Study On Fiber Sensor Based On Fabry-Perot Interference

Fabry-Perot interferometric fiber optic sensor realizes the interference between beams by constructing FP cavity on the optical fiber.When the measured physical quantity changes,the phase difference of its two coherent light also changes,and the interference spectrum drifts.F-P sensors have the advantages of simple structure,small size and easy packaging.Therefore,based on the principle of optical fiber Fabry-Perot interference,two types of sensors were fabricated in this paper,and the gas concentration and temperature were detected and studied respectively.It is intended to solve the problems of high temperature,low selectivity,poor stability,and low sensitivity in conventional gas detection;and the high cost of sensor production in temperature detection,the circuit is prone to corrosion and short circuit,the results are subject to background radiation,measurement distance and gas composition,etc.Factors affecting issues.The main research work of this article is as follows:(1)Use a fiber cleaver to cut the end surfaces of single-mode optical fibers and photonic crystal fibers flat.By adjusting the fiber fusion splicer program(changing the discharge intensity and discharge time),the collapse layer of the two fiber fusion splicing surfaces is weakened to form a reflective end surface.Coated with sensitive material on the end,the double FP sensor structure was successfully prepared.(2)Composite polyaniline and tri-cobalt tetroxide material,through X-ray photoelectron spectroscopy(XPS),Raman spectrum,X-ray diffraction(XRD),Fourier Infrared spectroscopy(Fourier transform infrared spectroscopy,FT-IR)analysis prove its successful preparation.The material is coated on the end surface of the EPCF fiber using a dip coating lifter coating machine,with a thickness of about 20 ?m.(3)Connect the prepared FP gas sensor to the test platform for carbon monoxide gas detection.In the range of gas volume fraction 0-70 ppm,the sensor has a good linear relationship and selectivity,sensitivity is 21.61pm/ppm,response and the recovery time is35 s and 84 s respectively.(4)In view of the problems of low stability,large influence by external background radiation,and high cost of existing temperature detection,this paper successfully used hydrofluoric acid etching technology to prepare an optical fiber with simple structure,low cost,and high stability FP temperature sensor.The linearity is good in the temperature range of 28-81?,and the sensitivity is 64.6pm/?.(5)In order to expand the temperature measurement range,another F-P temperature sensing structure was prepared using ultraviolet glue and capillary,and the temperature measurement system was improved.The sensitivity was 41pm/ ? in the temperature measurement range of 25.7-250?.