Open AccessQuasi-distributed acoustic sensing with interleaved identical chirped pulses for multiplying the measurement slew-rate
Author(s) -
Zinan Wang,
Jialin Jiang,
Zinan Wang,
Ji Xiong,
Zijie Qiu,
Chunye Liu,
Y. Yaswanth Naidu K. Ananda Rao
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.408757
Subject(s) - reflectometry , optics , demodulation , slew rate , multiplexing , bandwidth (computing) , optical time domain reflectometer , physics , computer science , time domain , telecommunications , optical fiber , fiber optic sensor , channel (broadcasting) , quantum mechanics , voltage , computer vision , graded index fiber
Quasi-distributed acoustic sensing (Q-DAS) based on ultra-weak fiber Bragg grating (UWFBG) is currently attracting great attention, due to its high sensitivity and excellent multiplexing capability. Phase-sensitive optical time-domain reflectometry (Φ-OTDR) based on phase demodulation is one of the most promising interrogation schemes for Q-DAS. In this article, a novel interleaved identical chirped pulse (IICP) approach is proposed on the basis of pulse compression Φ-OTDR with coherent detection. Different from the frequency-division-multiplexing (FDM) method, the identical pulses are used for multiplexing in the IICP scheme, and the mixed reflection signals can be demodulated directly, so the inconsistent phase offsets in FDM can be avoided. As a result, this scheme can enlarge the measurement slew-rate (SR) of Q-DAS by times compared with traditional single pulse scheme. In the proof-of-principle experiment, the SR of 28.9 mɛ/s has been achieved with an 860 m sensing range, which is 5 times as that of the traditional single pulse scheme; meanwhile, the response bandwidth has been enlarged by 5 times. The 277 kHz response bandwidth has been achieved, with 5 m spatial resolution and 2.8 p ε /Hz strain sensitivity.