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Photonics Research 2024年第1期12卷 141-153页

作者： YUAN WANG PEDRO TOVAR JUNTONG YANG LIANG CHEN xiaoyi bao Nexus for Quantum Technologies University of OttawaOttawaOntario K1N 6N5Canada

A Brillouin dynamic grating(BDG) can be used for distributed birefringence measurement in optical fibers,offering high sensitivity and spatial resolution for sensing ***,it is quite a challenge to simultaneously achieve dynamic measurements with both high accuracy and high spatial *** this work,we propose a sensing mechanism to achieve distributed phase-matching measurement using a chirped pulse as a probe *** BDG reflection,the peak reflection corresponds to the highest four-wave mixing(FWM) conversion efficiency,and it requires the Brillouin frequency in the fast and slow axes to be equal,which is called the phase-matching *** condition changes at different fiber positions,which requires a range of frequency injection for the probe *** proposed method uses a chirped pulse as a probe wave to cover this frequency range associated with distributed birefringence *** allows us to detect distributed phase matching for birefringence changes that are introduced by temperature and strain *** to the single shot and direct time delay measurement capability,the acquisition rate in our system is only limited by the fiber ***,unlike conventional BDG spectrum recovery-based systems,the spatial resolution here is determined by both the frequency chirping rate of the probe pulse and the birefringence profile of the *** the experiments,an acquisition rate of 1 k Hz(up to fiber length limits) and a spatial resolution of 10 cm using a 20 ns probe pulse width are *** minimum detectable temperature and strain variation are 5.6 mK and 0.37 με along a 2 km long polarization-maintaining fiber(PMF).

关键词： fiber scattering polarization

THEORETICAL AND EXPERIMENTAL STUDIES ON THE DOUBLE-FREQUENCY MODE-LOCKED Ar^(+) LASER

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Chinese Physics Letters 1987年第1期4卷 37-40页

作者： bao xiaoyi WU Cunkai Anhui Institute of Optics and Fine Mechanics Academia SinicaHefei

The principle and characteristics of the double-frequency mode-locked Ar+laser are *** are two light pulses in the Ar+laser cavity at any time,and the mode spacing is doubled at about *** leads to a factor of about tw... 详细信息

关键词： laser LASER mode

装配式粮食钢板仓仓壁加劲肋受挠曲二阶效应的影响

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现代食品 2024年第11期30卷 5-7,11页

作者：单良肖彦民鲍小义尹鸿翔中粮工科迎春农牧机械(山东)有限公司山东东营257092

本文综合考虑挠曲二阶效应的影响,对工程实例中装配式粮食钢板仓仓壁加劲肋强度进行计算,并将计算结果与规范公式的计算结果进行比较和分析。同时,分析了初始缺陷和仓壁变形对钢板仓加劲肋受到的挠曲二阶效应的影响程度,为装配式粮食钢... 详细信息

本文综合考虑挠曲二阶效应的影响,对工程实例中装配式粮食钢板仓仓壁加劲肋强度进行计算,并将计算结果与规范公式的计算结果进行比较和分析。同时,分析了初始缺陷和仓壁变形对钢板仓加劲肋受到的挠曲二阶效应的影响程度,为装配式粮食钢板仓的安全设计和实际应用提供部分理论支撑和技术指导。

关键词：装配式粮食钢板仓仓壁加劲肋挠曲二阶效应初始缺陷变形

Investigation of combined Brillouin gain and loss in a birefringent fiber with applications in sensing

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Chinese Optics Letters 2014年第12期12卷 126-132页

作者： Daisy Williams xiaoyi bao Liang Chen Department of Physics University of OttawaOttawa ON K1N 6N5 Canada

The most general model of elliptical birefringence in an optical fiber is extended to describe a transient Bril-louin interaction including both gain and loss. The effects of elliptical birefringence cause a Brillouin spectral shape distortion, which is detrimental for fiber sensing techniques. The model investigates the effects of bire- fringence and the corresponding evolution of spectral distortion effects along the fiber, and also investigates regimes where this distortion is minimal.

关键词： 310.5448 Polarization, other optical properties 290.5900 Scattering, stimulated Brillouin 290.5830 Scattering, Brillouin 190.4370 Nonlinear optics, fibers

Improved all-optical OR logic gate based on combined Brillouin gain and loss in an optical fiber

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Chinese Optics Letters 2014年第8期12卷 68-71页

作者： Daisy Williams xiaoyi bao Liang Chen Department of Physics University of OttawaMacDonald Hall150 Louis Pasteur

Improved all-optical OR gates are proposed, using a novel fiber nonlinearity-based technique, based on the principles of combined Brillouin gain and loss in a polarization-maintaining fiber （PMF）. Switching contrasts are simulated to be between 82.4%-83.6%, for two respective configurations, and switching time is comparable to the phonon relaxation time in stimulated Brillouin scattering （SBS）.

关键词： NAND ASW Improved all-optical OR logic gate based on combined Brillouin gain and loss in an optical fiber

Recent Progress in Optical Fiber Sensors Based on Brillouin Scattering at University of Ottawa

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Photonic Sensors 2011年第2期1卷 102-117页

作者： xiaoyi bao Liang CHEN Fiber Optics Group Physics Department University of Ottawa Ottawa ON KIN 6N5 Canada

The distributed sensor is proven to be a powerful tool for civil structural and material process monitoring. Brillouin scattering in fiber can be used as point sensors or distributed sensors for measurement of temperature, strain, birefringence and vibration over centimeters （Brillouin grating length） for point sensor or the pulse length for the distributed sensor. Simultaneous strain and temperature measurement with a spatial resolution of 20 cm is demonstrated in a Panda fiber using Brillouin grating technique with the temperature accuracy and strain accuracy of 0.4 ℃ and 9 με. This technique can also be used for distributed birefringence measurement. For Brillouin optical time domain analysis （BOTDA）, we have developed a new technique to measure differential Brillouin gain instead of Brillouin gain itself. This technique allows high precision temperature and strain measurement over long sensing length with sub-meter spatial resolution： 50-cm spatial resolution for 50-km length, using return-to-zero coded optical pulses of BOTDA with the temperature resolution of 0.7 ℃, which is equivalent to strain accuracy of 12 με. For over 50-km sensing length, we proposed and demonstrated frequency-division-multiplexing （FDM） and time-division-multiplexing （TDM） based BOTDA technique for 75-km and 100-km sensing length without inline amplification within the sensing length. The spatial resolution of 2m （100km） and Brillouin frequency shift accuracy of 1.5 MHz have been obtained for TDM based BOTDA and 1-m resolution （75 km） with Brillouin frequency shift accuracy of 1 MHz using FDM based BOTDA. The civil structural health monitoring with BOTDA technique has been demonstrated.

关键词： Brillouin scattering distributed sensor Brillouin grating temperature strain birefringence

Effects of polarization on stimulated Brillouin scattering in a birefringent optical fiber

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Photonics Research 2014年第5期2卷 126-137页

作者： Daisy Williams xiaoyi bao Liang Chen Department of Physics University of OttawaMacDonald Hall150 Louis PasteurOttawaOntario K1N 6N5Canada

The most general model of elliptical birefringence in an optical fiber has been developed for a steady-state and transient stimulated Brillouin scattering *** impact of the elliptical birefringence is to induce a Brillouin frequency shift and distort the Brillouin spectrum—which varies with different light polarizations and *** model investigates the effects of birefringence and the corresponding evolution of spectral distortion effects along the fiber,providing a valuable prediction tool for distributed sensing applications.

关键词： polarization fiber scattering

Characterization of high nonlinearity in Brillouin amplification in optical fibers with applications in fiber sensing and photonic logic

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Photonics Research 2014年第1期2卷 1-9页

作者： Daisy Williams xiaoyi bao Liang Chen Fiber Optics Group University of OttawaOttawaOntario K1N 6N5Canada

A highly accurate,fully analytic solution for the continuous wave and the probe wave in Brillouin amplification,in lossless optical fibers,is *** is experimentally confirmed that the reported analytic solution can account for spectral distortion and pump depletion in the parameter space that is relevant to Brillouin fiber sensor applications,as well as applications in photonic *** analytic solutions are valid characterizations of Brillouin amplification in both the low and high nonlinearity regime,for short fiber lengths.

关键词： fiber optical pump

Study of Ф-OTDR Stability for Dynamic Strain Measurement in Piezoelectric Vibration

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Photonic Sensors 2016年第3期6卷 199-208页

作者： Meiqi REN Ping LU Liang CHEN xiaoyi bao Department of Physics University of Ottawa Ottawa ON K1S5G5 Canada

In a phase-sensitive optical-time domain reflectometry （Ф-OTDR） system, the challenge for dynamic strain measurement lies in large intensity fluctuations from trace to trace. The intensity fluctuation caused by stochastic characteristics of Rayleigh backscattering sets detection limit for the minimum strength of vibration measurement and causes the large measurement uncertainty. Thus, a trace-to-trace correlation coefficient is introduced to quantify intensity fluctuation of Ф-OTDR traces and stability of the sensor system theoretically and experimentally. A novel approach of measuring dynamic strain induced by various driving voltages of lead zirconate titanate （PZT） in Ф-OTDR is also demonstrated. Piezoelectric vibration signals are evaluated through analyzing peak values of fast Fourier transform spectra at the fundamental frequency and high-order harmonics based on Bessel functions. High trace-to-trace correlation coefficients varying from 0.824 to 0.967 among 100 measurements are obtained in experimental results, showing the good stability of our sensor system, as well as small uncertainty of measured peak values.

关键词： Optical fiber sensors phase-sensitive optical time domain reflectometry (OTDR) vibration

Distributed static and dynamic detection of an acoustic wave in a Brillouin random fiber laser

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Photonics Research 2021年第5期9卷 772-780页

作者： ZICHAO ZHOU HAIYANG WANG YUAN WANG LIANG CHEN xiaoyi bao Department of Physics University of OttawaOttawaOntario K1N 6N5Canada

The interaction of random laser and gain medium is important to understand the noise origin in random fiber lasers. Here, using the optical time domain reflectometry method, the time-resolved distributed acoustic wave generated by a Brillouin random fiber laser(BRFL) is characterized. The dynamic property of the acoustic wave reflects the gain dynamics of the BRFL. The principle is based on the polarization-decoupled stimulated Brillouin scattering(SBS)-enhanced four-wave mixing process, where the probe light experiences maximum reflection when the phase match condition is satisfied. Static measurements present exponentially depleted Brillouin gain along the gain medium in the BRFL, indicating the localized random SBS frequency change in the maximum local gain region, which varies with time to contribute random laser noise as revealed in the dynamic measurement. The SBS-induced birefringence change in the Brillouin gain fiber is approximately 10^(-7) to 10^(-6). The phase noise of the BRFL is observed directly inside the random laser gain medium for the first time via time and spatially varied acoustic wave intensity. By counting the temporal intensity statistical distribution, optical rogue waves are detected near the lasing threshold of the BRFL. Different temporal intensity statistical distribution at high and low gain positions is found, which is caused by the SBS nonlinear transfer function and localized gain. The distributed characterization methods in the paper provide a new platform to study the interaction of random lasers and gain medium, giving us a new perspective to understand the fundamental physics of the random lasing process and its noise property.

关键词： fiber polarization random