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Spectral technique for measuring phase retardation of a wave plate

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Chinese Optics Letters 2015年第1期13卷 82-87页

作者：王伟陈建中刘中波 Shandong Jiaotong University College of ScienceChangqing University Science & Technology Park

We present a technique and algorithm for measuring the phase retardation of a wave plate based on spectral transmission curve. Through accurately extracting the intersection points＇ wavelengths from the spectral transmission curve, the effective phase retardation, absolute phase retardation, order, and physical thickness of the wave plate can be measured simultaneously in a wide spectral range. Experimental results show that the proposed technique has many advantages, such as higher data utilization, simpler extraction algorithm, and no strict requirement for the directions of transmission axes of the polarizer and analyzer, and the fast axis of the wave plate.

关键词： Algorithms optical devices

Analysis of coupling between nanotaper SiGe-SOI waveguide and fiber

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Journal of Semiconductors 2014年第7期35卷 78-83页

作者：冯松高勇 Department of Electronic Engineering Xi’an University of Technology School of Science Xi’an Polytechnic University

Based on a submicrometer-sized SiGe-SOI waveguide, the coupling loss mechanism is analyzed between the submicrometer-sized SiGe-SOI waveguide and the fiber. The main sources of coupling loss are analyzed, and the mismatch loss of the mode field is the mainly lost during connection between the submicrometer-sized waveguide and the fiber. In order to reduce the mismatch loss of the mode field, the structure ofa nanotaper SiGeSOI waveguide with a nanometer-sized tip is adopted. By reducing the waveguide dimensions to increase the mode field size, coupling loss could be reduced between the waveguide and the fiber. Different mode field dimensions ofnanotaper SiGe-SOI waveguides and fiber are quantitatively analyzed, and the quantitative relationship between nanotaper SiGe-SOI waveguide dimensions and mode field dimensions are obtained. Finally, nanotaper SiGe-SOI waveguides are made, and the test and analysis have been done. The final experimental results accord well with the theoretical analysis. When the waveguide width is 0.5 μm, the minimum coupling loss of the SiGe-SOI waveguide is 0.56 dB/facet, and also the correctness of the design method and theoretical analysis are verified.

关键词： optical devices nanotaper SiGe-SOI waveguide mode field coupling loss

Electro-optically Q-switched 946 nm laser of a composite Nd:YAG crystal

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Chinese Optics Letters 2015年第2期13卷 49-52页

作者：黄晶胡秀寒陈卫标 Key Laboratory of Space Laser Communication and Detection Technology Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

A depolarization phenomenon in an electro-optical crystal in a quasi-three-level 946 nm Nd：YAG laser is observed. A compensation of the thermal effects in electro-optical crystals is achieved by employing a quarter-wave plate, with one optical axis parallel to the laser polarization. This technique allows for the production of an electro-optically Q-switched 946 nm Nd：YAG laser at 1 k Hz. A maximum output power of 350 m W at 1 k Hz repetition frequency and 11 ns pulse duration are achieved with an output coupler of 10% transmission under the incident pump power of 11.1 W, corresponding to a peak power of ～32 k W.

关键词： Light polarization optical devices optical pumping Q switching

Generation of polarization vortex beams by segmented quarter-wave plates

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Chinese Optics Letters 2016年第7期14卷 19-22页

作者：辛璟焘娄小平周哲海董明利祝连庆 Beijing Engineering Research Center of Optoelectronie Information and Instruments Beijing Information Science and Technology University Beijing 100192 China Beijing Key Laboratory of Optoelectronic Measurement Technology Beijing Information Science and Technology University Beijing 100192 China

A spatially variable retardation device, an SQWP, is designed to generate polarization vortex beams. The transformation of Laguerre--Gaussian beams by the SQWP is further studied, and it is found that the SQWPs can al... 详细信息

关键词： optical devices Polarization Vortex flow

Channel power control in optical amplifiers to mitigate physical impairment in optical network

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Science China(Information Sciences) 2015年第10期58卷 119-126页

作者： ZHAO DongYan LONG KePing ZHENG YiChuan SUN Jian GONG WeiBing Institute of Advanced Network Technology and New Services University of Science and Technology Beijing

The signal quality degradation, which occurs due to the aspects of fiber attenuation, splitter switch,and amplified spontaneous noise in erbium-doped fiber amplifier, may substantially erode the performance of optical communications. Among the above-mentioned factors, the physical-layer impairments may significantly weaken the signal quality at the receiver. In this paper, the impact of both the channel power adjustment and the optical signal noise rate on the optimization of optical amplifiers over the optical propagation links is studied.Our objective is to employ a proper control strategy to effectively adjust the signal power level in the chain network. A new algorithm, which takes into account the physical-layer impairments in performance optimization,facilitates an impairment aware-proportional-integral-derivative neuron controller for improving the quality of transmission. Numerical results show that the proposed controller is capable of effectively compensating for the power impairments in optical links.

关键词： optical devices communication system performance optical signal noise rate(OSNR) optimization control

Fiber-optic Fourier-domain common-path OCT

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Chinese Optics Letters 2008年第12期6卷 899-901页

作者： Xuan Liu Xiaolu Li Do-Hyun Kim Ilko Ilev Jin U. Kang Department of Electrical and Computer Engineering Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA Center for devices and Radiological Health FDA 10903 New Hampshire Avenue Silver Spring MD 20993-0002 USA

We experimentally and theoretically investigated the performance of a fiber-optic based Fourier-domain common-path optical coherence tomography （OCT）. The fiber-optic common-path OCT operated at the 840-nm center wavelength. The resolution of the system was 8.8 μm （in air） and the working depth using a bare fiber probe was approximately 1.5 mm. The signal-to-noise ratio （SNR） of the system was analyzed. OCT images obtained by the system were also presented.

关键词： Fast Fourier transforms Image display Light emitting diodes Multiple scattering optical coherence tomography optical devices

Three-component hybrid-integrated optical accelerometer based on LiNbO_3 photoelastic waveguide

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Chinese Optics Letters 2009年第1期7卷 32-35页

作者：唐东林梁政张晓东何山郭峰 Faculty of Mechanical and Electronic Engineering Southwest Petroleum UniversityKey Laboratory of Petroleum-Gas EquipmentMinistry of Education of China

A novel three-component hybrid-integrated optical accelerometer based on LiNbO3 photoelastic waveguide is presented. The photoelasitcity of LiNbO3 due to three-dimensional stress states is obtained analytically. We analyze the level of sensitivity to cross-axis accelerations which is a very important parameter for three-component accelerometer. Theoretically, the designed three-component hybrid-integrated optical accelerometer has a transverse sensitivity ratio （TSR） of zero. The sensor has a high natural frequency of 3.5 kHz and a linear broad working freauency.

关键词： optical devices optical instruments Three dimensional Waveguide couplers Waveguides

Control of plasmonic wave propagating in nanocavity with tooth-shaped configuration

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Chinese Physics B 2011年第1期20卷 468-472页

作者：李旭峰潘石郭英楠王乔 School of Physics and Optoelectronic Technology Dalian University of Technology

Characteristics of plasmonic wave propagating in nanocavity formed by two silver films are studied numerically. The groove etched inside wall of the top film makes it possible to control the propagation when light goes through the top film along a nanoslit into the cavity. It is found that the transmission wave through the channel of groove etched side can be filtered linearly with the groove of a certain depth; while the other side is still open for this wave and its intensity can be enhanced periodically with the variable groove position in both films, which are explained well based on the interference of plasmonic waves in the system.

关键词： plasmonic wave optical devices FDTD

Sensitivity improvement of broadband electro-optic polymer-based optical phase modulator using 1D and 2D photonic crystal structures

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Chinese Optics Letters 2017年第1期15卷 8-12页

作者： K.Receveur K.Wei M.Hadjloum M.El Gibari A.De Rossi H.W.Li A.S.Daryoush Department of ECE Drexel University IETR Université Bretagne Loire University of Nantes Thales Research and Technology France

This Letter introduces the design and simulation of a microstrip-line-based electro-optic （EO） polymer optical phase modulator （PM） that is further enhanced by the addition of photonic crystal （PhC） structures that are in close proximity to the optical core. The slow-wave PhC structure is designed for two different material configurations and placed in the modulator as a superstrate to the optical core; simulation results are depicted for both 1D and 2D PhC structures. The PM characteristics are modeled using a combination of the finite element method and the optical beam propagation method in both the RF and optical domains, respectively. The phase-shift simulation results show a factor of 1.7 increase in an effective EO coefficient （120 pm/V） while maintaining a broadband bandwidth of 40 GHz.

关键词： Integrated optics Optoelectronics Photonic crystal waveguides Modulators Polymer waveguides Nanomaterials Electro-optical materials optical devices Optoelectronics