Simultaneous measurement of temperature and humidity based on FBG-FP cavity

Based on Fresnel reflection and Fabry-Perot (FP) interference theory, the FBG-FP cavity sensor is designed, which combines fiber Bragg grating (FBG) with Fresnel reflection on the fiber end face. The transmission characteristics of the sensor are investigated, and the temperature and humidity sensing experiments are carried out. The experimental results show that the change of temperature only affects the characteristic wavelengths of the interference spectrum, while the change of humidity only relates to the transmission intensity of the interference spectrum, and the sensitivities of temperature and humidity are 10.88 pm.degrees C-1 and 0.0682 dB.% RH-1, respectively. Therefore, using the different influence factors of temperature and humidity on interference spectrum of the FBG-FP cavity sensor, the simultaneous measurement of temperature and humidity is realized. The sensor is used for single-end measurement, which makes the operation simple and fast. Given the simple structure, easy preparation, and low cost, the sensor promises an excellent application prospect in the fields of industry and agriculture.