Research On Double Parameter Synchronous Measurement Optical Fiber Sensor

In recent years,two-parameter measurement based on optical fiber sensing has played a very important role in many fields such as aerospace,civil engineering,environmental monitoring and petrochemical industry.In this thesis,the monitoring requirements of gas pressure,transverse load,curvature and temperature in practical engineering are studied.The dual-parameter sensing applications of gas pressure and temperature,transverse load and temperature,curvature and temperature are realized respectively.Specific work is as follows:A sensor based on Antiresonance(AR)mechanism and Fabry Perot(FP)interference for simultaneous measurement of gas pressure and temperature is proposed.The sensing structure is composed of a single-mode fiber that has been polished using a fiber polishing machine and fused with a hollow core fiber-single mode fiber structure.A microchannel is formed between the polishing end face of the single mode fiber and the fusion interface of the hollow core fiber,so that the sensing structure maintains the same pressure with the outside world.The light field distribution of the sensor structure is simulated by the beam propagation method.The influence of hollow core fiber length on reflection spectrum is studied.Based on AR mechanism and FP interference theory,the sensor structure is tested by gas pressure and temperature,and its sensitivity and linearity are analyzed.Combined with the sensitivity coefficient matrix,the two-parameter measurement of gas pressure and temperature is realized.A sensor for simultaneous measurement of transverse load and temperature based on three beam FP interference is proposed.The sensing structure is simple.It is made of a single mode fiber and a hollow core fiber for fusion,using arc discharge technology to melt the hollow core fiber into an air bubble under high current intensity,and fusing a section of single mode fiber at the rear end of the air bubble.The air bubble in the structure and the end single mode fiber can be used as two double-beam FP cavities respectively to test the transverse load and temperature of the sensor structure.The reflection spectra of the FP cavity of the air-bubble and the FP cavity of the single mode fiber are extracted by filtering method,and the different responses of the two FP cavities to the transverse load and temperature are analyzed.The simultaneous measurement of transverse load and temperature is realized by combining the two-parameter sensor matrix.A sensor based on Mach-Zehnder interference(MZI)is proposed to measure the curvature and temperature simultaneously.The sensing structure is formed by a hollow core fiber with both ends polished by an optical fiber polishing machine and completely filled with polydimethylsiloxane(PDMS)polymer,and two sections of multimode fiber-single mode fiber structure.The beam propagation method is used to simulate the light field distribution of the proposed sensor structure.The transmission spectrum of the sensor structure is simulated by finite element analysis software.The influence of the length of hollow core fiber on the transmission spectrum is studied by experiments.The proposed sensing structure is measured by curvature and temperature,and its sensitivity and linearity are analyzed.The simultaneous measurement of curvature and temperature is realized by using a two-parameter sensor matrix.