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Precision spectroscopy and frequency stabilization using coin-sized laser modules

Feng-Lei Hong, Junia Nomura, Kazumichi Yoshii, and Yusuke Hisai

Doc ID: 355076 Received 10 Dec 2018; Accepted 17 Jan 2019; Posted 17 Jan 2019  View: PDF

Abstract: We demonstrate high-resolution spectroscopy of molecular iodine using coin-sized laser modules at 531 nm, 561 nm, and 594 nm. Hyperfine components of the R(36)32-0, P(64)20-0, and P(69)12-1 transitions are observed with a signal-to-noise ratio of several tens over a bandwidth of 100 Hz. The laser modules are frequency-stabilized to the observed hyperfine components and achieve stabilities at a level of 10-12 for a 1-s averaging time. The frequency-stabilized coin-sized laser modules are useful for various applications, including interferometric measurements and studies of molecular iodine.

Broadband thermophotovoltaic emitter usingmagnetic polaritons based on optimized one and twodimensional multilayer structures

yaser khorrami and Davood Fathi

Doc ID: 353106 Received 30 Nov 2018; Accepted 16 Jan 2019; Posted 16 Jan 2019  View: PDF

Abstract: Thermophotovoltaic (TPV) devices via efficient emitterare used to convert the thermal radiation into electricity.We propose new one and two dimensional (1D & 2D)nanostructures to reach the broadband high efficientTPV emitters. The performance of the model is enhancedby more interaction between the excited surface plasmonpolaritons (SPPs) and the magnetic polaritons (MPs)based on the multilayer structure using 1D periodicshallow grating and 2D bi-periodic cylindrical deepgrating. The highly improved rigorous coupled-waveanalysis (RCWA) method is used to predict the emittancewith the least diffraction orders. It is shown that, theproposed wavelength-selective and diffuse-like 1Demitter has high emittance more than 0.9 and 0.96 in thebroadband spectral regions from 0.7 to 1.87 μm and 0.73to 1.83 μm, respectively and is silicon-compatibleespecially for integrated device technology. Also for 2Dpolarization-insensitive proposed structure, there is highemittance more than 0.97 from 0.6 to 1.6 μm. Theemittance of both structures are below 0.2 atwavelengths longer than 2.55 μm. The strip width ofgrating and emission angle can be set to change theemittance spectrum to improve conversion efficiency ofphotovoltaic cell.

Fiber Optic Fabry-Perot Interferometer sensor: an efficient and fast approach for ammonia gas sensing

Rajesh Kanawade, AJAY KUMAR, Dnyandeo Pawar, Dattatray Late, Samir Mondal, and Ravindra Sinha

Doc ID: 346169 Received 18 Sep 2018; Accepted 16 Jan 2019; Posted 17 Jan 2019  View: PDF

Abstract: In this work, we proposed and demonstrated Fabry-Perot Interferometer (FPI) based PDMS/PMMA composite coated optical sensor for ammonia and volatile organic compounds (VOCs) detection at room temperature. The principle of sensing is based on change in the cavity length of the FP cavity in presence of varied concentration of gases which results changes in the total reflectance due to the shift in wavelength of an interference pattern. The sensing composite material was coated on a single mode optical fiber by using simple dip coating technique and explored it for sensing. The ammonia and VOCs measurements were performed for the concentration ranging from 5 to 500 ppm. The corresponding sensitivity and limit of detection (LOD) of the developed sensor for ammonia gas detection was observed of the order of around 4.16 pm/ppm and 4.8 ppm respectively. The response and recovery time of sensor were found to be of the order of 50 seconds and 10 seconds respectively for the ammonia gas. This sensor provides simple, cost-effective, highly sensitive, and repeatable approach to measure ammonia gas and other VOCs at room temperature and could fulfill the demands of industrial applications.

Proposed narrowband biphoton generation from an ensemble of solid-state quantum emitters

Heejeong Jeong, Shengwang Du, and Na Young Kim

Doc ID: 344686 Received 10 Sep 2018; Accepted 15 Jan 2019; Posted 15 Jan 2019  View: PDF

Abstract: We explore a mechanism for producing time-frequency entangled photon pairs (termed as biphoton) from an ensemble of atom-like solid-state quantum emitters. Four distinct energy levels of the solid-state system rendering four spin-conserving optical transitions, as observed in color centers, open up the possibility to generate an electromagnetic inducedtransparency (EIT) based spontaneous four-wave mixing biphoton for long-coherence quantum communication as demonstrated in cold atomic systems. We propose a narrow EIT window below lifetime-limited linewidth of a SiV-, assuming a few hundred MHz. Consequently, the EIT-induced narrowband guarantees at least a few tens of nanosecond biphoton time without acavity. This study shows that a realization of negligible ground state dephasing of a solid-state sample will be the crucial step toward a solid-state biphoton generation for more than a hundred nanosecond time scale with a subnatural atomic linewidth of a few MHz.

Continuous variable quantum key distribution with multi-mode signals for noisy detectors

Rupesh Kumar, Xinke Tang, Adrian Wonfor, Richard Penty, and Ian White

Doc ID: 348540 Received 17 Oct 2018; Accepted 14 Jan 2019; Posted 15 Jan 2019  View: PDF

Abstract: This paper proposes a multi-mode Gaussian modulated continuous variable quantum key distribution (CV-QKD) scheme able to operate at high bandwidth despite using conventional noisy, coherent detectors. We demonstrate enhancement in shot noise sensitivity as well as reduction in the electronic noise variance of the coherent receiver of the multi-mode CV-QKD system. A proof of concept simulation is presented using multiple modes. This demonstrates an increase in signal to noise ratio (SNR) and secure key rate at various transmission distance with increasing signal modes.

Difference Frequency Generation of Ultraviolet from X-Ray Pulses in Opaque Materials

Eviatar Minerbi and Sharon Shwartz

Doc ID: 351817 Received 14 Nov 2018; Accepted 14 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: We suggest a new approach for observing x-ray nonlinear wave mixing in opaque materials. We focus on difference frequency generation of ultraviolet radiation from two short x-ray pulses by measuring the depletion of the pumping pulses. Like other processes involving nonlinear interactions between x-rays and longer wavelengths, our method can lead to the development of a probe for spectroscopy of valence electrons at the atomic scale resolution. The two main advantages of the method we propose over the direct observation of the generated signal are the ability to probe the properties of materials at wavelengths where they are opaque, and the higher predicted efficiency in the ultraviolet regime. We describe a possible experimental setup with realistic specifications that are optimized with respect to the characteristics of the input pulses. We expect that experimental observations of the effect will be feasible with the new emerging high repetition rate x-ray free-electron lasers.

Highly chromatic retardation via multi-twist liquid crystal films

Kathryn Hornburg, ravi komanduri, and Michael Escuti

Doc ID: 352545 Received 04 Dec 2018; Accepted 14 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: Here we study birefringent films with highly customizable chromatic retardation spectra, using multi-twist (MT) liquid crystal (LC) films. These are made of two or more layers of chiral nematic LC polymer network materials, also known as reactive mesogens, which form a monolithic thin-film wherein the in-plane orientation of subsequent layers is automatically determined by the single alignment layer on the substrate. The multiple layer thicknesses and twists present many degrees of freedom to tailor the retardation. While prior work examined achromatic spectra, here we show how to use Mueller matrix analysis to create highly chromatic spectra. We experimentally demonstrate both a uniformly aligned retarder as a green/magenta color filter and a ``hot' polarization grating (PG) that diffracts infrared while passing visible light. The three-twist color filter shows a contrast ratio in transmittance between polarizers as high as 10:1 between the half- and zero-wave retardation bands. The "hot" PG shows an average first-order efficiency of about 90% for 1000-2700 nm and average zero-order efficiency of about 90% for 500-900 nm. The principles here can be extended to nearly any chromatic retardation spectra, including high/low/bandpass, and to nearly any LC orientation pattern, in general known as geometric-phase holograms.

Using birefringence colors to evaluate a tunable liquid-crystal q-plate

Maria del Mar Sanchez-Lopez, David Marco, Pascuala Garcia-Martinez, and Ignacio Moreno

Doc ID: 353350 Received 04 Dec 2018; Accepted 14 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: Q-plates are geometrical phase elements that enable the realization of vector beams in simple and compact optical setups. In this work, we consider a tunable liquid-crystal commercial q-plate operative in the visible and near IR range and study its spectral and color birefringence properties under broadband illumination. We first characterize the spectral retardance function of the device in a wide range from 400-1600 nm and determine how it changes upon applied voltage. Then we evaluate the color transmission characteristics when inserting the q-plate between crossed and parallel linear polarizers. These color properties agree with the trajectory in the CIExy chromaticity diagram as the applied voltage changes. Finally, we demonstrate that a simple visual inspection of the transmitted birefringence color perceived when placing the q-plate between crossed polarizers can be used to obtain a rapid estimation of the q-plate retardance at given wavelength ranges.

Double V-groove dielectric loaded plasmonic waveguide for sensing applications

Amir Habibzadeh-Sharif and Farnaz Jabbarzadeh

Doc ID: 340625 Received 24 Jul 2018; Accepted 14 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: In this study, a novel double V-groove dielectric loaded plasmonic waveguide (DVG-DLPW) structure suitable for sensing applications is proposed and simulated. Two symmetrical V-grooves are cut into the vertical surfaces of the dielectric ridge to increase the interaction of analyte with the waveguide surface and increase sensing depth of surface plasmon polaritons while increasing propagation length of guided modes. Double V-groove dielectric ridge is placed on a graphene surface to take the advantages of using graphene as a sensitivity enhancing material for plasmonic biosensors. A detailed analysis of the sensing and propagation properties of this structure is performed under different device parameters. The results show that under optimal conditions, the proposed plasmonic waveguide demonstrates not only longer propagation length but also a higher sensitivity as compared with conventional dielectric loaded plasmonic waveguide (DLPW) counterpart.

Millimeter-Structured Nondiffracting SurfaceBeams

Leonardo Ambrosio

Doc ID: 354692 Received 05 Dec 2018; Accepted 13 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: A new type of scalar nondiffracting beam is presented whose main feature isthe freedom on the choice of a two-dimensional spatial intesity pattern dependent upon thelongitudinal coordinate. Examples of such millimeter-structured surface beams are providedover Cartesian and cylindrical planes and, motivated by the idea of designing beams capable ofsimultaneous manipulation, guidance and/or trapping of micro- and millimeter-sized particles,here we also derive analytical expressions for their beam shape coefficients in the framework ofthe generalized Lorenz-Mie theory, a first step towards the analysis of light-matter interactionswith spherical particles from such light fields.

Modal Analysis Of TE And TM Excitations In Metallic Slotted Micromirror

Muhammad Othman, Yasser Sabry, Ahmed Othman, Ismail Nassar, and Diaa Khalil

Doc ID: 328448 Received 02 Oct 2018; Accepted 13 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: In this work we present a modal analysis for the metallic slit, where closed form expressions for slotted micromirror transmittance are derived for different polarizations. This can be handy in the design of optical MEMS devices and their applications, where the metallic is analyzed by solving the eigenvalue problem. The modes of a metallized slotted micromirrors (slit inner structure) are approximated to be parallel plate waveguide modes for TE and TM excitations. The metallic parallel plate waveguide is assumed to be infinite in vertical direction. The transmittance of the micromirror with a vertical slit has been calculated for both TE and TM polarizations based on Gaussian beam excitation. Finite-difference time-domain (FDTD) simulation is carried out for the slotted micromirror transmittance and the results are compared to the modal analysis prediction. A noticeable conformity has been observed.

Study of dielectric coatings for broad band operation of surface-emitting semiconductor lasers

Christopher Head, Theo Chen Sverre, Jonathan Woods, Alexander Hein, Markus Polanik, Andrew Turnbull, Edward Shaw, Peter Unger, Anne Tropper, and Vasilis Apostolopoulos

Doc ID: 354725 Received 18 Dec 2018; Accepted 12 Jan 2019; Posted 15 Jan 2019  View: PDF

Abstract: We investigate anti-reflection coating materials for two different operation lasingregimes requiring broad spectral bandwidth. We characterize high-power continuous-wave (CW) wavelength-tunable vertical-external-cavity surface-emitting semiconductor lasers and their passive mode-locking capabilities when using semiconductor saturable absorber mirrors.One laser gain design was investigated with different single dielectric layers as AR-coatings. The dielectric coating materials used were SiO₂, Al₂0₃, Ta₂O₅ and TiO₂. The AR-coating wasdesigned to reduce pump reflection and increase the confinement factor of the micro-cavity.Average power of 4.6 W in CW and a total wavelength-tuning range of 42 nm has been observedwith the SiO₂-coated structure. The shortest pulse of 708 fs was also observed for the SiO₂-coatedstructure, with corresponding CW wavelength-tuning range of 36 nm.

Ultracompact AZO-based TE-pass and TM-pass hybrid plasmonic polarizers

AHMED EL-SAYED ABD-ELKADER, Mohamed Hameed, Nihal Areed, Hossam El-Din Mostafa, and Salah Obayya

Doc ID: 348788 Received 22 Oct 2018; Accepted 12 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: Ultracompact transverse electric (TE) and transverse magnetic (TM)-pass polarizers based on hybrid plasmonic silicon-on-insulator platform are reported and studied. The Aluminum-doped zinc oxide (AZO) is used as an alternative plasmonic material in the proposed structures due to its attractive advantages, including high optical tunability, high thermal stability, and low ohmic loss. The reported polarizers are analyzed using full vectorial finite element method with perfect matched layer boundary condition. Additionally, the three dimensional finite difference time domain method is used to study the propagation through the suggested designs. The numerical results show that the TE-pass polarizer of a compact device length of 3 μm has 20.6 dB extinction ratio (ER) and 0.21 dB insertion loss (IL) at operating wavelength of 1.55 μm. However, the TM-pass polarizer achieves 22 dB ER and 0.11 dB IL at only 1 μm device length. Further, the fabrication tolerance of the proposed polarizers is studied, which ensures the high robustness of the suggested designs to the fabrication errors.

Excitons in hexagonal boron nitride single-layer: a new platform for polaritonics in the ultraviolet

Fábio Ferreira, Andre Chaves, Nuno Peres, and Ricardo Ribeiro

Doc ID: 348880 Received 25 Oct 2018; Accepted 11 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: The electronic and optical properties of 2D hexagonal boron nitride are studied by using first principle calculations.GW and BSE methods are employed in order to predict with better accuracy the excited and excitonic properties of this material.We determine the values of the band gap, optical gap, excitonic binding energies and analyse the excitonic wave functions.We also calculate the exciton energies following an equation of motion formalism and the Elliot formula, and find a very good agreementwith the $GW$+BSE method. The optical properties are studied for both the TM and TE modes, showing that 2D hBN is a good candidateto polaritonics in the UV range. In particular it is shown thata single layer of h-BN can act as an almost perfect mirror forultraviolet electromagnetic radiation.

Ab-initio theory of quantum fluctuations and relaxation oscillations in multimode lasers

Adi Pick, Alexander Cerjan, and Steven Johnson

Doc ID: 349843 Received 01 Nov 2018; Accepted 11 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: We present an \emph{ab-initio} semi-analytical solution for the noise spectrum of complex-cavity micro-structured lasers, including central Lorentzian peaks at the multimode lasing frequencies and additional sidepeaks due to relaxation-oscillation (RO) dynamics. In~Ref.~1, we computed the central-peak linewidths by solving generalized laser rate equations, which we derived from the Maxwell--Bloch equations by invoking the fluctuation--dissipation theorem to relate the noise correlations to the steady-state lasing properties; Here, we generalize this approach and obtain the entire laser spectrum, focusing on the RO sidepeaks. Our formulation treats inhomogeneity, cavity openness, nonlinearity, and multimode effects accurately. We find a number of new effects, including new multimode RO sidepeaks and three generalized $\alpha$ factors. Last, we apply our formulas to compute the noise spectrum of single- and multimode photonic-crystal lasers.

Impact of III-V ratio and growth temperature on V-shaped pits in InGaN layer grown by PA-MBE: An empirical study

Apurba Laha, Dhiman Nag, Tarni Aggarwal, Ritam Sarkar, Swagata Bhunia, Swaroop Ganguly, and Dipankar Saha

Doc ID: 351778 Received 12 Nov 2018; Accepted 10 Jan 2019; Posted 11 Jan 2019  View: PDF

Abstract: We have investigated the effect of surface morphology on the optical properties of thick InGaN layers (200nm) with high Indium content (>20%), grown on GaN/Sapphire template by PA-MBE (Plasma Assisted Molecular Beam Epitaxy). Morphology of the InGaN was studied as a function of growth temperature and nitrogen plasma. We find that V-shaped pit formation on InGaN surface diminishes with the decrease of the growth temperature and remains unchanged with variation in III/V ratio while exhibiting a significant impact on surface roughness, crystal quality and eventually the optical properties.

Efficient side-coupling to photonic crystal nanobeam cavities via state-space overlap

Francis Afzal, Sami Halimi, and Sharon Weiss

Doc ID: 354649 Received 06 Dec 2018; Accepted 10 Jan 2019; Posted 11 Jan 2019  View: PDF

Abstract: We present design guidelines for realizing side-coupled photonic crystal nanobeam (PCN) cavities with efficient coupling to low order resonances through adjusting the overlap of the PCN cavity mode and a feeding bus waveguide in both physical and k-space. We show that optimal side-coupled configurations function at a non-zero k-vector offset between the bus waveguide and PCN cavity modes. The straightforward design of side-coupled PCNs with high contrast resonances opens the door to their practical implementation in multiplexed, on-chip photonic devices.

Nonclassical effects in optomechanics: Dynamics and collapse of entanglement

Pradip Laha, S Lakshmibala, and V Balakrishnan

Doc ID: 340843 Received 14 Aug 2018; Accepted 10 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: We have investigated the wide range of nonclassical behaviour exhibited by a tripartite cavity optomechanical system comprising a two-level atom placed inside a Fabry-P\'{e}rot type optical cavity with a vibrating mirror attached to one end. We have shown that the atomic subsystem von Neumann entropy collapses to its maximum allowed value over a significant time interval. This feature is sensitive to the nature of the initial state, the specific form of intensity-dependent tripartite coupling, and system parameters. The extent of nonclassicality of the field is assessed through the Mandel Q parameter and Wigner density. Both entropic and quadrature squeezing properties of the field are quantified directly from optical tomograms, thereby avoiding tedious state reconstruction procedures.

Coupled-ring resonance and unitary groups

Jerzy Kocik and Mohammad Sayeh

Doc ID: 342447 Received 15 Aug 2018; Accepted 10 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: The group-theoretic content of photonic coupled microrings resonance phenomena is shown, in particular, an interesting emergence of pseudo-unitary group. The application to the resonance condition in a tri-microring configuration is solved exactly. A practical application of this work will be in the resonance frequency tuning based on the coupling coefficient, in particular, the Mach-Zehnder interferometer approach was analyzed for the coupling modulation.

Invited Paper: Excitation of E1-forbidden Atomic Transitions with Electric, Magnetic or Mixed Multipolarity in Light Fields Carrying Orbital and Spin Angular Momentum

Maria Solyanik, Andrei Afanasev, Carl Carlson, Christian Schmiegelow, and Ferdinand Schmidt-Kaler

Doc ID: 352066 Received 15 Nov 2018; Accepted 10 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: Photons carrying a well-defined orbital angular momentum have been proven to modify spectroscopic selection rules in atomic matter.Excitation profiles of electric quadrupole transitions have been measured with single trapped $^{40}$Ca$^+$ ions for varying polarizations.We further develop the photo-absorption formalism to study the case of arbitrary alignment of the beam's optical axis with respect to the ion's quantization axis and mixed multipolarity. Thus, predictions for M1-dominated $^{40}Ar^{13+}$, E3-driven $^{171}Yb^+$ and $^{172}Yb^+$, and B-like $^{20}Ne^{5+}$ are presented. The latter case displays novel effects, coming from the presence of a strong photon -- magnetic dipole coupling.

Optical properties of reflective liquid crystal polarization volume gratings

Shin-Tson Wu, Yun-Han Lee, and Ziqian He

Doc ID: 352552 Received 21 Nov 2018; Accepted 10 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: Polarization volume gratings are self-organized liquid crystal helical structures. They exhibit high diffraction efficiency and unique polarization selectivity. In this work, we investigate and compare two different configurations of polarization volume gratings: planar and slanted structures. We present the optical properties of polarization volume gratings with emphasis on its polarizing nature. Further experimental results reveal the existence of the slanted configuration.

Polarization grating exposure method with easily tunable period via dual rotating polarization grating masks

Jihwan Kim and Michael Escuti

Doc ID: 353344 Received 04 Dec 2018; Accepted 10 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: We introduce a new approach to record polarization gratings (PGs) based on dual rotating polarization grating masks. In prior approaches, the linear variation of orientation angle of the PG pattern was accomplished using discrete holographic optics, which require careful precision alignment, and wherein the relative distances between those optics limit the upper range of PG periods that can be made. Conversely, the setup described and demonstrated here as a single stage is very compact and more robust to vibration compared to other approaches. Moreover, this approach can easily tune the PG period while maintaining the compact size of the setup. This technique enables easy fabrication of arbitrarily large period PGs. In this work, we discuss general design principles and critically evaluate this fabrication method, as compared to the best of prior approaches.

Numerical analysis of Bragg polarization gratings

Xiao Xiang and Michael Escuti

Doc ID: 353410 Received 04 Dec 2018; Accepted 10 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: Here we study Bragg regime polarization gratings (PGs) using an anisotropic rigorous coupled-wave analysis (RCWA) method. We simulate the most important diffraction properties without paraxial approximation, including the angular, spectral, and polarization responses. We first focus on the angular and spectral bandwidths of the transmissive and reflective Bragg PGs optimized for normal incidence. The effects of material birefringence and average index of refraction were investigated. Second, we examine the non-ideal Bragg PGs with non-planar director profile and identified degradation in optical performance due to high tilt of the liquid crystal director. Third, we simulate the polarization response of both types of Bragg PGs and observed complicated angular dependence of the polarization output. Qualitatively, good agreement can be observed between the simulation results and prior experimental work. Finally, we fit the measured angular and polarization data to retrieve actual grating parameters and demonstrated excellent quantitative correspondence, which can be particularly useful in closing the gap between design and fabrication.

Doubling the geometric phase of reflective Pancharatnam-Berry diffractive waveplates

Masaru Ono, Junji Kobashi, Hiroyuki Yoshida, and Masanori Ozaki

Doc ID: 354826 Received 10 Dec 2018; Accepted 10 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: Cholesteric liquid crystals with a helical modulation of the anisotropic optic axis function as holographic optical elements whereby Bragg reflected light is phase modulated by the Berry phase, which is acquired in proportion to twice the spatial phase of helical structure. One of the limitations of such holographic optical elements is that a π rotation in helix phase is required to modulate the optical phase by 2π. Here, we propose a double-layered reflective structure comprising uniaxial and helical anisotropic materials that can modulate the reflected optical phase twice as much compared to conventional elements. We present results of numerical simulations and confirm them through the fabrication of two devices: (i) a reflective deflector and (ii) an optical vortex generator, in which a two-fold increase is achieved in diffraction angle and topological charge of the generated optical vortex beam, respectively. The proposed device structure should be useful for use in compact catoptric optical systems.

Direct fabrication of a q-plate array by scanning wave photopolymerization

Miho Aizawa, Megumi Ota, Kyohei Hisano, Norihisa Akamatsu, Takeo Sasaki, Christopher Barrett, and Atsushi Shishido

Doc ID: 353341 Received 18 Dec 2018; Accepted 10 Jan 2019; Posted 14 Jan 2019  View: PDF

Abstract: Topological lightwave technologies are expected to be applied in a wide range of emerging optical fields such as q-plates, one of the most attractive devices in this research area, prepared by controlling the high-resolution alignment patterning of liquid crystals. Here, we present a simple and direct fabrication technique of a q-plate which is able to oscillate a vector beam, by employing our newly-developed photoalignment concept termed scanning wave photopolymerization (SWaP). SWaP generates precise arbitrary molecular alignment patterns concurrent with irradiated light patterns, successfully fabricating a polymer film with a radial molecular alignment arranged in an array pattern in a single step. This array patterned alignment structure was able to simultaneously generate a vector beam, indicating that SWaP can be utilized for producing such topological lightwave applications.

Effect of Ultrafast Laser Pulse Shape on the Electron-Plane Wave Interaction in Vacuum

Hossein Akou and Mahmoud Fouldai

Doc ID: 346617 Received 24 Sep 2018; Accepted 09 Jan 2019; Posted 11 Jan 2019  View: PDF

Abstract: In this study the effects of laser pulse shape on the laser-electron acceleration in vacuum have been considered. It was found that the laser plane wave with a finite duration trapezoidal envelope was more effective in transferring energy to the electrons. A MeV single electron axially injected to the front of a trapezoidal short laser pulse with a linearly chirping frequency was shown to gain more than 50 GeV energy.

Finite-key analysis of practical decoy-state measurement-device-independent quantum key distribution with unstable sources

Yang Wang, Wan-Su Bao, Chun Zhou, Mu-Sheng Jiang, and Hong-Wei Li

Doc ID: 347116 Received 01 Oct 2018; Accepted 09 Jan 2019; Posted 09 Jan 2019  View: PDF

Abstract: Measurement-device-independent quantum key distribution (MDI-QKD) is immune to detector side channel attacks, which is a notorious security loophole problem in QKD. Importantly, both finite-key effects and intensity fluctuations of the practical photon sources are nonnegligible in a full key rate analysis of practical QKD. In this paper, for the case with finite-key effects and without intensity fluctuations, we present a way to estimate the phase error rate for MDI-QKD and compare performances of the parameter estimation based on Hoeffding's inequality and the Chernoff bound. By using Azuma's inequality, we also present the finite-key analysis with composable security against general attacks for a biased decoy-state MDI-QKD protocol with intensity fluctuations. Our simulation results show that the effect of our phase error rate estimation is almost the same with results in [Physical Review A 91, 02 13 (2015)], and the parameter estimation using the Chernoff bound is tighter than that using Hoeffding's inequality. What's more, the influence of intensity fluctuations is more obvious when the data size of total transmitting signals is small. Our results highlight that it is important to keep the stability of the intensity modulator and estimate accurately the emitted pulse's intensity for practical implementations.

Comparison of cylinder- and planar-effective medium approximations on calculation of scattering properties of cylindrical hyperbolic metamaterials

Kotaro Kajikawa and Rahul Kumar

Doc ID: 347267 Received 01 Oct 2018; Accepted 09 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: In this report we compare the applicability of the planar effective medium approximation (PEMA) and cylinder effective medium approximation (CEMA), for analyzing the scattering properties of cylindrical hyperbolic metamaterials (CHMMs). We show that approximation of scattering properties of CHMMs calculated on the basis of the CEMA is better than those calculated using the conventional PEMA. We also show the applications of CHMMs as superscatterers.

Parameters Optimization and Real-Time Calibration of Measurement-Device-Independent Quantum Key Distribution based on Back Propagation Artificial Neural Network

Feng-Yu Lu, Zhen-Qiang Yin, Chao Wang, Chaohan Cui, Jun Teng, Shuang Wang, Wei Chen, Wei Huang, Bingjie Xu, Zhen-fu Han, and Guang-can Guo

Doc ID: 348281 Received 15 Oct 2018; Accepted 08 Jan 2019; Posted 10 Jan 2019  View: PDF

Abstract: When the number of users of a measurement-device-independent quantum key distribution network becomes larger, its parameters choosing (such as probabilities of choosing X base or Z base, intensity of signal state and decoy state, etc.) and system calibrating will be more challenging. At present people usually use optimization algorithm to search best parameters and stop the system to recalibrate it. It brings burdens to system.We present a scheme to choose parameters and calibrate system based on Back Propagation Artificial Neural Network. Through numerical simulation, we find that the proposed scheme is very faster, doesn't need any additional devices, and only recycles discarded data generated by communication.

Weak measurement of the Goos-Hanchen shift of partially coherent light beams

Octávio Santana and Luis de Araujo

Doc ID: 344583 Received 30 Aug 2018; Accepted 07 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: Optical beam shifts are very small and challenging phenomena to measure. Weak measurement techniques have been developed to amplify and more easily measure the shifts of spatially coherent beams. We here investigate theoretically a weak measurement technique for measuring the Goos-Hanchen shift of partially spatially-coherent beams. We show that the amplification factor of the technique depends on the global coherence degree of the field and on the size of the Goos-Hanchen shift experienced by the beam. Large amplification factors can be obtained for low shifts, even for very incoherent beams. But, for higher beam shifts, such as those occurring near critical incidence, the amplification factors are modest to low for beams of low coherence.

Three-Dimensional Nonlinear Stokes - Mueller Polarimetry

Serguei Krouglov and Virginijus Barzda

Doc ID: 348264 Received 17 Oct 2018; Accepted 07 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: The formalism is developed for a tree-dimensional (3D) nonlinear Stokes-Mueller polarimetry that describes a method of acquiring a complete complex valued 3D nonlinear susceptibility tensor of a material. The expressions are derived for generalized $3D$ linear and nonlinear Stokes vectors, and the corresponding nonlinear Mueller matrix.The coherency-like Hermitian square matrix X of susceptibilities is introduced, which is derived from the nonlinear Mueller matrix. The X-matrix is characterized by the index of depolarization. Several decompositions of the X-matrix are introduced that provide a possibility to obtain nonlinear susceptibility tensors of constituting materials in the heterogeneous media. The 3D nonlinear Stokes-Mueller polarimetry formalism can be applied for three and higher wave mixing processes. The 3D polarimetric measurements can be used for structural investigations of materials, including heterogeneous biological structures. The 3D polarimetry is applicable for nonlinear microscopy with high numerical aperture objectives.

Cesium optical-RF resonance line reversals and doubles

FeiYun Fang, Xiaochao Cao, Yao Hu, Yunfei Xu, and Zhaoying Wang

Doc ID: 348932 Received 31 Oct 2018; Accepted 07 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: We report an experimental study on the classical ground-state magnetic resonances of optically pumped, Cesium vapors. A longitudinal static magnetic field is applied along the single laser beam to control the splitting of the Zeeman sublevels of the ground state. When the laser frequency is set to the Cesium D1 spectral line ( ), by modifying the transverse radio frequency field, we find the unusual weaker absorption and zero-dip resonance phenomenon occur in the optical-magnetic resonance effects, which is stated that the cesium optical-RF resonance line reversals and doubles in this paper. We explore a theoretical description for these phenomena by using density matrix equations, our calculated results are in approximate agreement with the experiment results.

Simple method on enhancing the measurement-device-independent quantum key distribution without reference frame calibration

Hao Zhang, Chunhui Zhang, Chunmei Zhang, Guang-Can Guo, and Qin Wang

Doc ID: 349928 Received 01 Nov 2018; Accepted 07 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: The protocol of reference-frame-independent measurement-device-independent quantum key distribution can show many advantages compared with other existing quantum key distribution protocols, and thus has many interesting applications in the field of quantum information. In this paper, we propose a new scheme on the reference-frame-independent measurement-device-independent quantum key distribution by implementing heralded singlephoton sources, where we only need to modulate pump light into two intensities (vacuum & non-vacuum). Through numerical simulations, we demonstrate that our new scheme can exhibit much longer transmission distance than the standard three-intensity decoy-state measurementdevice-independent quantum key distribution under reference-frame-independent scenario.

Multi-watt passively Q-switched self-Raman laser based on a c-cut Nd:YVO₄ composite crystal

Shi Dai, Mengting Chen, Si-Qi Zhu, Hao Yin, Zhen Li, and Zhenqiang Chen

Doc ID: 352939 Received 26 Nov 2018; Accepted 07 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: An in-band pumped passively Q-switched (PQS) self-Raman laser with a c-cut Nd:YVO₄ composite crystal is demonstrated for the first time. A Cr4+:YAG composite crystal was utilized to improve the stability and misalignment sensitivity of the resonator. The PQS self-Raman output performance was systematically investigated with different initial transmissions (T0) of Cr4+:YAG and different transmissions (TS) of Raman output coupler. In addition, the focus position of incident pump beam and cavity length have been optimized during the experiment. With Cr4+:YAG of T₀ = 90% and output coupler of TS = 10%, the maximum average output power at 1178 nm was up to 2.53 W under the absorbed pump power of 20.6 W, corresponding to an optical-to-optical conversion efficiency of 12.3%. The pulse repetition frequency and pulse width were measured to be 39.1 kHz and 20.4 ns, respectively, and the corresponding peak power was calculated to be 3.2 kW. At the full output power, the fluctuation of Raman output power was less than ±0.5% within one hour. To the best of our knowledge, we have improved the PQS self-Raman laser about 3.2 times.

Feedback induced spin-phonon polaron

Hojat Habibi, Majid Ghanaatshoar, and Mahdi Hosseini

Doc ID: 340993 Received 30 Jul 2018; Accepted 07 Jan 2019; Posted 09 Jan 2019  View: PDF

Abstract: We study a hybrid system composed of a three-level atomic ensemble inside an optomechanical cavity. The mechanical oscillator is coupled to the internal state of the atomic ensemble via electromagnetically induced transparency (EIT), created by the intra-cavity field and an off-resonancecontrol laser. The fluctuation in the output-coupled cavity field is fed back to the mechanical oscillator. We use a combination of feedback and EIT-assisted cooling of the oscillator to its quantum ground state and then establish coherent coupling between the oscillator and the atomic spin. The superposition of the atomic state and oscillator is studied in different regimes of optomechanical and light-atom coupling strengths and the conditions for creating a single atom-phonon polaron is identified. We observe coherent superposition of fluctuations in a range of optomechanical and atomic cooperativities.

Simulation of Unconventional Lithography with Metasurface Comprised of Bow-Tie Nanoantennas

Szabo Zsolt and Anna Vermes

Doc ID: 347382 Received 03 Oct 2018; Accepted 06 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: A plasmonic metasurface comprised of a single layer silver bow-tie antenna array is presented for unconventional photolithography below diffraction limit. The proposed structure can be fabricated by self-assembling a mask of dielectric spheres on top of a photoresist layer, followed by metal deposition and removal of the spheres. The nanoantennas can focus light to expose the photoresist in a similar way as it occurs in multi-photon lithography. The intensity distribution in the photoresist is calculated by solving Maxwell’s equations, then resist dissolution models are applied to predict the clearance profile after development. Several exposure conditions with different metasurface parameters are investigated. The simulations can provide the size of the nanospheres, the thickness of the metallic bow-tie antennas and of the photoresist, the optimum wavelength of the illumination and can present guidelines for the development conditions to obtain array of holes arranged in honeycomb lattice. It is shown that other geometries can be obtained as well by precise control of the process conditions.

Ultrafast time-domain wave packet evolution of atomic photoionization

Xu Wang, Ruihua Xu, and Zhaoyan Zhou

Doc ID: 345520 Received 12 Sep 2018; Accepted 06 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: We present a combined numerical and theoretical study of atomic photoionization in the time domain. We show how a photoelectron wave packet rapidly changes its shape after being emitted, from a complex multi-peak structure to eventually a relatively simple single-peak structure. This time-domain shape evolution provides information beyond the time-dependent average position of the wave packet, which for example has been used to retrieve the Wigner time delay. For few-cycle laser pulses, the asymptotic velocity of the photoelectron can be different from long-pulse-based expectations due to non-negligible changes of the dipole matrix element within the spectra of the laser pulses.

Acoustic sensor based on fiber-optic polymeric resonator

Amir Ali, Haidi Badawi, and Momen Al-Johary

Doc ID: 345754 Received 12 Sep 2018; Accepted 06 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: In this paper, an opto-mechanical frequency analyzer is designed using micro-optical dielectric sensors based on whispering gallery modes (WGM). This phenomenon commonly referred as WGM, is excited by evanescently coupling light from a tunable laser diode using a tapered single-mode optical fiber. The proposed design is composed of a tuner that consists of chambers with different geometries with dielectric beams placed on each one. These beams are made from polydimethylsiloxane (PDMS). The spherical optical polymeric resonators are mechanically coupled to the dielectric beams placed at each chamber. The tuner has different resonant frequency at each chamber that depends on the effective length of the beam. Sound waves deform the polymeric cavity causing a shift in its transmission spectrum. Cross-correlation technique is used to calculate that shift which is known as (WGM shifts). An analysis and calibrations are carried out along with preliminary designs and experiments. Results proved that the proposed technique could be used as a very high resolution frequency analyzer due to the high quality factor (Q-factor) of the resonators. Similar to an optical prism, this device can be used to split the sound into its constituent frequencies.

Quantum hacking on a free-space QKD system without measuring quantum signals

Min-Soo Lee, Min Ki Woo, Yong-Su Kim, Young-Wook Cho, Sang-Wook Han, and Sung Moon

Doc ID: 347182 Received 01 Oct 2018; Accepted 03 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: We hack a practical free-space quantum key distribution (QKD) system using active wavelength control attacks without measuring quantum signals. Unlike conventional hacking, which simply analyzes the initial characteristic difference between the laser light sources in transmitter, our method actively changes the wavelength of the laser sources, even if the characteristics of the system lasers were originally the same. In this paper, beyond feasibility test, the proposed QKD hacking method is verified with the complete QKD system. Furthermore, we also suggest a new quantum hacking scheme in which the quantum signal does not need to be measured during the hacking process. Hence, Eve does not require complex hardware such as single photon detectors and sources. Using the proposed quantum hacking method, we confirm that Eve can acquire not only a complete quantum key but also basis information without revealing her presence.

Efficiency and stability of an all-fiber unidirectional optical parametric oscillator

Peter Horak and Ioannis Begleris

Doc ID: 352544 Received 21 Nov 2018; Accepted 03 Jan 2019; Posted 07 Jan 2019  View: PDF

Abstract: An all-fiber optical parametric oscillator comprising a highly nonlinear optical fiber and wavelength division multiplexing couplers is numerically simulated. The model is based on a set of coupled nonlinear Schroedinger equations which spectrally resolve the gain bandwidth of the pump, signal and idler waves. We show that such high wavelength resolution is necessary to obtain the correct threshold pump powers, stationary output powers, and relative intensity noise. Finally, we compare seeded and unseeded configurations and find that the seeded configuration generates low-noise idler output at conversion efficiencies of up to 10% below the threshold power for unseeded operation, but that both seeded and unseeded oscillators produce comparable results above threshold.

Wavelength Assignment in Quantum Access Networks with Hybrid Wireless-Fiber Links

Sima Bahrani, Osama Elmabrok, Guillermo Curras Lorenzo, and Mohsen Razavi

Doc ID: 347304 Received 02 Oct 2018; Accepted 03 Jan 2019; Posted 03 Jan 2019  View: PDF

Abstract: We propose a low-complexity near-optimal wavelength allocation technique for quantum key distribution access networks that rely on wavelength division multiple access. Such networks would allow users to send quantum and classical signals simultaneously on the same optical fiber infrastructure. Users can be connected to the access network via optical wireless or wired links. We account for the background noise present in the environment, as well as the Raman noise generated by classical channels, and calculate the secret key generation rate for quantum channels in the finite-key setting. This allows us to examine the feasibility of such systems in realistic scenarios when the secret key exchange needs to be achieved in a limited time scale. Our numerical results show that, by proper choice of system parameters for this noisy system, it is possible to exchange a secret key in tens of seconds. Moreover, our proposed algorithm can enhance the key rate of quantum channels, especially in high noise and/or high loss regimes of operation.

Study of cavity-enhanced dipole emission on a hyperbolic metamaterial slab

Yue Cheng, Cheng-Ting Liao, Zhi-Hong Xie, Yu-Chueh Hung, and Ming-Chang Lee

Doc ID: 352480 Received 20 Nov 2018; Accepted 31 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: We theoretically study strong coupling of a dipole emitter positioned close to a hyperbolic metamaterial (HMM) slab. Enhanced dipole emission with a large Purcell factor originated from the superposition of p-wave resonant coupling and critical coupling to the high-k waveguide modes in a HMM slab is addressed, and the dependence of the slab thickness and the fill ratio of metallic nanorods in HMM on the emission strength is explicitly summarized. Via optimizing the mode coupling condition, we point out a general design rule for the HMM structure to yield a large Purcell factor. Furthermore, by incorporating a Si bullseye grating on the HMM slab, 18 folds of far-field radiation enhancement owning to extraction of the mainly coupled resonant mode in HMM is presented.

Amplitude scaling and lateral shift of leaky radiationfrom surface plasmon excitation

Zhichao Ruan and Jiahao Zhang

Doc ID: 349107 Received 23 Oct 2018; Accepted 29 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: We investigate spatial field transformation in surface plasmon excitation by a prism coupling configuration. By exciting surface plasmon polariton (SPP), the total reflected field is contributed by the direct reflection of the incident wave and the outgoing radiation of the SPP leakage. We show that the SPPleaky radiation field enables both an amplitude scaling and a lateral shift, which play an important role in forming total reflected field profile. We classify the spatial field transformation by different coupling conditions from weak coupling to critical and strong cases. A method is proposed to evaluate loss rate ratio between the leaky radiation and the material intrinsic absorption, by measuring reflected beam profile under flat-top beam illumination. This study paves the way for fast computing and optimizing the incident light to control the total reflected field intensity distribution, which is practically significant in the applications of spatial field, such as plasmonic tweezers and computations.

Beam propagation at an arbitrary angle in uniaxialcrystals

Mohamed Nawareg

Doc ID: 348261 Received 15 Oct 2018; Accepted 29 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: Studying the beam propagation through different types of media is an active topic in scientific researchdue to its great importance for a variety of technological and industrial applications. In this current paperwe derive a general theoretical model for describing the beam propagation through uniaxial crystals at anarbitrary angle with the crystal’s optical axis. In addition we show that our model goes to the previouslysolved cases at the particular angles of propagation 0 and 90 with the optical axis. We then apply thederived model to the propagation of quasi-Gaussian beam through rutile crystal at different angles withthe crystal axis. In particular we compare its propagation at different crystal’s thicknesses and at angles(0, 45, 70) with the optical axis. The results show big changes in both the polarization and spatialstructure of the light beam by propagating through the uniaxial crystal at different angles.

Optical angular momentum transfer on total internal reflection

Atirach Ritboon, Sarah Croke, and Stephen Barnett

Doc ID: 346223 Received 28 Sep 2018; Accepted 29 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: We study the mechanism of optical angular momentum transfer from light to a dielectric medium on total internal reflection. We employ a quantized approach and, in particular, work with a single-photon pulse. This allows us to evaluate the force and torque per photon and also, crucially, to evaluate forces and torques conditioned on transmission or reflection at an interface. The reflected electric and magnetic fields of an incident paraxial beam carrying orbital and spin angular momentum are obtained using an angular spectrum method. We calculate the expectation value of the single-photon torque exerted on the dielectric due to total internal reflection of a single-photon pulse is evaluated by dipole-based Lorentz force density, and apply this result to describe the angular momentum transfer from light on passing through an M-shaped Dove prism.

Supercontinuum radiation in fluorescence microscopy and biomedical imaging applications

Chetan Poudel and Clemens Kaminski

Doc ID: 347224 Received 01 Oct 2018; Accepted 28 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: Compact, high brightness supercontinuum sources have already made a big impact in the fields of fluorescence microscopy and biomedical imaging like OCT and CARS. In this review, we provide a brief overview on the generation and properties of supercontinuum radiation tailored for imaging, along with schemes to select desired wavelength output. We focus mostly on the specific applications (with examples) of supercontinuum sources and also their limitations and caveats in fluorescence microscopy and biomedical research. We conclude with technical challenges in the field and recent advances, in regards to UV generation, near-IR microscopy, exciting new potentials of hollow core PCFs, on-chip supercontinuum and tweaking supercontinuum stability for certain applications.

Temporal variation of the spectrum of continuously-pumped random fiber laser. Phenomenological model.

Yury Bliokh, Elena Chaikina, Ilya Vatnik, and Dmitry Churkin

Doc ID: 348280 Received 17 Oct 2018; Accepted 27 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: A temporal variation of a spectrum of excited modes in a continuously pumpederbium-doped random fiber laser (RFL), based on randomly distributed Bragg gratings, is studied. Developed phenomenological theoretical model assumes hard excitation mechanism of the eigenmodes instability. The model explains qualitatively peculiarities of the spectrum variation, observed experimentally.

Entropic uncertainty relations and the measurement range problem, with consequences for high-dimensional quantum key distribution

Joseph Bourassa and Hoi-Kwong Lo

Doc ID: 347087 Received 01 Oct 2018; Accepted 26 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: The measurement range problem, where one cannot determine the data outside the range of the detector, limits the characterization of entanglement in high-dimensional quantum systems when employing, among other tools from information theory, the entropic uncertainty relations. Practically, the measurement range problem weakens the security of entanglement-basedlarge-alphabet quantum key distribution (QKD) employing degrees of freedom including time-frequency or electric field quadrature. We present a modified entropic uncertainty relation that circumvents the measurement range problem under certain conditions, and apply it to well-known QKD protocols. For time-frequency QKD, although our bound is an improvement, we find that high channel loss poses a problem for its feasibility. In continuous variable QKD, we find our bound provides a quantitative way to monitor for saturation attacks.

Analytic self-testing bound of the singlet for binary measurements

Xinhui Li, Wang Kun, Yun-Guang Han, Qin Sujuan, Fei Gao, and Qiao-Yan Wen

Doc ID: 342502 Received 17 Aug 2018; Accepted 26 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: Self-testing refers to a device-independent way to uniquely identify the state and the measurement for uncharacterized quantum device, i.e. based on certain extremal quantum correlations.Already known in the ideal case of two-qubit singlet, all the extremal points that can be obtained by measuring the singlet form the whole criteria for self-testing singlet and the associated measurements. To make these self-testing criteria suitable for practical applications, relevant self-testing bounds is necessary to discuss. However, the previous robustness analysis for these criteria are obtained by swap method which may not guaranteed to be tight, meanwhile the localizing matrix for searching unitary control operator also add to the lack of tightness. In this paper we construct a general extraction map applying to the all self-testing criteria of singlet state and derive analytic self-testing bounds of singlet for binary measurements. The comparative results show that our robustness is better than the known results.

Three-dimensional FDTD analysis of a Nanostructured Plasmonic Sensor in the Near-infrared range

ali farmani

Doc ID: 353303 Received 30 Nov 2018; Accepted 26 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: Finding new ways to access the nano-scale and high-Q-factor plasmonics resonance remains a major challenge in the field of plasmonic metasurfaces. In the present paper, we aim to report a nanoscale gold metasurface containing structure to realize high quality plasmon-induced transparency (PIT) responses. The properties of the proposed model are numerically investigated with different physical parameters by 3D-FDTD method. For this purpose, the effect of the geometrical parameters, metasurface materials,dielectric constant, and incident angle in visible to near infrared region are studied. To obtain of dynamical tunability of the proposed model, graphene metasurface are then utilized. Numerical results show that the proposed devices are able to operate as high quality PIT sensor with maximum figure-of-merit of 1090, and sensitivity of 700 nm/refractive index unit for slight change of n= 0.15, in the refractive index of dielectric layer, which originates from its ultra-narrow transparency window and strong couplingbetween dark-bright modes. Moreover, the structure has a nano-scale footprint of 40 nm × 60 nm × 31 nm. We believe that the proposed sensor can be used as a promising platform for future nano sensing applications such as nanostructure plasmonic sensors.

Tunable Wide Band Graphene Plasmonics Nano Color-Sorter: Application in Scanning Near Field Optical Microscopy

Bizhan Rashidian, Hesam Heydarian, Payam Yazdanfar, and Afsaneh Shahmansouri

Doc ID: 348318 Received 15 Oct 2018; Accepted 24 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: Tunability of the Fermi level of graphene is exploited to implement a plasmonic nano color sorter for SNOM applications, capable of handling large tip sample couplings.Nano color sorting have been used in SNOM, through creating multiple spatially separated hot spots for different incident wavelengths.We show that in the presence of high refractive index samples an unwanted red shift in spectral response of dual color probe occurs.This limitation can be compensating through using graphene, and adjusting its chemichal potential to obtain a blue shift in probe spectral response.Method of Moments (MoM) analysis technique is employed to engineer the probe numerically.This probe is tuned to work at standard Nd-YAG laser lines (1054 and 1319 nm) and achieve sub-wavelength resolution as small as 0.002λ^2.

Amplitude noise and coherence degradation of femtosecond supercontinuum generation in all-normal-dispersion fibers

Etienne Genier, patrick bowen, Thibaut Sylvestre, John Dudley, Peter Moselund, and Ole Bang

Doc ID: 347414 Received 03 Oct 2018; Accepted 23 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: Supercontinuum (SC) generation via femtosecond pumping in all-normal dispersion (ANDi) fiber is predicted to offer completely coherent broadening mechanisms, potentially allowing for substantially reduced noise levels in comparison to those obtained when operating in the anomalous dispersion regime. However, previous studies that cover this topic typically treat only the one-photon-per-mode noise, not considering other technical noise contributions that will affect the stability of the pump laser and thus the coherence of the SC generation process. In this work, we discuss the various sources of noise that can be added to a numerical simulation, and provide numerical analysis showing that the coherence limits of ANDi SC generation are considerably reduced when amplitude and pulse duration noise are taken into account.

Multioctave supercontinua and subcycle lightwave electronics

Aleksei Zheltikov

Doc ID: 347242 Received 01 Oct 2018; Accepted 22 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: Multioctave supercontinua provide a unique resource for ultrafast optical science, offering advanced tools for time-resolved spectroscopy, frequency-comb technologies, nonlinear microscopy, and lightwave engineering. The physical scenarios that enable the generation of such ultrabroadband wave packets are not always easy to describe in terms of standard models of ultrafast nonlinear optics, their properties are often unusual, and their nonlinear dynamics is much more than meets the eye. To adequately understand this new electrodynamics and to identify scenarios whereby multioctave supercontinua can coherently add up yielding subcycle field waveforms, some basic concepts and models of ultrafast nonlinear optics have to be revisited. Originally intended to refer to a rapid buildup of the spectral bandwidth of ultrashort laser pulses propagating, as waveguide modes or as free beams, in media with a third-order optical nonlinearity, within the past decade, the term “supercontinuum generation” has been seamlessly extended, thanks to its all-embracing character, to include very-high-order and nonperturbative nonlinear-optical processes and now applies to ultrabroadband field waveform generation in the ultraviolet and x-ray ranges, as well as high-harmonic atto- and zeptosecond supercontinua. This paper offer a brief overview of this rapidly growing field of research.

Mechanical Ringdown Studies of Large-Area Substrate-Transferred GaAs/AlGaAs Crystalline Coatings

Steven Penn, Maya Kinley-Hanlon, Ian MacMillan, Paula Heu, David Follman, Christoph Deutsch, Garrett Cole, and Gregory Harry

Doc ID: 351638 Received 12 Nov 2018; Accepted 22 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: We investigated elastic loss in GaAs/AlGaAs multilayers to help determine the suitability of these coatings for future gravitational wave detectors. We measured large ($\approx 70$-mm diameter) substrate-transferred crystalline coating samples with an improved substrate polish and bonding method. The elastic loss, when decomposed into bulk and shear contributions, was shown to arise entirely from the bulk loss, $\phi_{\mathrm{Bulk}} = (5.33 \pm 0.03)\times 10^{-4}$, with $\phi_{\mathrm{Shear}} = (0.0 \pm 5.2) \times 10^{-7}$. These results predict the coating loss of an 8-mm diameter coating in a 35-mm long cavity with a 250-$\mu$m spot size (radius) to be $\phi_{\mathrm{coating}} = (4.78 \pm 0.05) \times 10^{-5}$, in agreement with the published result from direct thermal noise measurement of $\phi_{\mathrm{coating}} = (4 \pm 4) \times 10^{-5}$. Bonding defects were shown to have a little impact on the overall elastic loss.

Experimental research on thermal and dynamic effects of K9 optical lenses irradiated by low frequency femtosecond laser

Enling Tang, Xiaochu Lin, and Yafei Han

Doc ID: 344944 Received 03 Sep 2018; Accepted 21 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: Damage of laser to materials are mainly caused by thermal and dynamic effects, and multiple effects caused by laser irradiating on the glass are referable for evaluating damage of laser to the optical lens and the design of laser system. In order to study the thermal and dynamic effects of K9 based glass lens which is commonly used in optical systems irradiated by low frequency femtosecond pulsed laser, the systems were established to obtain temperature field distribution, stress and laser supported detonation wave when low frequency femtosecond laser irradiated frontally on the coated or uncoated K9 based glass lenses by using laser loading system combining with infrared thermal imaging, dynamic strain gauge and high speed video. Experimental researches have been performed based on this series of testing systems. The experimental results show that the plasma has a strong shielding effect to the low frequency laser whose oscillation frequency is 500 Hz, and the discharge of plasma occurs when there is no laser pulse, so the heat transfer is unbalanced in experiments. However, the compressive stress of the first pulse acting on the material surface is 900MPa, and the average compressive stress about 1.1 GPa during the process of irradiation. Laser supported detonation wave attenuates rapidly to Lamb waves when it acts on the glass surface. For the low frequency femtosecond laser, the higher the frequency is, the more obvious the isotherm is, and the greater the temperature gradient is, the stronger the detonation effect to the glass lenses will be. The coating on the lens surface can significantly reduce the stress produced by irradiation and decreasing the radius of heat-affected zone to one third compared to that without coating, which has a protective effect to the glass substrate.

Broadband lasers for trapped-ion operations

Thomas Fordell and thomas lindvall

Doc ID: 345333 Received 10 Sep 2018; Accepted 20 Dec 2018; Posted 21 Dec 2018  View: PDF

Abstract: A frequency-stable, broadband laser is presented for experiments on trapped ions. Since the design is based on widely available semiconductor optical amplifier technology, similar lasers can be realized for virtually any wavelength in the near-infrared, and the coherence properties and output power allow efficient second harmonic generation into the blue part of the electromagnetic spectrum. No closed-loop frequency stabilization for addressing Doppler- or naturally-broadened, dipole-allowed transitions is needed, and the light source can be turned on and off during a measurement cycle with sub-microsecond response time. As a case study, a 921.7-nm laser with an output power of 20~mW and a linewidth of 10~GHz is realized, which is then frequency doubled to 460.9-nm for excitation of strontium as the first step in photo-ionization. The excitation efficiency is compared to that achievable with a narrow-linewidth distributed Bragg reflector laser as well as to theory.

Giant lateral shift via properly engineered cavity

Salman Khan, Farrah Shafiq, and Arif Ullah

Doc ID: 344778 Received 05 Sep 2018; Accepted 19 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: We propose a scheme to modify the susceptibility of a two level coherently driven atomic medium enclosed inside a cavity and to enhance the Goos-H$\ddot{\text{a}}$nchen shift of a probe field via atom-cavity coupling and their detuning. The numerical simulation of the analytical results show that a suitably designed cavity leads to transparency windows both under off and in resonance conditions of the probe field. The scheme leads to considerably enhanced lateral shifts, of the order of 760 times the wavelength used, both positive and negative in the transmitted and reflected beams.

Noise of supercontinuum sources in spectral domain optical coherence tomography

Mikkel Jensen, Iván Bravo Gonzalo, Rasmus Dybbro, Michael MARIA, Niels Israelsen, Adrian Podoleanu, and Ole Bang

Doc ID: 347222 Received 03 Oct 2018; Accepted 19 Dec 2018; Posted 03 Jan 2019  View: PDF

Abstract: In this paper, we investigate the effect of pulse-to-pulse fluctuations of supercontinuum sources on the noise in spectral domain optical coherence tomography (OCT) images. The commonly quoted theoretical expression for the OCT noise is derived for a thermal light source, which is not suitable if a supercontinuum light source is used. We therefore propose a new, measurement-based OCT noise model that predicts the noise without any assumptions on the type of light source. We show that the predicted noise values are in excellent agreement with the measured values. The spectral correlation evaluated for the photodetected signal when using a supercontinuum determines the shape of the OCT noise floor, which must be taken into account when characterizing the sensitivity roll-off of a supercontinuum-based OCT system. The spectral correlations using both conventional supercontinuum sources and low-noise all-normal dispersion supercontinuum sources are investigated, and the fundamental physical effects that cause these correlations are discussed.

Phase noise reduction of mutually tunable lasers with an external acousto-optic modulator

Gene Polovy, Julian Schmidt, Denis Uhland, Erik Frieling, Kahan Dare, and Kirk Madison

Doc ID: 346319 Received 24 Sep 2018; Accepted 18 Dec 2018; Posted 21 Dec 2018  View: PDF

Abstract: Phase noise reduction in an optical phase locked loop (OPLL) is investigated using an acousto-optic actu- ator external to the laser cavity and primary stabilization lock. This method does not require modification of the laser cavity or primary lock and is compatible with continuous frequency tuning schemes for a laser locked to a femto-second frequency comb (FFC) [1, 2]. We achieve a cross-over frequency of 275 kHz and we demonstrate a Single Side Band (SSB) phase noise of -92 dBc/Hz at a 10 kHz offset. Using two indepen- dently tunable lasers equipped with this locking system, we demonstrate quantum state manipulation of ultra-cold 6Li dimers using Stimulated Raman Adiabatic Passage (STIRAP).

Simultaneous measurement of pulse front tilt and pulse duration with a double trace autocorrelator

Goncalo Figueira, Luis Braga, Sajidah Ahmed, Alexis Boyle, Marco Galimberti, Mario Galletti, and Pedro Bernardino Machado Andrade Oliveira

Doc ID: 348421 Received 17 Oct 2018; Accepted 18 Dec 2018; Posted 21 Dec 2018  View: PDF

Abstract: We describe the design and demonstrate the operation of a single shot autocorrelator capable of measuring independently and simultaneously the duration and the pulse front tilt of ultrashort laser pulses. The device is highly versatile, self-calibrating, exhibits a high resolution and is able to detect the presence of pulse front tilt in unknown pulses, providing instantaneous feedback about their magnitude and signal.

The effect of laser noise on the propagation of laser radiation in dispersive and nonlinear media

Joshua Isaacs and Phillip Sprangle

Doc ID: 342264 Received 17 Aug 2018; Accepted 18 Dec 2018; Posted 21 Dec 2018  View: PDF

Abstract: The effect of laser noise on the atmospheric propagation of high-power CW lasers and high-intensity short pulse lasers in dispersive and nonlinear media is studied. We consider the coupling of laser intensity noise and phase noise to the spatial and temporal evolution of laser radiation. High-power CW laser systems have relatively large fractional levels of intensity noise and frequency noise. We show that laser noise can have important effects on the propagation of high-power as well as high-intensity lasers in a dispersive and nonlinear medium such as air. A paraxial wave equation, containing dispersion and nonlinear effects, is expanded in terms of fluctuations in the intensity and phase. Longitudinal and transverse intensity noise and frequency noise are considered. The laser propagation model includes group velocity dispersion, Kerr, delayed Raman response, and optical self-steepening effects. A set of coupled linearized equations are derived for the evolution of the laser intensity and frequency fluctuations. In certain limits these equations can be solved analytically. We find, for example, that in a dispersive medium, frequency noise can couple to and induce intensity noise (fluctuations), and vice versa. At high intensities the Kerr effect can reduce this intensity noise. In addition, significant spectral modification can occur if the initial intensity noise level is sufficiently high. Finally, our model is used to study the transverse and longitudinal modulational instabilities. We present atmospheric propagation examples of the spatial and temporal evolution of intensity and frequency fluctuations due to noise for laser wavelengths of 0.85, 1, and 10.6 microns.

Saturation and competing pathways in four-wave mixing in rubidium

Erik Brekke and Noah Swan

Doc ID: 343133 Received 27 Aug 2018; Accepted 18 Dec 2018; Posted 21 Dec 2018  View: PDF

Abstract: We have examined the frequency spectrum of the blue light generated via four-wave mixing in a rubidium vapor cell inside a ring cavity. At high atomic density and input laser power, two distinct frequency components separated by 116±4 MHz are observed, indicating competing four-wave mixing channels through the 6p hyperfine states. The dependence of the generated light on excitation intensity and atomic density are explored, and indicate the primary process has saturated. This saturation results when the excitation rate through the 6p state becomes equal to the rate through the 5p state, giving no further gain with atomic density while a quadratic intensity dependence remains.

Analysis of Nonlinear Polarization Rotation by an Ultrashort Optical Pump and Probe Pulses in Strained Semiconductor Optical Amplifier

Ahvan Sharifi, Mohammad Razaghi, and Vahid Ahmadi

Doc ID: 344815 Received 05 Sep 2018; Accepted 18 Dec 2018; Posted 21 Dec 2018  View: PDF

Abstract: In this paper, a comprehensive dynamic model is used to study the nonlinear polarization rotation (NPR) of probe signal in the presence of co-propagating pump signal in a strained semiconductor optical amplifier (SOA). Pump and probe signals are Gaussian pulse with 200 fs pulse width, which propagate in 500 µm SOA. In the present model, the effects of carrier dynamics on the SOA gain and phase are considered and the NPR of probe signal is measured by the ellipticity angle using Stokes vector and Mueller matrices. The effects of several important factors on NPR of probe signal are investigated. These factors include: pump signal energy, free carrier absorption and two photon absorption nonlinear effects, tensile/compressive strain, pump-probe pulse width and pump-probe delay time. The results show that the pulse width and strain have considerable effect on the ellipticity angle deviation (EAD), specially we see that the tensile strain increases the EAD and the compressive strain reduces the EAD as compared with the no strain structure. For a specific range of pulse width (here 0.2 ps to 1 ps), EAD increases noticeably with the pulse width. It is also shown that, for pump-probe delay time, the maximum EAD is obtained when the delay time is 0.1 ps.

Vector vortex coronagraphy for exoplanet detection with spatially-variant diffractive waveplates

Gene Serabyn, camilo mejia prada, Pin Chen, and Dimitri Mawet

Doc ID: 354564 Received 11 Dec 2018; Accepted 15 Dec 2018; Posted 09 Jan 2019  View: PDF

Abstract: Optical vortex coronagraphs have recently been deployed on most of the world’s largest ground-based telescopes to assist in the search for faint exoplanetary and dust emission near stars. These instruments typically make use of vector vortex phase masks, and at short near-infrared wavelengths, the phase masks tend to be spatially-variant liquid-crystal-polymer-based diffractive waveplates. Optical vortex coronagraphs also hold great promise as a potential means of imaging terrestrial exoplanets in nearby solar systems with space-based telescopes, for which nearly-ideal vortex phase masks will be needed. Here we briefly summarize the optical vortex coronagraph, foreseen performance requirements for terrestrial exoplanet imaging detection, the obstacles to nearly-ideal diffractive-waveplate-based vortex phase masks, and recent broadband performance demonstrations.

Optoelectronic performance of modified nanopyramid solar cell

AMR K. MAHMOUD, Mohamed Hussein, Mohamed Hameed, M Abdel-Aziz, H Hosny, and Salah Obayya

Doc ID: 346447 Received 20 Sep 2018; Accepted 14 Dec 2018; Posted 20 Dec 2018  View: PDF

Abstract: The optical and electrical characteristics of modified nanopyramid grating silicon solar cell (SC) are numerically reported and analyzed. The modified grating SC consists of upper tapered nanopyramid and lower nano-rectangular parts. The geometrical parameters of the proposed design are tuned to maximize the optical absorption and hence the ultimate efficiency. The finite difference time domain (FDTD) and finite element methods are utilized via Lumerical software packages for studying the optoelectronics performance of the suggested design. In this investigation, short circuit current density (Jsc), optical generation rate, open circuit voltage (Voc), electrical fill factor (FF) and electrical power conversion efficiency (PCE) are calculated thoroughly. Moreover, the effects of the doping concentration and carrier lifetime on the device performance are also studied. The modified design provides an optical ultimate efficiency of 40.9 % and optical Jsc of 33.5 mA/cm2, respectively with an improvement of 28.3% over conventional nanopyramid SC. This enhancement is due to the ability of the grating sidewalls to trap more light through the active layer. Additionally, the spacing between the adjacent nanopyramid structures can exhibit microcavity resonance which contribute to light broadband absorption improvement. The p-i-n axial doping of the suggested SC exhibits Voc of 0.57 volt, JSC of 28.6 mA/cm2 and PCE of 13.36% which are better than 0.559, 8.95 mA/cm2 and 13.37% of conventional nanopyramid SC.

Macroscopic tripartite entanglement of nitrogen–vacancy centers in diamond coupled to a superconducting resonator

Yusef Maleki and Aleksei Zheltikov

Doc ID: 346341 Received 19 Sep 2018; Accepted 04 Dec 2018; Posted 14 Dec 2018  View: PDF

Abstract: We show that a hybrid quantum device consisting of three ensembles of nitrogen--vacancy (NV) centers whose spins are collectively coupled to a superconducting coplanar waveguide resonator enables the generation of controllable macroscopic tripartite entangled states. At the instants of time when the waveguide resonator is completely depleted of photons and is thus disentangled from the NV-center ensembles, macroscopic Greenberger--Horne--Zeilinger-type states are generated in NV-diamond memories.

Mid-infrared supercontinuum generation from 2 to 14 µm in various arsenic- and antimony-free chalcogenide glass fibers

Arnaud Lemière, frederic desevedavy, Pierre Mathey, Paul froidevaux, Gregory Gadret, Jules jean-charles, Bertrand Kibler, Pierre Bejot, Franck Billard, Olivier Faucher, Frederic Smektala, and Christophe Aquilina

Doc ID: 345983 Received 17 Sep 2018; Accepted 28 Nov 2018; Posted 10 Jan 2019  View: PDF

Abstract: We demonstrate the fabrication of arsenic- and antimony-free chalcogenide glasses compatible with glass fiber processing. Optical fibers with distinct index profiles are presented and characterized, namely single material fibers with or without a suspended core and standard step-index fibers with varying core diameter. In addition, we evidence their potential for nonlinear photonic devices in the mid-infrared spectral region by means of supercontinuum generation experiments in the femtosecond regime. Spectral broadenings extend on several octaves in the mid-infrared from 2 to 14 µm.

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