新型动态和双参量测量布里渊光纤传感技术和机理的研究

The Brillouin optical time domain analysis (BOTDA) based on stimulated Brillouin scattering (SBS) is one of the key distributed sensing technique for temperature and strain measurement. BOTDA with its strong detection signal, long sensing distance and high measurement accuracy is widely used in the structure health monitoring (SHM).The necessity to scan the pump–probe frequency shift leads to a relatively long acquisition time, of the order of tens of seconds to minutes. Therefore, traditional BOTDA is not suitable to acquire time-varying strain changes. However, for a broad range of structural phenomena there is a critical need for dynamic strain acquisition. Moreover, the requisite of access to both fiber-end and cross sensitivity limits the practice of the sensor in SHM. In this project, we propose a novel Brillouin gain spectrum (BGS) double slope-assisted BOTDA (DSA-BOTDA) and a single access DSA-BOTDA for dynamic strain measurement. And on this basis, the coherent detection technology is used to improve the signal to noise ratio, and the double sideband (DSB) probe technique is employed to suppress the non local effect, and thus a long distance, high accuracy dynamic BOTDA sensing system could be realized. Furthermore, the theoretical correlation between the working point and the strain measurement range and resolution would be explored systematically. It is expected that the proposed configuration can offer a novel Brillouin distributed optical fiber sensing technology with dynamic sensing and simultaneous temperature and dynamic strain measurement, which would provide some key academic and technological supports for our country in the structure health monitoring.

基于受激布里渊散射效应的布里渊光时域分析仪（BOTDA）是一种具有温度和应变测量的分布式光纤传感技术。BOTDA技术具有探测信号较强，传感距离长、测量精度高的特点，在大型结构健康监测中有着广泛的应用。由于需要扫描布里渊增益谱才能获取布里渊频移变化，故其测量时间在几十秒-分量级，因此BOTDA不适合用于动态的应变测量。此外，由于双端接入和交叉敏感问题的存在，传统BOTDA难以胜任实际的结构健康监测。本项目旨在提出一种基于布里渊增益谱(BGS)双边带响应实现动态应变测量的BOTDA系统和单端结构的动态BOTDA传感系统，并在此基础上利用相干探测技术提高信噪比，利用双边带探测方案实现非局域效应的抑制，实现长距离、高精度的动态BOTDA传感系统；针对该技术，建立不同频点作为工作点与应变测量范围的理论关系。本项目的研究为我国自主构建高效结构健康监测新体系提供部分关键学术积累与技术支持。

高性能光纤传感器在基础设施、环境监测等领域具有广泛的应用前景，双参量或者多参量同时测量是新型光纤传感技术研究的重要方向。项目实施以来,我们主要开展了以下的研究：提出了一种基于相干探测和双边带探测的，能进行动态应变和温度同时传感的BOTDA传感技术，对工作频率点的选择做了理论模拟分析，实验上对双参量同时传感做了充分的研究，最终在10.6km的传感光纤上实现了一个温度事件和2个应变引起的低频(7.00Hz 和10.00Hz)振动事件的同时传感测量，实现了3m的空间分辨率，1.2°C温度精度和0.67Hz 频率测量分辨率，该方案在一些需要对温度和动态应变进行同时测量的场合有潜在的应用。为了实现双参数传感，提出并实验证实了一种高性价比的温度和液体折射率光纤传感器，该传感器由在Sagnac光纤圆环中嵌入保偏-D形光纤结构构成。实验研究了该传感器的温度和折射率特性，利用不同谐振波谷具有不同的温度和折射率响应特性，实现了温度和折射率的同时测量,温度和折射率灵敏度分别达到1.804nm/°C 和131.49nm/RIU。采用拉伸法和光纤光栅实现了对金属丝杨氏模量的测量，该方法在选材领域有着潜在的应用前景。设计和实现了一种七芯光纤-保偏(MCF-PM)光纤结构的温度传感器，传感器获得最高-2.38nm/℃的温度灵敏度，36dB干涉谱消光比。设计实现了基于单模光纤-保偏光纤-单模光纤(SPS)的光纤结构高灵敏度曲率和温度传感器，实验获得 59.849nm/m-1 曲率灵敏度和1.678nm/°C温度灵敏度。设计了基于布里渊激光器移频的BOTDA系统、动态分布式布里渊光纤传感方案、单端结构动态测量的布里渊光纤传感系统、基于脉冲编码和边沿滤波法的光纤光栅振动测量系统、基于D型光纤环形镜远程pH值监测装置和融合OTDR和弱反射光栅的振动传感方案。在微纳米尺度下，研究了热扰动和针尖形状对基于粘附力微纳米颗粒的拾取操作的影响研究，为后续开展微纳尺度光学传感提供理论支撑。