Research On Hybrid Optical Material Based Fiber Optic Interferometric Sensing Technology

Fiber-optic sensors have many practical advantages,such as high sensitivity,corrosion resistance,light weight and so on.They have been widely used in the fields of petroleum exploitation,geological exploration and biochemical detection.Among them,the all-fiber structure of multimode-single-mode-multimode(MSM)and the silicon structure sensor based on Fabry-Perot(FP)interference have the advantages of simple structure,low cost and high sensitivity,which have attracted extensive attention from researchers.This paper aims to construct the theoretical model of MSM structure all-optical fiber sensing system and silicon-based microstructural sensing system based on FP interference,calibrated and optimized the refractive index(RI)sensitivity of the system,effectively reduced the adverse influence of temperature on the test accuracy,and realized the monitoring research of liquid level parameters by using the above-mentioned sensing system.Firstly,this paper summarized the development and research status of fiber optic sensor,respectively to Mach-zehnder,Fabry-Perot four common interferometric fiber optic sensor are introduced,analyzed the various sensing principle and the characteristics of structure,compares the application field of different sensors,as this paper provides evidence for the selection of sensor principle at work.Secondly,the basic principle of Mach-Zehnder interference is analyzed,and the research status of fiber optic sensor based on Mach-Zehnder interference principle is discussed.The theoretical model of MSM all-fiber optic structure sensor system is established,and the application research direction of MSM structure sensor is introduced.A kind of liquid level sensing scheme based on fiber MSM structure is proposed,and the change of external liquid level is analyzed by detecting the dip wavelength drift of interference.The highest refractive index sensitivity of the sensor is 131.63nm/RIU.As the length of the middle single-mode fiber increases,the liquid level sensitivity also increases.When the length of single-mode fiber is 26 mm,the liquid level sensitivity can reach 264.6pm/mm.In addition,the sensor structure is temperature-insensitive,and its sensitivity to temperature is only 6.63pm/°C,which can reduce or avoid the influence of temperature change on the experimental results.Furthermore,the optical fiber interference sensor with silicon wafer structure is studied.Based on the analysis of the principle of FP interference fiber optic sensor structure,a theoretical model of fiber optic interference sensor based on silicon wafer material is established.Because silicon has high thermo-optical coefficient and thermal expansion coefficient,this paper proposed an FP interference fiber optic sensor system based on silicon structure,which has the advantages of simple structure,low production cost and high sensitivity to temperature detection.A theoretical sensing model of silicon fiber FP interference was established,and the sensing structure was fabricated by UV curing.The silicon structure cylinder was used as the FP interference cavity,and the temperature sensitivity was up to 87.1pm/°C by sensing the deformation of the FP cavity caused by temperature change.Finally,the research contents of MSM all-fiber structure sensor and silicon fiber FP sensor proposed in this paper are summarized,and the future research planning is prospected.