Phase demodulation method based on a dual-identical-chirped-pulse and weak fiber Bragg gratings for quasi-distributed acoustic sensing  

作　　者：Guanhua Liang Junfeng Jiang Kun Liu Shuang Wang Tianhua Xu Wenjie Chen Zhe Ma Zhenyang Ding Xuezhi Zhang Yongning Zhang Tiegen Liu 

机构地区：[1]School of Precision Instruments and Opto-electronics Engineering,Tianjin University,Tianjin 300072,China [2]Institute of Optical Fiber Sensing of Tianjin University,Tianjin Optical Fiber Sensing Engineering Center,Tianjin 300072,China [3]Key Laboratory of Opto-electronics Information Technology(Tianjin University),Ministry of Education,Tianjin 300072,China

出　　处：《Photonics Research》2020年第7期1093-1099,共7页光子学研究（英文版）

基　　金：National Natural Science Foundation of China(61675152,61735011);National Key Scientific Instrument and Equipment Development Projects of China(2013YQ030915);Tianjin Talent Development Special Plan for High Level Innovation and Entrepreneurship Team;open project of Key Laboratory of Opto-electronics Information Technology(2019KFKT007)。

摘　　要：A phase demodulation method for quasi-distributed acoustic sensing(DAS)systems based on a dual-identicalchirped-pulse and weak fiber Bragg gratings(WFBGs)is proposed.Compared to the use of Rayleigh backscattering light in optical fibers,the implementation of WFBGs can contribute to obtaining an optical signal with a higher signal-to-noise ratio(SNR).The dual-identical-chirped-pulse is generated by a time-delay fiber,and the sinusoidal carrier is generated by the interference between the two chirped pulses reflected by adjacent WFBGs.The phase of the sinusoidal carrier represents the dynamic strain change posed on the sensing fiber.Discrete Fourier transform is used to directly retrieve the phase information.The performance of the phase demodulation from interference signals under different sinusoidal carrier frequencies and SNRs is numerically investigated.The piezoelectric transducer is employed to emulate the sound in the experiment to verify the effectiveness of our method.It is shown that the dynamic strain can be well reconstructed at the end of a 101.64 km fiber when the signal SNR is down to 3.234 d B.Our proposed method enables the application of the long-distance sensing in quasi-DAS systems.

关 键 词：fiber PULSE identical 

分 类 号：TN253[电子电信—物理电子学] TP212[自动化与计算机技术—检测技术与自动化装置]