基于布里渊动态光栅的可移动探针式分布式光纤传感技术

Brillouin dynamic grating (BDG) is a novel optical fiber sensing technology, the numerous measurement methods based on which have become popular research focus in recent years. The deficiency in terms of the inferior frequency response in the traditional distributed optical fiber vibration sensor is heretofore unsolvable, considering the issue of being unable to simultaneously respond to multiple intrusion events when it is conjunctively used with Mach-Zehnder interferometer. This project proposed a movable probe-type optical fiber sensor based on the technique of Brillouin dynamic grating. Via theoretical analysis and experimental tests, a pair of mirror Brillouin dynamic gratings at any two positions along the fiber are supposed to be created by injecting two sweep-frequency pump waves in the opposite transmission direction with specific frequency relationship. The formed Brillouin dynamic gratings serve as two reflectors which are capable of reflecting the probe wave whose frequency satisfies the phase matching condition, such that a dynamic and tunable Michelson interferometer can be flexibly fabricated based on which the high-frequency consecutive detection for vibration events can be reasonably realized. Temperature and strain can also be resolved by exploiting their effect on the Brillouin frequency shift and the birefringence frequency shift. Thus the vibration, temperature and strain around the BDG probe can be simultaneously measured. The project involves certain key scientific issues and is believed to exhibit obvious novelty, scientific value, social significance and promising application prospects.

布里渊动态光栅是一种新型光纤传感技术，基于布里渊动态光栅的众多测量手段近年来成为光纤传感领域的研究热点。传统分布式光纤振动传感器频率响应的不足，即使同马赫泽德干涉仪复用，系统也无法同时对多点信号进行响应。本项目提出基于布里渊动态光栅的可移动探针式光纤传感器，拟通过理论和实验研究，通过向保偏传感光纤中对向注入具有特定频率关系的扫频泵浦光，在光纤中的任意两个位置形成一对镜像布里渊动态光栅探针。形成的光栅通过受激布里渊散射效应对波长满足相位匹配条件的探测光进行反射，从而形成动态可调配的迈克尔逊干涉仪结构，以实现对待测点振动的高频率响应连续探测能力。同时利用布里渊频移和双折射频移对应变和温度的交叉敏感性，进行温度和应变的解耦，从而实现探针附近位置振动，温度，应变的同时测量。该课题的研究涉及若干关键科学问题，具有较高的创新性、科学价值、社会意义和非常可观的应用前景。

布里渊动态光栅是一种新型光纤传感技术，基于布里渊动态光栅的众多测量手段近年来成为光纤传感领域的研究热点。传统分布式光纤振动传感器频率响应的不足，即使同马赫泽德干涉仪复用，系统也无法同时对多点信号进行响应。本项目提出了基于布里渊动态光栅的可移动探针式光纤传感器.通过理论和实验研究，利用向保偏传感光纤中对向注入具有特定频率关系的扫频泵浦光，在光纤中的任意两个位置形成一对镜像布里渊动态光栅探针。形成的光栅通过受激布里渊散射效应对波长满足相位匹配条件的探测光进行反射，从而形成动态可调配的迈克尔逊干涉仪结构，以实现对待测点振动的高频率响应连续探测能力。同时利用布里渊频移和双折射频移对应变和温度的交叉敏感性，进行温度和应变的解耦，从而实现探针附近位置振动，温度，应变的同时测量。本项目在5km传感光纤上实现了探针点50kHz的高频振动响应，探针点由布里渊动态光栅对形成，可通过改变扫频光的初始频率和扫频速度调整探针点的空间位置和大小，从而实现可移动探针式目标点高频振动跟踪。另外，在振动测量时，可同时完成温度和应变的解调，通过实验对传感光纤的温度系数和应变系数进行了标定，并在高低温、阶梯拉伸试验中测试了温度、应变测量效果。温度精度为1℃，应变精度为20微应变。