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A transmission-bias metaheuristic for design optimization of optical structures

Sacha Verweij and Shanhui Fan

Doc ID: 290297 Received 10 Mar 2017; Accepted 18 May 2017; Posted 19 May 2017  View: PDF

Abstract: Search algorithms play a crucial role in systematic design optimization of optical structures. Though many sophisticated methods appear in the literature, physically motivated guiding principles for the design and enhancement of such methods are few. We introduce such a guiding principle --- a transmission- bias metaheuristic --- and demonstrate its value in practice. Specifically, we present a case study in which application of this metaheuristic leads to significantly better performing variants of a simple stochastic local search algorithm --- restarted iterative best improvement --- on a challenging design optimization problem --- combinatorial design optimization of a multi-spatial-mode photonic crystal waveguide bend that preserves modal content.

Generation and dynamics of one-, two- and threedimensionalcavity soliton in VCSEL with saturableabsorber and frequency-selective feedback

Soumendu Jana and BALDEEP KAUR

Doc ID: 279891 Received 10 Nov 2016; Accepted 17 May 2017; Posted 19 May 2017  View: PDF

Abstract: Cavity solitons are predicted in vertical-cavity surface emitting laser with a saturable absorber and coupledto an external frequency-selective feedback element. An entirely variational method based analyticalstudy of the complex Ginzburg-Landau equation; the governing equation of the system, gives rise to one-,two- and three-dimensional cavity solitons. All three types of cavity solitons are verified stable by Lyapunovstability analysis. Stability regions are identified for all three types and are found to shrink withincreasing dimensionality. Split-step Fourier method based direct numerical analysis of the governingequation exhibits matching results for existence and stability of the cavity solitons. Cavity soliton interactionhas been studied numerically. All-optical control on cavity soliton has been demonstrated byintroducing phase gradient. Cavity solitons thus generated have potential applications in optical informationtechnology.

Investigation of Multimode Interference Based High Sensitive Refractive index Sensor by Shining Zero-order Bessel-Gauss Beam

Ardhendu Saha and ARIJIT DATTA

Doc ID: 290508 Received 13 Mar 2017; Accepted 15 May 2017; Posted 15 May 2017  View: PDF

Abstract: A novel multimode interference based refractive index sensor in Higher-order-mode-No-core-Higher-order-mode fiber structure by shining zero-order Bessel-Gauss beam is reported here. The effect of higher order mode coupling on the performance of the proposed sensor is investigated and verified numerically. Based on the simulation results, the proposed sensing scheme offers a very high sensing resolution of 5.54x10-6 RIU over the refractive index range of 1.33-1.42 for a no core fiber length of 15 mm. So, the sensor we proposed has significant advantages in the field of any physical, biological and chemical sensing purposes as it provides measurement with very high sensitivity.

Entanglement transfer from entangled nonlinear coherent states to separable qubits

Davood Afshar, Azam Anbaraki, and Mojtaba Jafarpour

Doc ID: 284653 Received 13 Jan 2017; Accepted 14 May 2017; Posted 15 May 2017  View: PDF

Abstract: We study entanglement transfer from even and odd two-mode nonlinear coherent states to two separable qubits. The separable qubits are assumed to be in the following three states: both of the qubits are in the ground state, one qubit in the ground state and the other in a mixed state, and both of them are in a mixed state. Jaynes-Cummings model is considered as the interaction between the field states and the system of qubits. We use negativity to evaluate the entanglement transfer to the system of qubits after interaction with the field states. The conditions for the production of maximum amount of entanglement between qubits will be discussed. We observe that the maximum value of entanglement transfer is related to the interaction of odd nonlinear coherent states with the qubits when both of the latter are in the ground state.

Photon echoes for a system of large negative spin and few photons

Michael Tavis

Doc ID: 287558 Received 27 Feb 2017; Accepted 14 May 2017; Posted 15 May 2017  View: PDF

Abstract: Persistent photon echoes (revivals) are seen for a large number (N) of two-level molecules (TLMs) prepared initially in the all-down state interacting in a lossless cavity with a photon distribution with a small mean photon number. This case has not been addressed previously revealing characteristic times proportional to the square root of N. Unexpectedly, this behavior is independent of the initial photon distribution (including thermal) and long after the initial echoes die out, they re-emerge completely. Entropy, disentanglement and the Q function are considered with complete disentanglement only occurring at the revival times. Comparison is made to established results.

Nonlinear temporal compression in cavities: theory

Marc Hanna, Xavier Delen, Loïc Lavenu, Florent Guichard, Yoann Zaouter, Frederic Druon, and Patrick Georges

Doc ID: 290927 Received 20 Mar 2017; Accepted 13 May 2017; Posted 15 May 2017  View: PDF

Abstract: The use of recirculating cavities as a way to spatially homogenize self-phase modulation and distribute its accumulation over the propagation distance is analyzed in details, with the aim to perform nonlinear temporal compression. In addition to the insertion of nonlinear media at specific locations in the cavity, as already demonstrated, we also propose to fill the cavity with a noble gas, as is done in hollow capillary-based setups. This makes the accumulation of B-integral continuous rather than discrete. In this case, analytical estimates for the B-integral per roundtrip and scaling rules are provided as a function of cavity geometry and gas parameters. Then, three-dimensional numerical simulations are performed to assess the spatio-temporal couplings in the output beam in various conditions. This model is checked against experimental data presented in the literature, and used to predict our proposed scheme performance. We believe that these techniques constitute a promising way to allow temporal compression at energy levels beyond 10 mJ, where capillary-based setups are difficult to implement.

Optical bistability induced by Gouy phase shift

Taro Hasegawa

Doc ID: 292404 Received 10 Apr 2017; Accepted 12 May 2017; Posted 12 May 2017  View: PDF

Abstract: Optical bistability in a passive ring cavity with no designed nonlinearmaterials is experimentally observed in near-infrared region.The nonlinear material that induces the optical bistabilityis considered to bewater molecules in atmosphere.In the model calculation, it is found that the optical bistabilityis induced by transversal distribution ofoptical power-dependent refractive index of water in the Gaussian beam, whichcauses the power-dependent Gouy phase shift in the cavity.The model calculation agrees qualitatively with the experimental results.This result suggests that the Gouy phase shift gives effectson cavity-enhanced molecular spectroscopy.

Analytical description of inverse filter emulating the plasmon injection loss compensation scheme and implementation for ultra-high resolution hyperlens

Durdu Guney, Wyatt Adams, and Xu Zhang

Doc ID: 291155 Received 22 Mar 2017; Accepted 10 May 2017; Posted 11 May 2017  View: PDF

Abstract: An inverse filter full analytical description and implementation of a recently proposed plasmon injection scheme for improving the resolution of a hyperlens is presented. Different types of loss mechanisms existing in the hyperlens imaging system are identified and studied in detail. It is shown that the plasmon injection scheme and its inverse filter analogue can compensate all the major loss mechanisms. As a result, an object with deep sub-wavelength features, otherwise unresolvable with a hyperlens alone, is fully reconstructed.

Scattering and absorption from super-spherical nanoparticles: analysis and design for transparent displays

Davide Ramaccia, Alessandro Toscano, and Filiberto Bilotti

Doc ID: 285991 Received 01 Feb 2017; Accepted 09 May 2017; Posted 09 May 2017  View: PDF

Abstract: Transparent displays enabled by nanoparticle scattering have potential attractive features, including simplicity, wide viewing angle, scalability to large size, and low cost. However, conventional nanoparticles made of noble metals require extreme geometrical dimensions to operate within the visible frequency range, making this intriguing setup unfeasible. Recently, to relax the realization constrains, the super-spherical geometry has been introduced. Exploiting this idea, we present the design of sub-pixels operating at the blue, green, and red wavelengths that can be used to make nanoparticle-based transparent displays feasible and practical.. We describe the analytical design of the super-spherical nanoparticles through their polarizability, and demonstrate its applicability to transparent screens.

Lamb shift multipolar analysis

Emmanuel Lassalle, Alexis Devilez, Nicolas Bonod, Thomas Durt, and Brian Stout

Doc ID: 287959 Received 03 Mar 2017; Accepted 09 May 2017; Posted 09 May 2017  View: PDF

Abstract: It is now well established that radiative decay of quantum systems can be strongly modified by their environment. In this paper we present an exact analytical expression to compute the Lamb (frequency) shift induced by an arbitrary set of resonant scatterers on a nearby quantum emitter, using multipolar multi-scattering theory. We also use a quasi-normal-mode approach to account for the line shape of the Lamb shift spectrum in the near-field of a plasmonic nanosphere. It is then shown that the Lamb shift resonance can be blue-shifted as the size of the nanoparticle increases, suggesting that nanoparticles may be used to tune this resonant interaction. Finally, a pragmatic calculation of the frequency-shift is made for a dimer configuration.

Effects of charges on the localized surface phonon polaritons in dielectric nanoparticles

Bing Yang, Tong Wu, Xiangdong Zhang, and Yue Yang

Doc ID: 288012 Received 03 Mar 2017; Accepted 09 May 2017; Posted 09 May 2017  View: PDF

Abstract: Recently, there has been a great deal of interest in studying the surface phonon polaritons (SPhPs) modes in polar dielectrics due to their potential applications in mid-infrared (MIR) spectral range. However, the effects of charges on the SPhPs modes have not been discussed up to now. In fact, the exotic electrons and electron-phonon (EPh) interactions widely exist in many nanostructures in practice. Here, we theoretically investigate effects of electrons and EPh interactions on the localized SPhPs in polar dielectric nanoparticles within the framework of Mie theory. Our results show that electrons have different effects on the localized SPhPs modes in the nanostructures with different electron affinity. For particles with negative electron affinity, such as MgO case, electrons only lead to blueshifts of the SPhPs resonances with little effects on the magnitudes of resonance absorptions and electric near-field enhancements. While for particles with positive electron affinity, such as Al2O3, except for blueshifts of the resonances, EPh interactions decrease the resonance absorptions largely, and almost annihilate multiple resonance modes into only one in multi-sphere nanostructures. Also, EPh terms reduce the electric near-fields dramatically to values far less than that of particles with no exotic electrons. Our results are helpful to the applications of polar dielectrics in nanoscale within MIR spectral range.

Integration in Analog Optical Computing using Metasurfaces Revisited: toward Ideal Optical Integrator

Zahra Kavehvash, Hossein Babashah, Somayyeh Koohi, and Amin Khavasi

Doc ID: 283153 Received 20 Dec 2016; Accepted 07 May 2017; Posted 08 May 2017  View: PDF

Abstract: In this paper, we introduce a modified optical integrator based on suitably designed metamaterial blocks. The integration is performed on an impinging wave pattern as it propagates through these blocks. So far, various metamaterial-based optical integrators have been implemented with appropriate performance in the case of zero-DC input signals. However, these integrators suffer from low accuracy when feed by signals rich in low-frequency contents. The latter property arises from truncation of low-frequency contents of the input wave in the Fourier domain. To solve this shortcoming, we propose a new metasurface-based structure which reflects low frequency parts of the input signal in the Fourier domain. This subtracted part is then measured in the input and compensated in the detected output signal. The numerically simulated output responses verify superior performance of the proposed structure compared to conventional metamaterial-based optical integrator in the case of input signals with considerable low-frequency contents. These findings may lead to remarkable achievements in light-based plasmonic signal processors at nanoscale, which can replace their bulky conventional dielectric lens-based counterparts.

Optimization of Electromagnetically Induced Transparency By Changing the Radial Size of Laguerre-Gaussian Laser Modes

Eric Abraham, Thomas Akin, Sean Krzyzewski, and Matthew Holtfrerich

Doc ID: 286871 Received 15 Feb 2017; Accepted 07 May 2017; Posted 08 May 2017  View: PDF

Abstract: We demonstrate electromagnetically induced transparency in ultracold rubidium 87 with the control laser in a Laguerre-Gaussian mode and the probe laser in a Gaussian mode. The effects on EIT transmission spectra due to varying control mode sizes are explored and optimized. The narrowest EIT features that still exhibit large signal contrast occur when the control and probe laser have equivalent waists, despite the differences in the radial intensity profiles of the probe and control beams.

Non Bianisotropic Complementar y Split Ring Resonators as Angular Selective Metasurfaces

Miguel Beruete and Pablo Rodríguez-Ulibarri

Doc ID: 285976 Received 02 Feb 2017; Accepted 04 May 2017; Posted 04 May 2017  View: PDF

Abstract: In this work, a metasurface with unconventional angular performance and composed by nonbianisotropic complementary split ring resonator (NB-CSRR) is analyzed numerically and experimentally. A numerical study comparing the performance with the original complementary split ring resonator is conducted showing very interesting transmission properties such as complete filtering under normal incidence and high transmission peaks at oblique incidence for the NB-CSRR metasurface. A bi-layeredNB-CSRR prototype working at millimeter waves with a total thickness of 100 microns (0.1 times the operation wavelength) is fabricated and tested with a good agreement between simulation results and experiments. Very exciting applications based on the presented structure such as advanced angular selectivity devices with great rejection level at normal incidence and angular sensing devices can be envisaged.

Coupled cavity optomechanical meta-waveguides

Andrea Alu and Mohammad-Ali Miri

Doc ID: 290210 Received 07 Mar 2017; Accepted 02 May 2017; Posted 03 May 2017  View: PDF

Abstract: We explore waveguiding in a one-dimensional array of coupled optomechanical cavities each supporting a pair of optical and mechanical modes. The dispersion relation of such waveguide is derived for different scenarios, as a function of the level of optical, mechanical and optomechanical coupling rates. The mechanical coupling with light is found to have a profound effect on the dispersion properties, leading to intriguing optical phenomena. In addition, the emergence of an exceptional point in the dispersion diagram is shown to induce anomalies, such as negative group velocity with low attenuation. The drive power and frequency can largely control the band diagram of such periodic structures, offering a great tool to engineering and reconfiguring the coupled cavity optomechanical meta-waveguide. The peculiar band structure of the system is probed investigating the linear propagation of short pulses, revealing interesting dynamics, such as deceleration and acceleration, and secondary pulse emission. These concepts may pave the way towards a new generation of meta-waveguides and metamaterials in which strong opto-mechanical interactions overcome some of the limitations of passive, linear optical metamaterials based exclusively on optical resonances.

Effect of Raman Scattering on Soliton Interactions in Optical Fibers

Prannay Balla, Shaival Buch, and Govind Agrawal

Doc ID: 284096 Received 04 Jan 2017; Accepted 02 May 2017; Posted 03 May 2017  View: PDF

Abstract: We investigate numerically the effect of Raman scattering on the interaction of two temporally separated pulses with identical spectra that propagate inside a single-mode fiber as fundamental solitons. We take into account all interpulse Raman scattering terms in the generalized nonlinear Schr\"odinger equation and study the interplay between the Kerr, intrapulse Raman and interpulse Raman effects. We observe considerable differences from the well-known two-soliton interaction behavior caused by the Kerr nonlinearity. We study in detail the mechanism for a net energy transfer from the leading pulse to the trailing pulse caused by the delayed nature of the Raman response in the case of two identical in-phase solitons. Long range interactions, where the pulses do not temporally overlap, are found to not cause any energy transfer between the pulses, but solitons are still shown to affect each others' phase owing to the long tail of the Raman response function. We also study and compare how a phase difference between two otherwise identical solitons affects the interaction scenario and changes the collision dynamics, both in the presence and absence of the Raman effect. Finally, we look at the effect of changing the relative amplitude of the two interacting solitons by a small amount.

Versatile setup for high quality rephasing, non-rephasing and double quantum 2D electronic spectroscopy

Luca Bolzonello, Andrea Volpato, Elena Meneghin, and Elisabetta Collini

Doc ID: 287258 Received 24 Feb 2017; Accepted 01 May 2017; Posted 03 May 2017  View: PDF

Abstract: Fully non-collinear setups for two-dimensional electronic spectroscopy (2DES) based on passively phase-stabilization methods are now well-known and widely employed worldwide.Here we propose several updates in the experiment geometry, calibration procedures and data acquisition and processing routines to enhance phase control and phase stability.In addition, the setup is easily tunable to record different phase-matching directions signal, still exploiting the advantages of a rotating frame approach.The improved quality of the 2DES maps achievable with this setup is exemplified by measures on the standard dye Zinc Phtalocyanine and porphyrin J-aggregates.

Continuous nondemolition measurement of boson number in a driven damped harmonic oscillator

Vlasta Perinova, Antonin Luks, jaromir krepelka, and Tomas Komarek

Doc ID: 287315 Received 24 Feb 2017; Accepted 30 Apr 2017; Posted 03 May 2017  View: PDF

Abstract: The continuous quantum nondemolition measurement represents a continuous \enquote{collapse} of the initial state into one of the photon number states. The initial state may be the stationary state of the driven damped harmonic oscillator. A simultaneous drive, damping and continuous quantum nondemolition measurement process behaves differently. Its stationary state shows a decrease in the mean photon number in the resonant case. For chosen values of parameters, a decrease of the mean number of detection events with detuning can be obtained by the Monte Carlo method.

Measurement of mass by optical forced oscillation of absorbing particles trapped in air

Jinda Lin, Jianliao Deng, Rong Wei, Yong-Qing Li, and Yu-zhu Wang

Doc ID: 284942 Received 17 Jan 2017; Accepted 30 Apr 2017; Posted 03 May 2017  View: PDF

Abstract: We demonstrate the measurement of mass of the absorbing micro-particle trapped in air by optical force oscillation. When the trapping light intensity is modulated sinusoidally, the particle in the trap undergoes forced oscillation and the amplitude of the oscillation depends directly on the modulated frequency. Based on a simple spring model, we fit the amplitudes versus the modulated frequencies and obtain the stiffness of the optical trap and the mass of the trapped particle. The fitting results show that, for a certain particle, the stiffness varies linearly with the trapping light intensity while the mass is consistent. The density of the micro-particle is then estimated and could be used to classify different kinds of absorbing particles, like C and CuO.

Collective dynamics in a laser-pumped mixture of two atomic ensembles

Luling Jin, Jörg Evers, and Mihai Macovei

Doc ID: 287435 Received 24 Feb 2017; Accepted 29 Apr 2017; Posted 03 May 2017  View: PDF

Abstract: We investigate the quantum dynamics of an atomic mixture composed of two multi-atom ensembles. Each ensemble is driven separately by a coherent laser field, respectively, and damped via the interactions with the environmental vacuum electromagnetic field reservoir. We find that due to the photon exchange among the two components, long-time excitation oscillations appear which may be significantly longer than the inverse life-time of a single emitter. Furthermore, few-atom ``jumps' to the excited state occur as function of the parameter characterizing the inter-components interactions around a certain working point.

Measurement of dispersive properties of a multi-window EIT in a Doppler-broadened atomic medium

Khoa Dinh, Trung Le Canh, Thuan Phan, Doai Le, and Bang Nguyen

Doc ID: 286690 Received 14 Feb 2017; Accepted 29 Apr 2017; Posted 03 May 2017  View: PDF

Abstract: We have measured dispersive profile of a multi-window EIT in the Rb atomic gaseous medium in the presence of Doppler broadening. The atomic medium is excited by a strong coupling and a weak probe laser lights via the V-type transitions within a D2 manifold. Under the EIT effect, an anomalous dispersive region of the medium is basically modified into multi- normal and anomalous dispersive regions. Furthermore, the slop and position of the dispersion can be controlled with intensity and frequency of the coupling light. An analytic model is proposed to simulate the observed spectrum with a good agreement. Such controllable dispersive properties with its analytic description would be useful for finding applications related to multi-window EIT phenomena.

Synthetic Lorentz force in an expanding cold atomic gas

Neven Santic, Tena Dubček, Damir Aumiler, Hrvoje Buljan, and Ticijana Ban

Doc ID: 286769 Received 15 Feb 2017; Accepted 29 Apr 2017; Posted 03 May 2017  View: PDF

Abstract: We implement a synthetic Lorentz force in a cold atomic gas released from a magneto-optical trap. The signature of this is an angular deflection of a rotationally asymmetrical cloud. The effect is a consequence of thermal expansion of the cold atomic cloud under the influence of the applied synthetic Lorentz force. The synthetic Lorentz force is based on radiation pressure and the Doppler effect making it straightforward to implement. The introduction of synthetic magnetism into our system, together with the fact that it is readily described by the Fokker-Planck equation, makes it an excellent candidate to emulate numerous complex classical systems.

Effects of photon scattering torque in off-axis levitated torsional cavity optomechanics

Mishkatul Bhattacharya, Brandon Rodenburg, Wyatt Wetzel, Bryan Ek, and Anand Jha

Doc ID: 285304 Received 23 Jan 2017; Accepted 28 Apr 2017; Posted 03 May 2017  View: PDF

Abstract: We consider theoretically a dielectric nanoparticle levitated in an optical ring trap inside a cavity and probed by an angular lattice, with all electromagnetic fields carrying orbital angular momentum. Analyzing the torsional motion of the particle about the cavity axis, we find that photon scattering from the trap beam plays an important role in the optomechanical system. First we show that the presence of the torque introduces an instability. Subsequently, we demonstrate that for bound motion near a stable equilibrium, varying the optical torque strength allows for tuning the linear optomechanical coupling. Finally, we indicate that the relative strengths of the linear and quadratic couplings can be detected directly by homodyning the cavity output. Our studies should be of interest to researchers exploring torsional optomechanics.

A dual-trap system for the study of charged rotating graphene nanoplatelets in high vacuum

Joyce Coppock, Jacob Murphy, Ian McAdams, Saimouli Katragadda, Bruce Kane, and Pavel Nagornykh

Doc ID: 285546 Received 31 Jan 2017; Accepted 28 Apr 2017; Posted 03 May 2017  View: PDF

Abstract: We discuss the design and implementation of a system for generating charged multilayer graphene nanoplatelets and introducing a nanoplatelet into a quadrupole ion trap in high vacuum. Levitation decouples the platelet from its environment and enables sensitive mechanical and magnetic measurements. The platelets are generated via liquid exfoliation of graphite pellets and charged via electrospray ionization. A single platelet is trapped at a pressure of several hundred millitorr and transferred to a trap in a second chamber, which is pumped to UHV pressures for further study.

A levitated nanoparticle as a classical two-level atom

Martin Frimmer, Jan Gieseler, Thomas Ihn, and Lukas Novotny

Doc ID: 290827 Received 16 Mar 2017; Accepted 28 Apr 2017; Posted 03 May 2017  View: PDF

Abstract: The center-of-mass motion of a single optically levitated nanoparticle resembles three uncoupled harmonic oscillators. We show how a suitable modulation of the optical trapping potential can give rise to a coupling between two of these oscillators, such that their dynamics are governed by a classical equation of motion that resembles the Schrödinger equation for a two-level system. Based on experimental data, we illustrate the dynamics of this parametrically coupled system both in the frequency and in the time domain. We discuss the limitations and differences of the mechanical analogue in comparison to a true quantum mechanical system.

Influence of the Kerr nonlinearity in a single nonstationary cavity mode

Ricardo Roman, carlos gonzalez gutierrez, and Jose Recamier

Doc ID: 286008 Received 01 Feb 2017; Accepted 26 Apr 2017; Posted 27 Apr 2017  View: PDF

Abstract: We study a simple version of the dynamical Casimir effect in an single electromagnetic cavity mode containing a Kerr medium. We obtain an approximate expression for the time evolution operator valid for short times and/or low average photon number. We have found that the generation of photons from quantum vacuum is strongly affected by the presence of the Kerr medium. In the time domain it shows strong oscillations whose frequency increases with the intensity of the nonlinear medium, sharing physical features with the case of two two-level atoms in a cavity with oscillating walls. Using a semiclassical approach we show that Kerr nonlinearity produce a faster decrease in the photon production rate than that reported in previous studies working on quasi-resonant nonstationary cavities. Also we found that the initial vacuum state can evolve in a cat sate. We expect that these results could be relevant for anystudy involving the dynamical Casimir effect that is willing to incorporate Kerr nonlinearities.

Direct comparison of time-resolved Terahertz spectroscopy and Hall Van der Pauw methods for measurement of carrier conductivity and mobility in bulk semiconductors

Brian Alberding, W. Thurber, and Edwin Heilweil

Doc ID: 283012 Received 16 Dec 2016; Accepted 20 Apr 2017; Posted 12 May 2017  View: PDF

Abstract: Charge carrier conductivity and mobility for various semiconductor wafers and crystals were measured by ultrafast above bandgap, optically excited Time-Resolved Terahertz Spectroscopy (TRTS) and Hall Van der Pauw contact methods to directly compare these approaches and validate the use of the non-contact optical approach for future materials and in-situ device analyses. Undoped and doped silicon (Si) wafers with resistances varying over six orders of magnitude were selected as model systems since contact Hall measurements are reliably made on this material. Conductivity and mobility obtained at room temperature by terahertz transmission and TRTS methods yields the sum of electron and hole mobility which agree very well with either directly measured or literature values for corresponding atomic and photo-doping densities. Careful evaluation of the optically-generated TRTS frequency-dependent conductivity also shows it is dominated by induced free-carrier absorption rather than small probe pulse phase shifts, which is commonly ascribed to changes in the complex conductivity from sample morphology and evaluation of carrier mobility by applying Drude scattering models. Thus, in this work, the real-valued, frequency-averaged conductivity was used to extract sample mobility without application of models. Examinations of germanium (Ge), gallium arsenide (GaAs), gallium phosphide (GaP) and zinc telluride (ZnTe) samples were also made to demonstrate the general applicability of the TRTS method, even for materials that do not reliably make good contacts (e.g., GaAs, GaP, ZnTe). For these cases, values for the sum of the electron and hole mobility also compare very favorably to measured or available published data.

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