Abstract

Dynamic strain sensing over a frequency range from 0.01 to 20 Hz can be used for monitoring earthquakes and volcanoes, charting rock and petroleum formations beneath the earth. However, significant laser frequency drifting (LFD) has limited the detection in this frequency range, especially for distributed frequency detection with phase optical time domain reflectometry (OTDR), where the LFD will introduce a time dependent noise destroying the dynamic strain reconstruction. In this study, a simple and effective method that utilizes the referenced random fiber grating to monitor the variation of laser frequency has been both theoretically analyzed and experimentally demonstrated. During the maximum up to 200 s data acquisition time, the frequency variation of a distributed feedback (DFB) laser with MHz linewidth is obtained from the referenced portion of sensing signal, and then the 1 Hz and 0.01 Hz dynamic strain variations with amplitude of 30 µ$\unicode{x03B5}$ are reconstructed with strain measurement standard deviation of 66 n$\unicode{x03B5}$. Due to signal-to-noise ratio (SNR) enhanced Rayleigh traces from random fiber gratings, a minimum detectable frequency drifting of 7.28 MHz could be achieved over the optical frequency of ${2} \times {{10}^{14}}\;{\rm Hz}$.

© 2021 Optical Society of America

Strain measurement range enhanced chirped pulse φ-OTDR for distributed static and dynamic strain measurement based on random fiber grating array

Yuan Wang, Ping Lu, Stephen Mihailov, Liang Chen, and Xiaoyi Bao
Opt. Lett. 45(21) 6110-6113 (2020)

Single-shot chirped pulse BOTDA for static and dynamic strain sensing

Yuan Wang, Liang Chen, and Xiaoyi Bao
Opt. Lett. 46(22) 5774-5777 (2021)

Distributed dynamic strain sensing in coherent Φ-OTDR with a pulse conversion algorithm

Heng Qian, Bin Luo, Haijun He, Yin Zhou, Xihua Zou, Wei Pan, and Lianshan Yan
Opt. Lett. 46(7) 1668-1671 (2021)

Dynamic strain measurement based on ultrafast Brillouin collision in the correlation domain

Zonglei Li, Yin Zhou, Biqiang Jiang, Xuetao Gan, Lianshan Yan, and Jianlin Zhao
Opt. Lett. 46(14) 3488-3491 (2021)

Observation on temperature and strain dependency of Brillouin dynamic grating in a few-mode fiber with a ring-cavity configuration

Yinping Liu, Guangyao Yang, Ning Wang, Lin Ma, J. C. Alvarado-Zacarias, J. E. Antonio-Lopez, Pierre Sillard, A. Amezcua-Correa, R. Amezcua-Correa, Xinyu Fan, Zuyuan He, and Guifang Li
Opt. Lett. 45(8) 2152-2155 (2020)