基于多光束干涉原理，设计了一种基于光纤微腔的温度及折射率同时测量的反射型光纤传感器.该传感器将渐变折射率多模光纤的一端用氢氟酸腐蚀形成一个空气腔，带空气腔的渐变折射率多模光纤一端和单模光纤熔接，另一端切平构成传感头.实验选取渐变折射率多模光纤的长度为538.1 μm，空气腔长度为40.8 μm.结果表明：光纤微腔结构所形成的多光束干涉光谱条纹对比度与光纤微腔外的溶液折射率相关，干涉波峰移动与环境温度相关，通过监测条纹对比度和干涉波峰的移动，可以实现对折射率和温度的同时测量.当折射率在1.341 5～1.432 0RIU变化时，反射强度对折射率的灵敏度为57.24 dB/RIU；当温度在30 ℃～70 ℃之间变化时，谐振波长对温度的灵敏度为12.3 pm/℃，可检测到的最小温度变化为1.2℃，测得最小折射率变化为3.4×10－4.该传感器也可应用于其他参量的测量，具有良好的应用前景.

Simultaneous measurement of refractive index and temperature based on an optical fiber cavity sensor was demonstrated, which is a reflective and multi-beam interference based sensor. The sensor head is made up of a normal single mode fiber, a graded-index multimode fiber and an air gap. The air gap just locates between the single mode fiber and the graded-index multimode fiber. The lengths of the graded-index multimode fiber and the air gap are 538.1 μm and 40.8 μm, respectively. The fringe contrast and the wavelength of the interference, due to multiple beam interferences in the sensor head, vary with the RI and temperature of the solution, respectively. Hence, the simultaneous measurements of refractive index and temperature, by monitoring the movement of the fringe contrast and the wavelength of the interference, were achieved. Experimental results show that the proposed optical fiber cavity sensor presents a RI sensitivity of 57.24 dB/RIU in the measurement 1.341 5~1.432 0RIU and a temperature sensitivity of 12.3 pm/℃ in the range of 30 ℃~70 ℃. The minimum temperature that can be detected is 1.2℃，the minimum resolution of RI that can be detected is 3.4×10－4. This optical fiber cavity sensor can also be applied in other sensing fields and has good prospects.