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February


Volume integrated phase-modulator based on funnel waveguides for reconfigurable miniaturized optical circuits

  • Jacopo Parravicini, Fabrizio Di Mei, Ruben Martinez Lorente, Davide Pierangeli, Ronny Agranat, and Eugenio Del Re
  • received 12/16/2014; accepted 02/19/2015; posted 02/20/2015; Doc. ID 230547
  • [full text: PDF (484) KB)]
  • Abstract: We demonstrate the integration of a miniaturized 30(x) μm × 30(y) μm × 2.7(z) mm electro-optic phase modulator operating in the near-infrared (λ=980 nm) based on the electro-activation of a funnel waveguide inside a paraelectric sample of photorefractive potassium-lithium-tantalate-niobate (KLTN). The modulator forms a basic tassel in the realization of miniaturized reconfigurable optical circuits embedded in a single solid-state three-dimensional chip.

Keywords (OCIS):

  • (130.3060) Integrated optics : Infrared
  • (190.5330) Nonlinear optics : Photorefractive optics
  • (350.5030) Other areas of optics : Phase
  • (130.4110) Integrated optics : Modulators

Kinetics of optically-pumped Kr metastables

  • Michael Heaven and Jiande Han
  • received 02/03/2015; accepted 02/19/2015; posted 02/20/2015; Doc. ID 233684
  • [full text: PDF (861) KB)]
  • Abstract: Optically-pumped atomic gas lasers that utilize metastable excited states of rare gas atoms (Rg*) have been demonstrated using both pulsed and CW pump sources. These devices resemble diode-pumped alkali vapor lasers, but have the advantage of using a chemically inert lasing medium. Collisional energy transfer is needed to sustain a population inversion, and He is used as the transfer agent. Consequently, values for the Kr*+He state-to-state energy transfer rate constants are needed for the analysis and prediction of laser performance characteristics. In the present study we report He energy transfer rate constants for Kr* in the 5p[5/2]2, 5p[5/2]3, 5p[1/2]1, and 5s[3/2]1 states.

Keywords (OCIS):

  • (140.0140) Lasers and laser optics : Lasers and laser optics
  • (140.1340) Lasers and laser optics : Atomic gas lasers
  • (140.3298) Lasers and laser optics : Laser beam combining

Tuning random lasing in photonic glasses

  • Michele Gaio, Riccardo Sapienza, and Matilda Peruzzo
  • received 02/09/2015; accepted 02/18/2015; posted 02/20/2015; Doc. ID 233577
  • [full text: PDF (667) KB)]
  • Abstract: We present a detailed numerical investigation of the tunability of a diffusive random laser when Mie resonances are excited. We solve a multimode diffusion model and calculate multiple light scattering in presence of optical gain which includes dispersion in both scattering and gain, without any assumptions about the β parameter. This allows us to investigate a realistic photonic glass made of latex spheres and rhodamine and to quantify both the lasing wavelength tunability range and the lasing threshold. Beyond what is expected by diffusive monochromatic models, the highest threshold is found when the competition between the lasing modes is strongest and not when the lasing wavelength is furthest from the maximum of the gain curve.

Keywords (OCIS):

  • (140.3600) Lasers and laser optics : Lasers, tunable
  • (290.1990) Scattering : Diffusion
  • (290.4020) Scattering : Mie theory
  • (290.4210) Scattering : Multiple scattering

Experimental Demonstration of a Novel Indoor Optical Wireless Localization System for High-Speed Personal Area Networks

  • KE WANG, Ampalavanapilla Nirmalathas, Christina Lim, and Efstratios Skafidas
  • received 12/17/2014; accepted 02/18/2015; posted 02/20/2015; Doc. ID 230912
  • [full text: PDF (720) KB)]
  • Abstract: In this paper, we propose a novel indoor localization system based on optical wireless technology. By using the same architecture as the high-speed full-duplex indoor optical wireless communication system, the “search and scan” process, and the added transmission power and beam footprint information in the “search and scan” message, indoor localization functionality is achieved. Proof-of-concept experiments are carried out and results show that an average error of <15 cm is achieved with a localization beam size of 1 m. In addition, the major localization accuracy limiting factors are analyzed both theoretically and experimentally. When incorporated with the optical wireless communication system, high-speed indoor wireless personal area networks can be achieved.

Keywords (OCIS):

  • (060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
  • (060.4510) Fiber optics and optical communications : Optical communications
  • (060.2605) Fiber optics and optical communications : Free-space optical communication

Tunable Q-factor silicon micro-ring resonators for ultra-low power parametric processes

  • Michael Strain, Cosimo Lacava, Laura Meriggi, Ilaria Cristiani, and Marc Sorel
  • received 12/09/2014; accepted 02/18/2015; posted 02/19/2015; Doc. ID 229224
  • [full text: PDF (733) KB)]
  • Abstract: A compact silicon ring resonator is demonstrated that allows simple electrical tuning of the ring coupling coefficient and Q-factor and therefore the resonant enhancement of on-chip non-linear optical processes. Fabrication induced variation in designed coupling fraction, crucial in the resonator performance, can be overcome using this post-fabrication trimming technique. Tuning of the micro-ring resonator across the critical coupling point is demonstrated, exhibiting a Q-factor tunable between 9000 and 96000. Consequently, resonantly enhanced Four Wave Mixing shows tunable efficiency between -40dB and -16.3dB at an ultra-low on-chip pump power of 0.7mW.

Keywords (OCIS):

  • (130.3120) Integrated optics : Integrated optics devices
  • (130.4310) Integrated optics : Nonlinear
  • (190.3270) Nonlinear optics : Kerr effect
  • (190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
  • (230.5750) Optical devices : Resonators
  • (130.3990) Integrated optics : Micro-optical devices

Diffraction of waves by a boundary between two resistive half-planes

  • Yusuf Umul
  • received 10/22/2014; accepted 02/18/2015; posted 02/20/2015; Doc. ID 225326
  • [full text: PDF (350) KB)]
  • Abstract: The solution of the diffraction problem of waves by a junction between two resistive half-screens is obtained by using the wedge diffraction field expression, introduced by Maliuzhinets. The new field expression is compared with the solution of Senior for the scattered waves. The important aspects of the approach are discussed in the light of the numerical results.

Keywords (OCIS):

  • (050.1960) Diffraction and gratings : Diffraction theory
  • (290.5825) Scattering : Scattering theory

Image quality improvement by structured light illumination method in optical readout cantilever array infrared imaging system

  • Yun Feng, Yuejin Zhao, Ming Liu, Liquan Dong, Xiaomei Yu, Lingqin Kong, Wei Ma, and Xiaohua Liu
  • received 11/20/2014; accepted 02/18/2015; posted 02/20/2015; Doc. ID 227201
  • [full text: PDF (924) KB)]
  • Abstract: Structured light illumination method is applied in an optical readout uncooled infrared imaging system to improve the IR image quality. The unavoidable nonuniform distribution of the initial bending angles of the bimaterial cantilever pixels in the focal plane array (FPA) can be well compensated by this method. An ordinary projector is used to generate structured lights of different intensity distribution. The projected light is divided into patches of rectangular regions, and brightness of each region can be set automatically according to the deflection angles of FPA and therefore the light intensity focused on the imaging plane. By this method, the FPA image on the CCD plane can be much more uniform and the image quality of infrared target improved significantly. A comparative experiment is designed to verify the effectiveness. The theoretical analysis and experimental results show that the proposed structured light illumination method outperforms the conventional one, especially when it is difficult to perfect the FPA fabrication.

Keywords (OCIS):

  • (110.3080) Imaging systems : Infrared imaging
  • (110.2945) Imaging systems : Illumination design
  • (040.6808) Detectors : Thermal (uncooled) IR detectors, arrays and imaging

Full characterization of dichroic samples from a single measurement by circular polarization orthogonality breaking

  • Noé Ortega-Quijano, Julien FADE, Emmanuel SCHAUB, François PARNET, and Mehdi Alouini
  • received 11/20/2014; accepted 02/18/2015; posted 02/20/2015; Doc. ID 227228
  • [full text: PDF (4744) KB)]
  • Abstract: We report a novel method to unambiguously determine the magnitude and orientation of linear dichroism from a single measurement. It is based on the use of a dedicated dual-frequency dual-polarization coherent source providing two orthogonal circularly polarized modes at the output. We show that the interaction of such beam with dichroic media gives rise to a beatnote signal whose amplitude and phase enable to fully determine the diattenuation coefficient and axis orientation respectively. The application of this method to polarimetric imaging provides single-shot sample characterization by its diattenuation coefficient and optical axis angle, with potential applications in biomedical imaging.

Keywords (OCIS):

  • (100.1930) Image processing : Dichroism
  • (120.2130) Instrumentation, measurement, and metrology : Ellipsometry and polarimetry
  • (120.5410) Instrumentation, measurement, and metrology : Polarimetry
  • (110.5405) Imaging systems : Polarimetric imaging

Monochromatic and plane wave decomposition of ergodic fields

  • Tan Nguyen, Hassaan Majeed, and Gabriel Popescu
  • received 12/05/2014; accepted 02/18/2015; posted 02/20/2015; Doc. ID 228959
  • [full text: PDF (693) KB)]
  • Abstract: We investigate the uniqueness of the plane wave decomposition of temporally deterministic, spatially random fields. Specifically, we consider decomposition of spatially ergodic and, thus, statistically homogeneous fields. It is easy to show that plane waves are always a solution for the Karhunen-Loéve expansion. However, we show that when the spatial power spectrum is injective, the plane waves are the only possible coherent modes. Furthermore, the randomness of such fields originates in the spatial spectral phase, i.e., the phase associated with the coefficients of each plane wave in the expansion. By contrast, the spectral amplitude is deterministic and is specified by the spatial power spectrum. We end with a discussion showing how the results can be translated in full to the time domain. Specifically, a temporally random field can be decomposed into a KarhunenLoéve series, with monochromatic waves as basis. If the temporal power spectrum is injective, this decomposition is unique. For temporally ergodic and, thus stationary fields, the spectral amplitude is deterministic and randomness is only due to the spectral phase.

Keywords (OCIS):

  • (030.0030) Coherence and statistical optics : Coherence and statistical optics
  • (030.1640) Coherence and statistical optics : Coherence
  • (030.6600) Coherence and statistical optics : Statistical optics

Phase noise measurement of wideband microwave sources based on a microwave photonic frequency down-converter

  • Shilong Pan, Dengjian Zhu, Fangzheng Zhang, and Pei Zhou
  • received 12/09/2014; accepted 02/18/2015; posted 02/20/2015; Doc. ID 229307
  • [full text: PDF (430) KB)]
  • Abstract: An approach for phase noise measurement of microwave signal sources based on a microwave photonic frequency down-converter is proposed. Using the same optical carrier, the microwave signal under test is applied to generate two +1st-order optical sidebands by two stages of electro-optical modulations. A time delay is introduced between the two sidebands through a span of fiber. By beating the two +1st-order sidebands at a photodetector, frequency down-conversion is implemented, and phase noise of the signal under test can be calculated thereafter. The system has very large operation bandwidth thanks to the frequency conversion in the optical domain, and good phase noise measurement sensitivity can be achieved since the signal degradation caused by electrical amplifiers is avoided. An experiment is carried out. The phase noise measured by the proposed system agrees well with that measured by a commercial spectrum analyzer or provided by the datasheet. A large operation bandwidth of 5- to 40-GHz is demonstrated using the proposed system. Moreover, good phase noise floor is achieved (-123 dBc/Hz@1kHz and -137 dBc/Hz@10kHz at 10 GHz), which is nearly constant over the full measurement range.

Keywords (OCIS):

  • (060.4080) Fiber optics and optical communications : Modulation
  • (120.5050) Instrumentation, measurement, and metrology : Phase measurement
  • (060.5625) Fiber optics and optical communications : Radio frequency photonics

Radiocarbon detection based on Cavity Ring-Down Spectroscopy and a Quantum Cascade Laser

  • Guillaume Genoud, Mikko Merimaa, Markku Vainio, Julian Dean, and Hilary Phillips
  • received 12/24/2014; accepted 02/18/2015; posted 02/25/2015; Doc. ID 230853
  • [full text: PDF (446) KB)]
  • Abstract: Monitoring of radiocarbon (¹⁴C) in carbon dioxide is demonstrated using mid-infrared spectroscopy and a quantum cascade laser. The measurement is based on cavity ring-down spectroscopy, and a high sensitivity is achieved with a simple setup. The instrument was tested using a standardised sample containing elevated levels of radiocarbon. ¹⁴C could be detected from samples with an isotopic ratio ¹⁴C/C as low as 50 parts-per-trillion, corresponding to an activity of 5 kBq/m³ in pure CO₂, or 2 Bq/m³ in air after extraction of the CO₂ from an air sample. The instrument is simple, compact and robust, making it the ideal tool for on-site measurements. It is aimed for monitoring of radioactive gaseous emissions in nuclear power environment, during the operation and decommissioning of nuclear power plants. Its high sensitivity also makes it the ideal tool for the detection of leaks in radioactive waste repositories.

Keywords (OCIS):

  • (300.1030) Spectroscopy : Absorption
  • (300.6340) Spectroscopy : Spectroscopy, infrared
  • (300.6390) Spectroscopy : Spectroscopy, molecular
  • (140.5965) Lasers and laser optics : Semiconductor lasers, quantum cascade

Light-shift modulated photon-echo

  • Thierry Chaneliere and Gabriel Hétet
  • received 01/20/2015; accepted 02/18/2015; posted 02/23/2015; Doc. ID 232858
  • [full text: PDF (800) KB)]
  • Abstract: We show that the AC-Stark shift (light-shift) is a powerful and versatile tool to control the emission of a photon-echo in the context of optical storage. As a proof-of-principle, we demonstrate that the photon-echo efficiency can be fully modulated by applying light-shift control pulses in an erbium doped solid. The control of the echo emission is attributed to the spatial gradient induced by the light-shift beam.

Keywords (OCIS):

  • (160.2900) Materials : Optical storage materials
  • (160.5690) Materials : Rare-earth-doped materials
  • (210.4680) Optical data storage : Optical memories
  • (270.1670) Quantum optics : Coherent optical effects
  • (270.5565) Quantum optics : Quantum communications
  • (270.5585) Quantum optics : Quantum information and processing

Multiple quasi-phase-matched nonlinear Raman-Nath diffraction

  • Andrey Vyunishev and Anatoly Chirkin
  • received 01/13/2015; accepted 02/18/2015; posted 02/23/2015; Doc. ID 232126
  • [full text: PDF (1052) KB)]
  • Abstract: The method of superposition of nonlinearity modulation is employed to design a (2D) two-dimensional nonlinear photonic lattice for efficient multiple quasi-phase-matched second harmonic (SH) generation in the process of nonlinear Raman-Nath diffraction. An analytical solution is proposed to calculate the SH intensity in rectangular 2D lattices. This approach can be useful for generation of multiple SH beams with the efficiency a few orders of magnitude higher than in the case of non-phase-matched generation via nonlinear Raman-Nath diffraction.

Keywords (OCIS):

  • (190.2620) Nonlinear optics : Harmonic generation and mixing
  • (190.4420) Nonlinear optics : Nonlinear optics, transverse effects in
  • (190.4223) Nonlinear optics : Nonlinear wave mixing

Frequency-agile dual-frequency lidar for integrated coherent radar-lidar architectures

  • Mirco Scaffardi, Valeria Vercesi, Daniel Onori, Francesco Laghezza, Filippo Scotti, and Antonella Bogoni
  • received 12/30/2014; accepted 02/18/2015; posted 02/24/2015; Doc. ID 231639
  • [full text: PDF (1267) KB)]
  • Abstract: We propose a novel architecture for implementing a dual-frequency lidar exploiting differential Doppler shift measurement. The two frequency tones, needed for targets velocity measurements, are selected from the spectrum of a mode locked laser operating in the C-band. The tones separation is easily controlled by using a programmable wavelength selective switch, thus allowing for a dynamic tradeoff among robustness to atmospheric turbulence and sensitivity. Speed measurements for different tones separation equal to 10, 40, 80 and 160 GHz are demonstrated, proving the system capability of working in different configurations. Thanks to the acquisition system based on analog-to-digital converter and digital signal processing, real-time velocity measurements are demonstrated. The MLL-based proposed architecture enables the integration of the dual-frequency lidar with a photonic-based radar which exploits the same laser for generating and receiving radio-frequency signal with high performance, thus allowing for simultaneous or complementary targets observations by exploiting the advantages of both radar and lidar.

Keywords (OCIS):

  • (010.3640) Atmospheric and oceanic optics : Lidar
  • (120.7250) Instrumentation, measurement, and metrology : Velocimetry

Modeling light scattering by forsterite particles

  • Evgenij Zubko
  • received 01/13/2015; accepted 02/17/2015; posted 02/18/2015; Doc. ID 232413
  • [full text: PDF (610) KB)]
  • Abstract: Laboratory optical measurements of forsterite particles reveal remarkably similar light-scattering responses in two samples that were thought to obey different size distributions. These measurements are modeled with irregularly shaped agglomerated debris particles having refractive index m = 1.6 + 0.0005i that is representative of forsterite in visible. Modeling closely reproduces the measurements of both samples, making retrieval of their size distributions possible.

Keywords (OCIS):

  • (260.2110) Physical optics : Electromagnetic optics
  • (290.5820) Scattering : Scattering measurements
  • (290.5850) Scattering : Scattering, particles
  • (280.4991) Remote sensing and sensors : Passive remote sensing
  • (290.5825) Scattering : Scattering theory
  • (290.5855) Scattering : Scattering, polarization

Experimental determination of generalized Stokes parameters

  • Rakesh Singh and VINU RV
  • received 01/16/2015; accepted 02/17/2015; posted 02/18/2015; Doc. ID 232487
  • [full text: PDF (546) KB)]
  • Abstract: A new technique to determine generalized Stokes parameters by making use of speckle holographic technique and two point intensity correlation is proposed and experimentally demonstrated. Assuming Gaussian statistics and spatial stationarity, a speckle hologram is generated prior to the fourth order correlation i. e two point intensity correlation. The measurement technique offers a complete retrieval of complex generalized Stokes parameters. Application of the proposed technique is experimentally demonstrated for two different random source structures.

Keywords (OCIS):

  • (030.0030) Coherence and statistical optics : Coherence and statistical optics
  • (030.6140) Coherence and statistical optics : Speckle
  • (030.6600) Coherence and statistical optics : Statistical optics
  • (260.5430) Physical optics : Polarization

Broadband carrier-envelope-phase stabilization for high-repetition-rate multi-pulse coherent synthesis

  • Richard McCracken, Ilaria Gianani, Adam Wyatt, and Derryck Reid
  • received 08/24/2014; accepted 02/17/2015; posted 02/18/2015; Doc. ID 233030
  • [full text: PDF (651) KB)]
  • Abstract: Using a zero-offset carrier-envelope locking technique, we have synthesized an octave-spanning composite frequency comb exhibiting 132-as timing jitter between the constituent pulses over a one-second observation window. In the frequency domain, this composite comb has a modal structure and coherence which are indistinguishable from those of a comb which might be produced by a hypothetical single modelocked oscillator of equivalent bandwidth. The associated phase stability enables the participating multi-color pulse sequences to be coherently combined, representing an example of multi-pulse synthesis using a femtosecond oscillator.

Keywords (OCIS):

  • (120.3940) Instrumentation, measurement, and metrology : Metrology
  • (190.4970) Nonlinear optics : Parametric oscillators and amplifiers
  • (320.7090) Ultrafast optics : Ultrafast lasers

Brightness calibrates particle size in single particle fluorescence imaging

  • Changfeng Wu, Zhihe Liu, Zezhou Sun, Weihua Di, WP Qin, and Zhen Yuan
  • received 01/05/2015; accepted 02/17/2015; posted 02/20/2015; Doc. ID 231829
  • [full text: PDF (677) KB)]
  • Abstract: This letter provides a novel approach to quantify the particle sizes of highly bright semiconductor polymer dots (Pdots) for single-particle imaging and photobleaching studies. A quadratic dependence of single-particle brightness on particle size was determined by single-particle fluorescence imaging and intensity statistics. In terms of the same imaging conditions, the particle diameter can be quantified by comparing the individual brightness intensity with associated calibration curve. Based on this sizing method, photobleaching trajectories and overall photon counts emitted by single particles were analyzed. It is found that photobleaching rate constants of different sized Pdots are not strongly dependent on particle diameter except the sparsely occurred fluorescence blinking in certain dim particles and the rapid photobleaching component in some bright particles. The overall photon counts increase with increasing particle diameter. However, those larger than 30 nm deviate away from the increasing tendency. These results reveal the significance of selecting appropriate Pdots (≤30 nm) for single-particle imaging and tracking applications.

Keywords (OCIS):

  • (170.6280) Medical optics and biotechnology : Spectroscopy, fluorescence and luminescence
  • (180.2520) Microscopy : Fluorescence microscopy
  • (160.4236) Materials : Nanomaterials

Fast beam self-trapping in LiNbO3 films by pyroelectric effect

  • Mathieu Chauvet, Fabrice Devaux, Herve Maillotte, Sylvain Ballandras, Florent Bassignot, Ludovic gauthier-Manuel, Fabien Henrot, and gwenn ulliac
  • received 01/28/2015; accepted 02/17/2015; posted 02/20/2015; Doc. ID 233320
  • [full text: PDF (503) KB)]
  • Abstract: We report light beam self-trapping triggered by the pyroelectric effect in an isolated ferroelectric thin film. Experiments are performed in an 8 micron thick congruent undoped LiNbO3 film bonded onto a silicon wafer. Response time two orders of magnitude faster than in bulk LiNbO3 is reported. The original underlying physics specific of this arrangement is discussed.

Keywords (OCIS):

  • (160.3730) Materials : Lithium niobate
  • (190.0190) Nonlinear optics : Nonlinear optics
  • (190.5330) Nonlinear optics : Photorefractive optics
  • (190.5940) Nonlinear optics : Self-action effects
  • (310.2785) Thin films : Guided wave applications
  • (190.6135) Nonlinear optics : Spatial solitons

Free Space Self-Similar Beams

  • Changqing Xie and Nan Gao
  • received 10/22/2014; accepted 02/17/2015; posted 02/18/2015; Doc. ID 225495
  • [full text: PDF (3653) KB)]
  • Abstract: It is well known that self-similar wave dynamics can happen with the coexistence of diffraction and nonlinearity. However, things are clearly different in linear systems, since simple extrapolation by approaching the nonlinear coefficient toward zero will lead to trivial solutions. Here, we show that a broad class of self-similar beams can propagate in linear wave systems governed by paraxial wave equation or the free particle Schrödinger equation. The linearity of free space allows us to construct these beams by superposition and eliminate instability problems. The technique of seeking exact or approximate solutions of the wave equations in transformed coordinates presented here should be a useful avenue to the manipulation of wave propagation in various linear systems.

Keywords (OCIS):

  • (050.1940) Diffraction and gratings : Diffraction
  • (140.3300) Lasers and laser optics : Laser beam shaping
  • (260.0260) Physical optics : Physical optics
  • (350.5500) Other areas of optics : Propagation

<< Previous Page Articles 21 to 40 of 131 Next Page >>





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