基于瑞利散射强度谱动态扩展的大量程分布式光纤传感系统  

Wide-Range Distributed Optical Fiber Sensing System Based on Dynamic Extension of Rayleigh Scattering Intensity Spectrum

作　　者：陈家豪 刘庆文 常晏铭 何祖源 Chen Jiahao;Liu Qingwen;Chang Yanming;He Zuyuan(State Key Laboratory of Advanced Optical Communication Systems and Networks,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学区域光纤通信网与新型光通信系统国家重点实验室,上海200240

出　　处：《光学学报》2024年第11期251-257,共7页Acta Optica Sinica

基　　金：国家重点研发计划(2021YFA0716800);国家自然科学基金(62175147)。

摘　　要：基于背向瑞利散射和啁啾脉冲的光纤分布式声传感器实现了动态信号的高性能测量,但其过小的量程限制了准静态信号的测量能力。为此,本文提出了一种基于瑞利频谱解调法的频谱扩展算法,利用光纤受到应变时瑞利散射强度谱发生频移的特点,在应变测量过程中动态扩展分布式光纤传感系统的参考频谱频率范围以提高测量量程。在实验中,利用扫频范围为1 GHz的啁啾脉冲,实现了198με应变信号的测量,测量量程相较于无扩展算法时扩大了65倍。Objective Based on Rayleigh backscattering in optical fibers,distributed acoustic sensing(DAS)can detect and locate vibration information at any position along a long-distance optical fiber.However,due to the complexity of the environment and events in practical applications,more information is required for accurately diagnosing events.Meanwhile,Rayleigh backscattering can provide rich information like strain and temperature about the testing object and its surrounding environment.However,the existing DAS systems have difficulty in measuring temperature and strain because of their limited measurement range.Thus,we propose a spectrum extension algorithm based on the Rayleigh spectrum method.During the measurement,the algorithm dynamically extends the frequency range of the spectrum as the strain or temperature changes,solving the limited measurement range of the Rayleigh spectrum method.In the experiment,the measurement range of the system is increased by 65 times compared to the non-extension algorithm,with stable demodulation achieved.Methods The experimental system is based on the time-gated digital optical frequency domain reflectometry(Fig.1).The collected Rayleigh backscattering signals are subjected to segmented matched filtering to obtain the Rayleigh scattering intensity spectra at each position on the optical fiber.The Rayleigh spectrum method is employed to calculate the spectral shift between the measured spectrum and the reference spectrum via cross-correlation under the strain occurrence(Fig.2),and then the corresponding strain or temperature variation is obtained.Generally,the measurement range is limited by the frequency range of the chirped probe pulse,and to overcome this limitation,we put forward a spectrum extension algorithm(Fig.3).Considering that non-uniform strain will result in spectral distortion,the algorithm dynamically splices and extends the spectrum via adopting the weight average of the existing spectrum and the new spectrum by the raised cosine window based on the spectral shift.Th

关 键 词：分布式光纤传感 瑞利散射 传感量程 互相关 频谱扩展 

分 类 号：TN247[电子电信—物理电子学]