为了实现液体折射率的高灵敏度测量，提出并制备了一种基于游标效应增敏的全光纤液体折射率传感器.该传感器由法布里-珀罗传感腔和法布里-珀罗参考腔并联构成，其中，传感腔为开放腔，由单模光纤错位熔接制得，参考腔为封闭腔，由单模光纤与空芯光纤熔接制得.传感腔和参考腔的自由光谱范围相近，但不相等，双腔反射光经光纤耦合器后叠加产生游标效应，达到增敏的效果.实验结果表明，该传感器的折射率灵敏度约为9 048.78 nm/RIU，约是单个传感腔的8倍.该传感器具有灵敏度高、结构简单、易于制备、成本低廉的优点，在生物医疗、环境检测等领域有潜在的应用前景.

In order to realize the high sensitivity measurement of the liquid refractive index, a sensitivity-enhanced all-fiber-optic liquid refractive index sensor based on vernier effect is proposed and demonstrated. The sensor is composed of a Fabry-Perot sensing cavity and a Fabry-Perot reference cavity in parallel. The sensing cavity is an open cavity made by offset splicing of single mode fiber, and the reference cavity is a sealed cavity, which is fabricated by fusion splicing of single mode fiber and hollow optical fiber. The free spectral ranges of the two Fabry-Perot cavities are similar, but not equal. Vernier effect is generated when the beams are superimposed via a fiber coupler to achieve the sensitization effect. Experimental results show that the refractive index sensitivity of the proposed sensor is about 9 048.78 nm/RIU, which is about 8 times that of a single sensing cavity. Due to the advantages of high sensitivity, simple structure, easy preparation and low cost, the sensor has potential application foreground in chemical and biomedical domain.