基于光纤开放式法布里-珀罗干涉仪的液体折射率测量

Refractive Index Measurement of Liquid Based on Open Fiber Fabry-Perot Interferometer

法布里-珀罗(F-P)干涉仪结构的光纤传感器因其结构简单、体积小、高灵敏度等优点得到了广泛的应用,开放式法布里-珀罗干涉仪传感器可对待测液体的折射率进行测量。利用机械切割、飞秒激光击穿等方法可以制成开放式法布里-珀罗干涉仪。利用玻璃焊剂将开放的空心毛细管和两段单模光纤焊接在一起,制成开放式法布里-珀罗干涉仪传感器,并采用交叉相关的信号处理技术实现对待测液体折射率的绝对测量。采用不同浓度的氯化钠溶液进行折射率测量实验,折射率测量分辨率可达到10^(-5) RIU量级,传感器的温度灵敏度为39.59nm/℃。

Fiber optic sensors based on the Fabry-Perot （F-P） interferometer have been widely used because of its simple structure, small size, and high sensitivity. The refractive index of liquid can be measured by the open F-P interferometer. We can make an：open F-P interferometer through mechanical cutting, femtosecond laser breakdown and some other methods. An open F-P interferometer sensor is fabricated with an open hollow capillary and two segments of single-mode fibers welded together by glass flux. Absolute measurement of refractive index of liquid can be achieved when the cross-correlation signal processing technology is used. Refractive index measurement experiments are performed for NaCl solutions with different concentrations. The measurement resolution for refractive index can reach 10^-5 RIU magnitude, and the temperature sensitivity of the sensor is 39.59 nm/℃.