title: Bi-Directional Brillouin Optical Time Domain Analyzer System for Long Range Distributed Sensing.
abstract: We propose and experimentally demonstrate a novel scheme of bi-directional Brillouin time domain analyzer (BD-BOTDA) to extend the sensing range. By deploying two pump-probe pairs at two different wavelengths, the Brillouin frequency shift (BFS) distribution over each half of the whole fiber can be obtained with the simultaneous detection of Brillouin signals in both channels. Compared to the conventional unidirectional BOTDA system of the same sensing range, the proposed BD-BOTDA scheme enables distributed sensing with a performance level comparable to the conventional one with half of the sensing range and a spatial resolution of 2 m, while maintaining the Brillouin signal-to-noise ratio (SNR) and the BFS uncertainty. Based on this technique, we have achieved distributed temperature sensing with a measurement range of 81.9 km fiber at a spatial resolution of 2 m and BFS uncertainty of ~0.44 MHz without introducing any complicated components or schemes.
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China. 13901767r@connect.polyu.hk.
authors.forename: Nan
authors.initials: N
authors.lastname: Guo
authors.affiliation: Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, China. lwang@ee.cuhk.edu.hk.
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Electrical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China. jayjay.wang@connect.polyu.hk.
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China. 15901369r@connect.polyu.hk.
authors.forename: Chao
authors.initials: C
authors.lastname: Jin
authors.affiliation: Department of Electrical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China. hwa-yaw.tam@polyu.edu.hk.
authors.forename: Hwa-Yaw
authors.initials: HY
authors.lastname: Tam
authors.affiliation: Department of Electrical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China. aping.zhang@polyu.edu.hk.
authors.forename: A Ping
authors.initials: AP
authors.lastname: Zhang
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China. chao.lu@polyu.edu.hk.
authors.forename: Chao
authors.initials: C
authors.lastname: Lu
keywords: Brillouin scattering; fiber optics sensors; optical time domain analyzer; temperature