Optical Fiber Temperature And Pressure Sensor Based On Microstructure Optical Fiber

In fields such as automated manufacturing,aerospace,and military,the measurement of temperature and pressure plays a crucial role.In recent years,fiber optic sensors have attracted attention due to their small size,low susceptibility to electromagnetic interference,and high accuracy.Guided by the high sensitivity of temperature and air pressure measurement,this paper introduces single-mode fiber and graded index fiber to form a collimating structure,and combines the principle of optical vernier effect to increase sensitivity,designs and successfully manufactures an optical fiber temperature and air pressure sensor based on microstructure fiber,and carries out simulation verification and experimental test on the sensing principle and characteristics of the sensor.The main job responsibilities include:(1)The properties of the collimation structure composed of single mode fiber(SMF)and graded index fiber(GIF)were analyzed and discussed from the perspectives of theory and simulation.From a theoretical perspective,the transmission characteristics of light in gradient index optical fibers were analyzed;The refractive index of the gradient index fiber used in this article was obtained through experiments and the refractive index distribution curve was fitted to calculate the required length of the gradient index fiber in the collimation structure;The RSOFT software was used to model and simulate the light field distribution of the collimating structure,verifying the feasibility of using gradient refractive index fibers to design the collimating structure.(2)A temperature sensor based on microstructure fiber was designed and fabricated.The sensor structure is: single-mode fiber,graded index fiber,hollow core fiber(HCF),polydimethylsiloxane(PDMS).Using a single mode fiber and a gradient index fiber to form a collimation structure,the fundamental mode field and beam of the single mode fiber are expanded and collimated;A dual cavity Fabry Perot sensor with a medium of air and a medium of polydimethylsiloxane was formed by filling the air cavity at the tail end of the hollow fiber with polydimethylsiloxane.The hybrid cavity formed by a single air cavity and two cavities generates an optical vernier effect,improving the sensitivity of the sensor.Theoretical analysis was conducted on the principle and characteristics of temperature sensing,and the sensing structure was simulated and verified using MATLAB software;The temperature sensitivity was measured through experiments,and the experimental results showed that the envelope of the cursor shifted red as the temperature increased,reaching a sensitivity of 0.96 nm/℃.(3)An optical fiber pressure sensor based on micro structure optical fiber is designed and fabricated.The structure is: single-mode optical fiber-graded index optical fiber-three hollow core optical fibers with different core diameters.Among them,a single mode fiber and a gradient index fiber form a collimation structure,which expands and collimates the fundamental mode field and beam of the single mode fiber;The hybrid cavity composed of the air cavity of the first hollow fiber and the air cavity of the first two hollow fibers forms an optical vernier effect,greatly improving the pressure sensitivity of the sensor.Theoretical analysis was conducted on the principle and characteristics of air pressure sensing,and the sensing structure was simulated and verified using MATLAB software;The pressure sensitivity of the sensor measured through experiments reaches 68pm/k Pa;Through temperature testing,the sensor exhibits strong resistance to temperature interference.