laser power of less than 1 microwatt. Several antibiotics of different generations: Amoxicillin, Azithromycin, Cephazolin, Chloramphenicol, Levofloxacin, Lincomicin Benzylpenicillin, Riphampicon both in deionized water and physiological solution had been used for measurements. Both spectral shift and the structure of resonance spectra were of specific interest in this investigation. Drag identification has been performed by developed multilayer perceptron network. The network topology was designed included: a number of the hidden layers of multilayered perceptron, a number of neurons in each of layers, a method of training of a neural network, activation functions of layers, type and size of a deviation of the received values from required values. For a network training the method of the back propagation error in various modifications has been used. Input vectors correspond to 6 classes of biological substances under investigation. The result of classification was considered as positive when each of the region, representing a certain substance in a space: relative spectral shift of an optical resonance maxima - relative efficiency of excitation of WGM, was singly connected. It was demonstrated that the approach described in the paper can be a promising platform for the development of sensitive, lab-on-chip type sensors that can be used as an express diagnostic tools for different drugs and instrumentation for proteomics, genomics, drug discovery, and membrane studies.

  16. Electron Spin Resonance and optical absorption spectroscopic studies of manganese centers in aluminium lead borate glasses

    Science.gov (United States)

    SivaRamaiah, G.; LakshmanaRao, J.

    2012-12-01

    Electron Spin Resonance (ESR) and optical absorption studies of 5Al2O3 + 75H3BO3 + (20-x)PbO + xMnSO4 (where x = 0.5, 1,1.5 and 2 mol% of MnSO4) glasses at room temperature have been studied. The ESR spectrum of all the glasses exhibits resonance signals with effective isotropic g values at ≈2.0, 3.3 and 4.3. The ESR resonance signal at isotropic g ≈ 2.0 has been attributed to Mn2+ centers in an octahedral symmetry. The ESR resonance signals at isotropic g ≈ 3.3 and 4.3 have been attributed to the rhombic symmetry of the Mn2+ ions. The zero-field splitting parameter (zfs) has been calculated from the intensities of the allowed hyperfine lines. The optical absorption spectrum exhibits an intense band in the visible region and it has been attributed to 5Eg → 5T2g transition of Mn3+centers in an octahedral environment. The optical band gap and the Urbach energies have been calculated from the ultraviolet absorption edges.

  17. Theoretical study of optical conductivity of graphene with magnetic and nonmagnetic adatoms

    Science.gov (United States)

    Majidi, Muhammad Aziz; Siregar, Syahril; Rusydi, Andrivo

    2014-11-01

    We present a theoretical study of the optical conductivity of graphene with magnetic and nonmagnetic adatoms. First, by introducing an alternating potential in a pure graphene, we demonstrate a gap formation in the density of states and the corresponding optical conductivity. We highlight the distinction between such a gap formation and the so-called Pauli blocking effect. Next, we apply this idea to graphene with adatoms by introducing magnetic interactions between the carrier spins and the spins of the adatoms. Exploring various possible ground-state spin configurations of the adatoms, we find that the antiferromagnetic configuration yields the lowest total electronic energy and is the only configuration that forms a gap. Furthermore, we analyze four different circumstances leading to similar gaplike structures and propose a means to interpret the magneticity and the possible orderings of the adatoms on graphene solely from the optical conductivity data. We apply this analysis to the recently reported experimental data of oxygenated graphene.

  18. Optical layer development for thin films thermal conductivity measurement by pulsed photothermal radiometry

    Energy Technology Data Exchange (ETDEWEB)

    Martan, J., E-mail: jmartan@ntc.zcu.cz [New Technologies Research Centre, University of West Bohemia, Univerzitní 8, 306 14 Plzeň (Czech Republic)

    2015-01-15

    Measurement of thermal conductivity and volumetric specific heat of optically transparent thin films presents a challenge for optical-based measurement methods like pulsed photothermal radiometry. We present two approaches: (i) addition of an opaque optical layer to the surface and (ii) approximate correction of the mathematical model to incorporate semitransparency of the film. Different single layer and multilayer additive optical layers were tested. The materials of the optical layers were chosen according to analysis and measurement of their optical properties: emissivity and absorption coefficient. Presented are thermal properties’ measurement results for 6 different thin films with wide range of thermal conductivity in three configurations of surface: as deposited, added Ti layer, and added Ti/TiAlSiN layer. Measurements were done in dependence on temperature from room temperature to 500 °C. The obtained thermal effusivity evolution in time after the laser pulse shows different effects of the surface layers: apparent effusivity change and time delay. Suitability of different measurement configurations is discussed and results of high temperature testing of different optical layers are presented.

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

    Science.gov (United States)

    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 (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 of this procedure. Moreover, an anti mouse-IgG, labelled with the same fluorophore (Alexa Fluor 488) was used for specificity-tests of the IgG/anti-IgG interaction. The immunoassay based on fluorescence was characterized using an optical microscope (Zeiss AXIO inverted fluorescence microscope) working at the wavelengths of 470 nm for excitation of Alexa Fluor 488. The real time measurement of the resonance broadening after each functionalization step together with the high Q factor (< 105) measured after the IgG/anti-IgG interaction in water, gives a further proof for the method validity.

  20. Optical bistability in a one-dimensional photonic crystal resonator using a reverse-biased pn-junction

    CERN Document Server

    Sodagar, Majid; Eftekhar, Ali A; Adibi, Ali

    2014-01-01

    Optical bistability provides a simple way to control light with light. We demonstrate low-power thermo-optical bistability caused by the Joule heating mechanism in a one-dimensional photonic crystal (PC) nanobeam resonator with a moderate quality factor (Q ~ 8900) with an embedded reverse-biased pn-junction. We show that the photocurrent induced by the linear absorption in this compact resonator considerably reduces the threshold optical power. The proposed approach substantially relaxes the requirements on the input optical power for achieving optical bistability and provides a reliable way to stabilize the bistable features of the device.

  1. Optical bistability in a one-dimensional photonic crystal resonator using a reverse-biased pn-junction.

    Science.gov (United States)

    Sodagar, Majid; Miri, Mehdi; Eftekhar, Ali A; Adibi, Ali

    2015-02-01

    Optical bistability provides a simple way to control light with light. We demonstrate low-power thermo-optical bistability caused by the Joule heating mechanism in a one-dimensional photonic crystal (PC) nanobeam resonator with a moderate quality factor (Q ~8900) with an embedded reverse-biased pn-junction. We show that the photocurrent induced by the linear absorption in this compact resonator considerably reduces the threshold optical power. The proposed approach substantially relaxes the requirements on the input optical power for achieving optical bistability and provides a reliable way to stabilize the bistable features of the device.

  2. OPTICAL BAND GAP AND CONDUCTIVITY MEASUREMENTS OF POLYPYRROLE-CHITOSAN COMPOSITE THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    Mahnaz M.Abdi; H.N.M.Ekramul Mahmud; Luqman Chuah Abdullah; Anuar Kassim; Mohamad Zaki Ab.Rahman; Josephine Liew Ying Chyi

    2012-01-01

    Electrical conductivity and optical properties of polypyrrole-chitosan (PPy-CHI) conducting polymer composites have been investigated to determine the optical transition characteristics and energy band gap of composite films.The two electrode method and Ⅰ-Ⅴ characteristic technique were used to measure the conductivity of the PPy-CHI thin films,and the optical band gap was obtained from their ultraviolet absorption edges.Depending upon experimental parameter,the optical band gap (Eg) was found within 1.30-2.32 eV as estimated from optical absorption data.The band gap of the composite films decreased as the CHI content increased.The room temperature electrical conductivity of PPy-CHI thin films was found in the range of 5.84 × 10-7-15.25 × 10-7 S.cm-1 depending on the chitosan content.The thermogravimetry analysis (TGA)showed that the CHI can improve the thermal stability of PPy-CHI composite films.

  3. Light-controlled microwave whispering-gallery-mode quasi-optical resonators at 50W LED array illumination

    Directory of Open Access Journals (Sweden)

    V. B. Yurchenko

    2015-08-01

    Full Text Available We present experimental observations of light-controlled resonance effects in microwave whispering-gallery-mode quasi-optical dielectric-semiconductor disk resonators in the frequency band of 5 GHz to 20 GHz arising due to illumination from a light emitting diode (LED of 50W power range. We obtain huge enhancement of photo-sensitivity (growing with the resonator Q-factor that makes light-microwave interaction observable with an ordinary light (no laser at conventional brightness (like an office lighting in quasi-optical microwave structures at rather long (centimeter-scale wavelength. We also demonstrate non-conventional photo-response of Fano resonances when the light suppresses one group of resonances and enhances another group. The effects could be used for the optical control and quasi-optical switching of microwave propagation through either one or another frequency channel.

  4. Slow light enhanced correlated photon pair generation in photonic-crystal coupled-resonator optical waveguides

    CERN Document Server

    Matsuda, Nobuyuki; Shimizu, Kaoru; Tokura, Yasuhiro; Kuramochi, Eiichi; Notomi, Masaya; 10.1364/OE.21.008596

    2013-01-01

    We demonstrate the generation of quantum-correlated photon pairs from a Si photonic-crystal coupled-resonator optical waveguide. A slow-light supermode realized by the collective resonance of high-Q and small-mode-volume photonic-crystal cavities successfully enhanced the efficiency of the spontaneous four-wave mixing process. The generation rate of photon pairs was improved by two orders of magnitude compared with that of a photonic-crystal line defect waveguide without a slow-light effect.

  5. Slow light enhanced correlated photon pair generation in photonic-crystal coupled-resonator optical waveguides.

    Science.gov (United States)

    Matsuda, Nobuyuki; Takesue, Hiroki; Shimizu, Kaoru; Tokura, Yasuhiro; Kuramochi, Eiichi; Notomi, Masaya

    2013-04-08

    We demonstrate the generation of quantum-correlated photon pairs from a Si photonic-crystal coupled-resonator optical waveguide. A slow-light supermode realized by the collective resonance of high-Q and small-mode-volume photonic-crystal cavities successfully enhanced the efficiency of the spontaneous four-wave mixing process. The generation rate of photon pairs was improved by two orders of magnitude compared with that of a photonic-crystal line defect waveguide without a slow-light effect.

  6. Circuit-tunable sub-wavelength THz resonators: hybridizing optical cavities and loop antennas.

    Science.gov (United States)

    Paulillo, B; Manceau, J M; Degiron, A; Zerounian, N; Beaudoin, G; Sagnes, I; Colombelli, R

    2014-09-08

    We demonstrate subwavelength electromagnetic resonators operating in the THz spectral range, whose spectral properties and spatial/angular patterns can be engineered in a similar way to an electronic circuit. We discuss the device concept, and we experimentally study the tuning of the resonant frequency as a function of variable capacitances and inductances. We then elucidate the optical coupling properties. The radiation pattern, obtained by angle-resolved reflectance, reveals that the system mainly couples to the outside world via a magnetic dipolar interaction.

  7. Carrier concentration dependence of the tunability of the dipole resonance peak in optically excited metamaterials

    Science.gov (United States)

    Chatzakis, Ioannis; Luo, Liang; Wang, Jigang; Shen, Nian Hai; Koschny, Thomas; Soukoulis, Costas

    2011-03-01

    Currently, there is strong interest to explore the dynamic control of the electromagnetic properties of metamaterials, which have important implications on their optoelectronic applications. While the design, fabrication and photo-doping of metamaterial/semiconductor structures have been actively pursued, some fundamental issues related to highly photo-excited states, their dynamic tuning and temporal evolution remain open. Using optical-pump terahertz probe spectroscopy, we report on the pump fluence dependence of the electric dipole resonance tunability in metamaterials. We find a previously undiscovered large non-monotonic variation on the strength of the dipole resonance peak with the photo-injected carrier concentration.

  8. Special optical fiber for temperature sensing based on cladding-mode resonance.

    Science.gov (United States)

    Pang, Fufei; Xiang, Wenchao; Guo, Hairun; Chen, Na; Zeng, Xianglong; Chen, Zhenyi; Wang, Tingyun

    2008-08-18

    A fiber-optic temperature sensor by using a multi-cladding special fiber is presented. It works on the basis of leaky mode resonance from fiber core to outer cladding. With the thin-thickness inner cladding, the cladding mode is strongly excited and the resonant spectrum is very sensitive to the refractive index variation of coating material. By coating the special fiber with temperature-sensitive silicone, the temperature response was investigated experimentally from -20 degrees C to 80 degrees C. The results show high temperature sensitivity (240 pm/degrees C at 20 degrees C) and good repeatability.

  9. Freely designable optical frequency conversion in Raman-resonant four-wave-mixing process

    Science.gov (United States)

    Zheng, Jian; Katsuragawa, Masayuki

    2015-01-01

    Nonlinear optical processes are governed by the relative-phase relationships among the relevant electromagnetic fields in these processes. In this Report, we describe the physics of arbitrary manipulation of Raman-resonant four-wave-mixing process by artificial control of relative phases. As a typical example, we show freely designable optical-frequency conversions to extreme spectral regions, mid-infrared and vacuum-ultraviolet, with near-unity quantum efficiencies. Furthermore, we show that such optical-frequency conversions can be realized by using a surprisingly simple technology where transparent plates are placed in a nonlinear optical medium and their positions and thicknesses are adjusted precisely. In a numerical simulation assuming practically applicable parameters in detail, we demonstrate a single-frequency tunable laser that covers the whole vacuum-ultraviolet spectral range of 120 to 200 nm. PMID:25748023

  10. Flip-chip light emitting diode with resonant optical microcavity

    Science.gov (United States)

    Gee, James M.; Bogart, Katherine H.A.; Fischer, Arthur J.

    2005-11-29

    A flip-chip light emitting diode with enhanced efficiency. The device structure employs a microcavity structure in a flip-chip configuration. The microcavity enhances the light emission in vertical modes, which are readily extracted from the device. Most of the rest of the light is emitted into waveguided lateral modes. Flip-chip configuration is advantageous for light emitting diodes (LEDs) grown on dielectric substrates (e.g., gallium nitride LEDs grown on sapphire substrates) in general due to better thermal dissipation and lower series resistance. Flip-chip configuration is advantageous for microcavity LEDs in particular because (a) one of the reflectors is a high-reflectivity metal ohmic contact that is already part of the flip-chip configuration, and (b) current conduction is only required through a single distributed Bragg reflector. Some of the waveguided lateral modes can also be extracted with angled sidewalls used for the interdigitated contacts in the flip-chip configuration.

  11. Analysis of mid-infrared optical conductivity in electron-doped cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Varshney, Dinesh [School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore-452017 (India); Patel, G S [School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore-452017 (India); Singh, R K [M P Bhoj (Open) University, Shivaji Nagar, Bhopal-462016, Madhya Pradesh (India)

    2003-05-01

    Observed frequency dependent optical conductivity {sigma}({omega}) of electron-doped cuprate Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4-{delta}} ({delta} {approx} 0.02, T{sub c} {approx} 25 K) superconductors has been theoretically analysed. Starting from an effective two-dimensional (2D) interaction potential for superlattice of electron-doped cuprates treated as a layered electron gas, the spectral function is developed. Calculations of {sigma}({omega}) have been made within the two component scheme: one is the coherent Drude carriers responsible for superconductivity and the other is incoherent motion of carriers from one site to the other that leads to a pairing between Drude carriers. The approach accounts for the anomalies observed (frequency dependence of optical conductivity) in the optical measurements for the normal state. Estimating the effective mass from specific heat measurement and {epsilon}{sub {infinity}} from band structure calculations for the low-energy charge density waves, the model has only one free parameter, the relaxation rate. The frequency dependent relaxation rates are expressed in terms of memory functions, and the coherent Drude carriers from the effective interaction potential lead to a sharp peak at zero frequency and a long tail at higher frequencies, i.e. in the infrared region, while the hopping of carriers from one site to the other (incoherent motion of doped carriers) yields a peak value in the optical conductivity centred at mid-infrared region. We find that both the Drude and hopping carriers in the superlattice of electron-doped cuprates will contribute to the optical process of conduction in the CuO{sub 2} planes and show similar results on optical conductivity in the mid-infrared as well as infrared frequency regions as those revealed from experiments.

  12. Analysis of mid-infrared optical conductivity in electron-doped cuprates

    Science.gov (United States)

    Varshney, Dinesh; Patel, G. S.; Singh, R. K.

    2003-05-01

    Observed frequency dependent optical conductivity sigma(omega) of electron-doped cuprate Nd1.85Ce0.15CuO4-delta (delta approx 0.02, Tc approx 25 K) superconductors has been theoretically analysed. Starting from an effective two-dimensional (2D) interaction potential for superlattice of electron-doped cuprates treated as a layered electron gas, the spectral function is developed. Calculations of sigma(omega) have been made within the two component scheme: one is the coherent Drude carriers responsible for superconductivity and the other is incoherent motion of carriers from one site to the other that leads to a pairing between Drude carriers. The approach accounts for the anomalies observed (frequency dependence of optical conductivity) in the optical measurements for the normal state. Estimating the effective mass from specific heat measurement and varepsiloninfty from band structure calculations for the low-energy charge density waves, the model has only one free parameter, the relaxation rate. The frequency dependent relaxation rates are expressed in terms of memory functions, and the coherent Drude carriers from the effective interaction potential lead to a sharp peak at zero frequency and a long tail at higher frequencies, i.e. in the infrared region, while the hopping of carriers from one site to the other (incoherent motion of doped carriers) yields a peak value in the optical conductivity centred at mid-infrared region. We find that both the Drude and hopping carriers in the superlattice of electron-doped cuprates will contribute to the optical process of conduction in the CuO2 planes and show similar results on optical conductivity in the mid-infrared as well as infrared frequency regions as those revealed from experiments.

  13. Folded-Cavity Resonators as Key Elements for Optical Filtering and Low-Voltage Electroabsorption Modulation

    Science.gov (United States)

    Djordjev, Kostadin D.; Lin, Chao-Kun; Zhu, Jintian; Bour, David; Tan, Michael R.

    2006-09-01

    Folded-cavity (FC) resonators, which are based on shallow-etched ridge waveguides combined with four deeply etched turning mirrors, are designed and fabricated. The device consists of a resonant FC and a bus waveguide coupled to it through a directional coupler. Optical passive filters, based on this technology, exhibit quality factors in the excess of 5000, with a low insertion loss of 5 dB (including the input coupling loss to a fiber) and more than 15-dB extinction at resonance. When the filter is combined with an electroabsorption active region and is designed to operate in the overcoupled regime, a low-voltage/high-extinction-ratio resonant modulation becomes feasible. The resonant modulator exhibits a low insertion loss (greater than 22-dB extinction at resonance) and offers a low-voltage operation. A change in the applied voltage by 0.7 V (close to the critically coupled conditions) leads to a transmission change of more than 16 dB. Open eye diagrams at 12 Gb/s are presented. To decrease the insertion loss, multiple material bangaps are further monolithically integrated across the wafer by utilizing the quantum-well-intermixing techniques.

  14. Magnetic resonance diffusion tensor imaging-based evaluation of optic-radiation shape and position in meningioma.

    Science.gov (United States)

    Lv, Xueming; Chen, Xiaolei; Xu, Bainan; Zhang, Jiashu; Zheng, Gang; Li, Jinjiang; Li, Fangye; Sun, Guochen

    2012-03-25

    Employing magnetic resonance diffusion tensor imaging, three-dimensional white-matter imaging and conventional magnetic resonance imaging can demonstrate the tumor parenchyma, peritumoral edema and compression on surrounding brain tissue. A color-coded tensor map and three-dimensional tracer diagram were applied to clearly display the optic-radiation location, course and damage. Results showed that the altered anisotropy values of meningioma patients corresponded with optic-radiation shape, size and position on both sides. Experimental findings indicate that the magnetic resonance diffusion tensor imaging technique is a means of tracing and clearly visualizing the optic radiation.

  15. Magnetic resonance diffusion tensor imaging-based evaluation of optic-radiation shape and position in meningioma

    Institute of Scientific and Technical Information of China (English)

    Xueming Lv; Xiaolei Chen; Bainan Xu; Gang Zheng; Jinjiang Li; Fangye Li; Guochen Sun; liusan

    2012-01-01

    Employing magnetic resonance diffusion tensor imaging, three-dimensional white-matter imaging and conventional magnetic resonance imaging can demonstrate the tumor parenchyma, peritumoral edema and compression on surrounding brain tissue. A color-coded tensor map and three-dimensional tracer diagram were applied to clearly display the optic-radiation location, course and damage. Results showed that the altered anisotropy values of meningioma patients corresponded with optic-radiation shape, size and position on both sides. Experimental findings indicate that the magnetic resonance diffusion tensor imaging technique is a means of tracing and clearly visualizing the optic radiation.

  16. Mode-locked pulse oscillation of a self-resonating enhancement optical cavity

    CERN Document Server

    Hosaka, Yuji; Kosuge, Atsushi; Omori, Tsunehiko; Sakaue, Kazuyuki; Takahashi, Tohru; Uesugi, Yuuki; Urakawa, Junji; Washio, Masakazu

    2016-01-01

    A power enhancement optical cavity is a compelling means of realizing a pulsed laser with a high peak power and a high repetition frequency, which is not feasible by using a simple amplifier scheme. However, a precise feedback system is necessary for maintaining the narrow resonance condition of the optical cavity, and has become a major technical issue in developing such cavities. We developed a new approach that does not require any active feedback system, by placing the cavity in the outer loop of a laser amplifier. We report on the first demonstration of a mode-locked pulse oscillation using the new system.

  17. Optical frequency comb generation from aluminum nitride micro-ring resonator

    CERN Document Server

    Jung, Hojoong; Fong, King Y; Zhang, Xufeng; Tang, Hong X

    2013-01-01

    Aluminum nitride is an appealing nonlinear optical material for on-chip wavelength conversion. Here we report optical frequency comb generation from high quality factor aluminum nitride micro-ring resonators integrated on silicon substrates. By engineering the waveguide structure to achieve near-zero dispersion at telecommunication wavelengths and optimizing the phase matching for four-wave mixing, frequency combs are generated with a single wavelength continuous-wave pump laser. The Kerr coefficient (n2) of aluminum nitride is further extracted from our experimental results.

  18. Four-channel optical demultiplexer based on hexagonal photonic crystal ring resonators

    Science.gov (United States)

    Fallahi, Vahid; Seifouri, Mahmood; Olyaee, Saeed; Alipour-Banaei, Hamed

    2017-08-01

    In this paper, photonic crystal ring resonators with hexagonal lattice structure are used to design a four-channel optical demultiplexer. The structure size, the average transfer coefficient, the quality factor, and the channel spacing are equal to 424.5 µm2, 95.8%, 1943, and 2 nm, respectively. The average crosstalk is also computed to be -18.11 dB. In this study, the plane wave expansion (PWE) and finite-difference time-domain (FDTD) methods are used, respectively, to characterize the photonic bandgap and to investigate the optical behavior of the structure. The proposed design can be used in dense wavelength division multiplexing (DWDM) systems.

  19. Nanolaser spectroscopy and micro-optical resonators for detecting, analyzing, and manipulating bioparticles

    Science.gov (United States)

    Gourley, Paul L

    2012-06-26

    This invention provides a new method for rapidly analyzing single bioparticles to assess their material condition and state of health. The method is enabled by use of a resonant cavity apparatus to measure an optical property related to the bioparticle size and refractive index. Measuring the refractive index is useful for determining material properties of the bioparticle. The material properties depend on the biomolecular composition of the bioparticle. The biomolecular composition is, in turn, dependent on the state of health of the bioparticle. Thus, measured optical properties can be used to differentiate normal (healthy) and abnormal (diseased) states of bioparticles derived from cells or tissues. The method is illustrated with data obtained from a resonator with a gain medium. The invention also provides new methods for making multiple measurements in a single device and detecting, analyzing, and manipulating bioparticles that are much smaller than the wavelength of light.

  20. Observation of vacuum-enhanced electron spin resonance of optically levitated nanodiamonds

    Science.gov (United States)

    Li, Tongcang; Hoang, Thai; Ahn, Jonghoon; Bang, Jaehoon

    Electron spins of diamond nitrogen-vacancy (NV) centers are important quantum resources for nanoscale sensing and quantum information. Combining such NV spin systems with levitated optomechanical resonators will provide a hybrid quantum system for many novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centers in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this novel system, we also investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. Our results show that optical levitation of nanodiamonds in vacuum not only can improve the mechanical quality of its oscillation, but also enhance the ESR contrast, which pave the way towards a novel levitated spin-optomechanical system for studying macroscopic quantum mechanics. The results also indicate potential applications of NV centers in gas sensing.

  1. Entanglement of two optically driven quantum dots mediated by phonons in nanomechanical resonator

    Science.gov (United States)

    He, Yong; Jiang, Meiping

    2017-01-01

    The exciton-phonon coupling between an optically driven quantum dot (QD) and a mechanical resonator can be described by Jaynes-Cummings model under a certain condition, revealing phonon absorption and emission. When two optically driven QDs share a common phonon mode, it shows the phonon-mediated coupling between the QDs. Based on the effective master equation for the reduced density matrix of the two QDs, the temporal evolution of each state and the concurrence (quantum entanglement) between them are studied. The results suggest that the stationary concurrence depends strongly on the resonator temperature. The non-negligible entanglement in the hybrid system is advantaged to develop solid-state quantum information processing.

  2. Optical magnetism and plasmonic Fano resonances in metal-insulator-metal oligomers.

    Science.gov (United States)

    Verre, R; Yang, Z J; Shegai, T; Käll, M

    2015-03-11

    The possibility of achieving optical magnetism at visible frequencies using plasmonic nanostructures has recently been a subject of great interest. The concept is based on designing structures that support plasmon modes with electron oscillation patterns that imitate current loops, that is, magnetic dipoles. However, the magnetic resonances are typically spectrally narrow, thereby limiting their applicability in, for example, metamaterial designs. We show that a significantly broader magnetic response can be realized in plasmonic pentamers constructed from metal-insulator-metal (MIM) sandwich particles. Each MIM unit acts as a magnetic meta-atom and the optical magnetism is rendered quasi-broadband through hybridization of the in-plane modes. We demonstrate that scattering spectra of individual MIM pentamers exhibit multiple Fano resonances and a broad subradiant spectral window that signals the magnetic interaction and a hierarchy of coupling effects in these intricate three-dimensional nanoparticle oligomers.

  3. Optical Analog to Electromagnetically Induced Transparency in Cascaded Ring-Resonator Systems

    Science.gov (United States)

    Wang, Yonghua; Zheng, Hua; Xue, Chenyang; Zhang, Wendong

    2016-01-01

    The analogue of electromagnetically induced transparency in optical methods has shown great potential in slow light and sensing applications. Here, we experimentally demonstrated a coupled resonator induced transparency system with three cascaded ring coupled resonators in a silicon chip. The structure was modeled by using the transfer matrix method. Influences of various parameters including coupling ratio of couplers, waveguide loss and additional loss of couplers on transmission characteristic and group index have been investigated theoretically and numerically in detail. The transmission character of the system was measured by the vertical grating coupling method. The enhanced quality factor reached 1.22 × 105. In addition, we further test the temperature performance of the device. The results provide a new method for the manipulation of light in highly integrated optical circuits and sensing applications. PMID:27463720

  4. Confined optical-phonon-assisted cyclotron resonance in quantum wells via two-photon absorption process

    Science.gov (United States)

    Phuc, Huynh Vinh; Hien, Nguyen Dinh; Dinh, Le; Phong, Tran Cong

    2016-06-01

    The effect of confined phonons on the phonon-assisted cyclotron resonance (PACR) via both one and two photon absorption processes in a quantum well is theoretically studied. We consider cases when electrons are scattered by confined optical phonons described by the Fuchs-Kliewer slab, Ridley's guided, and Huang-Zhu models. The analytical expression of the magneto-optical absorption coefficient (MOAC) is obtained by relating it to the transition probability for the absorption of photons. It predicts resonant peaks caused by transitions between Landau levels and electric subband accompanied by confined phonons emission in the absorption spectrum. The MOAC and the full-width at half-maximum (FWHM) for the intra- and inter-subband transitions are given as functions of the magnetic field, temperature, and quantum well width. In narrow quantum wells, the phonon confinement becomes more important and should be taken into account in studying FWHM.

  5. On the optical properties of carbon nanotubes. Part I. A general formula for the dynamical optical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Morten Grud, E-mail: morteng@math.aau.dk [Department of Mathematical Sciences, Aalborg University, Fredrik Bajers Vej 7G, 9220 Aalborg (Denmark); Ricaud, Benjamin, E-mail: benjamin.ricaud@epfl.ch [Laboratoire de Traitement des Signaux 2, École Polytechnique Fédérale de Lausanne, Lausanne, Vaud (Switzerland); Savoie, Baptiste, E-mail: baptiste.savoie@gmail.com [Dublin Institute for Advanced Studies, School of Theoretical Physics, 10 Burlington Road, Dublin 04 (Ireland)

    2016-02-15

    This paper is the first one in a series of two articles in which we revisit the optical properties of single-walled carbon nanotubes (SWNTs). Produced by rolling up a graphene sheet, SWNTs owe their intriguing properties to their cylindrical quasi-one-dimensional (quasi-1D) structure (the ratio length/radius is experimentally of order of 10{sup 3}). We model SWNT by circular cylinders of small diameters on the surface of which the conduction electron gas is confined by the electric field generated by the fixed carbon ions. The pair-interaction potential considered is the 3D Coulomb potential restricted to the cylinder. To reflect the quasi-1D structure, we introduce a 1D effective many-body Hamiltonian which is the starting-point of our analysis. To investigate the optical properties, we consider a perturbation by a uniform time-dependent electric field modeling an incident light beam along the longitudinal direction. By using Kubo’s method, we derive within the linear response theory an asymptotic expansion in the low-temperature regime for the dynamical optical conductivity at fixed density of particles. The leading term only involves the eigenvalues and associated eigenfunctions of the (unperturbed) 1D effective many-body Hamiltonian and allows us to account for the sharp peaks observed in the optical absorption spectrum of SWNT.

  6. Study on Band Structure of YbB6 and Analysis of Its Optical Conductivity Spectrum

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The electronic structure of YbB6 crystal was studied by means of density functional (GGA+U) method.The calculations were performed by FLAPW method.The high accurate band structure was achieved.The correlation between the feature of the band structure and the Yb-B6 bonding in YbB6 was analyzed.On this basis, some optical constants of YbB6 such as reflectivity, dielectric function, optical conductivity, and energy-loss function were calculated.The results are in good agreement with the experiments.The real part of the optical conductivity spectrum and the energy-loss function spectrum were analyzed in detail.The assignments of the spectra were carried out to correlate the spectral peaks with the interband electronic transitions, which justify the reasonable part of previous empirical assignments and renew the missed or incorrect ones.

  7. Efficient monolithic MgO:LiNbO3 singly resonant optical parametric oscillator

    Science.gov (United States)

    Kozlovsky, W. J.; Gustafson, E. K.; Eckardt, R. C.; Byer, R. L.

    1988-01-01

    A monolithic MgO:LiNbO3 singly resonant optical parametric oscillator (OPO) was operated as both a standing-wave and a ring-geometry resonator. The OPO was pumped by the second harmonic of an amplified single-mode diode-laser-pumped Nd:YAG laser. Pump depletions of greater than 60 percent were observed when pumping four times greater than the 35-W threshold. The OPO output at the resonant signal tuned with temperature from 834 to 958 nm, while the corresponding idler tuned from 1.47 to 1.2 microns. The spectral characteristics of the OPO signal output and the relative merits of a standing wave versus a ring geometry are discussed.

  8. Improvement of the chirality near avoided resonance crossing in optical microcavity

    Institute of Scientific and Technical Information of China (English)

    SONGQingHai[1,2; GUZhiYuan[1; ZHANGNan[1; WANGKaiYang[1; YINingBo[1; XIAOShuMin[1

    2015-01-01

    Chirality is one of the important phenomena at the vicinity of exceptional point (EP). The conventional understanding is that the chirality is determined by asymmetrical scattering efficiency (η), which reaches to zero only when the resonance ap- proaches EP. Here we study the possibility to enhance the chirality in open systems with a more robust mechanism. By com- bining chirality with avoided resonance crossing, we show that the chirality and 7 can be dramatically modified. Taking a spi- ral shaped annular cavity as an example, we show that the chirality of optical resonances can be significantly improved when two sets of chiral states approach each other, The imbalance between counterclockwise (CCW) components and clockwise (CW) components has been enhanced by more than an order of magnitude. Our research provides a new route to tailor and control the chirality in open systems.

  9. Optical and acoustic sensing using Fano-like resonances in dual phononic and photonic crystal plate

    Energy Technology Data Exchange (ETDEWEB)

    Amoudache, Samira [Institut d' Electronique, de Microélectronique et de Nanotechnologie, Université de Lille 1, 59655 Villeneuve d' Ascq (France); Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri, B.P. 17 RP, 15000 Tizi-Ouzou (Algeria); Moiseyenko, Rayisa [Department of Physics, Technical University of Denmark, DTU Physics, Building 309, DK-2800 Kongens Lyngby (Denmark); Pennec, Yan, E-mail: yan.pennec@univ-lille1.fr; Rouhani, Bahram Djafari [Institut d' Electronique, de Microélectronique et de Nanotechnologie, Université de Lille 1, 59655 Villeneuve d' Ascq (France); Khater, Antoine [Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, l' UNAM, Université du Maine, 72085 Le Mans (France); Lucklum, Ralf [Institute of Micro and Sensor Systems (IMOS), Otto-von-Guericke-University, P.O. Box 4120, D-39016 Magdeburg (Germany); Tigrine, Rachid [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri, B.P. 17 RP, 15000 Tizi-Ouzou (Algeria)

    2016-03-21

    We perform a theoretical study based on the transmissions of optical and acoustic waves normally impinging to a periodic perforated silicon plate when the embedded medium is a liquid and show the existence of Fano-like resonances in both cases. The signature of the resonances appears as well-defined asymmetric peaks in the phononic and photonic transmission spectra. We show that the origin of the Fano-like resonances is different with respect to the nature of the wave. In photonic, the origin comes from guided modes in the photonic plate while in phononic we show that it comes from the excitation of standing waves confined inside the cavity coming from the deformation of the water/silicon edges of the cylindrical inclusion. We finally use these features for sensing and show ultra-sensitivity to the light and sound velocities for different concentrations of analytes.

  10. Optical back-action in silicon nanowire resonators: bolometric versus radiation pressure effects

    Science.gov (United States)

    Gil-Santos, E.; Ramos, D.; Pini, V.; Llorens, J.; Fernández-Regúlez, M.; Calleja, M.; Tamayo, J.; San Paulo, A.

    2013-03-01

    We study optical back-action effects associated with confined electromagnetic modes in silicon nanowire resonators interacting with a laser beam used for interferometric read-out of the nanowire vibrations. Our analysis describes the resonance frequency shift produced in the nanowires by two different mechanisms: the temperature dependence of the nanowire's Young's modulus and the effect of radiation pressure. We find different regimes in which each effect dominates depending on the nanowire morphology and dimensions, resulting in either positive or negative frequency shifts. Our results also show that in some cases bolometric and radiation pressure effects can have opposite contributions so that their overall effect is greatly reduced. We conclude that Si nanowire resonators can be engineered for harnessing back-action effects for either optimizing frequency stability or exploiting dynamic phenomena such as parametric amplification.

  11. Rabi oscillations of two-photon states in nonlinear optical resonators

    Science.gov (United States)

    Sherkunov, Y.; Whittaker, David M.; Fal'ko, Vladimir

    2016-02-01

    We demonstrate that four-wave mixing processes in high-quality nonlinear resonators can lead to Rabi-like oscillations in photon occupation numbers and second-order correlation functions, being a characteristic feature of the presence of entangled photon pairs in the optical signal. In the case of a system driven by a continuous coherent pump, the oscillations occur in the transient regime. We show that driving the system with pulsed coherent pumping would generate strongly antibunched photon states.

  12. Combining an Optical Resonance Biosensor with Enzyme Activity Kinetics to Understand Protein Adsorption and Denaturation

    OpenAIRE

    Wilson, Kerry A.; Finch, Craig A.; Anderson, Phillip; Vollmer, Frank; Hickman, James J.

    2014-01-01

    Understanding protein adsorption and resultant conformation changes on modified and unmodified silicon dioxide surfaces is a subject of keen interest in biosensors, microfluidic systems and for medical diagnostics. However, it has been proven difficult to investigate the kinetics of the adsorption process on these surfaces as well as understand the topic of the denaturation of proteins and its effect on enzyme activity. A highly sensitive optical whispering gallery mode (WGM) resonator was us...

  13. Length control of an optical resonator using second-order transverse modes

    CERN Document Server

    Miller, John

    2014-01-01

    We present the analysis of an unorthodox technique for locking a laser to a resonant optical cavity. Error signals are derived from the interference between the fundamental cavity mode and higher-order spatial modes of order two excited by mode mismatch. This scheme is simple, inexpensive and, in contrast to similar techniques, first-order-insensitive to beam jitter. After mitigating sources of technical noise, performance is fundamentally limited by quantum shot-noise.

  14. Continuous-wave singly resonant optical parametric oscillator placed inside a ring laser

    DEFF Research Database (Denmark)

    Abitan, Haim; Buchhave, Preben

    2003-01-01

    A cw singly resonant optical parametric oscillator (SRO) was built and placed inside the cavity of a ring laser. The system consists of a diode-end-pumped Nd:YVO4 ring laser with intracavity periodically poled lithium niobate as the nonlinear gain medium of the SRO. When the laser was operated...... the laser was coupled with the SRO. The results show that it is preferable to couple a SRO with a unidirectional ring laser....

  15. Use of nondegenerate resonant leaky modes to fashion diverse optical spectra.

    Science.gov (United States)

    Ding, Y; Magnusson, Robert

    2004-05-03

    In this paper, we show that bandstop and bandpass filters with versatile spectral attributes can be implemented with modulated films possessing asymmetric grating profiles. The profile asymmetry breaks the resonant leaky mode degeneracy at normal incidence thereby permitting precise spectral spacing of interacting leaky modes with interesting implications in optical filter design. Several example filters, containing only a single grating layer, are designed with this methodology to demonstrate the concept.

  16. Optical conductivity in A3C60 (A=K, Rb)

    NARCIS (Netherlands)

    Brink, J. van den; Gunnarsson, O.; Eyert, V.

    1997-01-01

    Published in: Phys. Rev. B 57 (1998) 2163-2167 Citing articles (CrossRef) citations recorded in [Science Citation Index] Abstract: We study the optical conductivity in A3C60 (A =K, Rb). The effects of the electron-phonon interaction is included to lowest order in the coupling strength lambda. It is

  17. Controlling optical responses through local dielectric resonance in nanometre metallic clusters

    Institute of Scientific and Technical Information of China (English)

    Chen Liang-Liang; Gu Ying; Wang Li-Jin; Gong Qi-Huang

    2007-01-01

    Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through varying the difference admittance ratio η[= (ε2 - ε0)/(ε1 - ε0)], we find that their optical responses are determined by the local resonance.There is a blueshift of absorption peaks with the increase of η. Simultaneously, it is known that the absorption peaks will be redshifted by enlarging the cluster size. By adjusting the nano-metallic cluster geometry, size and admittances,we can control the positions and intensities of absorption peaks effectively. We have also deduced the effective linear optical responses of three-comPonent composites εe = ε0 (1 + ∑nsn=1 [(γn1 + ηγn2 )/(ε0 (s - sn))]), and the sum rule of cross sections: ∑nsn=1 (γn1 + ηγn2) = Nh1 + Nh2, where Nh1and Nh2 are the numbers of ε1 and ε2 bonds along the electric field, respectively. These results may be beneficial to the study of surface plasmon resonances on a nanometre scale.

  18. Optical conductivity and resistivity in the two-band Emery model

    Science.gov (United States)

    Minh-Tien, Tran

    1994-01-01

    The temperature- and frequency-dependent conductivity due to the scattering of oxygen holes by antiferromagnetic spin fluctuations of the copper spins in the two-band Emergy model is calculated. Using the dynamic spin susceptibility obtained in the mean-field Schwinger boson approach, the resistivity obeys a near linear temperature dependence at high temperatures, whereas at low temperatures a quadratic behaviour holds. At the same time, the optical conductivity contains the Drude peak around zero frequency, whereas the scattering rate of quasiparticle appears to be proportional to frequency. Our results are essentially in agreement with experiments, at least qualitatively, and support the conclusion that the normal-state basal-plane resistivity and optical conductivity of high- Tc superconductors may be explained by two-dimensional spin-fluctuation scattering in the Fermi-liquid picture.

  19. Mimic the optical conductivity in disordered solids via gauge/gravity duality

    CERN Document Server

    Sun, Jia-Rui; Zhang, Hai-Qing

    2014-01-01

    We study the optical conductivity in a (2+1)-dimensional non-relativistic field theory holographically dual to a (3+1)-dimensional charged Lifshitz black brane with the Einstein-Maxwell-dilaton theory. Surprisingly, we find that the optical AC conductivity satisfies the nontrivial (non-)power law scaling in the high frequency regime rather than approaching to a constant when the dynamical critical exponent $z>1$, which is qualitatively similar to those in various disordered solids in condensed matter systems. Besides, this (non-)power law scaling behavior shows some universality, which is robust against the temperatures. We argue that the peculiar scaling behavior of AC conductivity may stem from the couplings of the dilaton field with the gauge fields and also the logarithmic behavior near the boundary in the Lifshitz spacetime.

  20. The correlation between magneto-optical response and magnetic dipole resonance excitation in subwavelength silicon-nickel nanogratings

    Science.gov (United States)

    Musorin, A. I.; Barsukova, M. G.; Shorokhov, A. S.; Neshev, D. N.; Kivshar, Y. S.; Fedyanin, A. A.

    2017-09-01

    The advantages of gyrotopic materials are combined with the field of high-index metamaterials. The enhancement of the magneto-optical response in the spectral vicinity of the magnetic dipole resonance of a dielectric silicon nanodisks is numerically shown.

  1. Underpotential deposition of a copper monolayer on a gold film sensed by integrated optical surface plasmon resonance

    OpenAIRE

    Abanulo, J.C.; Harris, R.D.; Bartlett, P.N.; Wilkinson, J.S.

    2000-01-01

    An integrated optical surface plasmon resonance sensor combined with electrochemical control is used to monitor the underpotential deposition of a copper monolayer onto a gold film from 1 mM Cu2+ in 0.1 M perchloric acid.

  2. Optical nucleation of bubble clouds in a high pressure spherical resonator.

    Science.gov (United States)

    Anderson, Phillip; Sampathkumar, A; Murray, Todd W; Gaitan, D Felipe; Glynn Holt, R

    2011-11-01

    An experimental setup for nucleating clouds of bubbles in a high-pressure spherical resonator is described. Using nanosecond laser pulses and multiple phase gratings, bubble clouds are optically nucleated in an acoustic field. Dynamics of the clouds are captured using a high-speed CCD camera. The images reveal cloud nucleation, growth, and collapse and the resulting emission of radially expanding shockwaves. These shockwaves are reflected at the interior surface of the resonator and then reconverge to the center of the resonator. As the shocks reconverge upon the center of the resonator, they renucleate and grow the bubble cloud. This process is repeated over many acoustic cycles and with each successive shock reconvergence, the bubble cloud becomes more organized and centralized so that subsequent collapses give rise to stronger, better defined shockwaves. After many acoustic cycles individual bubbles cannot be distinguished and the cloud is then referred to as a cluster. Sustainability of the process is ultimately limited by the detuning of the acoustic field inside the resonator. The nucleation parameter space is studied in terms of laser firing phase, laser energy, and acoustic power used.

  3. Optimization of the sinusoidal phase modulation technique in resonant fiber optic gyro

    Science.gov (United States)

    Wang, Linglan; Li, Hanzhao; Zhang, Jianjie; Ma, Huilian; Jin, Zhonghe

    2017-03-01

    The sinusoidal wave phase modulation and demodulation have been widely used in the signal processing system of the resonant fiber optic gyro (RFOG). An appropriate selection of the modulation frequency is of great importance, for the frequency value directly affects the slope of the demodulation curve at the resonance point which carries the gyro output information. A large demodulation slope is pursued in a high-performance RFOG. In this paper, an analytical expression of the demodulation slope is for the first time deduced in both transmission-type and reflection-type fiber ring resonators without any approximation. The relationship between the slope value and the modulation frequency at the resonance point is accurately calculated. The calculated best modulation frequency maximizing the demodulation slope at the resonance point is different from previous widely used optimal frequency given by the Lorentzian approximation method. More importantly, both theoretical and experimental results indicate that the achieved maximal demodulation slope from the proposed analytical expression method is double of that obtaining from the Lorentzian approximation method.

  4. Fiber-optic surface plasmon resonant sensor with low-index anti-oxidation coating

    Institute of Scientific and Technical Information of China (English)

    Yong Chen; Rongsheng Zheng; Yonghua Lu; Pei Wang; Hai Ming

    2011-01-01

    A multimode fiber-optic surface plasmon resonance (SPR) sensor with a MgF2 film as a modulated layer is studied. The fiber-optic SPR sensor is investigated theoretically, specifically the influence of the dielectric protecting layer, using a four-layer model. The sensor is then fabricated with the optimal parameters suggested by the theoretical simulation. The sensor has a high sensitivity in the analyte refractive index (RI) range of 1.33-1.40. The best sensitivity of 4464 nm/RIU is achieved in the experiment. The use of dielectric film (MgF2) can not only modulate the resonance wavelength of the sensor, but also protect the silver film from oxidation.%A multimode fiber-optic surface plasmon resonance (SPR) sensor with a MgF2 film as a modulated layer is studied.The fiber-optic SPR sensor is investigated theoretically,specifically the influence of the dielectric protecting layer,using a four-layer model.The sensor is then fabricated with the optimal parameters suggested by the theoretical simulation.The sensor has a high sensitivity in the analyte refractive index (RI) range of 1.33-1.40.The best sensitivity of 4 464 nm/RIU is achieved in the experiment.The use of dielectric film (MgF2) can not only modulate the resonance wavelength of the sensor,but also protect the silver film from oxidation.Surface plasmon resonance (SPR) is a kind of coherent oscillation between the free electrons at a metal/dielectric interface and the optical wave.The hybridized excitation,called surface plasmon polariton (SPP),is the electromagnetic excitation that propagates along the interface as a longitudinal wave.At a given wavelength and angle that satisfy the wave-vector matching condition,the incident light will be intensively absorbed.Due to its high sensitivity to the refractive index (RI) of the adjacent material,the SPR phenomenon was firstly applied to gas detection in 1983[1].The SPR sensing technology has been widely used in the detection of biological and chemical analytes

  5. Double-Slot Hybrid Plasmonic Ring Resonator Used for Optical Sensors and Modulators

    Directory of Open Access Journals (Sweden)

    Xu Sun

    2015-11-01

    Full Text Available An ultra-high sensitivity double-slot hybrid plasmonic (DSHP ring resonator, used for optical sensors and modulators, is developed. Due to high index contrast, as well as plasmonic enhancement, a considerable part of the optical energy is concentrated in the narrow slots between Si and plasmonic materials (silver is used in this paper, which leads to high sensitivity to the infiltrating materials. By partial opening of the outer plasmonic circular sheet of the DSHP ring, a conventional side-coupled silicon on insulator (SOI bus waveguide can be used. Experimental results demonstrate ultra-high sensitivity (687.5 nm/RIU of the developed DSHP ring resonator, which is about five-times higher than for the conventional Si ring with the same geometry. Further discussions show that a very low detection limit (5.37 × 10−6 RIU can be achieved after loaded Q factor modifications. In addition, the plasmonic metal structures offer also the way to process optical and electronic signals along the same hybrid plasmonic circuits with small capacitance (~0.275 fF and large electric field, which leads to possible applications in compact high-efficiency electro-optic modulators, where no extra electrodes for electronic signals are required.

  6. Detection and identification of microparticles/nanoparticles and blood components using optical resonance of whispering-gallery modes in microspheres

    Science.gov (United States)

    Tcherniavskaia, E. A.; Saetchnikov, V. A.

    2010-11-01

    We present experimental data on the dependence of optical resonance spectra of whispering-gallery modes in dielectric microspheres on the constituent composition of solutions modeling blood plasma and also containing disease indicators and virus ghosts. We observe substantial changes in the optical resonance spectra of whispering-gallery modes, associated both with a change in the macroscopic parameters of the microsphere environment and with possible interaction between the microsphere surface and components of the solution.

  7. Design and analysis of a dual-axis resonator fiber-optic gyroscope employing a single source.

    Science.gov (United States)

    Pinnoji, Prerana Dabral; Nayak, Jagannath

    2013-08-01

    In this paper, design of a resonator fiber-optic gyroscope comprised of a single laser source and two optical fiber resonator rings is presented. A typical gyroscope measures angular rotation around a fixed axis, whereas the proposed design can sense simultaneous rotation about two orthogonal axes. Two variants of the design are proposed and analyzed using a mathematical model based on Jones matrix methodology.

  8. An on-chip coupled resonator optical waveguide single-photon buffer.

    Science.gov (United States)

    Takesue, Hiroki; Matsuda, Nobuyuki; Kuramochi, Eiichi; Munro, William J; Notomi, Masaya

    2013-01-01

    Integrated quantum optical circuits are now seen as one of the most promising approaches with which to realize single-photon quantum information processing. Many of the core elements for such circuits have been realized, including sources, gates and detectors. However, a significant missing function necessary for photonic quantum information processing on-chip is a buffer, where single photons are stored for a short period of time to facilitate circuit synchronization. Here we report an on-chip single-photon buffer based on coupled resonator optical waveguides (CROW) consisting of 400 high-Q photonic crystal line-defect nanocavities. By using the CROW, a pulsed single photon is successfully buffered for 150 ps with 50-ps tunability while maintaining its non-classical properties. Furthermore, we show that our buffer preserves entanglement by storing and retrieving one photon from a time-bin entangled state. This is a significant step towards an all-optical integrated quantum information processor.

  9. An on-chip coupled resonator optical waveguide single-photon buffer

    CERN Document Server

    Takesue, Hiroki; Kuramochi, Eiichi; Munro, Willian J; Notomi, Masaya

    2013-01-01

    Integrated quantum optical circuits are now seen as one of the most promising approaches with which to realize single photon quantum information processing. Many of the core elements for such circuits have been realized including sources, gates and detectors. However, a significant missing function necessary for photonic information processing on-chip is a buffer, where single photons are stored for a short period of time to facilitate circuit synchronization. Here we report an on-chip single photon buffer based on coupled resonator optical waveguides (CROW) consisting of 400 high-Q photonic crystal line defect nanocavities. By using the CROW, a pulsed single photon was successfully buffered for 150 ps with 50-ps tunability while maintaining its non-classical properties. Furthermore, we showed that our buffer preserves entanglement by storing and retrieving one photon from a time-bin entangled state. This is a significant step towards an all-optical integrated quantum information processor.

  10. A 2-dimensional optical architecture for solving Hamiltonian path problem based on micro ring resonators

    Science.gov (United States)

    Shakeri, Nadim; Jalili, Saeed; Ahmadi, Vahid; Rasoulzadeh Zali, Aref; Goliaei, Sama

    2015-01-01

    The problem of finding the Hamiltonian path in a graph, or deciding whether a graph has a Hamiltonian path or not, is an NP-complete problem. No exact solution has been found yet, to solve this problem using polynomial amount of time and space. In this paper, we propose a two dimensional (2-D) optical architecture based on optical electronic devices such as micro ring resonators, optical circulators and MEMS based mirror (MEMS-M) to solve the Hamiltonian Path Problem, for undirected graphs in linear time. It uses a heuristic algorithm and employs n+1 different wavelengths of a light ray, to check whether a Hamiltonian path exists or not on a graph with n vertices. Then if a Hamiltonian path exists, it reports the path. The device complexity of the proposed architecture is O(n2).

  11. Radiation-Suppressed plasmonic open resonators designed by nonmagnetic transformation optics

    Science.gov (United States)

    Xu, Hongyi; Wang, Xingjue; Yu, Tianyuan; Sun, Handong; Zhang, Baile

    2012-01-01

    How to confine light energy associated with surface plasmon polaritons (SPPs) in a physical space with minimal radiation loss whereas creating maximum interacting section with surrounding environment is of particular interest in plasmonic optics. By virtue of transformation optics, we propose a design method of forming a polygonal surface-plasmonic resonator in fully open structures by applying the nonmagnetic affine transformation optics strategy. The radiation loss can be suppressed because SPPs that propagate in the designed open structures will be deceived as if they were propagating on a flat metal/dielectric interface without radiation. Because of the nonmagnetic nature of the transformation strategy, this design can be implemented with dielectric materials available in nature. An experimentally verifiable model is subsequently proposed for future experimental demonstration. Our design may find potential applications in omnidirectional sensing, light harvesting, energy storage and plasmonic lasing. PMID:23136641

  12. Magnetic resonance imaging (MRI) in the diagnosis of optic neuritis and neuropathy

    Energy Technology Data Exchange (ETDEWEB)

    Kakisu, Yonetsugu; Adachi-Usami, Emiko; Kojima, Shigeyuki; Hirayama, Keizo

    1989-02-01

    Magnetic resonance imaging (MRI) was performed in thirty patients who had been suffering from optic neuritis (ON). Twenty-one cases were caused by multiple sclerosis (MS) and in 9 cases the causes been defined. In MRI, abnormalities were found in 17 out of 21 MS cases in several places such as near the ventricles, mid-brain, spinal cord etc. Increased signals from the optic chiasm to optic radiation were found in 5 cases. However, abnormal MRI findings did not always correspond to Goldmann visual field defects. In 3 out of 9 cases of ON with unknown causes, high signals in the white matter of the brain were found, and it was suggested that those may develop to MS. MRI was, thus, proved to be very useful for the diagnois of MS.

  13. Chip-integrated optical power limiter based on an all-passive micro-ring resonator

    Science.gov (United States)

    Yan, Siqi; Dong, Jianji; Zheng, Aoling; Zhang, Xinliang

    2014-10-01

    Recent progress in silicon nanophotonics has dramatically advanced the possible realization of large-scale on-chip optical interconnects integration. Adopting photons as information carriers can break the performance bottleneck of electronic integrated circuit such as serious thermal losses and poor process rates. However, in integrated photonics circuits, few reported work can impose an upper limit of optical power therefore prevent the optical device from harm caused by high power. In this study, we experimentally demonstrate a feasible integrated scheme based on a single all-passive micro-ring resonator to realize the optical power limitation which has a similar function of current limiting circuit in electronics. Besides, we analyze the performance of optical power limiter at various signal bit rates. The results show that the proposed device can limit the signal power effectively at a bit rate up to 20 Gbit/s without deteriorating the signal. Meanwhile, this ultra-compact silicon device can be completely compatible with the electronic technology (typically complementary metal-oxide semiconductor technology), which may pave the way of very large scale integrated photonic circuits for all-optical information processors and artificial intelligence systems.

  14. Performances of different metals in optical fibre-based surface plasmon resonance sensor

    Indian Academy of Sciences (India)

    Navneet K Sharma

    2012-03-01

    The capability of various metals used in optical fibre-based surface plasmon resonance (SPR) sensing is studied theoretically. Four metals, gold (Au), silver (Ag), copper (Cu) and aluminium (Al) are considered for the present study. The performance of the optical fibre-based SPR sensor with four different metals is obtained numerically and compared in detail. The performance of optical fibre-based SPR sensor has been analysed in terms of sensitivity, signal-to-noise (SNR) ratio and quality parameter. It is found that the performance of optical fibre-based SPR sensor with Au metal is better than that of the other three metals. The sensitivity of the optical fibre-based SPR sensor with 50 nm thick and 10 mm long Au metal film of exposed sensing region is 2.373 m/RIU with good linearity, SNR is 0.724 and quality parameter is 48.281 RIU-1. The thickness of the metal film and the length of the exposed sensing region of the optical fibre-based SPR sensor for each metal are also optimized.

  15. Chip-integrated optical power limiter based on an all-passive micro-ring resonator.

    Science.gov (United States)

    Yan, Siqi; Dong, Jianji; Zheng, Aoling; Zhang, Xinliang

    2014-10-20

    Recent progress in silicon nanophotonics has dramatically advanced the possible realization of large-scale on-chip optical interconnects integration. Adopting photons as information carriers can break the performance bottleneck of electronic integrated circuit such as serious thermal losses and poor process rates. However, in integrated photonics circuits, few reported work can impose an upper limit of optical power therefore prevent the optical device from harm caused by high power. In this study, we experimentally demonstrate a feasible integrated scheme based on a single all-passive micro-ring resonator to realize the optical power limitation which has a similar function of current limiting circuit in electronics. Besides, we analyze the performance of optical power limiter at various signal bit rates. The results show that the proposed device can limit the signal power effectively at a bit rate up to 20 Gbit/s without deteriorating the signal. Meanwhile, this ultra-compact silicon device can be completely compatible with the electronic technology (typically complementary metal-oxide semiconductor technology), which may pave the way of very large scale integrated photonic circuits for all-optical information processors and artificial intelligence systems.

  16. AM-to-PM conversion in a resonant microwave optical rectification detector.

    Science.gov (United States)

    Kolner, Brian H; Kang, Lanbing

    2017-01-15

    A LiNbO3-loaded microwave cavity pumped with weakly AM-modulated 30 fs optical pulses was used as a platform to investigate AM-to-PM conversion in the optical rectification process. Theoretical treatment of AM-to-PM conversion (i.e., peak-induced electrical phase deviation βi due to optical power modulation with index m) suggests that the dominant mechanism is self-group-velocity modulation due to χ(3) and cascaded χ(2) processes with a value of δ=βi/m=-151  dB, linearly dependent on the optical power at intensities of 6×1010  W/m2 in a 40 mm long LiNbO3 crystal. This is in stark contrast to p-i-n photodiodes which can exhibit an AM-to-PM conversion gain δ>0  dB. In this experiment, we measured values of δ for a resonant optical rectification detector using typical mode-locked Ti:sapphire laser pulses (100 MHz, 30 fs, Pavg≈100  mW) and found an instrumentation-limited lower bound of δ≈-43.5  dB, independent of the optical power.

  17. Equilateral Triangular Dielectric Resonator Nantenna at Optical Frequencies for Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Waleed Tariq Sethi

    2015-01-01

    Full Text Available The last decade has witnessed a remarkable growth in the telecommunication industry. With the introduction of smart gadgets, the demand for high data rate and bandwidth for wireless applications have increased exponentially at the cost of exponential consumption of energy. The latter is pushing the research and industry communities to devise green communication solutions that require the design of energy saving devices and techniques in one part and ambient energy harvesting techniques in the other part. With the advent of nanocomponents fabrication technology, researchers are now able to tap into the THz frequency regime and fabricate optical low profile antennas at a nanoscale. Optical antennas have proved their potential and are revolutionizing a class of novel optical detectors, interconnectors, sensors, and energy harvesting related fields. Authors in this paper propose an equilateral triangular dielectric resonator nantenna (ETDRNA working at 193.5 THz standard optical frequency. The simulated antenna achieves an impedance bandwidth from 192.3 THz to 197.3 THz with an end-fire directivity of 8.6 dBi, covering the entire standard optical window of C-band. Numerical demonstrations prove the efficiency of the nantenna at the frequencies of interest, making it a viable candidate for future green energy harvesting and high speed optical applications.

  18. Optically resonant subwavelength films for tamper-indicating tags and seals

    Energy Technology Data Exchange (ETDEWEB)

    Alvine, Kyle J.; Suter, Jonathan D.; Bernacki, Bruce E.; Bennett, Wendy D.

    2015-05-23

    We present the design, modeling and performance of a proof-of-concept tamper indicating approach that exploits newly-developed subwavelength-patterned films. These films have a nanostructure-dependent resonant optical reflection that is wavelength, angle, and polarization dependent. As such, they can be tailored to fabricate overlay transparent films for tamper indication and authentication of sensitive or controlled materials not possible with currently-known technologies. An additional advantage is that the unique optical signature is dictated by the geometry and fabrication process of the nanostructures in the film, rather than on the material used. The essential structure unit in the subwavelength resonant coating is a nanoscale Open-Ring Resonator (ORR). This building block is fabricated by coating a dielectric nanoscale template with metal to form a hemispherical shell-like structure. This curved metallic shell structure has a cross-section with an intrinsic capacitance and inductance and is thus the optical equivalent to the well-known “LC” circuit where the capacitance and inductance are determined by the nanoshell dimensions. For structures with sub 100 nm scale, this resonance occurs in the visible electromagnetic spectrum, and in the IR for larger shells. Tampering of the film would be visible though misalignment of the angular dependence of the features in the film. It is additionally possible to add in intrinsic oxidation and strain sensitive matrix materials to further complicate tamper repair and counterfeiting. Cursory standoff readout would be relatively simple using a combination of a near-infrared (or visible) LED flashlight and polarizer or passively using room lighting illumination and a dispersive detector.

  19. Optically resonant subwavelength films for tamper-indicating tags and seals

    Science.gov (United States)

    Alvine, Kyle J.; Suter, Jonathan D.; Bernacki, Bruce E.; Bennett, Wendy D.

    2015-05-01

    We present the design, modeling and performance of a proof-of-concept tamper indicating approach that exploits newlydeveloped subwavelength-patterned films. These films have a nanostructure-dependent resonant optical reflection that is wavelength, angle, and polarization dependent. As such, they can be tailored to fabricate overlay transparent films for tamper indication and authentication of sensitive or controlled materials not possible with currently-known technologies. An additional advantage is that the unique optical signature is dictated by the geometry and fabrication process of the nanostructures in the film, rather than on the material used. The essential structure unit in the subwavelength resonant coating is a nanoscale Open-Ring Resonator (ORR). This building block is fabricated by coating a dielectric nanoscale template with metal to form a hemispherical shell-like structure. This curved metallic shell structure has a cross-section with an intrinsic capacitance and inductance and is thus the optical equivalent to the well-known "LC" circuit where the capacitance and inductance are determined by the nanoshell dimensions. For structures with sub 100 nm scale, this resonance occurs in the visible electromagnetic spectrum, and in the IR for larger shells. Tampering of the film would be visible though misalignment of the angle-sensitive features in the film. It is additionally possible to add in intrinsic oxidation and strain sensitive matrix materials to further complicate tamper repair and counterfeiting. Cursory standoff readout would be relatively simple using a combination of a near-infrared (or visible) LED flashlight and polarizer or passively using room lighting illumination and a dispersive detector.

  20. Study of thermal conductivity of magnetorheological fluids using the thermal-wave resonant cavity and its relationship with the viscosity

    Science.gov (United States)

    Forero-Sandoval, I. Y.; Vega-Flick, A.; Alvarado-Gil, J. J.; Medina-Esquivel, R. A.

    2017-02-01

    The thermal conductivity and viscosity of a magnetorheological suspension composed of carbonyl iron particles immerse in silicone oil were studied. Thermal wave resonant cavity was employed to measure the thermal diffusivity of the magnetorheological fluid as a function of an externally applied magnetic field. The dynamic viscosity was also measured and its relationship with the concentration of the particles and the magnetic field strength was investigated. The results show that higher concentrations of carbonyl iron particles as well as higher magnetic field intensities lead to a significant increase in thermal conductivity. The relationship between the thermal conductivity and the dynamic viscosity was explored. Our measurements were examined using an analytical relation between the thermal conductivity and the dynamic viscosity. The results show that by using highly viscous materials, the order induced in the micro particles can be kept for a relatively long time and therefore the increase in thermal conductivity can also be maintained.

  1. Linear and nonlinear intra-conduction band optical absorption in (In,Ga)N/GaN spherical QD under hydrostatic pressure

    Science.gov (United States)

    El Ghazi, Haddou; Jorio, Anouar; Zorkani, Izeddine

    2014-11-01

    Linear, third-order nonlinear and total optical absorption coefficients of intra-conduction band 1s-1p transition with hydrogenic shallow-donor impurity in wurtzite (In,Ga)N/GaN spherical quantum dot are reported. Hydrostatic pressure effect is investigated within the framework of single band effective-mass approximation using a combination of Quantum Genetic Algorithm (QGA) and Hartree-Fock-Roothaan (HFR) method. The results show that the pressure has a great influence on optical absorption coefficients of QDs. A blue-shift of the resonant peak is observed while the maximum of the amplitude of optical absorption coefficients decreases under hydrostatic pressure effect. A good agreement is shown compared with results of the finding.

  2. Microwave-induced excess quasiparticles in superconducting resonators measured through correlated conductivity fluctuations

    NARCIS (Netherlands)

    De Visser, P.J.; Baselmans, J.J.A.; Yates, S.J.C.; Diener, P.; Endo, A.; Klapwijk, T.M.

    2012-01-01

    We have measured the number of quasiparticles and their lifetime in aluminium superconducting microwave resonators. The number of excess quasiparticles below 160 mK decreases from 72 to 17 μm−3 with a 6 dB decrease of the microwave power. The quasiparticle lifetime increases accordingly from 1.4 to

  3. Analysis of electro-optic switches with series-coupled multiple microring resonators

    Institute of Scientific and Technical Information of China (English)

    YAN Xin; MA Chun-sheng; ZHENG Chuan-tao; WANG Xian-yin; ZHANG Da-ming

    2009-01-01

    In terms of the coupled mode theory, microring resonance and electro-optic modulation princeple, a reasonable project is proposed for designing an electro-optic switch with the series-coupled multiple microring resonators. The simulation and optimization are performed at the resonant wavelength of 1550 nm. The results are as follows: the core size of the microring is 1.6 μm×1.6 μm, the confined layer between the core and the electrode is 1.6 μm, the thickness of the electrode is 0.15 μm, the radius ofthe microring is 15.2 μm, the coupling gap between the microring and the channel is 0.14 μm, and the one between the microring and the microring is 0.6 μm, microring number M is 4, the switching voltage is 4 V, the insertion loss is 5.4 dB, and the crosstalk is -20 dB. The output spectrum is much flatter and much steeper than that of the single microring.

  4. Resonance-inclined optical nuclear spin polarization of liquids in diamond structures

    Science.gov (United States)

    Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

    2016-02-01

    Dynamic nuclear polarization (DNP) of molecules in a solution at room temperature has the potential to revolutionize nuclear magnetic resonance spectroscopy and imaging. The prevalent methods for achieving DNP in solutions are typically most effective in the regime of small interaction correlation times between the electron and nuclear spins, limiting the size of accessible molecules. To solve this limitation, we design a mechanism for DNP in the liquid phase that is applicable for large interaction correlation times. Importantly, while this mechanism makes use of a resonance condition similar to solid-state DNP, the polarization transfer is robust to a relatively large detuning from the resonance due to molecular motion. We combine this scheme with optically polarized nitrogen-vacancy (NV) center spins in nanodiamonds to design a setup that employs optical pumping and is therefore not limited by room temperature electron thermal polarization. We illustrate numerically the effectiveness of the model in a flow cell containing nanodiamonds immobilized in a hydrogel, polarizing flowing water molecules 4700-fold above thermal polarization in a magnetic field of 0.35 T, in volumes detectable by current NMR scanners.

  5. On-column micro gas chromatography detection with capillary-based optical ring resonators.

    Science.gov (United States)

    Shopova, Siyka I; White, Ian M; Sun, Yuze; Zhu, Hongying; Fan, Xudong; Frye-Mason, Greg; Thompson, Aaron; Ja, Shiou-jyh

    2008-03-15

    We developed a novel on-column micro gas chromatography (microGC) detector using capillary based optical ring resonators (CBORRs). The CBORR is a thin-walled fused silica capillary with an inner diameter ranging from a few tens to a few hundreds of micrometers. The interior surface of the CBORR is coated with a layer of stationary phase for gas separation. The circular cross section of the CBORR forms a ring resonator and supports whispering gallery modes (WGMs) that circulate along the ring resonator circumference hundreds of times. The evanescent field extends into the core and is sensitive to the refractive index change induced by the interaction between the gas sample and the stationary phase. The WGM can be excited and monitored at any location along the CBORR by placing a tapered optical fiber against the CBORR, thus enabling on-column real-time detection. Rapid separation of both polar and nonpolar samples was demonstrated with subsecond detection speed. Theoretical work was also established to explain the CBORR detection mechanism. While low-nanogram detection limits are observed in these preliminary tests, many methods for improvements are under investigation. The CBORR is directly compatible with traditional capillary GC columns without any dead volumes. Therefore, the CBORR-based muGC is a very promising technology platform for rapid, sensitive, and portable analytical devices.

  6. Interspecies Feshbach resonances in an ultracold, optically trapped Bose-Fermi mixture of cesium and lithium

    Energy Technology Data Exchange (ETDEWEB)

    Repp, Marc

    2013-05-08

    This thesis reports on the tunability of interactions in ultracold Bose-Fermi mixtures of Cesium and Lithium. The first realization of an optically trapped {sup 6}Li - {sup 133}Cs mixture enabled to perform trap loss spectroscopy measurements to identify magnetic Feshbach resonances. A total of 19 interspecies Feshbach resonances, all in the magnetic field range between 650 G and 950 G, were observed for the two energetically lowest spin states of each species. Two 5 G broad and especially two 60 G broad s-wave resonances give perspectives to produce a dipolar quantum gas of LiCs ground state molecules as well as to study the Efimov effect in highly mass imbalanced systems. In addition, a unique relative tunability of intra- and interspecies scattering lengths was found which makes the {sup 6}Li - {sup 133}Cs system also well suited for the investigation of polarons. Evaporative cooling was performed on optically trapped samples which contained only one of the species. In this way, Bose-Einstein condensates of {sup 6}Li molecules as well as {sup 133}Cs samples at a phase-space density of ρ = 4 . 10{sup -2} were prepared. All experiments were performed in a new apparatus, which has been designed and set up during this thesis.

  7. Single exosome detection in serum using microtoroid optical resonators (Conference Presentation)

    Science.gov (United States)

    Su, Judith

    2016-03-01

    Recently exosomes have attracted interest due to their potential as cancer biomarkers. We report the real time, label-free sensing of single exosomes in serum using microtoroid optical resonators. We use this approach to assay the progression of tumors implanted in mice by specifically detecting low concentrations of tumor-derived exosomes. Our approach measures the adsorption of individual exosomes onto a functionalized silica microtoroid by tracking changes in the optical resonant frequency of the microtoroid. When exosomes land on the microtoroid, they perturb its refractive index in the evanescent field and thus shift its resonance frequency. Through digital frequency locking, we are able to rapidly track these shifts with accuracies of better than 10 attometers (one part in 10^11). Samples taken from tumor-implanted mice from later weeks generated larger frequency shifts than those from earlier weeks. Control samples taken from a mouse with no tumor generated no such increase in signal between subsequent weeks. Analysis of shifts from tumor-implanted mouse samples show a distribution of unitary steps, with the maximum step having a height of ~1.2 fm, corresponding to an exosome size of 44 ± 4.8 nm. This size range corresponds to that found by performing nanoparticle tracking analysis on the same samples. Our results demonstrate development towards a minimally-invasive tumor "biopsy" that eliminates the need to find and access a tumor.

  8. Tapered Glass-Fiber Microspike: High-Q Flexural Wave Resonator and Optically Driven Knudsen Pump

    Science.gov (United States)

    Pennetta, Riccardo; Xie, Shangran; Russell, Philip St. J.

    2016-12-01

    Appropriately designed optomechanical devices are ideal for making ultra-sensitive measurements. Here we report a fused-silica microspike that supports a flexural resonance with a quality factor greater than 100 000 at room temperature in vacuum. Fashioned by tapering single-mode fiber (SMF), it is designed so that the core-guided optical mode in the SMF evolves adiabatically into the fundamental mode of the air-glass waveguide at the tip. The very narrow mechanical linewidth (20 mHz) makes it possible to measure extremely small changes in resonant frequency. In a vacuum chamber at low pressure, the weak optical absorption of the glass is sufficient to create a temperature gradient along the microspike, which causes it to act as a microscopic Knudsen pump, driving a flow of gas molecules towards the tip where the temperature is highest. The result is a circulating molecular flow within the chamber. Momentum exchange between the vibrating microspike and the flowing molecules causes an additional restoring force that can be measured as a tiny shift in the resonant frequency. The effect is strongest when the mean free path of the gas molecules is comparable with the dimensions of the vacuum chamber. The system offers a novel means of monitoring the behavior of weakly absorbing optomechanical sensors operating in vacuum.

  9. Two-dimensional electron gas in the regime of strong light-matter coupling: Dynamical conductivity and all-optical measurements of Rashba and Dresselhaus coupling

    Science.gov (United States)

    Yudin, Dmitry; Shelykh, Ivan A.

    2016-10-01

    A nonperturbative interaction of an electronic system with a laser field can substantially modify its physical properties. In particular, in two-dimensional (2D) materials with a lack of inversion symmetry, the achievement of a regime of strong light-matter coupling allows direct optical tuning of the strength of the Rashba spin-orbit interaction (SOI). Capitalizing on these results, we build a theory of the dynamical conductivity of a 2D electron gas with both Rashba and Dresselhaus SOIs coupled to an off-resonant high-frequency electromagnetic wave. We argue that strong light-matter coupling modifies qualitatively the dispersion of the electrons and can be used as a powerful tool to probe and manipulate the coupling strengths and adjust the frequency range where optical conductivity is essentially nonzero.

  10. Effect of Holstein phonons on the optical conductivity of gapped graphene

    Science.gov (United States)

    Jahanbani, Kh.; Asgari, R.

    2010-01-01

    We study the optical conductivity of a doped graphene when a sublattice symmetry breaking is occurred in the presence of the electron-phonon interaction. Our study is based on the Kubo formula that is established upon the retarded self-energy. We report new features of both the real and imaginary parts of the quasiparticle self-energy in the presence of a gap opening. We find an analytical expression for the renormalized Fermi velocity of massive Dirac Fermions over broad ranges of electron densities, gap values and the electron-phonon coupling constants. Finally we conclude that the inclusion of the renormalized Fermi energy and the band gap effects are indeed crucial to get reasonable feature for the optical conductivity.

  11. Beyond the effective mass approximation: predictive theory of the nonlinear optical response of conduction electrons

    CERN Document Server

    Yu, Shukai; Talbayev, Diyar

    2016-01-01

    We present an experimental and computational study of the nonlinear optical response of conduction electrons to intense terahertz (THz) electric field. Our observations (saturable absorption and an amplitude-dependent group refractive index) can be understood on the qualitative level as the breakdown of the effective mass approximation. However, a predictive theoretical description of the nonlinearity has been missing. We propose a model based on the semiclassical electron dynamics, a realistic band structure, and the free electron Drude parameters to accurately calculate the experimental observables in InSb. Our results open a path to predictive modeling of the conduction-electron optical nonlinearity in semiconductors, metamaterials, as well as high-field effects in THz plasmonics.

  12. Derivation of second-order nonlinear optical conductivity by the projection-diagram method

    Directory of Open Access Journals (Sweden)

    Nam Lyong Kang

    2012-03-01

    Full Text Available A projection-diagram method is introduced for optical conductivity with lineshape functions, which takes into account the population criterion that the electron and phonon distribution functions are multiplicatively combined along with the energy conservation factors for proper interpretation of emission and absorption of phonons and photons in all the processes of electron transitions. It is further shown that the second order nonlinear optical conductivity of the system of electrons interacting with phonons, obtained using this method, is identical with that derived by using the state dependent projectors and the KC reduction identities [J. Phys. A: Math. Theor. 43, 165203 (2010]. We expect that this method can reduce the amount of many-body calculation and can be of help in providing physical intuition into solid state quantum dynamics and representing perturbation expressions for such systems.

  13. Entangled States in a Single-Qubit Structure with SQUID Coupled with a Super-conducting Resonator

    Institute of Scientific and Technical Information of China (English)

    SONG Jian-Wen; LIANG Bao-Long; HAI Wen-Hua; WANG Ji-Suo; ZHONG Hong-Hua; MENG Xiang-Guo; LUO Xiao-Bing

    2008-01-01

    In this paper, the number-phase quantization scheme of the mesoscopic circuit, which consists of a single-qubit structure with superconducting quantum interference device coupled with a super-conducting resonator, is given. By introducing a unitary matrix and by means of spectral decomposition, the Hamiltonian operator of the system is exactly formulated in compact forms in spin-1/2 notation. The eigenvalues and the eigenstates of the system are investigated. It is found that using this system the entangled states can not only be prepared, but also be manipulated by tuning the magnetic flux through the super-conducting loop.

  14. Effect of Zn addition on non-resonant third-order optical nonlinearity of the Cu-doped germano-silicate optical glass fiber.

    Science.gov (United States)

    Ju, Seongmin; Watekar, Pramod R; Jeong, Seongmook; Kim, Youngwoong; Han, Won-Taek

    2012-01-01

    Cu/Zn-codoped germano-silicate optical glass fiber was manufactured by using the modified chemical vapor deposition (MCVD) process and solution doping process. To investigate the reduction effect of Zn addition on Cu metal formation in the core of the Cu/Zn-codoped germano-silicate optical glass fiber, the optical absorption property and the non-resonant third-order optical nonlinearity were measured. Absorption peaks at 435 nm and 469 nm in the Cu/Zn-codoped germano-silicate optical glass fiber were contributed to Cu metal particles and ZnO semiconductor particles, respectively. The effective non-resonant optical nonlinearity, gamma, of the Cu/Zn-codoped germano-silicate optical glass fiber was measured to be 1.5097 W(-1) x km(-1) by using the continuous-wave self-phase modulation method. The gamma of the Cu/Zn-codoped germano-silicate optical glass fiber was about four times larger than that of the reference germano-silicate optical glass fiber without any dopants. The increase of the effective non-resonant optical nonlinearity, gamma, of the Cu/Zn-codoped germano-silicate optical glass fiber, can be attributed to the enhanced nonlinear polarization due to incorporated ZnO semiconductor particles and Cu metal ions in the glass network. The Cu/Zn-codoped germano-silicate optical glass fiber showed high nonlinearity and low transmission loss at the optical communication wavelength, which makes it suitable for high-speed-high-capacity optical communication systems.

  15. INVERSE COMPUTATION OF OPTICAL-ABSORPTION COEFFICIENT IN INHOMOGENEOUS MATERIAL WITH VARIED THERMAL CONDUCTIVITY

    Institute of Scientific and Technical Information of China (English)

    ZhuJianxin

    2002-01-01

    In this paper,for an inhomogeneous material in which the thermal conductivity varies as a function of depth,an efficient treatment is proposed to inversely calculate the depth distribution of optical-absorption coefficient by the surface temperature of the material. It is demonstrated that the results of inverse computation by that method are more similar to the experimental ones measured by some destructive method. Thus ,the treatment is more feasible to nondestructively estimate the distribution.

  16. Spin-Induced Optical Conductivity in the Spin-Liquid Candidate Herbertsmithite

    Science.gov (United States)

    Pilon, D. V.; Lui, C. H.; Han, T.-H.; Shrekenhamer, D.; Frenzel, A. J.; Padilla, W. J.; Lee, Y. S.; Gedik, N.

    2013-09-01

    We report a direct measurement of the low-frequency optical conductivity of large-area single-crystal herbertsmithite, a promising spin-liquid candidate material, by means of terahertz time-domain spectroscopy. In the spectral range below 1.4 THz, we observe a contribution to the real part of the in-plane conductivity σab(ω) from the spin degree of freedom. This spin-induced conductivity exhibits a power-law dependence on frequency σab(ω)˜ωβ with β≈1.4. Our observation is consistent with the theoretically predicted low-frequency conductivity arising from an emergent gauge field of a gapless U(1) Dirac spin liquid.

  17. Properties of Optical Resonant Modes in Ⅲ-Nitride Semiconductor Micro-Cone Cavities

    Institute of Scientific and Technical Information of China (English)

    DAI Lun; ZHANG Bei; LIN Jing-Yu; JIANG Hong-Xing

    2001-01-01

    Arrays of Ⅲ-nitride semiconductor micro-cone cavities with a base diameter of 3.3μm were fabricated by ion beam etching. The micro-cones consisted of 58 nm thick multiple quantum wells of ln0.22Ga0.78N/In0.06Ga0.94N as well as a 1.5μm thick epilayer of GaN. Optical resonant modes from a single micro-cone could be clearly observed in the photoluminescence spectra at temperatures up to 200K under a pumping power density two orders of magnitude lower than that for the Ⅲ-nitride semiconductor micro-disk or micro-ring cavity. Using a novel optical ray tracing method, we have figured out four main types of optical resonant cavities inside the three-dimensional micro-cone, including two Fabry-Perot (F-P) mode types as well as two Whispering Gallery mode types. The three corresponding mode spacings among the four agree perfectly with the experimental results. The advantages of this new class of micro-cavity over the other micro-cavities are discussed. These findings are expected to have an impact on the design of the ultraviolet/blue micro-cavity laser diodes.

  18. The role of Magnetic Resonance Imaging and Visual Evoked Potential in management of optic neuritis

    Science.gov (United States)

    Al-Eajailat, Suha Mikail; Al-Madani Senior, Mousa Victor

    2014-01-01

    Introduction To report our experience in management of patients with optic neuritis. The effects of brain magnetic resonance imaging and visual evoked potential on management were investigated Methods This is a four years clinical trial that included patients presenting with first attack of optic neuritis older than 16 years with visual acuity of less than 6/60 and presentation within first week of illness. Brain magnetic resonance imaging and visual evoked potentials were done for all patients. Patients were classified into three groups. First group received placebo, second received oral steroids and third received intravenous and oral steroids. Primary outcome measure was improvement in visual acuity. Results A total number of 150 patients were enrolled in the study. Ocular pain was seen 127 patients Relative afferent pupillary defect in 142 patients and color vision impairment in 131 patients. Abnormal MRI findings were seen in 84 patients. Pattern reversal VEP was abnormal in all patients. Using oral or intravenous steroid resulted in faster recovery but did not affect the final visual outcome. Recurrence rate was higher in patients with multiple MRI lesions and diminished VEP amplitude. Using intravenous steroids decreased recurrence rate in patients with three and more MRI lesions and non recordable VEP response. Conclusion MRI and pattern reversal VEP are recommended to be done in all patients presenting with optic neuritis. We advise to give intravenous methyl prednisolone in patients with multiple MRI white matter lesions and non recordable VEP at presentation. PMID:25018804

  19. Optical and electronic properties of conductive ternary nitrides with rare- or alkaline-earth elements

    Science.gov (United States)

    Kassavetis, S.; Hodroj, A.; Metaxa, C.; Logothetidis, S.; Pierson, J. F.; Patsalas, P.

    2016-12-01

    Conductive nitrides, such as TiN, are key engineering materials for electronics, photonics, and plasmonics; one of the essential issues for such applications is the ability of tuning the conduction electron density, the resistivity, and the electron scattering. While enhancing the conduction electron density and blueshifting the intraband absorption towards the UV were easily achieved previously, reducing the conduction electron density and redshifting the intraband absorption into the infrared are still an open issue. The latter is achieved in this work by alloying TiN by rare earth (RE = Sc, Y, La) or alkaline earth (AE = Mg, Ca) atoms in Ti substitutional positions. The produced TixRE1-xN and TixAE1-xN thin film samples were grown by a hybrid arc evaporation/sputtering process, and most of them are stable in the B1 cubic structure. Their optical properties were studied in an extensive spectral range by spectroscopic ellipsometry. The ellipsometric spectra were analyzed and quantified by the Drude-Lorentz model, which provided the conduction electron density, the electron mean free path, and the resistivity. The observed interband transitions are firmly assigned, and the optical and electrical properties of TixRE1-xN and TixAE1-xN are quantitatively correlated with their composition and crystal structure.

  20. Novel electro-optical coupling technique for magnetic resonance-compatible positron emission tomography detectors.

    Science.gov (United States)

    Olcott, Peter D; Peng, Hao; Levin, Craig S

    2009-01-01

    A new magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL) diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs.