Ma Fu, Song Ningfang, Wang Xiaxiao, Wang Peng, Ma Haoyu, Wang Yizhen, Peng Xiao, Yu Jia
Opt Express. 2021 May 10;29(10):15425-15433. doi: 10.1364/OE.424010.
A novel fiber-optic distributed acoustic sensor (DAS) utilizing a LiNbO straight through waveguide phase modulator as phase generation carrier (PGC) modulation module for the detection of acoustic signal is presented. The sensitive principle and the phase demodulation method of the system based on phase-sensitive optical time domain reflectometer (Φ-OTDR) are described. This scheme solves the problems of low modulation frequency and unstable performance of piezoelectric transducer (PZT) in the traditional homodyne detection system and depends only on the pulse repetition frequency. The efficacy of the new approach is demonstrated experimentally, showing that the weak acoustic signal can be demodulated accurately. The noise level of the system is < 4.2×10 rad/√Hz, the signal to noise ratio (SNR) is > 16 dB, and the spatial resolution is 10 m, as well as a detection frequency can theoretically achieve 25 kHz at 2 km sensing fiber. It provides a new research idea for DAS and is expected to replace PZT to achieve a high-frequency response, which has good potential in the applications of low cost, long distance and high frequency detection.
提出了一种新型光纤分布式声学传感器（DAS），它利用铌酸锂直通波导相位调制器作为相位生成载波（PGC）调制模块来检测声学信号。描述了基于相敏光时域反射仪（Φ-OTDR）的系统的敏感原理和相位解调方法。该方案解决了传统零差检测系统中压电换能器（PZT）调制频率低和性能不稳定的问题，并且仅依赖于脉冲重复频率。通过实验证明了新方法的有效性，表明可以准确解调微弱声学信号。系统的噪声水平<4.2×10 rad/√Hz，信噪比（SNR）>16 dB，空间分辨率为10 m，并且在2 km传感光纤上理论上检测频率可以达到25 kHz。它为DAS提供了一种新的研究思路，有望取代PZT以实现高频响应，在低成本、长距离和高频检测应用中具有良好的潜力。
