Open AccessDistributed optical fiber vibration sensor based on Sagnac interference in conjunction with OTDR
Author(s) -
Chao Pan,
Xiaorui Liu,
Hui Zhu,
X. Shan,
Xiaohan Sun
Publication year - 2017
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.25.020056
Subject(s) - optical time domain reflectometer , optics , vibration , reflectometry , distributed acoustic sensing , optical power , optical fiber , interference (communication) , fiber optic sensor , physics , position (finance) , power (physics) , materials science , acoustics , time domain , graded index fiber , channel (broadcasting) , telecommunications , computer science , laser , finance , quantum mechanics , economics , computer vision
A real-time distributed optical fiber vibration sensing prototype based on the Sagnac interference in conjunction with the optical time domain reflectometry (OTDR) was developed. The sensing mechanism for single- and multi-points vibrations along the sensing fiber was analyzed theoretically and demonstrated experimentally. The experimental results show excellent agreement with the theoretical models. It is verified that single-point vibration induces a significantly abrupt and monotonous power change in the corresponding position of OTDR trace. As to multi-points vibrations, the detection of the following vibration is influenced by all previous ones. However, if the distance between the adjacent two vibrations is larger than half of the input optical pulse width, abrupt power changes induced by them are separate and still monotonous. A time-shifting differential module was developed and carried out to convert vibration-induced power changes to pulses. Consequently, vibrations can be located accurately by measuring peak or valley positions of the vibration-induced pulses. It is demonstrated that when the width and peak power of input optical pulse are set to 1 μs and 35 mW, respectively, the position error is less than ± 0.5 m in a sensing range of more than 16 km, with the spatial resolution of ~110 m.