Fiber-optic Temperature Sensor Based On SMS Structure

The study of fiber-optic temperature sensor based on Singlemode-Multimode-Singlemode(SMS) fiber structure at home and abroad almost about the parallel fiber-optic temperature sensor. Inspired by FOG and fiber-optic bending sensor’s structures and principles, SMS fiber structure was wound spirally on a metal tube to fabricate a kind of wavelength-encoded winding fiber-optic temperature sensor, which is the main research object. Parallel fiber-optic temperature sensor with the same parameter configuration would be made to compare the performance with that of winding fiber-optic temperature sensor. The thesis includes comprehensive theoretical analysis, experimental research and BPM simulation. Theory and experiment proved that winding fiber-optic temperature sensor has higher sensitivity than parallel fiber-optic temperature sensor with the same experimental parameters when appropriate length of Multimode Fiber(MMF)、suitable cross-sectional radius of metal tube and winding pitch of fiber were used. Absolute linear relationship exists in the full temperature range between wavelength-temperature to parallel fiber-optic temperature sensor, but only a limit linear temperature range exists to winding fiber-optic temperature sensor. Temperature sensor without MMF coating has slightly higher sensitivity than that with it. When aluminum tube、copper pipe、stainless steel tube were used as the metal tube, the sensitivity of winding fiber-optic temperature sensor were0.4504nm/℃、0.3049nm/℃and0.1140nm/℃respectively. Replace the metal tube with aluminum tube、copper pipe and stainless steel tube, the parallel fiber-optic temperature sensor with MMF coating has sensitivity-0.0507nm/℃、-0.0654nm/℃and-0.0513nm/℃respectively. In the same circumstances, the parallel fiber-optic temperature sensor with MMF coating has sensitivity-0.0510nm/℃、-0.0660nm/℃and-0.0513nm/℃respectively.