基于多频矢量布里渊分析的实时动态分布式传感技术研究

The current dynamic distributed Brillouin sensing techniques are facing the problem of small measurement range or bad performance in real-time sensing. A multi-frequency vector Brillouin optical-domain analysis (BOTDA) technique is proposed in the proposal. Compared with other dynamic Brillouin sensing techniques, the multi-frequency vector BOTDA has two main characteristics. First, the measurement of the Brillouin frequency shift(BFS) is based on the ratio of Brillouin phase shift to Brillouin gain of the probe wave, which leads to real-time measuring with high precision. Because both the gain and phase shift are employed, it is classified as the vector Brillouin analysis. Second, the BFS is measured by multi-slope analysis, in which a chain of cascaded slopes is formed, which makes it capable of measuring large stain. This method has the merits of large strain measurement range, excellent real-time performance and low measurement error. The characteristics of the Brillouin gain spectrum and phase shift spectrum will be studied first, which aims to achieve the influence of various of conditions on the shape of the spectrums, such as the strain and pump parameters. Then the vector BOTDA based on single-frequency pump and multi-frequency pump will be studied in order to realize real-time dynamic sensing with large measurement range. Furthermore, the capability of maximum strain measurement will be studied. The research is significantly meaningful in the fields of the structure health monitoring and precaution, the study of mechanical behaviors of materials and the intrusion detection for defense security.

现有的动态分布式布里渊光纤传感技术存在应变测量范围小或实时性差的问题。本项目提出一种基于多频矢量布里渊光时域分析的动态分布式光纤传感方法。此方法主要具有两个技术特点。首先，此方法利用布里渊相移与增益比形成的“相移增益比斜坡”曲线测量动态应变，为矢量布里渊分析方法，具备实时性高、测量误差小的优点；第二，此方法为多斜坡矢量布里渊分析法，通过构造多个首尾级联的相移增益比斜坡，可显著拓展应变的测量范围，有效解决此前斜坡法存在的应变测量范围小的问题。本项目研究从布里渊增益谱和相移谱特性入手，研究应变和泵浦条件等因素对相移增益比斜坡的影响规律。在此基础上，开展基于单频泵浦和捷变频泵浦的矢量布里渊光时域分析动态传感技术研究，实现大测量范围的、实时的动态分布式光纤传感，并探究该方法的应变测量极限。该项目研究在结构健康监测与预警、材料力学性能研究、周界安防等领域有重要的应用价值。

本项目主要针对动态传感技术开展研究工作。针对现有的动态分布式布里渊光纤传感技术存在应变测量范围小或实时性差的问题，本项目提出了基于多频矢量布里渊光时域分析的动态分布式光纤传感方法。该方法通过测量矢量布里渊谱的两个分量：布里渊增益谱和相移谱分量，利用布里渊相移与增益比形成的“相移增益比斜坡”曲线测量动态应变。相对于单一的基于布里渊增益谱的斜坡辅助型传感技术，该方法应变测量范围大，测量结果不受泵浦光功率波动干扰。在实验上，利用单相移增益比斜坡布里渊传感技术实现了多达2467微应变的动态应变测量，该测量范围显著大于单增益斜坡传感技术。在此基础上，利用捷变频术构造了多个首尾级联的相移增益比斜坡，将单斜坡的应变测量范围拓展至多斜坡，从而使之具备动态大应变测量能力。在实验中实现了最大为5373微应变的动态应变信号测量（该结果并非受限于多斜坡技术，而是受限于动态应变产生装置的应变产生能力）。该项目研究在结构健康监测与预警等领域有重要的应用价值。除完成预计研究任务以外，我们又拓展了研究内容，开展了基于双调制捷变频技术的分布式应变传感技术和基于应变传感的形状传感技术的研究工作。