The Simulation And Demodulation Of Optical Fiber FP Sensing Structure

As a typical representative of interferometric optical fiber sensors,the optical fiber Fabry-Perot sensing structure is one of the most universal and mature optical fiber sensors in practice.It has the advantages of large dynamic range,high sensitivity,good stability,anti-electromagnetic interference,suitable for harsh environments,and the ability to achieve remote multiplexing,etc.it has a wide range of applications in electric power,transportation,biochemistry,aerospace,humanities,meteorology and other fields.However,there are two major bottlenecks about the current application and development of the fiber Fabry-Perot sensing technology.The first is how to design and manufacture sensors with high stability,low cost and excellent performance,and the second is how to develop a fast,high-resolution and stable demodulation system.Based on these,in this paper,the extrinsic fiber-optic Fabry-Perot interferometer(EFPI)sensor is used as the research goal.In view of the related problems in scientific research and industrial practice,a systematic and in-depth research was carried out on three core contents of sensing principle and characteristic analysis,sensor design and production,demodulation system design and application.The scientific research achievements and novelty of this paper can be summarized as the following three points:(1)Based on the research status of the fiber-optic Fabry-Perot sensors at home and abroad,the structure types and demodulation methods of current fiber-optic FP sensors were summarized.At the same time,combined with MATLAB,RSoft,COMSOL Multiphysics software and simulation theory algorithms,the sensing characteristics of two special sensor structures SCS-FP and FBG-FP were simulated and analyzed.(2)A high-precision extrinsic fiber-optic Fabry-Perot interferometric(EFPI)demodulation system was designed.Based on this,a sensing structure(SMF-Capillary-SMF)with excellent optical and mechanical properties was designed and fabricated,and its sensing characteristics were experimentally investigated.The device design layout and software programming control of the demodulation system were accomplished.A demodulation method(nonlinear least squares fitting algorithm)based on spectrum sampling and reconstruction was proposed and it was successfully embedded in the LabVIEW demodulation program.(3)The practical sensing applications of strain and temperature for the high-precision optical fiber FP sensing system were investigated.Based on these,the whole extrinsic fiber-optic Fabry-Perot interferometric(EFPI)demodulation system was established and the feasibility and accuracy of the system demodulation algorithm were verified experimentally.The strain sensing demodulation of the demodulation system was investigated,and the resolution and stability of the demodulation system were analyzed.An automatic temperature sensing device was designed and combined with the demodulation system it could achieve automatic sensing measurements of temperature.