Research On Fiber Temperature-pressure Sensing Method Based On Hybrid Fabry-Perot Cavity

Optical fiber sensing technology has been studied deeply in many fields,such as biological industry,petroleum chemical industry and aviation industry.Not only a single parameter,but also double parameters such as temperature-refractive index,temperature-stress and temperature–pressure can be measured using optical fiber sensing technology.This paper studies the principle of low-coherence interference in the field of optical fiber sensing.Based on the low-coherence interference system,a kind of optical fiber temperature-pressure sensing method for composite F-P cavity sensor is proposed.At the same time,to solve the problem that the interference fringe envelope is too wide to affect the measurement range,the compression effect of the dual-light-source module on the interference fringe's envelope is studied.Finally,a temperature-pressure dual-parameter sensing experiment was carried out.The finished research works are as follows:1 ? The basic principle of optical fiber F-P low-coherence interference demodulation system is studied and a low-coherence interference theoretical model is constructed.The influence of the light source bandwidth on the envelope width of the interference signal is emphatically studied,the polarization of O and E in the birefringent crystal wedge is analyzed.Several main demodulation methods of low coherent interference system are introduced,and their distinguishing features are compared.2?In this paper,an optical fiber temperature and pressure dual-parameter sensing method based on the composite F-P cavity sensor is proposed.The compression effect of the dual-light-source module on the interference fringe envelope is studied to solve the problem that the interference fringe envelope is too wide.The nonlinear compensation algorithm between spatial frequency sampling points and wave number is studied by analyzing the position correlation dispersion of birefringent crystal wedge.3?An optical fiber temperature-pressure sensing method based on the composite F-P cavity sensor is constructed,and two different types of composite F-P cavity sensors are used to carry out the temperature-pressure dual-parameter sensing experiments.In pressure scope of 3 kpa to 228 kPa and temperature scope of-20 ? to 70 ?,the silicon ring structure sensor's pressure measurement accuracy is 0.3% F.S.,temperature measurement accuracy is 1% F.S..In pressure scope of 3 kpa to 283 kPa and temperature scope of-20 ? to 70 ?,MEMS sensor's pressure measurement accuracy is 0.15%F.S.,temperature measurement accuracy is 0.41% F.S..Meanwhile,the effectiveness of the dual-parameter sensing method is verified.