提出一种复合结构应变传感器,该结构将高灵敏度光纤法布里-珀罗干涉仪(FPI)内置于光纤Sagnac干涉仪(FSI)中。利用FPI光谱与定标的FSI光谱叠加产生的游标效应实现了FPI应变传感器灵敏度的大幅度提升。理论计算结果表明,复合结构传感器的灵敏度可以通过两套干涉谱的相对自由光谱区的差来调控。实验结果表明,复合结构传感器的灵敏度相对于单个FPI应变传感器提升了19.7倍,达到65.1 pm·με-1。复合结构传感器在需要高灵敏度测量以及精确测量的场景中具有重要作用。

A composite structural strain sensor is proposed, which incorporates a high-sensitivity fiber Fabry-Pérot interferometer (FPI) into the fiber Sagnac interferometer (FSI). The sensitivity of the FPI strain sensor is greatly improved by the vernier effect, which is caused by the superposition of the FPI and calibrated FSI spectra. The results of theoretical calculation show that, the sensitivity of the composite structure sensor can be regulated by the free spectral range difference between two sets of interference spectra. Further, the experiment results show that, the sensitivity of the composite structure sensor is increased 19.7 times compared with that of a single FPI strain sensor, reaching 65.1 pm·με^-1. The composite structure sensor plays an important role in scenarios requiring high sensitivity measurement and accurate measurement.