基于周期性多布里渊动态光栅的长距离快速分布式光纤传感系统

Brillouin dynamic grating (BDG) based on stimulated Brillouin scattering is a new technique proposed in recent years. This technique can break the restriction of the limited phonon lifetime in traditional Brillouin distributed sensing system, and thus simultaneously obtains high spatial resolution and high accuracy. However, according to reported papers, defects of long measurement time and short measurement distance exist in Brillouin distributed sensing systems based on the BDG technique. Aimed at solving these application problems, the project intends to start from the basic theory of BDG, propose a new technique of producing and probing a periodic multi-BDG, differing from the traditional producing and probing way of single BDG. The proposed periodic multi-BDG technique is able to simultaneously generate multiple equally spaced BDG along the sensing fiber. The reflection spectrum of each BDG can be read out by a probe pulse all at once. Thereby, this periodic multi-BDG technique can greatly shorten the measurement time. Moreover, the project would increase the sensing distance up to km magnitude by optimizing the parameters of pump and probe pulses. Distributed sensing systems based on this periodic multi-BDG technique can achieve temperature/strain measurement with long-distance, speediness and high-precision. This periodic multi-BDG technique will play a significant role in expanding the scope of application of fully distributed sensing technology and has broad application prospect.

基于受激布里渊散射的布里渊动态光栅（BDG）是近几年提出的一项新技术，该技术在分布式传感领域中打破了传统布里渊传感系统中声子寿命的限制，可同时获得高空间分辨率和高测量精度。但目前文献报道的BDG应用于全分布式传感技术存在测量时间长和测量距离短的应用缺陷。本项目拟从BDG的基础理论出发，针对前述应用缺陷，区别于文献报道的单BDG产生与读取方法，提出一种周期多BDG产生与读取的方法，在传感光纤中同时产生多个等间隔BDG，通过探测脉冲一次性读取出各个BDG反射谱信号，从而极大缩短测量时间；同时，通过优化泵浦、探测脉冲各项参数，将传感距离扩展至km量级。这种基于周期性多BDG技术的分布式传感方案可实现温度/应变的长距、快速、高精测量，对扩展全分布式传感技术应用范围有重要作用，具有广泛的应用前景。

本项目立足于见诸文献报道的BDG传感技术测量时间长和测量距离短的应用缺陷，探索研究基于周期性多布里渊动态光栅的长距离快速光纤传感技术。以耦合波理论为基础，完成了周期性多BDG产生与探测的理论模型建立，分析了不同条件下多BDG各项特性参数。优化泵浦脉冲序列时序，搭建了周期性多BDG传感系统平台，实现了基于周期性多BDG的长距离快速分布式温度/应变传感监测，对扩展分布式光纤传感技术应用范围具有重要作用。在该项目的资助下，项目组发表论文8篇，其中SCI论文1篇，EI论文2篇，核心期刊论文3篇；申请发明专利3项，其中授权1项。