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2005
Volume: 3 Issue 6
19 Article(s)
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Fiber Optics and Optical Communications
High gain low noise L-band preamplifier with cascade double-pass structure
Dongfang Jia, Yanyong Wang, Huanmin Bao, Tianxin Yang, and Shichen Li
An optimized two-stage-cascade double-pass structure L-band preamplifier was proposed and experimentally studied to overcome the shortcomings of low gain coefficient and high noise figure of L-band erbium-doped fiber amplifier (EDFA). The fiber lengthes of 6.5 and 32.5 m, pump powers of 130 and 119 mW for the first andAn optimized two-stage-cascade double-pass structure L-band preamplifier was proposed and experimentally studied to overcome the shortcomings of low gain coefficient and high noise figure of L-band erbium-doped fiber amplifier (EDFA). The fiber lengthes of 6.5 and 32.5 m, pump powers of 130 and 119 mW for the first and second stages respectively are used in the experiment. When input signal power is -30 dBm, the amplifier can provide gain above 38.84 dB in a wavelength range of 34 nm (1568---1602 nm), gain ripple less than 2.04 dB (40.88---38.84 dB), and noise figures lower than 5.29 dB with the lowest value of 3.95 dB at 1590 nm. Experimental and simulation results show that this low cost and high pump efficiency amplifier is suitable for the application as an L-band preamplifier in the broadband fiber communication system..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06311 (2005)
Numerical simulation and analysis of losses in air-core plastic photonic bandgap fibers
Tieshan Guan, Mingyang Chen, Zhilong Zhang, and Rongjin Yu
The loss properties of air-core plastic photonic bandgap fibers are analyzed by multipole method. Despite the relatively large absorption loss of plastics (PMMA), the contribution of material absorption loss can be reduced significantly through appropriate selection of operating wavelength, number of cladding air-hole The loss properties of air-core plastic photonic bandgap fibers are analyzed by multipole method. Despite the relatively large absorption loss of plastics (PMMA), the contribution of material absorption loss can be reduced significantly through appropriate selection of operating wavelength, number of cladding air-hole rings, radius of air-core, and position of photonic band gap. The transmission loss in this type of fiber can be decreased by an order of magnitude in comparison with that of conventional plastic optical fiber..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06313 (2005)
An experiment for obtaining DOP ellipsoid using particle swarm optimization algorithm
Xiaoguang Zhang, Jianzhong Zhang, Gaoyan Duan, Li Yu... and Bojun Yang|Show fewer author(s)
The degree of polarization (DOP) ellipsoid can be used as either feedback or feedforward signal for automatic polarization mode dispersion compensation. We have realized the experiment for obtaining DOP ellipsoid from 100 sampling data of output states of polarization using particle swarm optimization (PSO) as ellipsoiThe degree of polarization (DOP) ellipsoid can be used as either feedback or feedforward signal for automatic polarization mode dispersion compensation. We have realized the experiment for obtaining DOP ellipsoid from 100 sampling data of output states of polarization using particle swarm optimization (PSO) as ellipsoid data fitting algorithm. It was shown that the PSO algorithm was powerful for ellipsoid data fitting with high precision within 250 ms..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06316 (2005)
Image Processing
Track before detect for point targets with particle filter in infrared image sequences
Hongtao Hu, Zhongliang Jing, and Shiqiang Hu
The problem of detecting and tracking point targets in a sequence of infrared images with very low signal-to-noise ratio (SNR) is investigated in this paper. A track before detect algorithm for infrared (IR) point target is developed based on particle filter. The particle filter is used to estimate the state of the tarThe problem of detecting and tracking point targets in a sequence of infrared images with very low signal-to-noise ratio (SNR) is investigated in this paper. A track before detect algorithm for infrared (IR) point target is developed based on particle filter. The particle filter is used to estimate the state of the target in track stage. The unnormalized weights of the output of the filter are used to approximately construct the likelihood ratio for hypothesis test in detection stage. Experiment results with the real image sequences that SNR is about 2.0 show that the proposed algorithm can successfully detect and track point target..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06322 (2005)
Particle filter based visual tracking with multi-cue adaptive fusion
Anping Li, Zhongliang Jing, and Shiqiang Hu
To improve the robustness of visual tracking in complex environments such as: cluttered backgrounds, partial occlusions, similar distraction and pose variations, a novel tracking method based on adaptive fusion and particle filter is proposed in this paper. In this method, the image color and shape cues are adaptively To improve the robustness of visual tracking in complex environments such as: cluttered backgrounds, partial occlusions, similar distraction and pose variations, a novel tracking method based on adaptive fusion and particle filter is proposed in this paper. In this method, the image color and shape cues are adaptively fused to represent the target observation; fuzzy logic is applied to dynamically adjust each cue weight according to its associated reliability in the past frame; particle filter is adopted to deal with non-linear and non-Gaussian problems in visual tracking. The method is demonstrated to be robust to illumination changes, pose variations, partial occlusions, cluttered backgrounds and camera motion for a test image sequence..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06326 (2005)
Face recognition using improved-LDA with facial combined feature
Dake Zhou, Xin Yang, and Ningsong Peng
Face recognition subjected to various conditions is a challenging task. This paper presents a combined feature improved Fisher classifier method for face recognition. Both of the facial holistic information and local information are used for face representation. In addition, the improved linear discriminant analysis (IFace recognition subjected to various conditions is a challenging task. This paper presents a combined feature improved Fisher classifier method for face recognition. Both of the facial holistic information and local information are used for face representation. In addition, the improved linear discriminant analysis (I-LDA) is employed for good generalization capability. Experiments show that the method is not only robust to moderate changes of illumination, pose and facial expression but also superior to the traditional methods, such as eigenfaces and Fisherfaces..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06330 (2005)
Integrated Optics
Linearization of Mach-Zehnder modulator using microring-based all-pass filter
Jianyi Yang, Fan Wang, Xiaoqing Jiang, Hongchang Qu... and Yuelin Wang|Show fewer author(s)
By applying the microring resonator to the Mach-Zehnder (MZ) optical modulator and employing the super-linear phase change characteristic of the all-pass filter, the sublinear modulation curve of the conventional MZ modulator is highly linearized. With properly controlled power coupling between the microring and the arBy applying the microring resonator to the Mach-Zehnder (MZ) optical modulator and employing the super-linear phase change characteristic of the all-pass filter, the sublinear modulation curve of the conventional MZ modulator is highly linearized. With properly controlled power coupling between the microring and the arm of the MZ modulator, the third-order distortion can be suppressed. If the transmission coefficient is set between 0.25 and 0.42, the linearity range larger than 90% can be easily achieved. The maximum linearity range is even up to 99.5%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06333 (2005)
Lasers and Laser Optics
Parameter study of RF excited diffusively cooled all-metal slab waveguide CO2 laser
Ning Su, Shuna Yao, Yanhong Zhong, and Jianguo Xin
In this paper, we have investigated some parameters of a radio frequency (RF) excited diffusively cooled all-metal slab waveguide CO2 laser based on the modified Rigrod theory by introducing a waveguide coupling efficiency which designates the coupling between the waveguide and the resonator mirrors. The parameters of In this paper, we have investigated some parameters of a radio frequency (RF) excited diffusively cooled all-metal slab waveguide CO2 laser based on the modified Rigrod theory by introducing a waveguide coupling efficiency which designates the coupling between the waveguide and the resonator mirrors. The parameters of the laser small signal gain g0, saturation intensity Is, and waveguide coupling efficiency (\eta) are studied theoretically and experimentally. In the experiments, three sets of output coupling flat mirrors with the different transitivities were used, and a maximum laser power output of 150 W was obtained from a gas discharge region of 2-mm height, 20-mm width, and 386-mm length coupled with a CASE-I optical waveguide resonator..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06336 (2005)
Polarized operation of Yb3+:YAl3(BO3)4 CW and mode-locked lasers
Yanrong Song, and Qingyue Wang
A diode-pumped Yb3+:YAl3(BO3)4 (Yb:YAB) laser system was demonstrated with continuous wave (CW) and pulsed output. The polarized CW outputs and femtosecond mode-locked lasers with semiconductor saturable-absorber mirrors (SESAM) at the fundamental wavelength were measured. For the CW output, polarization ratios were 88A diode-pumped Yb3+:YAl3(BO3)4 (Yb:YAB) laser system was demonstrated with continuous wave (CW) and pulsed output. The polarized CW outputs and femtosecond mode-locked lasers with semiconductor saturable-absorber mirrors (SESAM) at the fundamental wavelength were measured. For the CW output, polarization ratios were 88.1% (for e-ray) and 87.2% (for o-ray). For the mode-locked system, polarization ratio reached 38.5%, and the repetition frequency was 117.6 MHz..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06339 (2005)
5.3-W Nd:YVO4 passively mode-locked laser by a novel semiconductor saturable absorber mirror
Zhiqiang Cai, Wuqi Wen, Yonggang Wang, Zhigang Zhang... and Jianquan Yao|Show fewer author(s)
We report a diode end-pumped continuous wave (CW) passively mode-locked Nd:YVO4 laser with a home-made semiconductor saturable absorber mirror (SESAM). The maximum average output power is 5.3 W at the incident pump power of 17 W, which corresponds to an optical-optical conversion efficiency of 31.2% and slope efficiencWe report a diode end-pumped continuous wave (CW) passively mode-locked Nd:YVO4 laser with a home-made semiconductor saturable absorber mirror (SESAM). The maximum average output power is 5.3 W at the incident pump power of 17 W, which corresponds to an optical-optical conversion efficiency of 31.2% and slope efficiency of 34.7%. The corresponding optical spectrum has a 0.2-nm full width at half maximum (FWHM), and the pulse repetition rate is 83 MHz..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06342 (2005)
A 110-W fiber laser with homemade double-clad fiber
Dong Xue, Qihong Lou, Jun Zhou, Lingfeng Kong... and Shiyu Li|Show fewer author(s)
A high-power ytterbium-doped fiber laser (YDFL) with homemade double-clad fiber (DCF) is introduced in this letter. The geometric parameter and laser characteristics of the fiber have been studied. With one-end-pumping scheme, pumped by a high-power laser diode with launching power of 280 W, a maximum continuous wave (A high-power ytterbium-doped fiber laser (YDFL) with homemade double-clad fiber (DCF) is introduced in this letter. The geometric parameter and laser characteristics of the fiber have been studied. With one-end-pumping scheme, pumped by a high-power laser diode with launching power of 280 W, a maximum continuous wave (CW) output of 110 W is obtained with an optical-to-optical efficiency of 40%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06345 (2005)
The phenomenon of stochastic resonance in a single-mode laser system with an input periodical signal
Dahai Xu, Li Cao, Dajin Wu, and Qinghua Cheng
Using the linear approximation method, we study a single-mode laser system driven by colored pump noise and quantum noise with coupling between the real and imaginary parts when the laser is operated well above threshold. The steady state mean intensity fluctuation C(0) and signal-to-noise ratio (SNR) are calculated. IUsing the linear approximation method, we study a single-mode laser system driven by colored pump noise and quantum noise with coupling between the real and imaginary parts when the laser is operated well above threshold. The steady state mean intensity fluctuation C(0) and signal-to-noise ratio (SNR) are calculated. It is found that there is a maximum in SNR when there is a minimum in the fluctuation of laser system if the coupling coefficient between real and imaginary parts of the quantum noise equals zero..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06348 (2005)
Materials
Two- and three-photon absorption in a novel fluorene-based compound
Wenbo Ma, Yiqun Wu, Donghong Gu, and Fuxi Gan
A novel symmetrical charge transfer fluorene-based compound 2,7-bis (4-methoxystyryl)-9, 9-bis (2-ethylhexyl)-9H-fluorene (abbreviated as BMOSF) was synthesized and its nonlinear absorption was investigated using two different laser systems: a 140-fs, 800-nm Ti:sapphire laser operating at 1-kHz repetition rate and a 38A novel symmetrical charge transfer fluorene-based compound 2,7-bis (4-methoxystyryl)-9, 9-bis (2-ethylhexyl)-9H-fluorene (abbreviated as BMOSF) was synthesized and its nonlinear absorption was investigated using two different laser systems: a 140-fs, 800-nm Ti:sapphire laser operating at 1-kHz repetition rate and a 38-ps, 1064-nm Nd:YAG pulsed laser operating at 10-Hz repetition rate, respectively. Unique nonlinear absorption properties in this new compound were observed that rise from multiphoton absorption. The nonlinear absorption coefficients were measured to be 6.02*10^(-3) cm/GW (due to two-photon absorption, exciting wavelength is 800 nm) and 3.6*10^(-20) cm3/W2 (due to three-photon absorption, exciting wavelength is 1064 nm). This new compound possesses strong fluorescence induced by two-photon absorption and obvious three-photon absorption optical limiting effects..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06351 (2005)
Nonlinear Optics
Broadband continuum generation in an irregularly multicore microstructured optical fiber
Peiguang Yan, Yaqing Jia, Hongxin Su, Yigang Li... and Lantian Hou|Show fewer author(s)
A broadband continuum generation is reported in a novel multicore microstructured optical fiber (MOF) where irregular air holes are randomly distributed in cladding. By launching ultrashort light pulses from a Ti:sapphire laser into a 190-mm-long fiber of this type, we have observed a group of continua generated from dA broadband continuum generation is reported in a novel multicore microstructured optical fiber (MOF) where irregular air holes are randomly distributed in cladding. By launching ultrashort light pulses from a Ti:sapphire laser into a 190-mm-long fiber of this type, we have observed a group of continua generated from different cores, each with distinct color. 20-dB bandwidth of the broadest continuum is 1260 nm with an average power of 143 mW. The result confirms that the multicore MOF can be fabricated, with different dispersion profiles tailored for specific supercontinuum (SC) generation towards practical applications..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06355 (2005)
High power 1.57-μm OPO pumped by MOPA with SBS
Youlun Ju, Baoquan Yao, and Sheng Qi
A Nd:YAG master oscillator power amplifier (MOPA) system, pumped by a pulse flash-lamps as the pump source of optical parametric oscillator (OPO), is employed to improve the pump beam quality of OPO pump source. A back amplifying configuration with stimulated Brillouin scattering (SBS) phase conjugation mirror is used.A Nd:YAG master oscillator power amplifier (MOPA) system, pumped by a pulse flash-lamps as the pump source of optical parametric oscillator (OPO), is employed to improve the pump beam quality of OPO pump source. A back amplifying configuration with stimulated Brillouin scattering (SBS) phase conjugation mirror is used. OPO pump laser energy of 611 mJ/pulse with 30-ns pulse duration is obtained, and near diffraction limited beam quality is achieved. Based on the type II degenerate non-critically phase-matched KTP crystal, the OPO is used to convert pump beam from 1.064 μm to 1.57 μm, eye-safe near infrared laser range source. 1.57-μm output energy of 209 mJ/pulse with 18-ns pulse duration is attained with a short cavity KTP OPO, when pump laser energy is approximately 611 mJ. OPO conversion efficiency is up to 38.7% when pump laser energy is approximately 200 mJ..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06358 (2005)
Holography
Encoded cell grating array in anti-counterfeit technology
Zhongyu Chen, N. K. Bao, and Po S. Chung
The dot matrix hologram (DMH) has been widely used in anti-counterfeiting label. With the same technology and cell array configuration, we can encode to the incidence beam. These codes can be some image matrix grating with different grating gap and different grating orientation. When the multi-level phase diffractive gThe dot matrix hologram (DMH) has been widely used in anti-counterfeiting label. With the same technology and cell array configuration, we can encode to the incidence beam. These codes can be some image matrix grating with different grating gap and different grating orientation. When the multi-level phase diffractive grating is etched, the incidence beam on the cell appears as an encoding image. When the encoded grating and DMH are used in the same label synchronously, the technology of multi-encoded grating array enhances the anti-counterfeit ability..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06319 (2005)
Quantum Optics
Electron acceleration in a tightly focused laser beam
Xinkui He, Ruxin Li, Bin Shuai, Xiaochun Ge, and Zhizhan Xu
Electron acceleration in a tightly focused ultra-intensity linear polarized laser beam is investigated numerically. It has been found that the acceleration is strong phase dependent and is periodic to the variety of the initial laser field phase. When optimal initial parameters are chosen, the electron can be acceleratElectron acceleration in a tightly focused ultra-intensity linear polarized laser beam is investigated numerically. It has been found that the acceleration is strong phase dependent and is periodic to the variety of the initial laser field phase. When optimal initial parameters are chosen, the electron can be accelerated effectively. The accelerated electrons are emitted in pulses of which the full width is less than the half period of the laser field..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06364 (2005)
OPTICAL DATA STORAGE
Simulation of an apodizer's effect for high-density optical storage
Xiumin Gao, Wendong Xu, and Fuxi Gan
The effect of an apodizer with two parallel taper refractive surfaces is theoretically investigated for high-density optical storage. The apodizer may modulate an incident Gaussian beam into an annular beam. Simulation shows that with the increasing inner radius of the modulated beam, the focal spot shrinks obviously. The effect of an apodizer with two parallel taper refractive surfaces is theoretically investigated for high-density optical storage. The apodizer may modulate an incident Gaussian beam into an annular beam. Simulation shows that with the increasing inner radius of the modulated beam, the focal spot shrinks obviously. The depolarization effect gets strong simultaneously, which induces the circular symmetry loss of the focal spot. In this process, pattern density of the orthogonal and longitudinal diffractive fields increases remarkably..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06361 (2005)
Spectroscopy
Measurements of pressure induced self-broadening and frequency shift coefficients of methane R9 manifold of 2ν3 band
Weiguang Ma, Lei Dong, Wangbao Yin, Linfeng Li... and Suotang Jia|Show fewer author(s)
An external-cavity diode laser (ECDL) has been used to investigate pressure-induced self-broadening as well as frequency shift of 2ν3 band R9 manifold of methane. A phase sensitivity detection technology has been employed to determine the pressure induced frequency shift coefficient, however, which is obtained by line An external-cavity diode laser (ECDL) has been used to investigate pressure-induced self-broadening as well as frequency shift of 2ν3 band R9 manifold of methane. A phase sensitivity detection technology has been employed to determine the pressure induced frequency shift coefficient, however, which is obtained by line shape analyses of the recorded absorption spectrum. F1 and F2 unresolved double lines near 6105.626 cm^(-1) were measured as an object because they are often used to the high sensitivity detection of trace methane. The results show that the self-broadening and pressure induced frequency shift coefficients are 0.0232(+-)0.003 and 0.0055(+-)0.0007 MHz/Pa, respectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 3, Issue 6, 06367 (2005)
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