2010

• Record 241 of
  
  Title:New adaptive threshold filtering for fiber optic gyroscopes
  
  Author(s):Liu, Ying(1,2); Li, Yan(1); Xu, Jin-Tao(2)
  Source: Yingyong Kexue Xuebao/Journal of Applied Sciences  Volume: 28  Issue: 1  DOI:   Published: January 2010  
  Abstract:Through Lipschitz index analysis of changes in wavelet factor of the signal and noise in different discrete scales, the signal model of fiber optic gyroscope (FOG) is established. Based on the discrete wavelet transform, a new adaptive filtering algorithm is studied. This algorithm can automatically adjust the threshold values of the wavelet coefficients at different scales in accordance with the energy level of FOG's output signal. Thus, a new threshold function is obtained, which weakens wavelet coefficients lower than the threshold and maximally reserves the true signal using a multinomial. Compared with the soft and hard threshold function, the new threshold function shows perfect performance with different SNR. Simulation shows that, compared with traditional fixed threshold wave filtering, the new method can effectively eliminate noise, and improve FOG's bias stability, random walking and other technique parameters.
  Accession Number: 20101612869415
• Record 242 of
  
  Title:Theoretical and experimental study of polarization characteristics of polarization maintaining fiber based on wavelength-sweeping modulation
  
  Author(s):Duan, Zuo-Liang(1); Ren, Li-Yong(1); Zhang, Ya-Ni(1); Wang, Han-Yi(1); Yao, Bao-Li(1); Zhao, Wei(1)
  Source: Microwave and Optical Technology Letters  Volume: 52  Issue: 7  DOI: 10.1002/mop.25244  Published: July 2010  
  Abstract:We analyze theoretically the polarization characteristics of polarization maintaining fiber and study the basic measurement principles of beat length and polarization extinction ratio of this kind of optical fiber. According to the dependence of the phase difference between two orthogonally polarized modes (denoted as HEx11 and HEy11) transmitted in the polarization maintaining fiber on the light wavelength, we propose the wavelength-sweeping modulation method to measure the beat length and the model birefringence. Based on this technique, the beat length and polarization extinction ratio of the PANDA polarization maintaining fibers (PMFs) (provided by Yangtze Optical Fiber and Cable Company, Wuhan, China) were investigated in detail. Experimental results show good consistent with the theoretical ones. We find that this method shows high measurement precision with the advantages of clear measurement principle and easy to operate. © 2010 Wiley Periodicals, Inc.
  Accession Number: 20102012931170
• Record 243 of
  
  Title:Carbon dioxide gas sensor derived from a 547-hole microstructured polymer optical fiber preform
  
  Author(s):Wang, Jian(1); Wang, Lili(1)
  Source: Optics Letters  Volume: 35  Issue: 19  DOI: 10.1364/OL.35.003270  Published: October 1, 2010  
  Abstract:In this Letter, we report a carbon dioxide gas sensor having 547 pieces of thin-film modified capillaries, which are derived from a microstructured polymer optical fiber preform. Compared with the conventional absorption-based sensor, the monolithic polymer capillary waveguide arrays have better sensitivity, because the huge sensing surfaces, composed of 547 pieces of dye-indicator-doped porous ethyl cellulose layers, interact directly with the gas molecules. As far as we know, a gas sensor based on multichannel capillary waveguide arrays has not been reported before. © 2010 Optical Society of America.
  Accession Number: 20104513370099
• Record 244 of
  
  Title:A new fluid state laser system realizes laser output
  
  Author(s):Gui, Luo(1); Hou, Chaoqi(2); Peng, Bo(2); Fan, Dianyuan(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 7843  Issue:   DOI: 10.1117/12.870197  Published: 2010  
  Abstract:This article demonstrates a diode-pumped pulse laser operation in a flowing fluid host containing Nd-glass particles, transversely pumped by 810nm laser diodes. A series of Laser pulse as the output are observed. The repetition frequency is 1Hz, and the pulse width is about 100μ s , and the maximum pulse energy is up to 2.93mJ, and the average pulse energy is 0.84mJ. Given that fluid circulation offers improved heat management, the realization of laser output of this new fluid state laser verifies a practical way to solve the heat-induced problems in high energy laser systems. © 2010 Copyright SPIE - The International Society for Optical Engineering.
  Accession Number: 20110113550886
• Record 245 of
  
  Title:Theoretical analysis of light transmission in a perfectly circular double clad fiber using coupled mode method
  
  Author(s):Xu, Zhongnan(1,2); Liu, Zejin(1); Duan, Kailiang(2); Zhao, Wei(2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 7843  Issue:   DOI: 10.1117/12.865515  Published: 2010  
  Abstract:Light propagation in a perfect circular double clad fiber (DCF) is numerically investigated by using the coupled mode method with translating the DCF into a single mode fiber (SMF) and an annular core fiber (ACF). The results show that for the coupling coefficients between the LP01 mode of the SMF and the guided modes (LP0n modes) of the ACF, the high-order mode has a larger coupling coefficient than the low-order mode for the ACF. By using the coupled mode equations the field distribution in the DCF core is calculated, the results show that the power shows a quasi-periodic distribution along the DCF core and its average period increases with increasing wavelength for different DCF parameters. The simulation results agree with the light ray propagation in the DCF. © 2010 Copyright SPIE - The International Society for Optical Engineering.
  Accession Number: 20110113550874
• Record 246 of
  
  Title:Effects of gain saturation on terahertz radiation via optical difference frequency generation
  
  Author(s):Huang, Nan(1,3); Li, Xuefeng(2); Liu, Hongjun(1); Xia, Caipeng(1,3)
  Source: Optics Communications  Volume: 283  Issue: 11  DOI: 10.1016/j.optcom.2010.01.072  Published: June 1, 2010  
  Abstract:Numerical studies on stability of terahertz (THz) radiation generation based on difference frequency generation in nonlinear crystals are reported. When the gain saturation is achieved at a wavelength that corresponds to an optimal crystal length, the maximal output of THz radiation could be obtained. As a result of crystal absorption, the gain saturation region of THz radiation is unstable region for output. The stability of THz radiation is determined by the stability of pump in the stable region where behind of the gain saturation. © 2010 Elsevier B.V. All rights reserved.
  Accession Number: 20101412822803
• Record 247 of
  
  Title:Incoherently coupled soliton pairs in nonlocal nonlinear media
  
  Author(s):Lu, Ke-Qing(1); Li, Ke-Hao(1,3); Zhao, Wei(1); Zhang, Yi-Qi(1); Zhang, Mei-Zhi(1); Zhang, Yu-Hong(1); Cheng, Guang-Hua(1); Zhang, Yan-Peng(2)
  Source: Chinese Physics B  Volume: 19  Issue: 2  DOI: 10.1088/1674-1056/19/2/024211  Published: 2010  
  Abstract:We show that incoherently coupled soliton pairs can exist in nonlocal Kerr-type nonlinear media. Such solitons can propagate in bright-bright, dark-dark, and gray-gray configurations. When the nonlocal nonlinearity is absent, these bright-bright and dark-dark soliton pairs are those observed previously in local Kerr-type nonlinear media. Our analysis indicates that for a self-focusing nonlinearity the intensity full width half maximum (FWHM) of the bright-bright pair components increases with the degree of nonlocality of the nonlinear response, whereas for a self-defocusing nonlinearity the intensity FWHM of the dark-dark and gray-gray pair components decreases with the increase in the degree of nonlocality of the nonlinear response. The stability of these soliton pairs has been investigated numerically and it has been found that they are stable. © 2010 Chinese Physical Society and IOP Publishing Ltd.
  Accession Number: 20101012754454
• Record 248 of
  
  Title:New scheme of Sagnac interferometric fiber-optic current sensor insensible to mechanical vibration
  
  Author(s):Mu, Jie(1,2); Zhao, Wei(1); Wang, Jia(1); Xu, Jin-Tao(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 7656  Issue: PART 1  DOI: 10.1117/12.863862  Published: 2010  
  Abstract:A new scheme of Sagnac interferometer fiber-optic current sensor insensible to mechanical vibration is presented. This scheme eliminates the Sagnac effect, which is responsible for the sensitivity to vibration according to theoretical analysis with Jones matrix. The improvement to the conventional Sagnac interferometer fiber-optic current sensor is achieved by changing the structure of sensing fiber coil. This coil is fabricated by the bifilar winding technique, and it consists of one half-wave plate embedded in the middle of sensing optical fiber and one quarter-wave plate rotated by 90 degrees in its lower input port. Experimental results suggest that, compared to the conventional design, this new-structured Sagnac interferometer fiber-optic current sensor has much better performance against strong mechanical vibration at accelerations up to 20 g and frequencies from 10 to 400 Hz. Furthermore, the current measurement accuracy of the improved fiber-optic current sensor achieves the 0.2-level at an acceleration of 20 g and a frequency of 150 Hz. © 2010 Copyright SPIE - The International Society for Optical Engineering.
  Accession Number: 20105013487554
• Record 249 of
  
  Title:Azimuthons in weakly nonlinear waveguides of different symmetries
  
  Author(s):Zhang, Yiqi(1,2); Skupin, Stefan(1,3); Maucher, Fabian(1); Galestian Pour, Arpa(3); Lu, Keqing(2); Kr´olikowski, Wieslaw(4)
  Source: Optics Express  Volume: 18  Issue: 26  DOI: 10.1364/OE.18.027846  Published: December 20, 2010  
  Abstract:We show that weakly guiding nonlinear waveguides support stable propagation of rotating spatial solitons (azimuthons). We investigate the role of waveguide symmetry on the soliton rotation. We find that azimuthons in circular waveguides always rotate rigidly during propagation and the analytically predicted rotation frequency is in excellent agreementwith numerical simulations. On the other hand, azimuthons in square waveguides may experience spatial deformation during propagation. Moreover, we show that there is a critical value for the modulation depth of azimuthons above which solitons just wobble back and forth, and below which they rotate continuously. We explain these dynamics using the concept of energy difference between different orientations of the azimuthon. © 2010 Optical Society of America.
  Accession Number: 20105213531508
• Record 250 of
  
  Title:Dressed four-wave mixing spectroscopy modified by polarization interference and atom-wall collision in micrometric thin cells
  
  Author(s):Li, Yuan-Yuan(1,2,4); Li, Li(1); Bai, Jin-Tao(2); Li, Chang-Biao(3); Zhang, Yan-Peng(3); Hou, Xun(2,4)
  Source: Chinese Physics Letters  Volume: 27  Issue: 4  DOI: 10.1088/0256-307X/27/4/044203  Published: 2010  
  Abstract:Dressed four-wave mixing (DFWM) spectroscopy is investigated theoretically in some micrometric thin cells. It is found that DFWM spectra can be modified by polarization interference of atoms and transient effects induced by atom-wall collision. This modification can lead to width-narrowing of DFWM lines and facilitates to implement experiment of high resolution DFWM spectroscopy in a confined atomic system. © 2010 Chinese Physical Society and IOP Publishing Ltd.
  Accession Number: 20220711658231
• Record 251 of
  
  Title:High energy dual-wavelength mid-infrared extracavity KTA optical parametric oscillator
  
  Author(s):Liu, Hongjun(1); Sun, Qibing(1); Huang, Nan(1); Zhu, Shaolan(1); Zhao, Wei(1)
  Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment  Volume:   Issue:   DOI: 10.1016/j.nima.2010.10.035  Published:   
  Abstract:A high energy dual-wavelength extracavity KTA optical parametric oscillator (OPO) with excellent stability and beam quality, which is pumped by a Q-switched single-longitudinal-mode Nd:YAG laser, has been demonstrated based on a type II noncritical phase matching (NCPM) KTA crystal. The maximum pulse energy of 10 mJ with the output stability of better than 4.5% rms at 3.467 μm is obtained at the repetition rate of 10 Hz and pulse width of 2 ns, and the 11.7 mJ of 1.535 μm radiation is obtained simultaneously. This extracavity NCPM KTA OPO is very useful when high energy, high beam quality and smooth time domain are needed. © 2010 Elsevier B.V. All rights reserved.
  Accession Number: IP51135820
• Record 252 of
  
  Title:Continuous-wave passively mode-locked Nd:YVO4/KTP green laser with a semiconductor saturable absorber mirror
  
  Author(s):Wang, X.(1); Li, M.(2)
  Source: Laser Physics  Volume: 20  Issue: 4  DOI: 10.1134/S1054660X10070297  Published: April 2010  
  Abstract:A diode-pumped passively mode-locked low-doped Nd:YVO4 green laser with a semiconductor saturable absorber mirror (SESAM) and an intracavity frequency-doubling KTP crystal is demonstrated. In order to efficiently release the thermal effect, a low-doped Nd:YVO4 crystal with the Nd 3+ concentration of 0.1 at % is employed as the gain medium. The maximum average output power of 3.1 W at 532 nm with a repetition rate of 102 MHz is obtained under the pump power of 25 W, corresponding to an optical conversion efficiency of 12.4%. The 532 nm mode locked pulse width is estimated to be approximately 6.1 ps. © 2010 Pleiades Publishing, Ltd.
  Accession Number: 20102012937743