相位敏感型光时域反射传感系统光学背景噪声的产生机理及其抑制方法

相位敏感型光时域反射(Φ-OTDR)传感系统具有响应速度快、灵敏度高等优点,能够实现对微弱扰动的分布式检测,在重大设施的入侵警戒、大型工程结构的健康监测等领域具有广阔应用前景.然而,与传统的OTDR传感系统不同,Φ-OTDR系统中存在着激光器中心频率漂移、偏振相关的噪声、光纤应变与干涉强度非线性对应关系引起的测量失真等光学背景噪声,对有效信号的提取形成了不可忽视的干扰,从而限制了Φ-OTDR传感系统在实际应用环境下的传感性能.本文对这些光学背景噪声的产生机理进行了深入分析,并提出了相应的噪声抑制方法.实验结果表明,本文提出的方法可以有效抑制Φ-OTDR传感系统中的光学背景噪声,并显著提高传感系统性能.

The mechanism and suppression methods of optical background noise in phase-sensitive optical time domain reflectometry

Phase-sensitive optical time domain reflectometry (Φ-OTDR) has the advantages of fast response and high sensitivity. Therefore, it can realize fully distributed monitoring of weak vibrations along an optical fiber, which is of great value in many applications such as perimeter security and structural health monitoring. However, the optical background noise in the Φ-OTDR will disturb the extraction of effective signals and limit the performance of this system. The optical background noise mainly includes the laser center frequency drift, the polarization-relevance noise and the distortion measurement due to the nonlinear relationship between optical fiber strain and interference intensity. In this paper, the generating mechanism of these optical background noise was analyzed and the corresponding noise suppression methods were proposed. The experiment results showed that the proposed methods could suppress the optical background noise effectively and improve the sensing performance significantly.