基于脉冲细分的多参量分布式光纤传感系

Multi-Parametric Distributed Fiber Optic Sensing System Based on Pulse Subdivision

摘要:

现有的分布式光纤传感系统通常只针对单一参量,当实际运行于复杂环境时,需要多种传感系统与技术集成以监测多个参量。利用相敏光学时域反射仪(φ-OTDR)和布里渊光学时域反射仪(BOTDR)对不同物理参量敏感的特性,设计了一种集成的分布式光纤传感系统,并基于瑞利散射与布里渊散射信号同时传感分离检测,在单根传感光纤上实现同一调制脉冲下的振动、温度、应变多参量监测。为了在维持集成系统脉冲的同一调制下提升BOTDR空间分辨率,采用脉冲细分叠加原理分析布里渊散射信号,在不改变脉冲宽度的基础上突破声子寿命限制,提升空间分辨率。经实验验证系统表明,在50 km传感距离下,基于瑞利散射以10 m空间分辨率可实现振动定位,基于布里渊散射引入脉冲细分叠加可将空间分辨率提升至1 m检测温度与应变,且布里渊频移量与温度、 应变变化具有较高的线性拟合度,实现了多参量监测。

Abstract:

Existing distributed fiber-optic sensing systems often target only a single parameter, whereas in prac tice, when operating in complex environments, multiple sensing systems and technologies need to be integrated to monitor various parameters. Using the characteristics of phase-sensitive optical time-domain reflectometer (-OT DR) and Brillouin optical time-domain reflectometer (BOTDR), which are sensitive to different physical parame ters, an integrated distributed fiber-optic sensing system was designed. By employing the concurrent detection of Rayleigh and Brillouin scattering signals, various parameters such as vibration, temperature, and strain can be ef fectively monitored using a singular sensing fiber under a unified modulation pulse. The system relies on the concur rent detection of Rayleigh and Brillouin scattering signals to enhance the spatial resolution of BOTDR while uphold ing the unaltered modulation of the integrated system pulse. The Brillouin scattering signal was analyzed based on the principle of pulse subdivision superposition, which breaks through the limitations of phonon lifetime and im proves spatial resolution without changing the pulse width. The system was experimentally verified to achieve vibra tion localization with a spatial resolution of 10 m based on Rayleigh scattering at a sensing distance of 50 km. Intro ducing pulse subdivision superposition based on Brillouin scattering increased the spatial resolution to 1 m for detec ting temperature and strain. The Brillouin frequency shifts displayed a highly linear correlation with the changes in temperature and strain, thereby realizing the monitoring of multiple covariates.