为实现高灵敏度的盐度测量，提出了一种基于空芯光纤的单模光纤–空芯光纤–单模光纤（SMF-HCF-SMF）复合双腔光纤法珀（F-P）盐度传感器。该传感器通过精密切割结合光纤熔接技术制备，结构小巧，工艺简单。通过HCF段空气腔与SMF段介质腔所对应的反射光谱干涉信号的振幅之比对盐度进行测量，可以有效剔除光源功率起伏以及其他外部干扰的影响，实现盐度的高灵敏度测量。利用该传感器进行了盐度测量实验，在0%～24%的范围内实现了高达0.101 %⁻¹的盐度测量灵敏度，同时传感器表现出了良好的线性响应。

A compound dual-cavity fiber-optic salinity sensor based on hollow core fiber with a structure of single-mode fiber-hollow-core fiber-single-mode fiber (SMF-HCF-SMF) was proposed and demonstrated. The sensor achieves the salinity measurement through the amplitude ratio of the reflection spectral interferometric signals form the HCF air cavity and the SMF dielectric cavity. By using this method, interferes from fluctuations of the source power and other external disturbances can be effectively removed, so high sensitivity measurement of salinity can be realized. By precise cutting and fiber fusion, corresponding compound dual-cavity Fabry Perott sensing structure was fabricated, and real salinity measurement experiment was carried out. In a salinity range of 0%-24%, a salinity sensitivity of 0.101%^-1 was achieved. Meanwhile, the sensor shows a good linear response.