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Accepted papers to appear in an upcoming issue

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Effect of atomic diffusion on the Raman-Ramsey CPT resonances

Irina Novikova, Eugeniy Mikhailov, and Elena Kuchina

Doc ID: 254508 Received 24 Nov 2015; Accepted 02 Feb 2016; Posted 05 Feb 2016  View: PDF

Abstract: We experimentally investigated the characteristics of two-photon transmission resonances in Rb vapor cells with different amount of buffer gas under the conditions of steady-state coherent population trapping (CPT) and pulsed Raman-Ramsey (RR-) CPT interrogation scheme. We particularly focused on the influence of the Rb atoms diffusing in and out of the laser beam. We showed that this effect modifies the shape of both CPT and Raman-Ramsey resonances, as well as their projected performance for CPT clock applications. In particular we found that at moderate buffer gas pressures RR-CPT did not improved the projected atomic clock stability compare to the regular steady-state CPT resonance.

Electromagnetic scattering by homogeneous, isotropic, dielectric-magnetic sphere with topologically insulating surface states

Akhlesh Lakhtakia and Tom Mackay

Doc ID: 254872 Received 01 Dec 2015; Accepted 01 Feb 2016; Posted 02 Feb 2016  View: PDF

Abstract: The Lorenz-Mie formulation of electromagnetic scattering by a homogeneous, isotropic, dielectric-magnetic sphere was extended to incorporate topologically insulating surface states characterized by a surface admittance $\gamma$. Closed-form expressions were derived for the expansion coefficients of the scattered field phasorsin terms of those of the incident field phasors. These expansion coefficients were used to obtain analytical expressions for the total scattering, extinction, forward scattering, and backscattering efficiencies of the sphere. Resonances exist for relatively low valuesof $\gamma$, when the sphere is either nondissipative or weakly dissipative. For large values of $\gamma$, the scattering characteristics are close to that of a perfect electrically conducting sphere,regardless of whether the sphere is composed of a dissipative or nondissipative material, and regardless of whether that material supports planewave propagation with positive or negative phase velocity.

Persistence of photonic nanojet formation under the deformation of circular boundary

Ibrahim Mahariq, Vasily Astratov, and Hamza Kurt

Doc ID: 255199 Received 06 Dec 2015; Accepted 01 Feb 2016; Posted 01 Feb 2016  View: PDF

Abstract: A photonic nanojet is a highly focused optical beam with a sub-wavelength waist on the shadow side of the dielectric micro-sphere or micro-cylinder. In this paper, photonic nanojets resulting from corrugated cylinders (with irregular boundaries) under normally incident plane-wave illumination are studied. Different level of corrugations induced at the boundaries of the dielectric micro-cylinders produce strong light focusing as well as photonic nanojet with unique performance compared to perfectly smooth cylinders. Spectral element method is utilized in this study for the sake of high accuracy. Interestingly, we found that, under some geometrical/material parameters, one may not need a highly perfect cylinder in order to obtain photonic nanojet. In addition, resonance behavior is reported and examined under larger variations in the parameters defining corrugated cylinders when compared with circular dielectric cylinders.

Polarizability Calculation of Arbitrary IndividualScatterers, Scatterers in Arrays and Substrated Scatterers

Mohammad Yazdi and Nader Komjani

Doc ID: 253625 Received 09 Nov 2015; Accepted 28 Jan 2016; Posted 01 Feb 2016  View: PDF

Abstract: We develop a semi-analytical approach for calculation of polarizability tensors of individual scatterers, scatterers in arrays and substrated scatterers. The approach is based on the integration from inducedcharges and currents on the scatterer. By taking the advantages of the present approach, we calculate the individual polarizability tensors of isolated scatterers in a homogeneous isotropic medium. Moreover, we present the procedure of obtaining the polarizability tensors of substrated scatterers: scatterers located between two different isotropic media. Furthermore, using the proposed method we determine the collective polarizability tensors of scatterers in a periodic array. To compare and verify the results of arrays, we also investigate two other methods for calculating collective polarizabilities of scatterers in arrays. We examine the validity of the proposed approach using some examples and compare the results with other approaches. The proposed approach, in comparison to other reported approaches, is simpler, easily implemented, and does not require spherical harmonics expansion or complicated far-field calculations.

Electromagnetic Surface Waves in Liquid Metacrystals

Nina Zharova, Alexander Zharov, and Alexander Zharov

Doc ID: 254544 Received 24 Nov 2015; Accepted 28 Jan 2016; Posted 01 Feb 2016  View: PDF

Abstract: We study linear electromagnetic waves guided by an interface between dielectric medium and liquid metacrystal (LMC) as well as by a slab of LMC. We derive the dispersion equation for such waves and find their transverse structure for arbitrary oriented anisotrophy axis of LMC controlled by an external constant electric field. High degree of anisotrophy can be reached in LMC near the resonance of the inclusions (meta-atoms), and it allows propagation of known Dyakonov surface waves below the resonance frequency and also specific surface modes above the resonance frequency, (in hyperbolic dispersion regime) along the LMC-dielectric interface. The both types of surface waves are characterized by sensitivity to the parameters (radiation frequency, orientation of the optical axis, etc.) and have hybrid (mixed ordinary and extraordinary) polarization. In LMC slab there can exist two families of eigenmodes: low-k and high-k modes, the latter arise only in hyperbolic dispersion regime. In the case when the normal to the slab interface is along the resonance cone generatrix in the LMC, very high density of eigenmodes can take place that results from the inherent property of hyperbolic medium - infinite density of photonic states.

Compensation method for temperature-induced phase-mismatch during frequency conversion in high-power laser systems

Cui zijian, Dean Liu, Meizhi Sun, Jie Miao, and Jianqiang Zhu

Doc ID: 254906 Received 02 Dec 2015; Accepted 28 Jan 2016; Posted 01 Feb 2016  View: PDF

Abstract: A compensation method for phase-mismatch caused by temperature variation during the frequency conversion process is proposed and the theoretical model is established. The method is based on the principle that phase-mismatch can be compensated via the electro-optic effect based on a compensation scheme consisting of two nonlinear crystals and an electro-optic crystal; further, a new dimension adjustment can be achieved by changing the voltage. In a proof-of-principle study, frequency conversion from 1053 nm to 526.5 nm and 351 nm by cascade KH2PO4 (KDP) and KD2PO4 (DKDP) crystals, respectively, is presented as an example. Three-dimensional numerical simulations are conducted to show that the conversion efficiency of frequency doubling and tripling varies with temperature. The results show that the temperature acceptance bandwidth of doubling and tripling can be 2.4 and 3.4 times larger, respectively, than that of the traditional method using a single crystal. We also analyze the stability of the conversion efficiency for 192 beams by our proposed method when the temperature is randomly varied within the range of 24-26 °C. The standard deviation of the conversion efficiency of frequency doubling and tripling decreases from 1.25% and 6.61% to 0.18% and 0.56%, respectively. In addition, the influence of the reflection loss on the output efficiencies is also analyzed and the results show that it is very small. This indicates that this method may be effective in reducing the temperature sensitivity of conversion efficiency.

Frequency domain noise analysis of optoelectronic oscillators considering the nonlinearity of the RF amplifier

Sajad Jahanbakht and S.Esmail Hosseini

Doc ID: 251982 Received 14 Oct 2015; Accepted 26 Jan 2016; Posted 27 Jan 2016  View: PDF

Abstract: A new physically consistent approach for considering the nonlinearity of the RF amplifier within optoelectronic oscillator (OEO) structure is presented which uses the measured amplitude and phase responses of the RF amplifier. This behavioral model along with the measured frequency response of the RF filter is used in frequency domain to predict the signal and noise spectrum of the OEO which is based on the well-known conversion matrix approach (CMA). A simple technique for computing the steady state of the OEO with high precision is introduced which prevents the ill-conditioning problem in computing the phase and amplitude noise power spectral densities (PSDs) at the near to the carrier offset frequencies. The validity of this approach is verified by the previously published data in the literature. By considering a hypothetical phase response for the RF amplifier, it is shown that the presented nonlinear modeling and the analysis algorithm are capable of taking the important phenomenon of amplitude-to-phase conversion into account which is responsible for converting the amplitude fluctuations into phase noise.

Quasi 3-level Model Applied to Measured Spectra of Nonlinear Absorption and Refraction in Organic Molecules

Trenton Ensley, Honghua Hu, Matthew Reichert, Manuel Ferdinandus, Davorin Peceli, Joel Hales, Joseph Perry, Zhong'an Li, Sei-Hum Jang, A Jen, Seth Marder, David Hagan, and Eric Van Stryland

Doc ID: 253962 Received 18 Nov 2015; Accepted 26 Jan 2016; Posted 26 Jan 2016  View: PDF

Abstract: Materials with a large nonlinear refractive index (n_2) and relatively small linear and nonlinear absorption losses, namely two-photon absorption (2PA, of coefficient α_2), have long been sought after for applications such as all-optical switching (AOS). Here we experimentally determine the linear and 2PA properties of several organic molecules, which we approximate as centrosymmetric and use a simplified essential state model (quasi 3-level model) to predict the dispersion of n_2. We then compare these predictions with experimental measurements of n_2 and find good agreement. Here ‘quasi’ 3-level means using a single one-photon allowed intermediate state and multiple (here two) two-photon allowed states. This also allows predictions of the figure-of-merit (FOM), defined as the ratio of nonlinear refractive phase shift to the 2PA fractional loss, that determines the viability for such molecules to be used in device applications. The model predicts that the optimized wavelength range for a large FOM lies near the short wavelength linear absorption edge for cyanine-like dyes where the magnitude of n_2 is quite large. However, 2PA bands lying close to the linear absorption edge in certain classes of molecules can greatly reduce this FOM. We identify two molecules having a large FOM for AOS: one where the main 2PA band is far from the linear absorption edge and the other having a large FOM in the telecommunications window. We note that the FOM is often defined as the ratio of real to imaginary parts of the third-order susceptibility (χ^((3)) ) with multiple processes leading to both components. As explained later in this paper, such definitions require care to only include the 2PA contribution to the imaginary part of χ^((3)) in regions of transparency.

Transient first-order interference of two independent thermal light beams

bai bin, Jianbin Liu, Songlin Zhang, Yuchen He, Mingnan Le, Wentao Wang, and Zhuo Xu

Doc ID: 252929 Received 29 Oct 2015; Accepted 25 Jan 2016; Posted 26 Jan 2016  View: PDF

Abstract: By analyzing the transient first-order interference of two independent thermal light beams in both classical and quantum theories, we conclude that for certain kind of thermal light, it is impossible to observe the transient first-order interference pattern by superposing two independent thermal light beams even if the degeneracy parameter of thermal light is much greater than one. The result suggests that the wellaccepted classical model of thermal light field within the coherence time is not valid for all kinds of thermal light, which is important and helpful to understand the first-order interference of thermal light.

Strong second-harmonic generation from bilayer-graphene-embedded in photonic crystals

Xiangdong Zhang and Shihao Zhang

Doc ID: 253602 Received 16 Nov 2015; Accepted 25 Jan 2016; Posted 26 Jan 2016  View: PDF

Abstract: We theoretically investigate second harmonic generation (SHG) from bilayer-graphene (BLG) embedded in photonic crystals (PCs) using transfer-matrix method. Two kinds of case are considered. One is a stack of BLG layers in the dielectric multilayer structure, the other is a single BLG layer embedded in the defect PCs. It is found that the improved field localization within the defect PCs enhances SHG by three orders of magnitude compared with the bare BLG. Although the SHG efficiency from the stack of BLG layers in the dielectric multilayer structure is lower than that from the defect PCs due to the effect of absorption, there are some advantages in controlling the polarization dependence of the SHG for such a case. For example, various ratios of s-polarized and p-polarized second harmonic outputs can be realized by adjusting the azimuthal rotational angles of the BLG layers for the incident wave with a certain polarization. We believe that these phenomena are very beneficial for the design of optical devices.

3D-PSTD for modelling second harmonic generation in periodically poled lithium niobate ridge-type waveguides

Fabrice Devaux, Mathieu Chauvet, and Eric Lantz

Doc ID: 250673 Received 22 Sep 2015; Accepted 25 Jan 2016; Posted 02 Feb 2016  View: PDF

Abstract: We report an application of the tri-dimensional pseudo-spectral time domain algorithm, that solves with accuracy the nonlinear Maxwell’s equations, to predict second harmonic generation in lithium niobate ridge-type waveguides with high index contrast. Characteristics of the nonlinear process such as conversion efficiency as well as impact of the multimode character of the waveguide are investigated as a function of the waveguide geometry in uniformlyandperiodicallypoledmedium.

Realization of the ultrawideband negative index metamaterials by its multiple-band

Peng Gao, Jingjing Ai, yongqiang kang, and Chunmin Zhang

Doc ID: 249258 Received 02 Sep 2015; Accepted 23 Jan 2016; Posted 25 Jan 2016  View: PDF

Abstract: In this paper, a concept of multiple-band is proposed to broaden the bandwidth of the negative index metamaterials. The multiple-band, which is realized by a new metamaterial sample composed of the double-E-ring, has more than two negative refraction bands at comparable frequencies. When the metamaterial produces a multiple-band, the bandwidth can be greatly enhanced, yielding an increased numbers of negative bands. The experimental measurement and computer simulation for the multiple-negative-passband metamaterial at microwave frequencies are presented. The effective permittivity and permeability of several resonant frequencies are retrieved from the simulation scattering data, and the experimental measurements show good agreement with the simulative results.

Extraordinary surface polaritons in obliquely-truncated dielectric/metal metamaterials

Xuan-Zhang Wang, Qiang Zhang, and Yu-Liang Zhang

Doc ID: 251735 Received 12 Oct 2015; Accepted 22 Jan 2016; Posted 22 Jan 2016  View: PDF

Abstract: The surface plasmonic polariton (SPP) of one obliquely-truncated metal/dielectric metamaterial is investigated in a particular geometry. The dispersion relations are obtained, and we predict an extraordinary SPP mode whose propagation seriously deviates from the metamaterial surface. Extraordinary behaviors of the SPP mode are found in the vicinities of the divergence and zero points of effective permittivity. Its energy-flux density reverses in direction when the mode frequency passes the divergence point, changing from parallel to anti-parallel to the in-plane wavevector. The dispersion curves terminate at the zero point for the metal filling ratio smaller than dielectric that. The numerical results are presented based on the one-dimensional metal/SiO2 metamaterial.

Non-classical properties and entanglement of superposition of two-mode separable nonlinear coherent states

Davood Afshar and Azam Anbaraki

Doc ID: 252204 Received 19 Oct 2015; Accepted 22 Jan 2016; Posted 22 Jan 2016  View: PDF

Abstract: Quasi Bell states are introduced as a result of superposition of two-mode separable nonlinear coherent states. In this paper, we consider the nonlinearity function related to the harmonious states. To evaluate the effectiveness of these states in quantum information theory, non-classical properties such as photon statistics, squeezing and entanglement would be studied. The entanglement of these states is examined by calculating the concurrence. According to our calculations, three of introduced states are maximally entangled states. In addition, cross correlation function of the three maximally entangled states is less than one for all values of the parameter α.

Mapping of surface plasmon dispersion in thin Ag-Au layered composite films

David McCloskey, John Donegan, Kyle Ballantine, Christopher Kervick, Christopher Smith, Chuan Zhong, Daragh Mullarkey, and Igor Shvets

Doc ID: 251124 Received 07 Oct 2015; Accepted 22 Jan 2016; Posted 02 Feb 2016  View: PDF

Abstract: Propagating surface plasmon polaritons (SPPs) at metal-dielectric interfaces allow extreme light confinement enabling important technologies such as label free real-time sensing, and nanoscale optical wave guiding. In this work, we experimentally and theoretically map the surface plasmon dispersion of thin films of sequentially deposited silver and gold based on the Kretschmann-Raether configuration using spectroscopic ellipsometry. The results show efficient excitation of SPPs modes related to the symmetric and anti-symmetric modes of an insulator-metal-insulator waveguide. Since the symmetric modes have larger electric field inside the bimetallic layer than the antisymmetric modes, we show that the dispersion for both modes can be tuned independently by controlling the thickness ratio and deposition order of metals in the film. This behavior is fundamentally different than modes in a single film, or thin film alloy. Results are in agreement with the analytical eigenmode dispersion of these modes, and with a full transfer matrix model. Our results provide a complete understanding of surface plasmon modes in thin bi-layer or multi-layer metallic films and their ability to influence the propagation of surface plasmon waves.

Evolution of Photonic Metasurfaces: from Static to Dynamic

Amr Shaltout, Alexander Kildishev, and Vladimir Shalaev

Doc ID: 251226 Received 01 Oct 2015; Accepted 21 Jan 2016; Posted 21 Jan 2016  View: PDF

Abstract: The realization of commercial photonic devices based on three dimensional optical metamaterials is challenged by large absorptive losses as well as complex, and costly fabrication. Metasurfaces – two dimensional metamaterials - have been introduced to overcome these major challenges. They provide simple, compact and power efficient solutions to problems of immense importance in photonics design. In addition to the strong potential of metasurfaces to enable next generation optical devices, their reduced dimensionality also allows for new physical effects which don’t have volumetric counterparts. Furthermore, various technologies are presently emerging to provide modulation of metasurface response using mechanical, electrical or optical control. Although the general purpose of these approaches is to obtain tunable versions of static metasurfaces, recent studies uncovered that the impact of dynamic metasurfaces far exceeds tunability alone and comprises new physical effects such as Lorentz non-reciprocity. Here, we start with reviewing recent developments of static metasurface devices and their applications. Then, we discuss the bourgeoning area of dynamic metasurfaces and demonstrate current evolving technologies to achieve time-varying properties and their conceivable applications.

Optical properties of plasmonic nanopillars in extended quasistatic limits

Atefe Fazel Najafabadi and Tavakol Pakizeh

Doc ID: 254850 Received 01 Dec 2015; Accepted 21 Jan 2016; Posted 21 Jan 2016  View: PDF

Abstract: An extended method based on the long-wavelength approximations is introduced to investigate the optical properties of finite-size metal nanopillars for different incident light polarizations. In this proposed method the optical depolarization factors are the key parameters and strongly depend on the position of the considered point-dipole inside the irregular shaped nanoparticles. It is discussed that various depolarization factors lead to the different retarded dipolar fields for each assigned point-dipole, adequately modeling the optical properties of the finite-size plasmonic nanoparticle. Interestingly depending on the polarization, it is shown that the point-dipole positioned at the center point of the non-spherical nanoparticle seldom is the proper choice as its simple electromagnetic model. The proper point, though, is determined and physically associated with the electric-field distribution inside the nanoparticle, supported by numerical computations. Clearly, the retarded dipolar field and related depolarization factors of the assigned point-dipole in the extended-MLWA could extend the quasistatic limits and consequently more accurately predicts the optical properties of the finite-size plasmonic nanopillar. It is found that for a circular and conical Au-nanopillar the appropriate point for the position of equivalent point-dipole is located on the pillars’ axis, severely depending on the incident light polarization and the geometrical parameters. By considering the inherent characteristics of the proper point-dipoles, the optical properties of nanopillars can be simply obtained for oblique incidences. The theoretical findings are well supported by the simulation results.

Tunable angular dependent second harmonic generation in glass by controlling femtosecond laser writing polarization

Bertrand Poumellec, Jing CAO, Francois Brisset, Anne-Laure Helbert, and Matthieu Lancry

Doc ID: 252714 Received 27 Oct 2015; Accepted 20 Jan 2016; Posted 20 Jan 2016  View: PDF

Abstract: Mastering second harmonic generation (SHG) in glasses is essential for achieving 2nd order nonlinear devices. For the first time, we wrote three-dimensional SHG patterns with controllable angular dependence in glass by femtosecond laser. We confirmed by electron backscatter diffraction that the angular dependence is associated to preferential nanocrystal orientation, which can be controlled with the writing laser polarization. We demonstrated that polar axes of nanocrystals distribute around a plan perpendicular to the writing laser polarization direction. A mechanism based on the application of laser induced torques on the nanocrystal electric dipole was proposed. This paves the way to design nano devices such as frequency agile laser based on electro-optical waveguides.

Time evolution of the screening effects on terahertz generation at the surface of InAs

Etienne Gagnon, Nana Kwame Owusu, and Amy Lytle

Doc ID: 254884 Received 01 Dec 2015; Accepted 19 Jan 2016; Posted 20 Jan 2016  View: PDF

Abstract: We study the effects of electron density and temperature, both experimentally and numerically, on the screening process responsible for saturation of the terahertz generation process at the surface of InAs. We use a pair of ultrafast pulses with adjustable time delay to generate terahertz radiation and compare the results to a 1D drift-diffusion equation model modified to include radial diffusion and cooling of the electrons through scattering. We demonstrate the necessity of these modifications by implementing the original drift-diffusion equation model, as reported by Liu et al.(PRB 73, 155330 (2006)), and show that it underestimates saturation by an order of magnitude. We find excellent agreement between our experimental and numerical results, confirming the validity of our improved model and demonstrating its potential use in a number of applications, such as terahertz pulse shaping with an ultrafast pulse train.

Defect modes in metamaterial photonic superlattices as tunneling resonances in trilayer structures

Alex Emanuel Costa, Jorge Mejía-Salazar, and Solange Cavalcanti

Doc ID: 252570 Received 23 Oct 2015; Accepted 19 Jan 2016; Posted 21 Jan 2016  View: PDF

Abstract: Within an effective medium theory, the transmission spectra of metamaterial defective photonic superlattices composed by subwavelength slab widths are shown, with a very good accuracy, to be equivalent to those found in trilayer systems with a metamaterial inclusion. Furthermore, we have derived a general condition which should be satisfied to observe resonance tunneling in these systems. Our analytical results may be useful from the applied point of view as it yields the ability to tailor and tune suitable resonance frequencies in the design and development of photonic-based filtering and light trapping compact devices.

Counterfactual entanglement distribution using quantum dot spins

Yuanyuan Chen, Lijun Chen, Dong Jiang, Xuemei Gu, and Ling Xie

Doc ID: 251211 Received 01 Oct 2015; Accepted 19 Jan 2016; Posted 27 Jan 2016  View: PDF

Abstract: Counterfactual quantum communication allows distant users to share a message without transmitting anyphysical particles over the quantum channel. Here, we present a counterfactual scheme to realize multipartyentanglement distribution. By using interaction-free measurement and quantum dot, we first realize bipartitecounterfactual entanglement distribution to create photon-electron entanglement. Then atom-cavity system isused to create many photon-photon entanglement pairs, which can connect photon-electron pairs with the helpof entanglement beam splitter. Consequently, the electron spins in distant optical microcavities are entangledby the coherent exchange of single flying photons. We also discuss the implementation issues to show thatthe present scheme can be achieved successfully in experiment. The numerical analysis about the efficiencyindicates that there is a trade-off between the entanglement fidelity and the number of users.

Vector beam generation via micrometer-scale photonic integrated circuits and plasmonic nano-antennae

Sylvain Blaize, Renaud Bachelot, Wei Ding, Yi-Zhi Sun, and Zhiyuan Li

Doc ID: 254303 Received 20 Nov 2015; Accepted 15 Jan 2016; Posted 19 Jan 2016  View: PDF

Abstract: We theoretically present an integrated photonic method of generating specific vector beam on a micrometer scale. A plasmonic nano-antenna array is embedded in a silicon resonator and helps to emit light with designed polarization pattern. A few-mode optical fiber is used as a spatial filter to purify mode component of the generated beam. Numerical simulations verify that our design scheme can produce very pure TM01, TE01, and HE21 vector beams (mode purity ~99%). Vector light vortices carrying certain orbital angular momentums can also be generated using this method. The suggested devices exhibit merit features of compactness and weak back-reflection and may find applications in large-scale photonic integration involving complex light beams.

Semiconductor mode-locked lasers with coherent dual mode optical injection: simulations, analysis and experiment

Rostislav Arkhipov, Tatiana Habruseva, Alexander Pimenov, Mindaugas Radziunas, Guillaume Huyet, and Andrei Vladimirov

Doc ID: 254795 Received 01 Dec 2015; Accepted 14 Jan 2016; Posted 14 Jan 2016  View: PDF

Abstract: Using a delay differential equations model we study the dynamics of a passively mode-locked semiconductor laser with dual frequency coherent optical injection. The locking regions where the laser pulse repetition rate is synchronized to the separation of the two injected frequencies were calculated numerically and measured experimentally. Asymptotic analysis performed in the limit of the small injection field amplitude revealed the dependence of the locking regions on the model parameters, such as optical bandwidth, absorber recovery time and linear losses.

Phase-controlled optical trap potential in a closed-loop atomic system

Mohammad Mahmoudi and S. Hamide Kazemi

Doc ID: 254458 Received 23 Nov 2015; Accepted 12 Jan 2016; Posted 26 Jan 2016  View: PDF

Abstract: The optical trap potential is studied in a four-level double-$\Lambda$ closed-loop atomic system in the multiphoton resonance condition. We apply four femtosecond Gaussian laser beams to generate a closed-loop configuration. It is shown that the induced optical dipole force on the system dramatically depends on the relative phase of applied fields and it switches from focusing to defocusing in the transverse direction, simply by properly changing the relative phase. Through special switching of the relative phase, the trapping potential splits into two positions which has novel applications in trapping and manipulating the particles. Moreover, it is also demonstrated that trap depth can be manipulated by the relative phase. Finally, a maximum coherent population transfer is achieved for a special value of the relative phase of applied fields.

Spontaneous Parametric Down Conversion and Quantum Walk Topology

Graciana Puentes

Doc ID: 252728 Received 27 Oct 2015; Accepted 12 Jan 2016; Posted 14 Jan 2016  View: PDF

Abstract: We propose a novel scheme for the \emph{all optical} quantum simulation of topological phases by means of implementation of a discrete-time quantum walk architecture. The main novel ingredient is the inclusion of the non-linear process of spontaneous parametric down conversion (SPDC) along the quantum network. By means of a simple theoretical model, the interplay between quantum walk lattice topology and spatial correlations of bi-photons produced by SPDC is numerically explored. We describe different \emph{optical} detection methods suitable for the implementation of our proposed experimental scheme.

Impact of delayed feedback of arbitrary duration in self-pulsations of a CO2 laser

Jason Gallas and Leandro Junges

Doc ID: 254082 Received 18 Nov 2015; Accepted 12 Jan 2016; Posted 14 Jan 2016  View: PDF

Abstract: We report the systematic investigation of a CO2 laser subjected to delayedelectro-optical feedback, as a function of relevant control parameters.The complex stability changes of the laser output when the delay is continuously tuned are illustrated by stability charts and with a video.Short delays, smaller than 1\mu s, are found to strongly clean chaos and periodic spiking with high periods.However, complex laser pulsations and chaos are significantly enhanced for tau > 1 mu s. In this range, one findsa complex alternation of periodic and chaotic phases which is very sensitiveto the feedback delay.

Tuning infrared guided-mode resonances with graphene

Domenico de Ceglia, Maria Antonietta Vincenti, Marco Grande, Giuseppe Bianco, Giovanni Bruno, Antonella D'Orazio, and Michael Scalora

Doc ID: 254624 Received 25 Nov 2015; Accepted 12 Jan 2016; Posted 14 Jan 2016  View: PDF

Abstract: We report a strategy to modulate the Fano-like signature of a guided-mode resonance supported by a graphene-based grating. The shape of the resonance is controlled by the amount of damping introduced by graphene. A symmetric-to-asymmetric lineshape transition and a significant narrowing of the linewidth occur at relatively moderate levels of chemical potential. Further increases of the chemical potential lead to a blueshift of the Fano resonance due to the modification of the imaginary part of the conductivity of graphene. Our results are supported by a quasinormal mode analysis of the grating. Using a perturbative approach, we provide analytical expressions for both the resonance wavelength shift and the linewidth modulation induced by changes of the graphene’s chemical potential. Electrostatic or electrochemical gating of graphene in the proposed structure provide dynamic control of the Fano-like resonance of the grating, suggesting new opportunities for the design of tunable photonic and optoelectronic devices at infrared wavelengths.

Fields of an ultrashort tightly-focused laser pulse

Jian-Xing Li, Yousef Salamin, Karen Hatsagortsyan, and Christoph Keitel

Doc ID: 249208 Received 02 Sep 2015; Accepted 10 Jan 2016; Posted 14 Jan 2016  View: PDF

Abstract: Analytic expressions for the electromagnetic fields of an ultrashort, tightly focused, linearly polarized laser pulse in vacuum are derived from scalar and vector potentials, using a small parameter which assumes a small bandwidth of the laser pulse. The derived fields are compared with those of the Lax series expansion and the complex-source-point approaches and are shown to be well-behaved and accurate even in the subcycle pulse regime. We further demonstrate that terms stemming from the scalar potential and due to a fast varying pulse envelope are non-negligible and may significantly influence laser-matter interactions.

Influence of misfit strain on the Goos-Hänchen shift upon light reflection from a magnetic film on a non-magnetic substrate

Yuliya Dadoenkova, Florian F.L. Bentivegna, Nataliya Dadoenkova, Igor Lyubchanskii, and YoungPak Lee

Doc ID: 252651 Received 26 Oct 2015; Accepted 10 Jan 2016; Posted 14 Jan 2016  View: PDF

Abstract: The influence of the misfit strain on the lateral shift (Goos-Hänchen effect) experienced by a near-infrared electromagnetic wave upon reflection from the surface of a bilayer consisting of a magnetic, gyrotropic (i.e., whose permittivity tensor elements depend upon magnetization) yttrium-iron garnet film deposited on a non-magnetic gadolinium-gallium garnet substrate is investigated theoretically. In the transverse magneto-optical configuration, it is shown that the mechanical strain near the geometrical film/substrate interface can induce a significant lateral shift of the beam for incidence angles close to normal incidence, where no shift appears in the absence of strain. Our calculations demonstrate positive as well as negative values of the lateral shift, depending on the incident light polarization and on the film thickness. In contrast to that of the misfit strain, the influence of the magnetization of the gyrotropic film on the lateral shift is more noticeable for a TM- than for a TE-polarized wave.

Frequency shifts of radiating particle moving in EITmetamaterial

David Ziemkiewicz and Sylwia Zielińska-Raczyńska

Doc ID: 255233 Received 07 Dec 2015; Accepted 10 Jan 2016; Posted 14 Jan 2016  View: PDF

Abstract: We consider the frequency shifts of particle moving in metamaterials exhibiting electromagnetically induced transparency effect. The dramatic change of the material dispersion due to the EIT influences the conditionsfor signal propagation in the medium and has a significant impact on the Doppler effect, possibly leading to the optical control over this phenomenon. The dependence of the Doppler shift to the source frequency and velocity and radiation spectra on external parameters is examined. It was found that for source frequencies fitting transparency window for particular range of source velocities cutoffs appear, i.e. the radiation is notemitted. The analysis of cutoffs dependence on the character of medium dispersion brings to light their physical interpretation. Our theoretical findings are proved analytically and confirmed by numerical simulations based on finite-difference time-domain method.

Dynamics of triple quantum beats retrieved from coupled four-wave-mixing signals

Changjun Zhu, Bei Xu, Qing CHU, Junfang He, and Xiang'an Yan

Doc ID: 254013 Received 18 Nov 2015; Accepted 09 Jan 2016; Posted 12 Jan 2016  View: PDF

Abstract: A theoretical model of coupled four-wave mixing (FWM) processes comprising 5 atomic energy levels was proposed to investigate the coherent characteristics of atomic wave packets using perturbation theory. As several states in atoms are coherently excited by two-photon transition, triple coupled FWM can be produced and triple quantum beats associated with the atomic energy levels are embedded in the FWM signals. Triple coupled FWM processes were achieved experimentally in Rb vapor by two-photon excitation using broadband optical pulses. Pump-probe scheme was utilized to record the time-varying FWM signals and Fourier transform was applied to retrieve the quantum beats. Furthermore, short-time Fourier transform was implemented to investigate the dynamics of quantum beats. The results show that the coherent characteristics of atomic wave packets, which are intimately related to the dynamics of quantum beats, can be probed by coupled nonlinear optical wave mixings.

Generation of three-dimensional entanglement between two spatially separated atoms via shortcuts to adiabatic passage

Xin Ji, Jing-Bo Lin, Yan Liang, Shou Zhang, and Chong Song

Doc ID: 252842 Received 28 Oct 2015; Accepted 08 Jan 2016; Posted 27 Jan 2016  View: PDF

Abstract: We propose a scheme for generating three-dimensional entanglementbetween two atoms trapped in two spatially separated cavities reapectively via shortcuts to adiabatic passage based on the approach of Lewis-Riesenfeld invariants in cavity quantum electronic dynamics. By combining Lewis-Riesenfeld invariants with quantum Zeno dynamics, we can generate three dimensional entanglement of the two atoms with high fidelity. The Numericalsimulation results show that the scheme is robust against the decoherences caused by the photon leakage and atomic spontaneous emission.

Picosecond-laser bulk modification induced enhancement of NV luminescence in diamond

Sergei Pimenov, Andrey Khomich, Beat Neuenschwander, Beat Jäggi, and Valerio Romano

Doc ID: 250885 Received 25 Sep 2015; Accepted 07 Jan 2016; Posted 08 Jan 2016  View: PDF

Abstract: We report on the enhancement of NV luminescence induced by the bulk structure modification of type IIa single-crystal diamond with visible picosecond laser. Using on-line monitoring of picosecond-laser-induced photoluminescence (PL) in the bulk regions, it is found that the integrated intensity of the NV PL (normalized to the Raman line intensity) is significantly increased after the bulk microstructure formation. The confocal PL spectroscopy investigations of the bulk microstructures have evidenced the enhanced NV luminescence and the splitting of the NV¯ emission. The increased concentration of the NV defects during picosecond-laser bulk modification correlates with the formation of sp3 carbon allotropic structures and other defect centers revealed in PL/Raman spectra of high-stress regions near the fabricated microstructures.

Complete and nondestructive polarization-entangled cluster state analysis assisted by cavity input-output process

Shou Zhang, Ji-Li Zhang, Shi-Lei Su, Ai-Dong Zhu, and Hong-Fu Wang

Doc ID: 253153 Received 02 Nov 2015; Accepted 07 Jan 2016; Posted 08 Jan 2016  View: PDF

Abstract: We present two schemes to realize four- and five-photon polarization-entangled cluster state analysis, respectively. For four- and five-photon polarization cluster states, the complete basis are composed of sixteen and thirty-two orthogonal state vectors, respectively. To distinguish all of these orthogonal basis completely and nondestructively, a parity analyzer, a polarization analyzer, and two cluster state phase analyzers are designed with some simple linear optical elements and auxiliary atoms trapped in cavities. After implementing the nondestructive cluster analysis process, the cluster states are preserved and thus could be used again in other schemes. The investigations of the fidelities show that our schemes are feasible under the current experimental technology. Our proposed schemes may be useful in multi-particle teleportation, quantum dense coding, and other quantum information processing tasks.

Controllable frequency hysteresis in semiconductor lasers

Samuel Alves, Hugo Cavalcante, Martine Chevrollier, Thierry Passerat de Silans, and Marcos Oria

Doc ID: 253764 Received 11 Nov 2015; Accepted 07 Jan 2016; Posted 08 Jan 2016  View: PDF

Abstract: Optical feedback with orthogonal polarization enables frequency sweep of semiconductor lasers and leads to frequency bistability when a resonant medium is used to filter the re-injected radiation. Here we explore a new configuration, with two lasers coupled through mutual injection. Each laser injects and receives light with a polarization orthogonal to the plane of emission. Both injections are independently filtered by a resonant atomic vapor. We show that this more versatile version also exhibits bistable states,and that it is possible to reduce the laser frequency jitter as well as to invert its frequency hysteresis cycle on demand (from counterclockwise to clockwise and vice-versa). Experimental demonstration is done with diode lasers emitting around 780 nm and using Rb thermal vapors as nonlinear filters.

Generic Propagation of Sharp Boundaries Elecromagnetic Signals in Any Linear Dispersive Medium

Er'el Granot

Doc ID: 254255 Received 24 Nov 2015; Accepted 07 Jan 2016; Posted 08 Jan 2016  View: PDF

Abstract: A generic formalism for the propagation of a pulse with sharp boundaries in any linear medium is derived. It is shown that such a pulse experiences generic deformations. For any given linear medium, the pulse deformation depends only on the values of the pulse (its amplitude and derivatives) at the singular points (the sharp boundary). The theory is then applied to Fabry-Perot etalon and to dispersive media with second order dispersion, third order dispersion and to a combination of both. Simple approximate expressions are also derived for relatively short, i.e., low dispersive, medium, and compared to exact numerical solutions.

Donor Impurity Effects on Optical Properties of GaN/AlN Constant Total Effective Radius Multi-Shells Quantum Dots

mehdi solaimani, Mahboubeh Ghalandari, and Leila Lavaei

Doc ID: 251535 Received 12 Oct 2015; Accepted 05 Jan 2016; Posted 19 Jan 2016  View: PDF

Abstract: In the current work, we have studied the effect a single donor impurity confined within GaN/AlN Constant Total Effective Radius Multi-Shells Quantum Dots (CTER-MSQDs) on optical properties, intersubband transition energies and normalized ground state wavefunctions. Systems with different number of wells and inner radius of the quantum dot have been explored. We have shown that, systems with largest inner quantum dot doll radius R1 values have smallest intersubband transition energies in both of systems with and without donor impurities. Now, it is possible to localize the electron in any part of our quantum dot structure by changing the number of wells and inner quantum dot radius R1. We also show that in the presence and absence of the donor impurity, maximum absorption decreases when R1 increases. Absorption coefficients experience a red shift by increasing of the R1 values for systems with small number of wells, while experience a blue shift by increasing of the R1 values for systems with larger number of wells. Adding the impurity do not affect on the absorption coefficient of the constant total effective radius multi-shells quantum dots with R1=400A0 and R2=600A0. Maximum absorption of most of the systems decreases when we add the impurity. Finally, when R1 values increases, the refractive index changes gradually decreases for systems with small number of wells and increases for systems with large number of wells.

Electronic control of optical tweezers using space-time-wavelength mapping

Shah Rahman, Rasul Torun, Qiancheng Zhao, and Ozdal Boyraz

Doc ID: 251506 Received 07 Oct 2015; Accepted 03 Jan 2016; Posted 06 Jan 2016  View: PDF

Abstract: We present a new approach for electronic control of optical tweezers by using space-time-wavelength mapping (STWM), a technique that uses time-domain modulation to control local intensity values, and hence the resulting optical force, in space. The proposed technique enables direct control of magnitude, location, and polarity of force hot-spots created by Lorentz force (gradient force). In this paper, we develop an analytical formulation of the proposed STWM technique for optical tweezing. In the case study presented here, we show that 150 fs optical pulses are dispersed in time and space to achieve a focused elliptical beam that is ~20 μm long and ~2 μm wide. By choosing the appropriate RF waveform and electro-optic modulator, we can generate multiple hot-spots with >200 pN force per pulse.

Enhanced and Tunable Resolution from an Imperfect Negative Refractive Index Lens

Kevin Webb, Yulu Chen, Yu-Chun Hsueh, and Mengren Man

Doc ID: 252566 Received 23 Oct 2015; Accepted 29 Dec 2015; Posted 06 Jan 2016  View: PDF

Abstract: Material loss diminishes the ability of a negative refractive index material to function as a super resolution lens. We find that the transmittance of a negative index slab can be greatly enhanced at a certain evanescent field spatial frequency if the imaginary parts of the permittivity and permeability in the slab can be tuned, even when the object, lens, and image domains have overall loss. This leads to a proposed method to image the far-subwavelength features of an object by reconstructing the evanescent part of its spectrum.

Soliton-induced transparency in disordered Kerr-metamaterial heterostructures

Ernesto Reyes-Gomez, Solange Cavalcanti, and Luiz Oliveira

Doc ID: 248892 Received 28 Aug 2015; Accepted 29 Dec 2015; Posted 06 Jan 2016  View: PDF

Abstract: The optical transmission properties of light in one-dimensional disordered nonlinear layered systems with metamaterial inclusions are theoretically studied. Layer widths of both nonlinear and metamaterial slabs are considered as random variables without any correlation between them. A thorough investigation of the influence of disorder in the vicinities of a Bragg gap, a zero$-n$ gap and a bulk-like longitudinal plasmon-polariton gap is performed. Disorder effects result in a considerable broadness of the transmission peaks as compared with periodic non-disordered structures. It is shown that the Bragg-gap soliton reveals itself as the most robust against disorder.

Effective-surface modeling of infinite periodic metascreens exhibiting the extraordinary transmission phenomenon

Alexandros Dimitriadis, Theodosios Karamanos, Nikolaos Kantartzis, and Theodoros Tsiboukis

Doc ID: 249281 Received 02 Sep 2015; Accepted 29 Dec 2015; Posted 06 Jan 2016  View: PDF

Abstract: The consistent analysis of metascreens perforated with subwavelength apertures of diverse geometrical patterns by means of a systematic methodology, is presented in this paper. The principal concept of the new technique stems from the efficient characterization − through effective surface parameters − of the complementary array of scatterers (metafilm) and the proper utilization of the Babinet duality principle. The metafilm model is carefully extended for the special case of normal plane wave incidence in order to include the frequencies where the extraordinary transmission peak typically occurs. General-purpose analytical formulas for the reflection and transmission coefficients of an arbitrary metascreen are also derived. Finally, the predictions for the extraordinary transmission spectra through various metascreens, operating in the microwave regime and obtained via two distinct realizations of the proposed formulation, are compared with the results of a commercial computational package, to verify the precision of the developed technique and provide instructive physical insights.

Birefringence and piezo-Raman analysis of single crystal CVD diamond and effects on Raman laser performance.

Hadiya Jasbeer, Robert Williams, Ondrej Kitzler, Aaron McKay, Soumya Sarang, Jipeng Lin, and Richard Mildren

Doc ID: 251269 Received 01 Oct 2015; Accepted 23 Dec 2015; Posted 24 Dec 2015  View: PDF

Abstract: Defect-induced stress effects have been mapped in optical grade synthetic diamond (CVD-grown “Type IIIa”) using Metripol polarimetry, Mueller polarimetry and Raman microscopy. Large circular birefringence was observed in the 8 mm-long <110> cut crystal with values up to 28⁰ for some paths along the major axis. Metripol-determined values for linear birefringence magnitude and fast-axis direction in such regions have significant error. Stress induced shifts in Raman frequency were observed up to 0.7 cm^-1 which, we deduce, result from uniaxial and biaxial stresses up to 0.86 GPa. We also elucidate the mechanism by which stress impacts diamond Raman laser performance. The direction of the linear birefringence axis is found to be primary factor determining laser threshold and the input-output polarization characteristics.

Unraveling coherent quantum feedback for Pyragas control

Alexander Carmele, Julia Kabuss, Florian Katsch, and Andreas Knorr

Doc ID: 253207 Received 03 Nov 2015; Accepted 22 Dec 2015; Posted 06 Jan 2016  View: PDF

Abstract: We present a Heisenberg operator based formulation of coherent quantum feedback and Pyragas control. This model is easy to implement and allows for an efficient and fast calculation of the dynamics of feedback-driven observables as the number of contributing correlations grows only linearly in time. Furthermore, our model unravels the quantum kinetics of entanglement growth in the system by explicitly calculating non-Markovian multi-time correlations, e.g., how the emission of a photon is correlated with an absorption process in the past. Therefore, the time-delayed differential equations are expressed in terms of insightful physical quantities. Another considerate advantage of this method is its compatibility to typical approximation schemes, such as factorization techniques and the semi-classical treatment of coherent fields. This allows the application on a variety of setups, ranging from closed quantum systems in the few excitation regimes to open systems and Pyragas control in general.

Dipole-Dipole interaction between trapped two-level ions interacting with a quantized field in the Lamb-Dicke regime

M Tavassoly and Navid Yazdanpanah1

Doc ID: 250837 Received 25 Sep 2015; Accepted 19 Dec 2015; Posted 22 Dec 2015  View: PDF

Abstract: In this paper, to achieve more accuracy in a system containing trapped two-level ions interacting with a single mode quantized field, we aim to consider the dipole-dipole interaction (DDI) between the trapped ions. In more details, we firstly suggest an appropriate form of a quantized DDI Hamiltonian between two trapped ions. Then, the case that the trapped ions interact with a single-mode quantized field in the Lamb-Dicke regime as well as the first vibrational sideband is considered, in which the DDI between the trapped ions is also taken into account.Using the state vector which is analytically obtained for the whole system under our consideration, we evaluate the amount of entanglement between the field and the two trapped ions by utilizing the linear entropy. We observe that, the entanglement depends on the distance between the two trapped ions; i.e., decreasing the distance led to decrement in the entanglement. In the continuation, we extend the proposed model at first to three ($N=3$) and then to more trapped ions ($N>3$) and the most general entangled state vectors related to the outlined systems are obtained by which the same scenario (for two trapped ions) is repeated. Comparing the latter cases ($N \geq 3$) with the previous one ($N=2$), we concludethat the entanglement is sensitive to the number of interacted trapped ions in addition to the distances between them in such a way that by increasing the number of the trapped ions the entanglement between them and the field is increased. These results help one to control the entanglement between the field and the trapped ions in a more accurate manner by tuning the distances between the trapped ions and their numbers.

Saturable and inverse saturable absorption in multi-walled-carbon-nano-tubes-doped fast Sol-gel hybrid glasses

Raphi Dror, ZeeV Burshtein, Raz Gvishi, and Mariana Pokrass

Doc ID: 232480 Received 14 Jan 2015; Accepted 10 Apr 2015; Posted 10 Apr 2015  View: PDF

Abstract: Dynamics of saturable absorption and inverse saturable absorption of Multi walled carbon nano tubes (MWCNT)-doped fast Sol-gel hybrid glasses was studied by optical transmission of 532-nm laser beam pulses at two extreme conditions: 6-ns long temporally isolated single pulses up to 0.02 J/cm2, and a pulse train at different intensities in the range 0.72-10.7 kW/cm2 (quasi-CW illumination). The temporally isolated single pulses were analysed by the slow saturable absorber limit; The quasi-CW illumination at steady state was analysed by the fast inverse saturable absorber limit. A fresh, corrected solution to the rate equation was developed for the latter. The time dependence of reaching steady state absorption in the quasi-CW case was analysed by a numerical simulation of a state model. The single-pulse case analysis yields a ground-state density N=5.1×1015cm-3, a ground-state absorption cross-section σgs=5.5×10-15cm2 , and a first excited-state absorption cross-section σes1=3.6×10-15cm2. The quasi-CW case analysis is consistent with the occurrence of the MWCNT transition upon illumination into a highly absorbing/scattering state ("plasma" state). The analysis yields a ground-state concentration estimation N=3.2×1015cm-3, and a ground-state absorption cross-section σgs=6.3×10-15cm2. The "plasma" lower-state absorption/ scattering cross-section is σes2=2.3×10-14cm2. The light-intensity dependent transition rate between the first MWCNT excited-state and its "plasma" lower state followed the relation τ-1inc[s-1]=12.25exp(4×10-7I[W/cm2]); the transition rate between the lowest "plasma" state and the MWCNT ground-state, was also light-intensity dependent, following the relation τ-1[s-1]=3.5exp(2.54×10-7I[W/cm2]).

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