非扫描式长距离动态分布式布里渊光纤传感研究

With the increase of China's investment in infrastructure construction, safety monitoring of highways, bridges and other facilities has became a top priority. Brillouin optical time domain analysis (BOTDA) has capacity of continuously distributed measurement. It can quantitative analyze the temperature and stress via measuring the frequency shift. And facility status can be evaluated from the data. However, traditional BOTDA takes a long measuring time. It is incapable to real-time detect and give early warning of the structural damage induced by parametric variation, over load, material degradation and so on. In order to breakthrough the limitation of measuring time, slope assisted BOTDA based on optical frequency comb (OFC) is proposed. It has merits of high sample rate and high spatial resolution without frequency sweep and Brillouin gain spectrum reconstruction. Using OFC as probe, the dynamic range canbe widened. Demodulation and matching algorithms can guarantee high measurement accuracy in the entire measurement range. Combined with orthogonal polarization modulation, differential pulse pair and pulse code, BOTDA can reduce the measuring time and improved the sensing distance significantly. This project aims to realize fast long-range distributed Brillouin optical fiber sensing with large dynamic range and high spatial resolution, which offers data for fault analysis and diagnosis through real-time measuring temperature and stress, to provide security for large infrastructure.

随着中国对基础设施投资力度的加大，公路、桥梁等重大工程的安全性监测已成为重中之重。布里渊光时域分析传感技术（BOTDA）能够实现连续分布式监测，通过测量频移来定量分析温度和应力，判断设施状态，而传统的BOTDA测量时间长，对参量变化、载荷过高、材料病变等造成的结构损伤无法实时测量并预警。为突破传统方案对测量时间的限制，本项目提出了基于光学频率梳的多斜坡辅助动态长距离分布式布里渊传感，无需扫频，也无需重构增益谱，具有采样率高、空间分辨率高的特点。频率梳作为探测光，能大幅度拓宽动态应变范围；同步解调和最优匹配算法能保证在整个测量范围内都有较高的测量精度；结合正交偏振调制、差分脉冲对和脉冲编码，进一步缩短测量时间，提高传感距离。研究成果有望实现大应变范围、高空间分辨率的长距离动态传感系统，通过对温度和应力的动态监测，为故障的分析与诊断提供数据，为大型基础设施的安全性提供保障。

本项目旨在实现大应变范围、高空间分辨率的长距离动态布里渊传感系统，通过对温度和应力的动态监测，为故障的分析与诊断提供数据，为大型基础设施的安全性提供保障。在3年的研究周期内，完成了任务书中的相关目标，发表SCI论文7篇，申请专利3项。培养在读研究生2名，协助培养毕业研究生2名，并参加3次国际学术会议。本项目完成的主要内容包括（1）对受激布里渊散射（SBS）声波场激发和能量传递过程建立了数学模型，数值仿真了探测光参数对布里渊增益/损耗谱（BGS）和相位谱的影响进；（2）建立了传感量从光信号转换成电信号的映射模型，理论分析了各类噪声对信噪比(SNR)的影响和提高SNR的方法；（3）采用IQ解调实现了对多频率相位增益比（BPGR）曲线的同步解调，得到BPGR曲线库，并分析了SNR对BPGR曲线线性范围的影响，从而建立了最优匹配算法，提高了动态范围和测量精度；（4）搭建了基于光学频率梳的多斜坡辅助布里渊传感系统，实现了大应变范围的高精度动态传感；（5）利用正交光学啁啾链消除了布里渊传感系统中的偏振衰落效应，在10km的单模光纤实现6m的空间分辨率和低于0.5MHz的布里渊频移不确定度；（6）利用图像反卷积提高了布里渊传感系统的空间分辨率，将BGS作为图像，通过一个点扩散函数将其模糊，再利用基于二维维纳滤波的图像反卷积可以消除布里渊响应的不明确性；（7）通过受激布里渊散射和光电振荡器实现了一种应力无关的温度传感器，可以消除光纤应力温度交叉敏感的问题；（8）提出了基于射频迈克尔干涉仪和贝塞尔谐波解调的振动传感器，该系统对外界温度和应力等静态量变化不敏感，可实现大动态范围和宽频率响应的振动传感器。