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Helmholtz decomposition analysis of electron energy loss: Differentiating resonances on polarization and radiation eigenmodes

Yuriy Akimov and LIN WU

Doc ID: 361979 Received 08 Mar 2019; Accepted 22 Apr 2019; Posted 22 Apr 2019  View: PDF

Abstract: Helmholtz decomposition is a powerful mathematical tool for investigation and analysis of vector fields, particularly in electrodynamic systems. In this paper, we apply it to electron energy loss spectroscopy of magnetically inactive structures to get insight into field composition of energy losses. The obtained results show that losses are incurred through two pathways -- excitation of transverse and longitudinal fields by solenoidal and conservative currents. Separation of these processes gives us important information about the fields and the type of eigenmodes (polarization or radiation) being in resonance with the electron beam. Capabilities of such analysis are demonstrated in the study case of metal nanofilms and nanodiscs, where we perform differentiation of the resonances occurred on plasmons (polarization eigenmodes) and plasmon polaritons (radiation eigenmodes).

Theoretical and experimental studies of photomechanical materials

Bojun Zhou, Elizabeth Bernhardt, Ankita Bhuyan, zoya Ghorbanishiadeh, Nathan Rasmussen, Joseph Lanska, and Mark Kuzyk

Doc ID: 359126 Received 30 Jan 2019; Accepted 22 Apr 2019; Posted 23 Apr 2019  View: PDF

Abstract: After a brief introduction to the field of light-responsive materials, this paper provides a general theory for modelling the photomechanical response of a material, applies it to the two best-known mechanisms of photothermal heating and photo-isomerization, and then describes an experimental apparatus for quantitative measurements of the stress response. Several different materials are characterized to illustrate how the experiments and theory can be used to isolate the contributing mechanisms both through photomechanical measurements and auxiliary measurements of laser heating and thermal expansion. The efficiency and figure of merit of the photomechanical response is defined on several scales form the molecule to the bulk, and the photomorphon -- the basic material element that determines the bulk response -- is introduced. The photomorphon provides a conceptual model that can be expressed in terms of viscoelastic elements such as springs in series and parallel with the photoactive molecule. The photomechanical response, figure of merit, and the deduced microscopic photomechanical properties are tabulated and proposals for new materials classes are made.

Reduction of Fluorescence Resonance Energy Transfer by Space Control between Quantum Dots via Direct Bonding of Reactive Ligands to the Polymer Matrix for Color Conversion Films

Changmin Lee, Bokyoung Kim, Hoseok Jin, Hyungsuk Moon, Jungwoo Kim, and Heeyeop Chae

Doc ID: 362049 Received 11 Mar 2019; Accepted 21 Apr 2019; Posted 22 Apr 2019  View: PDF

Abstract: Fluorescence resonance energy transfer (FRET) between quantum dots (QDs) is one of main mechanisms that cause efficiency to drop in photo-luminescence (PL) applications. In this work, we reduced FRET by controlling the distance between the QDs via chemical reactions between the QD ligands and long chain linkers. The oleic acid ligands of the QDs were replaced with ligands containing reactive alcohol groups without any degradation in the quantum yield by a one-pot reaction. The alcohol groups of the QD ligands were reacted with poly-caprolactone diol, which acted as a spacer, and tris(isocyanatohexyl)cyanurate to form cross-linked urethane bonds. The inter-connected QD film showed 26% higher quantum efficiency and 19% longer PL decay time than that of a conventional film in which the QDs were randomly embedded in PMMA. The inter-connection of the designed QD and the long spacer with the cross-linker is believed to prevent FRET between QDs and enhance the quantum yield of the QD films.

Size and shape dependent luminescence properties of trioctylphosphine (TOP) capped CdSe quantum dots

Aditya Nath Bhatt, Upendra Verma, and Brijesh Kumar

Doc ID: 360133 Received 13 Feb 2019; Accepted 21 Apr 2019; Posted 22 Apr 2019  View: PDF

Abstract: In this work, we have analyzed the size and shape dependent effects on the quantum yield (QY) and average life time during growth of the trioctylphosphine (TOP)-capped CdSe nanoparticles. The decrease in the average fluorescence life time and quantum yield with the increase in particle size of the quantum dots (QDs) has been reported. TEM analysis shows that as the size of QDs increases, the shape changes from spherical to approximately ovoid and the surface area increases at higher rate. We have found that TOP has capability of capping cationic (Cd+2) facets hence there is increase in the weakly bonded anionic (Se-2) facets per unit area, and there are atomic dislocations during fabrication process. So, these two factors create large number of trap states, resulting in the increment of the non-radiative recombination centre. The effect of these trap states on radiative life time, non-radiative life time, average life time, and quantum yield has been analyzed.

Active metamaterial nearly perfect light absorbers: a review [Invited]

Hodjat Hajian, Amir Ghobadi, Bayram Butun, and Ekmel Ozbay

Doc ID: 361230 Received 27 Feb 2019; Accepted 21 Apr 2019; Posted 22 Apr 2019  View: PDF

Abstract: Achieving nearly perfect light absorption from the microwave to optical region utilizing metamaterials has begun to play a significant role in photonics and optoelectronics due to their vital applications in thermal emitters, thermal photovoltaics, photovoltaics, sensing, filtering, and photodetection. However, employing passive components in designing perfect absorbers based on metamaterials and photonic crystals imposes some limits on their spectral operation. In order to overcome those limits, extensive research has been conducted on utilizing different materials and mechanisms to obtain active metamaterial light absorbers. In this review paper, we investigate the recent progresses in tunable and reconfigurable metamaterial light absorbers through reviewing different active materials and mechanisms, and we provide a perspective for their future development and applications.

Mueller matrix polarimetry of bianisotropic materials

Oriol Arteaga and Bart Kahr

Doc ID: 361433 Received 04 Mar 2019; Accepted 18 Apr 2019; Posted 22 Apr 2019  View: PDF

Abstract: Mueller Matrix polarimetry is a powerful optical technique for the characterization of both anisotropic and bianisotropic materials. This review paper emphasizes methods for the interpretation of measured Mueller matrices, from the meanings of matrix symmetries, to \textit{ab initio} calculations of Mueller matrices that begin with Maxwell's equations operating on materials with permittivity, permeability and magneto-electric constitutive tensors. We present an overview of measurements in crystals as well as metamaterials that have optically responsive features on the order of the wave length of visible light. As a consequence of large spatial dispersion over the wavelength, chiroptical perturbations to the state of polarization can become dominant and thus are adjunct to natural crystals which are generally insensitive to circular polarization differences. Examples of the effects of anisotropy and orientation of bianisotropic media on the form of the Mueller matrix, collected either in transmission or reflection, are illustrated for natural crystals, polycrystals and nanofabricated metamaterials.

Asymmetric interactions induced by spatio-temporal couplings of femtosecond laser pulses in transparent media

Selcuk Akturk, Nadezhda Bulgakova, and Vladimir Zhukov

Doc ID: 360496 Received 19 Feb 2019; Accepted 18 Apr 2019; Posted 18 Apr 2019  View: PDF

Abstract: Numerous experimental studies in recent years have revealed intriguing symmetry breakings during nonlinear interaction of ultrashort laser pulses with materials. Dependence of the formed structures on the direction of laser scanning and polarization, an effect known as non-reciprocal writing, is one of the most commonly observed asymmetries. These observations are generally attributed to spatio-temporal couplings (primarily pulse-front tilt) in the laser pulses. Even though such couplings indeed break the spatial symmetry of the light-matter interactions, a detailed understanding of ongoing phenomena in the microscopic level is still lacking. In this work, we present our theoretical results, which to best of our knowledge, constitute the first demonstration of the physical mechanisms behind non-reciprocal writing and related effects in transparent media. Our model is based on nonlinear Maxwell’s equations supplemented by the hydrodynamic equations for free electron plasma; and rate equations for the evolution of defects inside the material. It has enabled to gain a qualitative insight into the features of propagation of ultrashort laser pulses with tilted pulse fronts, in the regimes of volumetric laser modification of transparent materials.

A VO2-hBN-graphene-based bi-functional metamaterial for bi-tunable asymmetric transmission and nearly perfect resonant absorption characteristics

Hodjat Hajian, Amir Ghobadi, A. Serebryannikov, Bayram Butun, Guy Vandenbosch, and Ekmel Ozbay

Doc ID: 358816 Received 28 Jan 2019; Accepted 17 Apr 2019; Posted 18 Apr 2019  View: PDF

Abstract: Bi-tunable asymmetric light transmission (AT) and nearly perfect resonant absorption functionalities are achieved by a Lorenz-reciprocal metamaterial for the operation in the mid-infrared (MIR) wavelengths and transverse magnetic (TM) polarization. The bi-tunable metamaterial with bi-functional features and a total thickness of 1.8 μm is based on an hBN-graphene-hBN (HGH) heterostructure that is bounded by Ge grating on the upper- and a hybrid VO2/Au grating on the lower-side. Through analytical calculations, we first investigate how the dispersion characteristics of the high-β hyperbolic phonon polaritons of hBN can be controlled through the insulator (i-VO2) to the metal (m-VO2) transition of VO2 (IMT). Then, at the absence of graphene and owing to the support of hybridized high-β modes, a broad and efficient AT of forward-to-backward contrast exceeding 40% is obtained by numerical calculations for the i-VO2 case, as the first functionality of the structure. Moreover, it is found that for the m-VO2 case, the device is no longer transmittive and a nearly perfect resonant absorption response, as the second functionality, is observed for the backward illuminations. Finally, by introducing multilayer graphene into the structure and considering the intermediate states of VO2 in the calculations, the bi-tunable transmission and absorption characteristics of the device are investigated. We believe the designed metamaterial is well-suited for optical diodes, sensors, and energy harvesting devices.

Polarization- and diffraction-controlled second harmonic generation from semiconductor metasurfaces

Carlo Gigli, Giuseppe Marino, Stephan Suffit, gilles patriarche, Grégoire Beaudoin, Konstantinos Pantzas, Isabelle Sagnes, Ivan Favero, and Giuseppe Leo

Doc ID: 359768 Received 21 Feb 2019; Accepted 17 Apr 2019; Posted 18 Apr 2019  View: PDF

Abstract: We experimentally demonstrate the capability of semiconductor monolithic metasurfaces to control the polarization state of optical second harmonic generation. Based on the properties of single Mie-resonator scattering, we design and fabricate AlGaAs-on-insulator metasurfaces whose spatial periodicity allows to decouple polarization and diffraction features. This enables to collect a polarization-engineered harmonic field in a small solid angle around the zero-diffraction order. Our metasurfaces rely on AlGaAs/AlAs/GaAs MOCVD structure which makes them promising for optoelectronic integration.

Tutorial on Optical Forces in Optical Tweezers

Antonio Neves and Carlos Cesar

Doc ID: 359363 Received 13 Feb 2019; Accepted 17 Apr 2019; Posted 22 Apr 2019  View: PDF

Abstract: Recently, the Nobel prize in physics was awarded for the invention of optical tweezers. Thus far, they have been used as tools to obtain measurements of microscopic systems, mainly by harnessing the optical forces. For quite some time, it has been used as a tool to measure microscopic systems, mainly due to optical forces. These optical forces are commonly deduced from assumptions based on the particle size with respect to the trapping laser wavelength. However, a complete electromagnetic model is accurate and does not depend on early approximations of the force model. Further, the model has several advantages, such as morphology-dependent resonances, size dependence for large spheres, and multipole effects from smaller particles, just to name a few. In this tutorial, we review and discuss the physical modeling of optical forces in optical tweezers, which are the resultant forces exerted by a trapping beam on a sphere of any size and composition. We discuss the highly focused Gaussian beam for trapping and also provide a description of the generalization for any other beam type.

Influence of multiple four-wave mixing processes on quantum noise of dual-pump phase-sensitive amplification in a fiber

Kyo Inoue

Doc ID: 360257 Received 15 Feb 2019; Accepted 16 Apr 2019; Posted 17 Apr 2019  View: PDF

Abstract: Phase-sensitive amplification (PSA) based on nonlinear parametric interaction provides low-noise amplification such that the noise figure can be 0 dB in principle. However, when an optical fiber is used as a nonlinear medium for PSA, multiple four-wave mixing (FWM) processes other than the PSA process are induced, that can degrade the PSA noise performance, especially in dual-pump PSA with a narrow signal-pump wavelength separation. This paper investigates influence of multiple FWM processes on quantum noise of dual-pump PSA in an optical fiber. The noise figure is formalized using quantum-mechanical operators, considering multiple FWM processes with the PSA process. Calculation examples are also presented, which indicate that the noise figure is degraded by 0.2 – 0.4 dB from the ideal 0 dB, depending on the signal-pump wavelength separation and fiber parameters.

Design and construction of a Raman microscope and characterisation of plasmon-enhanced Raman scattering in graphene

Maryam Alshehab, Saba Siadat Mousavi, Maude Amyot-Bourgeois, Jaspreet Walia, Anthony Olivieri, Behnood Ghamsari, and Pierre Berini

Doc ID: 361267 Received 28 Feb 2019; Accepted 15 Apr 2019; Posted 16 Apr 2019  View: PDF

Abstract: Nanometallic structures efficiently convert light to surface plasmon-polaritons (SPPs) localized to ultra-small volumes. Such structures provide highly enhanced fields and are of interest in applications involving SPP-enhanced nonlinear optics. We report the design and construction of a spontaneous Raman microscope augmented with in-situ reflectance measurement capabilities, and demonstrate its use for nonlinear plasmonics. The structures investigated consist of rectangular gold nanoantennas on graphene on a SiO2/Si substrate. Specifically, SPP-enhanced Raman scattering from graphene is investigated using nanoantennas that are spectrally-aligned with the Stokes wavelength of the graphene 2D peak. We use the microscope to demonstrate Raman scattering enhancement in graphene based on plasmonic resonant enhancement of the Stokes emission, where a maximum cross-sectional gain of ~500 per antenna was measured. We also measure the reflectance response of nanoantenna structures of different dimensions (length, width) to determine how the resonant wavelength shifts with dimensions and ensure spectral alignment with the Stokes wavelengths of interest.

ِDesigning a Reflectionless and Bianisotropic Metasurface Antenna Using Dihedral Corner Reflector Excitation

Seyed Ali Hosseini Farahabadi, Ahmad Bakhtafrouz, and Abolghasem Zeidaabadi Nezhad

Doc ID: 352024 Received 15 Nov 2018; Accepted 13 Apr 2019; Posted 15 Apr 2019  View: PDF

Abstract: In this paper, the design process of a bianisotropic metasurface for acquiring a highly directive beam is presented. We propose a dihedral corner reflector-excited metasurface antenna through which the aperture of a single-fed reflector is covered by a metasurface such that optimal aperture illumination is accomplished. Fields within the reflector are derived based on modal technique combined with geometrical theory of diffraction to consider edge diffractions. The general susceptibility synthesis method is used to design passive, lossless, and reflectionless metasurface by introducing bianisotropy into it. To achieve the optimal radiation characteristics, a more rigorous semianalytical method is utilized to predict directivity, side-lobe level, and source position. Owing to thoroughness of our approach, the designed metasurface has a plethora of applications at microwave, terahertz and optical frequencies, especially for designing highly-directive antennas. The semianalytical results are verified using finite-element method by commercial COMSOL Multiphysics electromagnetic solver.

Transformation of photonic spin Hall effect from momentum space to position space

Xunong Yi, Xiaohui Ling, Mengting Zhao, Yuxin Cai, Huan Chen, Qian-Guang Li, and Jiacheng Zhao

Doc ID: 357184 Received 08 Jan 2019; Accepted 13 Apr 2019; Posted 15 Apr 2019  View: PDF

Abstract: Photonic spin Hall effect (PSHE) in momentum space can lead to a giant spin-dependent splitting (SDS). But the SDS in momentum space increases linearly with beam propagation distance, so it’s some applications are limited. In this work, a simple method is proposed to transform the PSHE from momentum space to position space. We first theoretically analyze the feasibility of the transformation. The results show that the transformation can be realized when a light wave passes through two identical PBP metasurfaces. Then an experimental setup is established to verify the theoretical results. Through the rational design of the optical path, only one metasurface is needed to complete the transformation of PSHE from momentum space to position space. The experimental results are good agreement with the theoretical calculations. We believe that these results are helpful for the design of photonics device based on photonic spin Hall effect.

Suppression of stimulated-Raman-scattering in high power fiber amplifier by inserting long transmission fibers in seed laser

Tenglong Li, Wei-Wei Ke, Yi Ma, Yinhong Sun, and Qingsong Gao

Doc ID: 358969 Received 29 Jan 2019; Accepted 13 Apr 2019; Posted 22 Apr 2019  View: PDF

Abstract: We demonstrate the suppression of stimulated-Raman-scattering (SRS) in a kilowatt fiber amplifier by reducing the temporal fluctuations of the seed oscillator, which is achieved by simply inserting a long piece of transmission fibers between the seed source and amplifier. We experimentally investigate the dependence of the amount of Raman light in amplifier on seed oscillator’s transmission fibers length. It is also numerically analyzed the temporal features of the corresponding seed sources and amplifiers. Experiments and simulations indicate that long transmission fibers will flatten temporal fluctuations of seed laser, and thereby the SRS effect in amplifier can be mitigated. The difference of the SRS suppression mechanisms between the method proposed here and the conventional method employing spectrally wider fiber Bragg grating (FBG) is also presented.

Large third-order nonlinear susceptibility from a gold metasurface far-off the plasmonic resonance

Leonardo Menezes, Lucio Acioli, Melissa Maldonado Cantillo, Jawad Naciri, Nicholas Charipar, Jake Fontana, Diego Rativa, Cid Bartolomeu de Araujo, and Anderson S. Gomes

Doc ID: 360611 Received 04 Mar 2019; Accepted 12 Apr 2019; Posted 15 Apr 2019  View: PDF

Abstract: A large third-order nonlinear susceptibility was measured at 1500 nm from a self-assembled metasurface composed of a 2D superlattice of ligand-capped gold nanospheres. A self-defocusing nonlinear refractive index (n2=−1.05×10^(−10) cm^2W^(−1)) and a nonlinear absorption coefficient (α2=3.00×10^(−6) cmW^(−1)) were determined using the Z-scan technique with 70 fs pulses at 1 kH z. The nonlinearity response time was measured to be 1.42 ps using an Optical Kerr Gate configuration. The large n2value is four orders of magnitude larger, in modulus, than in the silica glass substrate at 1500 nm. We show the nonlinear enhancement depends on the morphology of the metasurface and is due to collective near-neighbor coupling between the nanospheres. The physical origin of the gold nonlinearity in the short-wave infrared region is discussed.

Goos-Hänchen shift on polar crystals

Sheng Zhou, Qiang Zhang, shufang fu, and Xuan-Zhang Wang

Doc ID: 358135 Received 18 Jan 2019; Accepted 12 Apr 2019; Posted 12 Apr 2019  View: PDF

Abstract: We investigated Goos-Hänchen shift (GHS) on a polar crystal, where a polarized beam was incident on the crystal from any positive-permittivity medium. Our attention was paid to GHS’s features for the incident-beam frequency lies near or in the reststrahlen band of the crystal. The GHS expressions were obtained for the s-polarized and p-polarized incident beams, respectively. Our results demonstrate that GHS properties are completely different for different polarized incidences. At the critical or Brewster angle, the concise expression of GHS was obtained for a low optical loss in the crystal, companied by an obviously larger GHS. In comparison with the optically-lossless case, the effect of the loss on the GHS was evidently indicated. Unlike photonic crystals and metamaterials, the crystal used here is a natural material whose interesting frequency range is in the infrared region and optical loss is much lower. The present GHS can be more easily observed and technically applied due to the incidence from any positive-permittivity medium. The numerical results were obtained from the interface structure of the ZnS crystal and free space.

Enhanced fluorescence of porous Al2O3 film using the gold nanoparticles on the self-assembled CdSe/Au/Al2O3 heterojunction

Bai zhongchen, Jing Zhou, man Peng, Zhengping Zhang, and Shuijie Qin

Doc ID: 358519 Received 23 Jan 2019; Accepted 11 Apr 2019; Posted 11 Apr 2019  View: PDF

Abstract: The enhanced photoluminescence (PL) effect of porous alumina film was studied on the interface of CdSe/Au/Al2O3 heterojunction by using the gold nanoparticles. We prepared respectively CdSe/Al2O3 heterojunction and CdSe/Au/Al2O3 heterojunction on the surface of porous Al2O3 film by using a colloidal self-assembly method. The results showed that the surface charged positively of porous Al2O3 film could facilitate the CdSe QDs aggregating toward their centre to form a cluster, while the porous Al2O3 surface modified of gold nanoparticles (NPs) could aggregate and extend the CdSe quantum dots (QDs) toward a specific direction for self-assembling the nano-wire structure. Compared with the PL spectra of two heterojunctions, the gold NPs was acted as an electron conductor to connect the porous Al2O3 film and CdSe QDs, which controlled the quantity of carriers from two interfaces of porous Al2O3 film and CdSe QDs and enhanced the their absorption and fluorescence. We believed that these results could be widely used in the fields of photovoltaic device, photo catalysis, photoelectric detection and high-precision sensor.

Compact and Efficient 2D and 3D Designs for Photonic to Plasmonic Coupler

Khaled Atia, Afaf Said, Ahmed Heikal, and Salah Obayya

Doc ID: 360044 Received 12 Feb 2019; Accepted 11 Apr 2019; Posted 12 Apr 2019  View: PDF

Abstract: This legacy template can be used to prepare a research article for In this paper, two ultra-compact designs of wideband photonic to metal-dielectric-metal (MDM) couplers are introduced. The two proposed couplers show high efficiency of 92% and 94% at unexpected very small coupling lengths using MDM as a coupling waveguide. Emerged from the half wavelength transformer concept, when the characteristic impedances of the coupled waveguides are equal in magnitude but have a phase difference, we report a slight shift in the coupler length of the first maximum. Relying on this concept, the length of the proposed couplers are 10 nm and 15 nm to match the phase shift. The proposed couplers also enjoy a very wide bandwidth of 1785 nm for the 10 nm design and 1865 nm for the 15 nm design because of the short coupling length. Also, we introduce a 3D design for the coupler based on a quasi-MDM waveguide of 20 nm silver layer to facilitate the fabrication process. The simulation results are produced by 2D finite element methods and verified by 3D finite difference time domain (FDTD) but with incomparable computational cost.

Plane-wave scattering by an ellipsoid composed of an orthorhombicdielectric-magnetic material with arbitrarily oriented constitutive principal axes

Hamad Alkhoori, Akhlesh Lakhtakia, James Breakall, and Craig Bohren

Doc ID: 359245 Received 31 Jan 2019; Accepted 10 Apr 2019; Posted 11 Apr 2019  View: PDF

Abstract: The extended boundary condition method can be formulated to study plane-wave scattering by an ellipsoid composed ofan orthorhombic dielectric-magnetic material whose relative permittivity dyadic is a scalar multiple of its relativepermeability dyadic, when the constitutive principal axes are arbitrarily oriented with respect to the shapeprincipal axes. Known vector spherical wavefunctions are used to represent the fields in the surrounding matter-free space. After deriving closed-form expressions for the vector spherical wavefunctions for the scattering material,the internal fields are represented as superpositions of those vector spherical wavefunctions.The unknown scattered-field coefficients are related to the known incident-field coefficients by a transition matrix. The total scattering and absorption efficiencies are highly affected by the orientation of the constitutive principal axes relative to the shape principal axes, and the effect of the orientational mismatch between the two sets of principal axes is more pronounced as the electrical size increases. The dependence of thetotal scattering efficiency, but not of the absorption efficiency, on the angle of rotation about a shape principalaxis can be predicted qualitatively from the variation of a scalar function with respect to the angle of rotation. The total scattering and absorption efficiencies do not depend on the polarization state of incident plane wave when the scattering material is impedance-matched to free space. The polarization state of the incident wave has a more discernible effect on the total scattering and absorption efficiencies for ellipsoids compared to spheres.

Thin-disk laser with multipass unstable ring resonator

Mikhail Volkov, Ivan Mukhin, Ivan Kuznetsov, and Oleg Palashov

Doc ID: 359464 Received 04 Feb 2019; Accepted 10 Apr 2019; Posted 10 Apr 2019  View: PDF

Abstract: We propose a scheme of ring unstable resonator with multipass geometry, which overcomes low gain of the disk active element. The original design of the laser resonator allows for power scaling by using larger pump aperture on the active element, maintaining near-diffraction beam quality. The developed resonator operates with disk Yb:YAG active element and output beam quality M2=2 at magnification K=2.5, which is well consistent with the modeling results.

The magnetic permeability in Fresnel’s equation

Hans Olaf Hågenvik and Johannes Skaar

Doc ID: 354897 Received 10 Dec 2018; Accepted 10 Apr 2019; Posted 10 Apr 2019  View: PDF

Abstract: Magnetic permeabilities derived for infinite, periodic media are used in the Fresnel equation to calculate the reflection from corresponding semi-infinite media. By comparison to finite-difference-time-domain (FDTD) simulations, we find that the Fresnel equation gives accurate results for 2D metamaterials which mimic natural magnetism, in a frequency range where the magnetic moment dominates the $\bigO(k^2)$ part of the total Landau--Lifshitz permittivity. For a 1D layered structure, or for large frequencies, the correspondence is poor. We also demonstrate that even if a medium is described accurately by a local permittivity and permeability, the Fresnel equation is not necessarily valid.

Cycloydal diffractive waveplates realized through a high-power diode-pumped solid state laser operating at 532nm

Luciano De Sio, Nelson Tabiryan, Michael McConney, and Timothy Bunning

Doc ID: 357634 Received 14 Jan 2019; Accepted 10 Apr 2019; Posted 11 Apr 2019  View: PDF

Abstract: Diffractive waveplates (DWs) are highly efficient optical components typically realized by means of a polarization holography setup which makes use of UV/blue gas laser sources. It is more convenient to perform the holographic recording process with green lasers (e.g. continuous wave operating at 532nm) because they offer compactness, efficiency and high power. Unfortunately, the photo-alignment materials used for DWs fabrication exhibit no sensitivity at 532nm. Herein, we report the realization of cycloidal diffractive waveplates (CDWs) by employing a polarization holographic setup made with a high-power diode-pumped solid-state laser operating at 532nm. The enabling factor is the utilization of a photo-alignment material possessing a broad absorption band extended to the visible part of the spectrum. Samples are characterized in terms of morphological and optical properties. They exhibit a regular morphology along with a very high diffraction efficiency (97%). The possibility to realize CDWs with larger aperture is under way, enabling the possibility to realize a new generation of optical components to be integrated in modern applications.

Modeling of a Compact Gas Vortex Lens for High Power Lasers

Luke Johnson, Dmitri Kaganovich, B. Hafizi, and Daniel Gordon

Doc ID: 359747 Received 07 Feb 2019; Accepted 09 Apr 2019; Posted 10 Apr 2019  View: PDF

Abstract: With steady-state fluid simulations, we show that a negative lens can be created from a rotating gas (vortex) in a compact structure. The gas flow is well described by a compressible Bernoulli principle in an adiabatic, ideal gas. The gas lens focal length can be varied by adjusting the mass flow rate. The dominant aberration is spherical. Transient simulations show a 60 μs timescale for switching of the focal length. This allows for the creation of self-healing lenses for high power lasers.

Axicon-based beam shaping for low loss nonlinear microscopic optics

Natsuha Ochiai, Jingwen Shou, and Yasuyuki Ozeki

Doc ID: 357384 Received 10 Jan 2019; Accepted 04 Apr 2019; Posted 05 Apr 2019  View: PDF

Abstract: Low loss and broadband optics is important in optical measurement and imaging. Here we design an axicon-based beam shaper for low loss and broadband microscopic optics by numerically calculating the transmittance and focusing performance assuming the application to stimulated Raman scattering (SRS) microscopy. Furthermore, we demonstrate the beam shaper equipped in an SRS microscope and confirm that the axicon-based optics increases the transmittance without sacrificing the spatial resolution or the signal intensity.

Optical Pressure Control with Aperiodic Nanostructured Material

Yu-Chun Hsueh, Li-Fan Yang, and Kevin Webb

Doc ID: 358116 Received 18 Jan 2019; Accepted 02 Apr 2019; Posted 02 Apr 2019  View: PDF

Abstract: The electromagnetic force on matter depends on both the geometry andmaterial properties, and for a contiguous material, the pressure is a useful metric. We present a statistical method with example results that allows the evaluation of pressure in relation to a nanostructured material arrangement. The two example materials considered are gold and silicon, both in a free space background. Both the magnitude of the pressure and also the direction can be regulated, depending on the geometry, and these effects are related to the specifics of the internal structure resonances. Negative pressure can be understood as being due to the total field, a superposition of the incident and scattered fields, where the structure regulates the local scattered field and hence the pressure through an integral of the resulting force density. The statistical analysis provides physical insight into how to constrain design framework for applications. The applicaiotn space includes biophysics, where information is obtained about biomolecules from force and torque measurements, cavity optomechanics related to basic science and sensing, and optical remote control and actuation, where regulation of the magnitude and direction, and the possibility of materials with multiple functionalities, provides new opportunities.

Analysis of Germanium Doped Silicon Vertical PN Junction Optical Phase Shifter

Darpan Mishra and Ramesh Sonkar

Doc ID: 356324 Received 03 Jan 2019; Accepted 02 Apr 2019; Posted 03 Apr 2019  View: PDF

Abstract: In this paper, the performance of a germanium doped silicon optical phase shifter with vertical PN junction has been investigated. The proposed phase shifter is simulated using process simulation tool and the 2D carrier distribution has been used to calculate the phase shifter performance metrics. The designed phase shifter is integrated into a Mach-Zehnder interferometer structure and the transfer characteristics is plotted. The proposed phase shifter has a phase shift of ∼141◦/mm, VπLπ of ∼0.64 V.cm and insertion loss of ∼1. dB at 5 V reverse bias.

Directional optical amplification arise from blue detuning in a quadratically coupled optomechanical system

Liu-Gang Si, Xiao-Yun Wang, zengxing liu, xiaohu lu, and Ying Wu

Doc ID: 359199 Received 30 Jan 2019; Accepted 01 Apr 2019; Posted 02 Apr 2019  View: PDF

Abstract: Directional optical amplification in a quadratically coupled optomechanical system in which two different cavity modes have been excited by two strong optical fields is discussed. We find that if the cavity mode 1 is driven by a strong control field on red detuning, and the cavity mode 2 is driven by a strong control field on blue detuning, amplification of output probe field can occur. On the contrary, when cavity mode 1 and cavity mode 2 are driven by two strong control fields which both are in the red-detuned regime, the dissipation of output probe field can occur. The characters of amplification of output probe field arise from blue detuning of control light field are analyzed. It is shown that the amplification of output probe field can be adjusted by controlling the strength of the control field under the two-phonon resonance condition. In addition, we also find that the reflectivity of the membrane has a significant impact on the probe transmission spectrum.The amplification of output probe field may be available in experiments and have extensive application for quantum communication, optical complex technology, and all-optical network.

Multi-party ring quantum digital signatures

Wenxiu Qu, Yong Zhang, Hong Wei Liu, Tianqi Dou, Jipeng Wang, zhenhua li, shunyu yang, and Hai-Qiang Ma

Doc ID: 351411 Received 08 Nov 2018; Accepted 28 Mar 2019; Posted 28 Mar 2019  View: PDF

Abstract: Quantum digital signatures (QDSs), which are unforgeable, non-repudiable, and transferable, are widely used in quantum communication networks. Unfortunately, previous protocols have often relied on three-party models for security analysis and experimental verification. As the number of parties increases, the number of quantum links required increases exponentially, undoubtedly leading to high channel losses and cost for multi-party QDSs. This study proposes a multi-party ring QDS scheme that can effectively deal with the issue of redundant quantum links. Furthermore, compared with the previously proposed QDS protocols, our protocol can prevent repudiation attack without symmetry operation or SWAP test. Hence it also can reduce the possibility of forging attack by eliminating the possibility of forgery using illegal strings.

Improving the Sensitivity of Weak Microwave Signal Detection with Optomechanical System under Non-Markovian Regime

Xun Li, Biao Xiong, Shi-Lei Chao, and Ling Zhou

Doc ID: 352010 Received 14 Nov 2018; Accepted 27 Mar 2019; Posted 29 Mar 2019  View: PDF

Abstract: Optomechanical system can convert the microwave signal into the optical signal, which offers us a potential candidate to detect weak microwave signal. Employing optomechanical system, we investigate the effects of the non-Markovian environment on improving the detection sensitivity of weak microwave signal. Our results show that the non-Markovian environment with superohmic spectrum supports improving sensitivity. Comparing with direct measurement, homodyne detection can enhance the output spectrum and reduce the additional noise because of the interference.

Lattice plasmon modes in an asymmetric environment: from far-field to near-field optical properties

Nordin Felidj, Leïla Boubekeur-Lecaque, Macilia Braik, Abdelaziz Mezeghrane, Abderrahmane Belkhir, and Iman Ragheb

Doc ID: 358435 Received 12 Feb 2019; Accepted 25 Mar 2019; Posted 05 Apr 2019  View: PDF

Abstract: Plasmonic nanostructures arranged in regular arrays support lattice plasmon modes. Such arrays supporting lattice modes can provide improved platforms, in the context of non-linear optics, molecular sensing,plasmon-based lasers, or surface enhanced spectroscopies. These lattice modes are characterized by a reduced linewidth of the resonance, and an important improvement of its quality factor. In this work, wediscuss the impact of these particular resonances on the far-field plasmonic response, in relation with their near-field optical properties. In particular, our results evidence that, for interparticle distances higher than a critical grating constant, the maximum of near-field enhancement is blue-shifted compared to the far-field localized surface plasmon (LSP) wavelength, which is the opposite of the usual trend.

Efficient nonlinear metasurfaces by using multiresonant high-Q plasmonic arrays

Mikko Huttunen, Orad Reshef, Timo Stolt, Ksenia Dolgaleva, Robert Boyd, and Martti Kauranen

Doc ID: 359213 Received 30 Jan 2019; Accepted 24 Mar 2019; Posted 25 Mar 2019  View: PDF

Abstract: We numerically investigate second-harmonic generation from multiresonant plasmonic metasurfaces by designing an array consisting of L-shaped aluminum nanoparticles that simultaneously supports two surface lattice resonances with relatively high quality factors (>100). Using an approach based on the nonlinear discrete-dipole approximation, we predict an over million-fold enhancement of the emitted second-harmonic intensity from a particle at the center of the metasurface compared to an individual particle and estimate that conversion efficiencies of around 10-⁵ could be achievable from the surface. Our results are an important step towards making nonlinear metasurfaces practical for nonlinear applications, such as for frequency conversion.

Application of vector diffraction theory in geometric-phase-based metasurfaces

Chengwei Dai, Yijia Huang, ying guo, Xiaoliang Ma, Yanqin wang, Mingbo Pu, Xiangang Luo, and Changtao Wang

Doc ID: 355993 Received 21 Dec 2018; Accepted 03 Mar 2019; Posted 09 Apr 2019  View: PDF

Abstract: In geometric-phase-based metasurfaces, phase modulation of the output light can be achieved by designing the shape and layout of the sub-wavelength structure. For traditional electromagnetic simulation software, the operating principle is often based on finite-difference time-domain (FDTD), finite element method (FEM) or finite integration technique (FIT). There are disadvantages, for example, the simulation is time-consuming, the modeling process is complicated and the computational accuracy can be affected by the size of divided grids. In this paper, an improved vector diffraction theory is investigated to calculate the distribution of the transmitted light field when the incident circular polarization light (CPL) passes through the geometric-phase-based metasurfaces. The structure acts as a diffraction screen when using the method to calculate the diffraction field. And when CPL is incident, the geometric phase is imparted to the output light, and the transmission light field is calculated by normal vector diffraction theory. Three kinds of structures, which can be seen as nano-objects arrays, have been designed and characterized to validate our method. The first and second devices realized the separation of cross-polarization and co-polarization components, and the third one realized the function of focusing lens with sub-wavelength array. The transmission fields calculated by the refined vector diffraction theory are in good agreement with FIT method. We believe this simple yet generalized method can be employed for efficient design of geometric-phase-based metasurfaces, such as Bessel beam generators, focusing lenses, holographic coding, etc.

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