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Accepted papers to appear in an upcoming issue

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Subwavelength metal grating metamaterial for polarization selective optical antireflection coating

Junpeng Guo, Wonkyu Kim, and Joshua Hendrickson

Doc ID: 235464 Received 02 Mar 2015; Accepted 20 May 2015; Posted 21 May 2015  View: PDF

Abstract: A metamaterial structure consisting of a 1D metal/air-gap subwavelength grating is investigated for optical antireflection for a germanium surface in the infrared regime. For incident light polarized perpendicularly to the metal grating lines, the metamaterial exhibits effective dielectric property and the Fabry-Perot like resonance results in the elimination of the reflection and the enhancement of optical transmission. It is found that the subwavelength grating metamaterial antireflection structure does not require a deep subwavelength grating period, which is advantageous for device fabrication. Optical transmittance as high as 93.4% with complete elimination of the reflection is shown in the mid-wave infrared range.

Influence of external reflection on the TE mode of photonic-crystal surface-emitting lasers

John Gelleta, Yong Liang, Hitoshi Kitagawa, and Susumu Noda

Doc ID: 236573 Received 19 Mar 2015; Accepted 20 May 2015; Posted 21 May 2015  View: PDF

Abstract: The lasing properties of a square-lattice photonic crystal surface-emitting laser with TE-mode polarization and external reflection are semi-analytically investigated. Modal frequencies, threshold gains, and fifield intensity envelopes are systematically calculated for various boundary conditions at one of the laser device's four sides. Additionally, external reflection is proposed as a technique for improving mode stability in cavities of modest (~100 μm²) area.

A theoretical scheme for the realization of the sphere-coherent motional states in an atom-assisted optomechanical cavity

Rasoul Roknizadeh, Foroud Bemani, and M H Naderi

Doc ID: 236937 Received 31 Mar 2015; Accepted 18 May 2015; Posted 19 May 2015  View: PDF

Abstract: A theoretical scheme for the realization of the sphere-coherent motional states in an optomechanical cavity in the presence of a two-level atom is proposed. To this end, the analogy between an atom-assisted optomechanical cavity and a laser-driven trapped-ion system is used. This analogy provides us with a theoretical tool to show how sphere-coherent states can be generated for the motional degree of freedom of the macroscopic mechanical oscillator from atom-field-mirror interactions in a multi-mode optomechanical cavity. Some nonclassical properties of the generated state of the mechanical oscillator, including the degree of quadrature squeezing and the negativity of the Wigner distribution are studied. We also examine the effects of the dissipation mechanisms involved in the system under consideration, including the atomic spontaneous emission and the damping of the motion of the mechanical oscillator, on the generated motional sphere-coherent states.

Preservation of transverse spatial coherence in the storage of double light pulses

Haihua Wang, Xiaoxiao Wang, Aijun Li, Lei Wang, Yi Chen, XiaoJun Zhang, Jin-Yue Gao, Jiaxiang Sun, and Yuanhang Sun

Doc ID: 239844 Received 27 Apr 2015; Accepted 18 May 2015; Posted 19 May 2015  View: PDF

Abstract: We experimentally report the preservation of transverse spatial coherence in the storage of double light pulses by using a solid. Under electromagnetically induced transparency (EIT), two probe pulses are stored into atomic coherence between ground-state levels and later retrieved. By analyzing the Young-type spatial interference patterns formed by two probe fields before and after the storage, we demonstrate that transverse spatial coherence of the probe fields are preserved in the storage process. This demonstration can be used for image processing and multiple information manipulation.

The analog multi-color electromagnetically induced transparency in multimode quadratic-coupling quantum optomechanics

Rui Xiao, Gui Pan, and Ling Zhou

Doc ID: 236753 Received 23 Mar 2015; Accepted 17 May 2015; Posted 21 May 2015  View: PDF

Abstract: We theoretically investigate the response of the output field of multiple mechanical modes coupled to a single quantized cavity field via quadratic optomechanical interactions. We focus specifically on two identical membranes in the optical cavity mode. Our study shows the double electromagnetically induced transparency (EIT) can be observed from the output field by adjusting the strength of quadratic coupling coefficient, which can be achieved by controlling the position of the membranes in the cavity. Moreover, for N membranes having same frequencies, the results indicate that there are at most multi-color (N) EIT in the transmitted probe field.

Application of Transfer Matrix Method to Second Harmonic Generation in Nonlinear Photonic Bandgap Structures: Oblique Incidence

Partha Banerjee, Joseph Haus, and Han Li

Doc ID: 236438 Received 18 Mar 2015; Accepted 17 May 2015; Posted 19 May 2015  View: PDF

Abstract: A generalization of the transfer matrix method is developed to analyze type I second harmonic generation in linear-nonlinear multilayer one dimensional photonic bandgap structures for oblique incidence of a nondepleted fundamental. The advantage of the transfer matrix method is that it takes into account reflections and interferences between all forward and backward propagating fundamental and second harmonic waves. The conversion efficiency is calculated as a function of the incident angle of the fundamental and the thicknesses of the linear and nonlinear layers. Specific incident angles and thicknesses may generate relatively high conversion efficiency inside of nonlinear material. Our analytical and numerical analyses show that the conversion efficiency of second harmonic generation depends on the fundamental pump power, second order susceptibility, and field enhancement in the photonic bandgap structure. Upper bounds on pump intensity can be found for a given incidence angle and sample thickness where the nondepleted pump approximation can be used to model such a nonlinear structure.

Spiny solitons and noise-like pulses

Wonkeun Chang, Jose Soto-Crespo, Peter Vouzas, and Nail Akhmediev

Doc ID: 237065 Received 31 Mar 2015; Accepted 13 May 2015; Posted 18 May 2015  View: PDF

Abstract: We have found new dissipative solitons in the laser model described by the complex cubic-quintic Ginzburg-Landau equation. These objects can be called "spiny solitons" because they chaotically generate spikes of extreme amplitude and ultra-short duration. We have calculated the probability density function of these spikes that demonstrate their rogue wave nature. We have also calculated the average profiles, autocorrelation functions, average spectra and XFROG diagram of "spiny solitons". They have no analogs among the noise-like pulses studied previously in experiments.

Magneto optical rotation in a GaAs Quantum Well Waweguide

Ali Mortezapour, Mohammad Mahmoudi, and Mohsen Ghaderi Goran Abad

Doc ID: 233266 Received 26 Jan 2015; Accepted 13 May 2015; Posted 19 May 2015  View: PDF

Abstract: The interaction of two orthogonally polarized beams and a four-level GaAs quantum well (QW) waveguide is investigated. It is shown that by applying a static magnetic field normal to the propagation direction of the driving beams, the birefringence can be induced in the QW waveguide. Moreover, it is demonstrated that the dephasing rate between two ground states of the QW waveguide makes it a dichromatic medium and can also diminish the induced birefringence. Our results show how a large and complete magneto optical rotation (MOR) in the QW waveguide can be obtained via adjusting the intensity of the magnetic field and also the length of the QW waveguide.

Anomalous reflection in the ultra-thin nano-strip antenna induced by incident field and displacement current phase matching

Dejiao Hu, Zhiyou Zhang, Ping Wang, Lin Pang, and Jinglei Du

Doc ID: 235486 Received 02 Mar 2015; Accepted 12 May 2015; Posted 13 May 2015  View: PDF

Abstract: Recently, ultra-thin nano-strip antenna (thinner than skin depth) has attracted extensive attention as a key structure unit of metasurface. It can be used to realize anomalous enhanced reflection and absorption as well as suppressed transmission, which has been used in photonic devices. However, there is still lack of clear analysis to systematically explain these phenomena. In this paper, we present the concept of phase matching between the displacement current and the incident field, which initially leads to the anomalous scattering property of a single ultra-thin nano-strip antenna. Base on the property of a single nano-strip, we study the coupling of multi- nano-strip antennas and demonstrate that the randomized and periodic array of nano-strips have the same anomalous reflection spectrum. The phase matching is also reflected in the theoretic model, from which the reflection and transmission formulas for nano-strip array are derived. The formulas successfully predict the thickness influence on the reflection spectra of a periodic array. Our results can promote the development of ultra-thin nano-strip based metasurfaces.

Diffractive switching by interference in a tailored PT symmetric grating

Nicolas Rivolta and Bjorn Maes

Doc ID: 234925 Received 19 Feb 2015; Accepted 08 May 2015; Posted 13 May 2015  View: PDF

Abstract: We numerically study the diffraction properties of a parity-time (PT) symmetric transmission grating, which operates through a limited number of guiding modes. The interferometric operation is altered by the introduction of balanced gain and loss, leading for example to efficient switching around the spontaneous symmetry breaking point. Furthermore, we examine the influence of the longitudinal reflections, which are not common in previous PT structures. In addition, we separately tailor the periodicities of gain and loss, so that the device remains PT symmetric. However, this gives a new way to control the mode merging phenomenon, as we obtain interactions between previously distinct modes.

Efficient three-dimensional atom localization via probe absorption

Zhiping Wang and Yu Benli

Doc ID: 236381 Received 17 Mar 2015; Accepted 06 May 2015; Posted 07 May 2015  View: PDF

Abstract: We present a new scheme for high-efficiency three-dimensional (3D) atom localization in a three-level atomic system via measuring the absorption of a weak probe field. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the probe absorption. It is found that, by properly varying the parameters of the system, the probability of finding the atom at a particular position can be almost 100%. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides a possibility to realize 3D precision quantum measurement and quantum control for quantum information processing.

Phase-dependent light switching in triple-Λ system

Hoonsoo Kang, Byoung-Uk Sohn, Bongjune Kim, and Do Kyeong Ko

Doc ID: 236457 Received 18 Mar 2015; Accepted 06 May 2015; Posted 07 May 2015  View: PDF

Abstract: We theoretically studied a triple-Λ system comprising three pairs of coupling-probe fields. Three probe fields were phase-dependently switched with a switching depth above 80%, at which the group-velocity matching of all probe pulses was available under slow light-propagation conditions. We considered the probe susceptibility as the superposition of three-photon transitions to systematically understand the multi-photon interference in a triple-Λ system, which can be applied to systems with N-Λ (N>=1 ). This helped us to tailor the probe susceptibility by adjusting the detuning and phases of the coupling and probe fields. This work can be applied to all-optical switching gates for triple-photons and can enhance the speed of processing optical information.

Effective scheme for preparation of spin-qubit Greenberger-Horne-Zeilinger state and W state in a quantum-dot-microcavity system

Yan Xia, Yi-Hao Kang, and Pei-Min Lu

Doc ID: 223010 Received 12 Sep 2014; Accepted 05 May 2015; Posted 11 May 2015  View: PDF

Abstract: We propose a scheme for preparation of spin-qubit Greenberger-Horne-Zeilinger (GHZ) state and W state by using quantum dots (QDs) in the double-sided optical microcavities with the help of polarized photons. The spin selective photon reflection from the cavity provides us a perfect way to achieve the scheme with adding some simple linear optical elements and conventional photon detectors. Numerical simulation demonstrates that a perfect scheme of the GHZ state and W state generation can be achieved in one-step, and the high fidelities can be realized when the side leakage and cavity loss are low, which is feasible in the weak-coupling regime. Therefore, our scheme might contribute to the quantum communication, quantum teleportation and some other fields in quantum information processing.

Frequency comb generation beyond the Lugiato-Lefever equation: multi-stability and super cavity solitons

Tobias Hansson and Stefan Wabnitz

Doc ID: 236070 Received 11 Mar 2015; Accepted 04 May 2015; Posted 05 May 2015  View: PDF

Abstract: The generation of optical frequency combs in microresonators is considered without resorting to the mean-field approximation. New dynamical regimes are found to appear for high intracavity power that cannot be modeled using the Lugiato-Lefever equation. Using the Ikeda map we show the existence of multi-valued stationary states and analyse their stability. Period doubled patterns are considered and a novel type of super cavity soliton associated with the multi-stable states is predicted.

Photonic skin-depth engineering

Zubin Jacob and Saman Jahani

Doc ID: 235861 Received 09 Mar 2015; Accepted 04 May 2015; Posted 15 May 2015  View: PDF

Abstract: Recently we proposed a paradigm shift in light confinement strategy showing how relaxed total internal reflection and photonic skin-depth engineering can lead to sub-diffraction waveguides without metal (S. Jahani and Z. Jacob, "Transparent sub-diffraction optics: nanoscale light confinement without metal," Optica 1, 96-100 (2014)). Here, we show that such extreme-skin-depth (e-skid) waveguides can counter-intuitively confine light better than the best-case all-dielectric design of high index silicon waveguides surrounded by vacuum. We also analytically establish that figures of merit related to light confinement in dielectric waveguides are fundamentally tied to the skin depth of waves in the cladding, a quantity surprisingly overlooked in dielectric photonics. We contrast the propagation characteristics of the fundamental mode of e-skid waveguides and conventional waveguides to show that the decay constant in the cladding is dramatically larger in e-skid waveguides, which is the origin of sub-diffraction confinement. We also propose an approach to verify the reduced photonic skin depth in experiment using the decrease in the Goos-Hanschen phase shift. Finally, we provide a generalization of our work using concepts of transformation optics where the photonic-skin depth engineering can be interpreted as a transformation on the momentum of evanescent waves.

Effects of sample dispersion on ultrafast laser focusing

Bangshan Sun, Patrick Salter, and Martin Booth

Doc ID: 236275 Received 16 Mar 2015; Accepted 03 May 2015; Posted 05 May 2015  View: PDF

Abstract: We theoretically investigate the effects of sample dispersion on the focusing of ultrashort laser pulses. Both the conventional point focusing and simultaneous spatial and temporal focusing (SSTF) are studied. The influences of laser parameters, objective lenses, and sample materials are discussed in detail. The sample dispersion introduces spatial and temporal distortions to the laser focus, and reduces the focal intensity. These effects are more significant when a laser with a shorter pulse duration is focused into the sample at a larger depth. The presented results show the significance of sample dispersion effects in different scenarios, and look to inform on a proper choice of specific focusing method in practical cases.

Leakage and bend losses in solid core Bragg fibers

Mikhail Likhachev, Yurii Uspenskii, Nikolay Popov, Svetlana Aleshkina, and Mikhail Bubnov

Doc ID: 233289 Received 28 Jan 2015; Accepted 29 Apr 2015; Posted 05 May 2015  View: PDF

Abstract: An analytical approach describing the modes of solid core Bragg fibers is presented. Our method does not assume the periodic structure of a fiber cladding, therefore it is applicable to a wide class of solid core Bragg fibers, including bent ones. To check derived formulas, six Bragg fibers with a core diameter from 8.4 μm to 42 μm and a number of cladding rings from 5 to 15 were fabricated. The measured loss spectra of the straight and bent Bragg fibers agree well with theoretical ones. Basing on these results, we show that bending affects leakage losses by two mechanisms: decreasing the reflection of light from interfaces and destroying the constructive interference of reflected waves in the cladding. The role of these mechanisms at low and large (near critical) fiber curvature is discussed.

(MINI REVIEW) Second harmonic generation by artificial chiral materials

Concita Sibilia, Alessandro Belardini, Mario Bertolotti, and Alessio Benedetti

Doc ID: 226413 Received 06 Nov 2014; Accepted 25 Apr 2015; Posted 05 May 2015  View: PDF

Abstract: It is possible to realize artificial chiral structures in the optical domain thanks to the recent successes in nanotechnology. A 2D and/or 3D chiral configuration can be artificially realized, opening the way to new functionalities on a spatial scale of few hundred on nms. The second order nonlinear response of nanostructured materials is an interesting and fascinating issue. In artificial chiral materials it takes advantage of the mutual interaction among electric and magnetic nonlinear response. In the present paper we report an overview of second harmonic generation raised by artificial chiral structures of different morphologies and material components

Dynamics of moving gap solitons in linearly coupled Bragg gratings with dispersive reflectivity

Javid Atai and Babak Barati

Doc ID: 236284 Received 16 Mar 2015; Accepted 21 Apr 2015; Posted 07 May 2015  View: PDF

Abstract: We investigate the existence, stability and collision dynamics of moving gap solitons in the model of two linearly coupled Bragg gratings with dispersive reflectivity. It is shown that the model supports both symmetric and asymmetric moving solitons that fill the entire bandgap. It is found that beyond a certain value of dispersive reflectivity parameter, the moving solitons develop sidelobes. To analyze the sidelobes, exact analytical expressions for the tails of the symmetric solitons are found and it is shown that they are in excellent agreement with the numerical solutions. By means of numerical stability analysis, we have identified stability regions within the bandgap for various values of dispersive reflectivity, coupling coefficient and velocity. It is found that the dispersive reflectivity has a stabilizing effect. We have also systematically investigated the collisions of in-phase and \pi -out-of-phase counterpropagating solitons. In-phase collisions lead to various outcomes such as separation of solitons with reduced, increased, or unchanged velocities, merger into a single quiescent soliton and generation of three solitons (one quiescent and two moving solitons). A key finding is that, depending on the velocity and coupling coefficient, collisions may lead to the formation of three solitons even in the absence of dispersive reflectivity. In the out-of-phase case, it is found that colliding solitons generally bounce off each other.

Non-separated states from squeezed dark-state polaritons in electromagnetically-induced-transparency media

Ray-Kuang Lee, Chuang You-Lin, and Ite Yu

Doc ID: 225151 Received 17 Oct 2014; Accepted 17 Apr 2015; Posted 29 Apr 2015  View: PDF

Abstract: Within the frame of quantized dark-state polaritons in electromagnetically-induced-transparency media, noise fluctuations in the quadrature components are studied. Squeezed state transfer, quantum correlation, and noise entanglement between probe field and atomic polarization are demonstrated in single- and double-Λ configurations, respectively. Even though a larger degree of squeezing parameter in the continuous variable helps to establish stronger quantum correlations, inseparability criterion is satisfied only within a finite range of squeezing parameter. The results obtained in the present study may be useful for guiding experimental realization of quantum memory devices for possible applications in quantum information and computation.

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]).

Bragg Holography in Active Semiconductor Microcavities

Hao Sun, David Nolte, Eric Harmon, and James Hyland

Doc ID: 232173 Received 26 Jan 2015; Accepted 20 Feb 2015; Posted 20 Apr 2015  View: PDF

Abstract: High-speed dynamic holography is studied numerically and experimentally in broad-area InGaAs/InP multiple-quantum-well asymmetric Fabry-Perot (ASFP) microcavities that have pumped gain gratings near the lasing threshold. Two numerical approximation methods are developed to predict Bragg diffraction effects in these active microcavities. The cavity Raman-Nath method assumes multipass Raman-Nath diffraction, while the Cavity Bragg method assumes an effective medium. Both methods predict that Raman-Nath diffraction in a micron thick cavity resonator can exhibit Bragg-like selectivity for angles near the Bragg angle. The angular and spectral selectivities are studied experimentally in optically-pumped free carrier gratings using a tunable 1.55 micron laser in a nondegenerate four-wave mixing configuration. The device operates at gigahertz speeds with transient diffraction efficiency near unity.

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