Research Of EFPI Sensor Demodulation Technology And Sensor System

Fabry-Perot?F-P?sensor as a new structure in the development of optical fiber sensing technology has shown excellent application value in military defense and aerospace,industrial production,medical and health and many other industries,due to its compactness,harsh environment,high sensitivity,multiplexing and other advantages.However,many F-P sensors are not only relatively complicated in production process,high in cost,but also have a tedious and slow demodulation scheme.These all restrict the application of F-P sensors in practice.Therefore,this paper proposes a differential dual-wavelength light intensity ratio method for the demodulation of the sensor signal of the extrinsic Fabry-Perot Interferonmenter?EFPI?sensor.And based on this,a set of EFPI sensor system with low cost,fast demodulation speed and simple and stable structure is designed.The main research contents are as follows:?1?The sensing principle and demodulation methods of F-P sensor are analyzed in detail.The reflected light and transmitted light intensity distribution of EFPI sensor at different end face reflectivity are simulated by Matlab software.The Rsoft software is used to simulate the light field distribution of EFPI sensors with different cavity lengths.The structure of EFPI sensor coated with polydimethylsiloxane?PDMS?on the outer layer of the sensing area is proposed for temperature sensing.The fabrication process of Single-Mode Fiber Capillary Single-Mode Fiber?SMF-CAPILLARY-SMF?EFPI sensor is introduced.?2?A differential dual-wavelength light intensity ratio method is proposed.There is a good linear relationship between the EFPI sensor interference cavity length variation and the differential dual-wavelength light intensity ratio.The theoretical derivation,Matlab simulation and strain experiments prove that the demodulation algorithm is accurate and fast.In the experiment,the minimum demodulation resolution of the EFPI sensor with d=196.851?m is 0.726 nm.When the dual wavelengths at different positions are selected,the linear range of the EFPI sensor cavity length variation are 180 nm,150 nm and 130 nm,respectively,and the corresponding sensitivity is-0.01099 nm^-1,-0.01485 nm^-1 and-0.02253nm^-1.This also shows that in practice there is more flexibility for dual wavelength selection.?3?An EFPI sensor system is designed,and the hardware and software development of the EFPI sensor system are completed.The strain and temperature sensing experiments on the EFPI sensor system show that the EFPI sensor system is stable and reliable.At the same time,the reconstruction of the EFPI sensor spectrum is realized by using LabVIEW software,and the control program development and interface design of the external temperature control equipment are completed.