Abstract

The tradeoff between the spatial resolution and estimation accuracy of the Brillouin frequency shift (BFS) sets a technical hurdle for Brillouin optical time-domain analyzers (BOTDAs) based on orthogonal frequency division multiplexing (OFDM), due to orthogonality between the OFDM subcarriers. To solve this problem, a novel BOTDA using spectrally efficient frequency-division multiplexing (SEFDM) is proposed. A partial Zadoff-Chu sequence that generates a centralized pulse after inverse discrete Fourier transform (IDFT) is used. SEFDM signaling is done by discarding the sidelobe of the time domain pulse before being sent as the probe wave. As such, the symbol period is dramatically reduced compared with OFDM signals, leading to a much higher spatial resolution. Meanwhile, the subcarrier spacing of the SEFDM signals remains the same as that of the OFDM signals, which ensures a high estimation accuracy of the BFS if a small subcarrier spacing is used. We experimentally demonstrate a 3.1 m spatial resolution with a 1.294 MHz measurement accuracy in a SEFDM based BOTDA over a 10 km sensing range. Moreover, by using SEFDM signals with very short symbol periods as the probe wave, the time-consuming frequency sweeping process is eliminated, which makes dynamic sensing possible. We successfully demonstrate a dynamic measurement with a vibration frequency of 26 Hz. The introduction of SEFDM provides the desirable flexibility for BOTDAs to be used in both static and dynamic distributed fiber sensing areas with a large dynamic range.

Dynamic polarization-insensitive BOTDA in direct-detection OFDM with CNN-based BFS extraction

Di Qi, Jingyu Li, Xun Guan, and Chun-Kit Chan
Opt. Express 30(5) 7725-7736 (2022)

BOTDA using channel estimation with direct-detection optical OFDM technique

Can Zhao, Ming Tang, Liang Wang, Hao Wu, Zhiyong Zhao, Yunli Dang, Jiadi Wu, Songnian Fu, Deming Liu, and Perry Ping Shum
Opt. Express 25(11) 12698-12709 (2017)

Scanning-free BOTDA based on ultra-fine digital optical frequency comb

Chao Jin, Nan Guo, Yuanhua Feng, Liang Wang, Hao Liang, Jianping Li, Zhaohui Li, Changyuan Yu, and Chao Lu
Opt. Express 23(4) 5277-5284 (2015)

Time-division multiplexing-based BOTDA over 100km sensing length

Yongkang Dong, Liang Chen, and Xiaoyi Bao
Opt. Lett. 36(2) 277-279 (2011)

Single-shot distributed Brillouin optical time domain analyzer

Jian Fang, Pengbai Xu, Yongkang Dong, and William Shieh
Opt. Express 25(13) 15188-15198 (2017)