Expand this Topic clickable element to expand a topic
OSA Publishing

Early Posting

Accepted papers to appear in an upcoming issue

OSA now posts prepublication articles as soon as they are accepted and cleared for production. See the FAQ for additional information.

Photon statistics of actively Q-switched erbium doped fiber laser

Josue Adin Minguela-Gallardo, Yuri Barmenkov, Alexander Kir'yanov, and Georgina Beltran Perez

Doc ID: 292138 Received 06 Apr 2017; Accepted 23 May 2017; Posted 23 May 2017  View: PDF

Abstract: We report the intensity noise properties of actively Q-switched erbium-doped fiber lasers implemented in two configurations, one with linear Fabry-Pérot cavity with two fiber Bragg gratings as narrowband reflectors and the other with ring cavity without spectrally-selective components. We demonstrate that the types of photon noise statistics of Q-switched pulsing in these two circumstances are dramatically different (Poissonian or Bose-Einstein), revealing a crucial role of cavity’s spectral selectivity. To determine the type of experimental statistics in terms of photon noise distribution, a detailed modeling is performed. Also, the noisy Q-switched pulses are employed as pump for generating broadband supercontinuum in telecom fiber, which affects their noise statistics.

Pulsed operation of a miniature scalar optically-pumped magnetometer

Vladislav Gerginov, Svenja Knappe, and Sean Krzyzewski

Doc ID: 291583 Received 06 Apr 2017; Accepted 22 May 2017; Posted 23 May 2017  View: PDF

Abstract: A scalar magnetic field sensor based on a millimeter-size 87Rb vapor cell is described. The magnetometer uses nearly co-propagating pump and probe laser beams, amplitude modulation of the pump beam, and detection through monitoring the polarization rotation of the detuned probe beam. The circularly-polarized pump laser resonantly drives a spin precession in the alkali atoms at the Larmor frequency. A modulation signal on the probe laser polarization is detected with a lock-in amplifier. Since the Larmor precession is driven all-optically, potential cross-talk between sensors is minimized. And since the pump light is turned off during most of the precession cycle large offsets of the resonance, typically present in a single-beam Bell-Bloom scheme, are avoided. At the same time, relatively high sensitivities can be reached even in millimeter-size vapor cells: The magnetometer achieves a sensitivity of 1 pT/Hz1/2 in a sensitive volume of 16 mm3, limited by environmental noise. When a gradiometer configuration is used to cancel the environmental noise, the magnetometer sensitivity reaches 300 fT/Hz1/2. We systematically study the dependence of the magnetometer performance on the optical duty cycles of the pump light and find that better performance is achieved with shorter duty cycles, with the highest values measured at 1.25 % duty cycle.

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.

Photon density wave resonances of amplifying inhomogeneities in a random medium

Lalruatfela Renthlei, S. Anantha Ramakrishna, and Harshawardhan Wanare

Doc ID: 288015 Received 03 Mar 2017; Accepted 18 May 2017; Posted 23 May 2017  View: PDF

Abstract: Amplification in random media is presented from the perspective of diffuse photon density waves (DPDW). These exponentially decaying waves in absorbing media exhibit significantly enhanced propagation characteristics in random amplifying media. Consequently, finite amplifying regions embedded in an absorbing random medium exhibit specific resonant features governed by the geometry of the amplifying region. For a spheroidal amplifying region, the scattered waves are dominated by the characteristic multipolar resonances, and these monopolar as well as dipolar resonances are closely related to random lasing thresholds. The levels of amplification at which the resonances (or lasing) occurs can be used to identify the size, shape and orientation of the amplifying region. These resonant modes are quite robust and survive even as the modulation frequency of the DPDW tends to zero, thereby, indicating a deeper connections with the ensemble averaged random lasing path distributions and the modal intensity distributions associated with DPDW.

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.

Optimized atomic flux from a frequency modulated two-dimensional magneto-optical trap for cold fermionic potassium atoms

Jae Hoon Lee and J Mun

Doc ID: 294651 Received 27 Apr 2017; Accepted 12 May 2017; Posted 23 May 2017  View: PDF

Abstract: We present our study on enhancement and optimization of ⁴⁰K atomic beam flux from a two-dimensional magneto-optical trap (2D MOT) by modulating the frequency of cooling laser. The laser cooling beam frequencies of the 2D MOT were effectively broadened via elecro-optical modulators at 10 MHz with modulation index ranging from β=0 to 7 depending on the laser intensity. Laser parameters of the 2D MOT beams and the magnetic field gradient were scanned for optimal settings for maximum atomic beam flux. When compared to a conventional 2D MOT with fixed laser frequencies, we were able to obtain a 3.7 times enhancement of the atomic flux when the total laser power was 640 mW. Numerical calculations predict further improvement for higher laser beam intensities.

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.

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.

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.

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.

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.

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.

Select as filters


    Select Topics Cancel
    © Copyright 2017 | The Optical Society. All Rights Reserved