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Chinese Optics Letters 第6卷 第11期

Author Affiliations
Abstract
1 中国科学院上海光学精密机械研究所, 上海 201800;理学院,河北工业大学科技,石家庄 050018
2 中国科学院上海光学精密机械研究所, 上海 201800
A new spectrum shaping method, based on electro-optic modulation, to alleviate gain narrowing in chirped pulse amplification (CPA) system, is described and numerically simulated. Near-Fourier transform-limited seed laser pulse is chirped linearly through optical stretcher. Then the chirped laser pulse is coupled into integrated waveguide electro-optic modulator driven by an aperture-coupled-stripline (ACSL) electrical-waveform generator, and the pulse shape and amplitude are shaped in time domain. Because of the direct relationship between frequency interval and time interval of the linearly chirped pulse, the laser pulse spectrum is shaped correspondingly. Spectrum-shaping examples are modeled numerically to determine the spectral resolution of this technique. The phase error introduced in this method is also discussed.
啁啾脉冲放大 增益窄化 光谱整形 电光波导调制器 孔径耦合带状线 
Chinese Optics Letters
2008, 6(11): 46
Author Affiliations
Abstract
School of Electronic Information, Wuhan University, Wuhan 430079
A laser beam propagating through turbulence experiences random amplitude and phase fluctuations, which can severely degrade the performance of free space optical communication systems. In this letter, time diversity is demonstrated as a technique which can decrease turbulence influence. Statistically, laser propagation along an atmospheric path is uncorrelated with an earlier-time path for a time interval greater than the atmospheric turbulence correlation time. To estimate time diversity system performance, a 2.2-km optical link is set up for comparing the fade probability of a system using time diversity with a system not using time diversity. The experimental results obtained under different turbulence conditions are shown which are in good agreement with the theory.
自由空间光通信 大气传输 大气湍流 060.2605 Free-space optical communication 010.1300 Atmospheric propagation 010.1330 Atmospheric turbulence 
Chinese Optics Letters
2008, 6(11): 797
Author Affiliations
Abstract
College of Mathematics and Physics, North China Electric Power University, Baoding 071003
The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization (DREMPI) is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2\sum and S2\sum intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.
双共振增强多光子离化 离化效率 光强指数 激光强度 NO 260.5210 Photoionization 020.4180 Multiphoton processes 
Chinese Optics Letters
2008, 6(11): 800
Author Affiliations
Abstract
Department of Physics, Xi'an University of Architecture and Technology, Xi'an 710055
The energy levels and lifetimes of 3pns 3P0(n=7-35) and 3pnd 3P0 (n=6-17) series of neutral silicon are calculated and predicted by means of multichannel quantum defect theory (MQDT). In addition, the perturbation caused by core-excited state 3s3p3 is discussed. The 3pnd 3P0 series, especially 3p4d 3P0, 3p5d 3P0, and 3p6d 3P0 are perturbed strongly by the core-excited state 3s3p3 3P0. These cause the lifetime of 3pnd 3P0 (n=5-7) to be less than that of 3p4d 3P0. The lifetimes of 3p14d 3P0 (65479.14 cm-1) and 3p16d 3P0 (65608.77 cm-1) are less than that of their frontal states respectively, because these states are perturbed by 3p22s 3P0 (65476.48 cm-1) and 3p30s 3P0 (65608.99 cm-1) respectively.
多通道量子数亏损理论 Rydbe 态 寿命 020.5780 Rydberg states 020.2930 Hyperfine structure 
Chinese Optics Letters
2008, 6(11): 804
Author Affiliations
Abstract
School of Electronics and Communication Engineering, Shri Mata Vaishno Devi University (J and K), India2 Department of Electronics and Communication Engineering, Thapar University (Punjab), India
A novel optical burst switching (OBS) high speed network architecture has been proposed. To verify its feasibility and evaluate its performance, just-enough-time (JET) signaling has been considered as a high performance protocol. In the proposed architecture, to avoid burst losses, firstly, a short-prior-confirmation-packet (SPCP) is sent over the control channel that simulates the events that the actual packet will experience. Once SPCP detects a drop at any of the intermediate nodes, the actual packet is not sent but the process repeats. In order to increase network utilization, cost effectiveness and to overcome some limitations of conventional OBS, inherent codes (e.g., orthogonal optical codes (OOC)), which are codified only in intensity, has been used. Through simulations, it shows that a decrease in burst loss probability, cost effectiveness and a gain in processing time are obtained when optical label processing is used as compared with electronic processing.
光突发交换网络 光正交码标记 SPCP排序 060.4250 Networks 060.4259 Networks, packet-switched 
Chinese Optics Letters
2008, 6(11): 807
Author Affiliations
Abstract
Polarization Research Center, Key Laboratory of Opto-Electronics Information and Technical Science, Ministry of Education, Tianjin University, Tianjin 300072
We describe a new algorithm in a cost effective polarization division multiplexing (PDM) system. Without modifying the existing transmitter, receiver electronics, or softwares, we use a special optical scheme to demultiplex the signal multiplexed and improve it with a conjugated gradient algorithm. We experimentally resume the polarization state with a deviation under 5% and the power loss less than 20 dB which proves the feasibility of the polarization control algorithm in the new polarization multiplexing system.
偏振控制 偏振复用 光纤通信 共轭梯度算法 060.0060 Fiber optics and optical communications 350.0350 Other areas of optics 260.0260 Physical optics 
Chinese Optics Letters
2008, 6(11): 812
Author Affiliations
Abstract
1 Key Laboratory of Photoelectric Gas-Oil Logging and Detecting Ministry of Education, Xi’an Shiyou University, Xi’an 710065
2 PetroChina Changqing Oilfield Company Communications Corporation, Xi’an 710018
The target type flowmeter based on fiber Bragg gratings (FBGs) is experimentally studied. The relationship between the central wavelength shift of FBG and the flux is derived and the analytic expression is also given. Simulation and preliminary experiments have been carried out, and experimental validation of the water further proves the feasibility of the sensor. The experimental results verify the proposed sensor which can measure flux range from 200 to 1200 cm3/s. And on this basis, the improvement program is raised.
布拉格光纤光栅 流量 传感器 流量传感器 060.3735 Fiber Bragg gratings 280.0280 Remote sensing and sensors 
Chinese Optics Letters
2008, 6(11): 815
Author Affiliations
Abstract
1 Key Lab of All Optical Network and Advanced Telecommunication Network, Ministry of Education of China, Beijing Jiaotong University, Beijing 100044
2 Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044
A novel fiber-laser-based strain sensor is proposed and experimentally demonstrated. The laser cavity is composed of a high-birefringence Sagnac fiber loop mirror (HiBi-SFLM) and a fiber Bragg grating (FBG) which also acts as a strain-sensing element. In the linear region of the HiBi-SFLM reflection spectrum, when the strain applied on the FBG makes the Bragg grating wavelength shift, the laser output power changes due to reflectivity variation of the HiBi-SFLM. Experimental results show that the laser output power varies almost linearly with the applied strain. The measurement of the output power can be performed by a conventional photo-detector.
光纤传感器 光纤激光器 光纤光栅 Sagnac环镜 应力传感 060.2370 Fiber optics sensors 140.3510 Lasers, fiber 050.2770 Gratings 
Chinese Optics Letters
2008, 6(11): 818
Author Affiliations
Abstract
Key Lab of All Optical Network and Advanced Telecommunication Network of EMC, Beijing Jiaotong University, Beijing 100044
We propose a new structure of broadband nearly-zero flattened dispersion highly nonlinear photonic crystal fiber (PCF). Through optimizing the diameters of the first two inner rings of air-holes and the GeO2 doping concentration of the core, the nonlinear coefficient is up to 47 W-1 km-1 at the wavelength of 1.55 \mum and nearly-zero flattened dispersion of \pm 0.5 ps/(nm km) is achieved in the telecommunication window (1460-1625 nm). Due to the use of GeO2-doped core, this innovative structure can offer not only a large nonlinear coefficient and broadband nearly-zero flattened dispersion but also low leakage losses.
光子晶体光纤 高非线性 近零平坦色散 宽带 060.2280 Fiber design and fabrication 060.2270 Fiber characterization 060.4370 Nonlinear optics, fibers 
Chinese Optics Letters
2008, 6(11): 821
Author Affiliations
Abstract
School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049
Fusion of multiple instances within a modality for biometric verification performance improvement has received considerable attention. In this letter, we present an iris recognition method based on multi-instance fusion, which combines the left and right irises of an individual at the matching score level. When fusing, a novel fusion strategy using minimax probability machine (MPM) is applied to generate a fused score for the final decision. The experimental results on CASIA and UBIRIS databases show that the proposed method can bring obvious performance improvement compared with the single-instance method. The comparison among different fusion strategies demonstrates the superiority of the fusion strategy based on MPM.
生物特征认证 虹膜识别 多实例融合 最小最大概率机 100.5010 Pattern recognition 100.2000 Digital image processing 100.2960 Image analysis 
Chinese Optics Letters
2008, 6(11): 824
Author Affiliations
Abstract
Department of Control Science and Engineering, Harbin Institute of Technology, Harbin 150001
An algorithm is proposed for registering images related by translation, rotation, and scale based on angular and radial difference functions. In frequency domain, the spatial translation parameters are computed via phase correlation method. The magnitudes of images are represented in log-polar grid, and the angular and radial difference functions are given and applied to measure shifts in both angular and radial dimensions for rotation and scale estimation. Experimental results show that this method achieves the same accurate level as classic fast Fourier transform (FFT) based method with invariance to illumination change and lower computation costs.
图像配准 角度差分函数 径向差分函数 仿射模型 100.0100 Image processing 100.2000 Digital image processing 
Chinese Optics Letters
2008, 6(11): 827
Author Affiliations
Abstract
Department of Optoelectronic Engineering, Ji'nan University, Guangzhou 510632
We present a simple but effective method for small-angle measurement based on optical feedback interferometry (or laser self-mixing interferometry). The absolute zero angle can be defined at the biggest fringe amplitude point, so this method can also achieve absolute angle measurement. In order to verify the method, we construct an angle measurement system. The Fourier-transform method is used to analysis the interference signal. Rotation angles are experimentally measured with a resolution of 10^{-6} rad and a measurement range of approximately from -0.0007 to +0.0007 rad.
角度测量 光回馈干涉 绝对测量 120.3180 Interferometry 120.1680 Collimation 120.3940 Metrology 
Chinese Optics Letters
2008, 6(11): 830
Author Affiliations
Abstract
School of Electronic Information, Wuhan University, Wuhan 430079
On the basis of optical property of cube corner retroreflector (CCR), a new perception and calculation approach for diffraction aperture of CCR in two different forms is presented. The relationship between diffraction apertures and incident light with six different combinations of reflection order and incident angle is established. Far-field diffraction patterns of CCR under various incident conditions are also provided.
角反射器 衍射孔径 入射角 方位角 050.1220 Apertures 050.1940 Diffraction 050.1960 Diffraction theory 
Chinese Optics Letters
2008, 6(11): 833
Author Affiliations
Abstract
1 Department of Applied Physics, Nanjing University of Science and Techonology, Nanjing 210094
2 College of Mathematics and Physics, Nanjing University of Posts and Telecommunications, Nanjing 210046
Laser shock peening is a well-known method for extending the fatigue life of metal components by introducing near-surface compressive residual stress. The surface acoustic waves (SAWs) are dispersive when the near-surface properties of materials are changed. So the near-surface properties (such as the thickness of hardened layers, elastic properties, residual stresses, etc.) can be analyzed by the phase velocity dispersion. To study the propagation of SAWs in metal samples after peening, a more reasonable experimental method of broadband excitation and reception is introduced. The ultrasonic signals are excited by laser and received by polyvinylindene fluoride (PVDF) transducer. The SAW signals in aluminum alloy materials with different impact times by laser shock peening are detected. Signal spectrum and phase velocity dispersion curves of SAWs are analyzed. Moreover, reasons for dispersion are discussed.
激光 声表面波 冲击硬化 色散 140.0140 Lasers and laser optics 240.6690 Surface waves 280.3375 Laser induced ultrasonics 160.0160 Materials 
Chinese Optics Letters
2008, 6(11): 837
Author Affiliations
Abstract
School of Instrument Science and Opto-Electronics Engineering, Beihang University, Beijing 100083
We demonstrate a 1550-nm narrow-linewidth fiber ring laser with stable single polarization by using single-mode Er-doped fiber as active fiber and saturable absorber. A polarization-maintaining circulator is used to acquire single-polarization laser light with the degree of polarization of 99.8%—99.9%. The linewidth measured using a delayed self-heterodyne method is less than 0.5 kHz. Frequency of the fiber laser can be modulated by driving the waveguide phase modulator with proper voltage. A Mach-Zehnder interferometer with the optical path difference between two arms of about 36 km is used to study the long-distance coherent detection of the fiber laser for frequency-modulated continuous-wave application.
光纤激光器 掺铒光纤 环形腔 140.3510 Lasers, fiber 140.3500 Lasers, erbium 140.3560 Lasers, ring 
Chinese Optics Letters
2008, 6(11): 845
Author Affiliations
Abstract
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062
We propose a new method to cool the Yb3+-doped ZBLANP glass in a standing-wave cavity. There are two advantages of this cavity-enhanced technique: the pumping power is greatly enhanced and the absorption of the cooling material is greatly increased. We introduce the basic principle of the cavity-enhanced laser cooling and discuss the cooling effect of a solid-state material in a cavity. From the theoretical study, it is found that the laser cooling effect is strongly dependent on the reflectivity of the cavity mirrors, the length of the solid material, the surface scattering of the material, and so on. Some optimal parameters for efficient laser cooling are obtained.
激光冷却 腔增强 反斯托克斯荧光 稀土离子 160.2540 Fluorescent and luminescent materials 300.2530 Fluorescence, laser-induced 140.3320 Laser cooling 
Chinese Optics Letters
2008, 6(11): 848
Author Affiliations
Abstract
Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
Using front face-pumped compact active mirror laser (CAMIL) structure, we have demonstrated an Yb:YAG/YAG composite ceramic disk laser with pumping wavelength at 970 nm. The laser has been operated in both continuous-wave (CW) and Q-switching modes. Under CW operation, laser output power of 1.05 W with 2% transmission output coupler was achieved at the wavelength of 1031 nm. Q-switched laser output was gotten by using an acousto-optic Q-switch. The repetition rate ranged from 1 to 30 kHz and the pulse width varied from 166 to 700 ns.
薄片激光器 复合陶瓷 调Q 140.3580 Lasers, solid-state 140.3540 Lasers, Q-switched 140.3480 Lasers, diode-pumped 
Chinese Optics Letters
2008, 6(11): 852
Author Affiliations
Abstract
1 College of Physics, Jilin University, Changchun 130023
2 Key Laboratory of Coherent Light, Atomic and Molecular Spectroscopy, Ministry of Education of China, Jilin University, Changchun 130023
Through the reversible isomerization of trans-cis-trans under the linear polarization light, the molecules of azo materials have the same tropism which is vertical to the polarization of light. This means that azo materials have photo-induced birefringence which is related to optical power and polarization angle of the light. Based on the photo-induced birefringence of azo materials, we design a new type of optically pumped semiconductor vertical external cavity surface emitting laser (OPS-VECSEL) which can control the polarization and frequency of the ejection laser. The functional molecules of azo materials are [3-azo-(4'nitro)]-(9-ethyl)-carbazole (ANECz).
光泵浦半导体外腔垂直激光器(OPS-VECSEL) 4-硝基-3-偶氮-9-乙基-咔唑(ANECz) 光致双折射 140.3580 Lasers, solid-state 140.3600 Lasers, tunable 140.5960 Semiconductor lasers 
Chinese Optics Letters
2008, 6(11): 855
Author Affiliations
Abstract
1 Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033
2 Graduate University of Chinese Academy of Sciences, Beijing 100049
In order to study the effect of mixing dye in ferroelectric liquid crystal (FLC) materials, the phase transition temperature and electro-optical properties of azo dye doped FLC samples have been investigated. All the properties have been found to be changed drastically. The results have revealed that not only the SmC*-SmA* transition temperature decreased markedly by the addition of azo-dye, but also dye-doped FLC had lower threshold voltage and saturation voltage than the pure FLC.
铁电液晶 偶氮染料 染料掺杂 相变温度 电光特性 160.0160 Materials 230.0230 Optical devices 
Chinese Optics Letters
2008, 6(11): 858
Author Affiliations
Abstract
1 Laser Institute of Qufu Normal University, Qufu 273165
2 Physics Department of Qufu Normal University, Qufu 273165
3 Physics Group of No.1 Middle School of Qufu, Qufu 273100
In order to reduce the error caused by the change of temperature, the relation between three-in-one composite compensator's phase retardation and temperature is calculated according to the characteristic of multiple-order quartz wave-plate. The results show that the influence on phase retardation increases with the increase of temperature and order of wave-plate. The phase retardation and the angle that the second wave-plate rotates are in a linear relationship in certain ranges. However, there is also some regularity in nonlinear areas which can be determined by theoretical calculation. The calculated result is well in agreement with experiments.
偏振光学 偏光器件 温度 补偿器 240.5420 Polaritons 230.5440 Polarization-selective devices 120.6780 Temperature compensator 
Chinese Optics Letters
2008, 6(11): 861
Author Affiliations
Abstract
Photonics Fabrication Science Center, Jiangsu University, Zhenjiang 212013
Great efforts has been made on fabricating photonic crystals (PCs) with photonic band gaps (PBGs) during the past decade. Three-dimensional (3D) log pile PC was fabricated fast by direct femtosecond laser writing in ORMOCER. Qualitative analysis of the errors of PC was investigated using the Image Pro Plus. Surface qualities such as bending, distortion, and surface roughness were shown, and the band gap in the infrared wavelength region was observed. Meanwhile, the theory was experimentally verified that the center of PBG diminishes as the crystal lattice period reduces. Therefore, it is possible to fabricate PCs whose band gap range is from the near-infrared to visible wave band.
飞秒激光 光子带隙 光子晶体 双光子 060.4510 Optical communications 250.2080 Polymer active devices 250.5300 Photonic integrated circuits 
Chinese Optics Letters
2008, 6(11): 864
Author Affiliations
Abstract
Physics Department, College of Science, Taiyuan University of Technology, Taiyuan 030024
We demonstrate the feasibility of multi-target real-time ranging with a chaotic laser radar. The used chaotic laser is emitted by a semiconductor laser with optical feedback. We design a proof-of-concept experiment based on the correlation detection and realize the range measurements of two targets simultaneously. The range resolution of 9 cm between two targets is achieved, which is limited by the bandwidth of the used real-time oscilloscope. A preliminary experiment of chaotic laser coherence is carried out to verify the high resolution of the chaotic lidar.
多目标测距 混沌 激光雷达 半导体激光器 280.3640 Lidar 140.1540 Chaos 190.3100 Instabilities and chaos 140.5960 Semiconductor lasers 
Chinese Optics Letters
2008, 6(11): 868
Author Affiliations
Abstract
1 University of Shanghai for Science and Technology, Shanghai 200093
2 Xuzhou Normal University, Xuzhou 221116
In this letter, the technique of laser self-mixing effect is employed for nano-particle size analysis. In contrast to the photon correlation spectroscopy (PCS) and photon cross correlation spectroscopy (PCCS), the main advantages of this technique are sensitive, compact, low-cost, and simple experimental setup etc. An improved Kaczmarz projection method is developed in the inversion problem to extract the particle size distribution. The experimental results prove that nano-particle size can be measured reasonably by using the self-mixing effect technique combined with the improved projection algorithm.
激光自混合干涉技术 纳米颗粒 颗粒粒径 投影算法 290.5820 Scattering measurements 290.5850 Scattering, particles 290.1350 Backscattering 290.3700 Linewidth 
Chinese Optics Letters
2008, 6(11): 871