Research On Fiber Optic Fabry-Perot Sensor Based On Fusion Technolog

Since the 1970s,Optical fiber sensing technology has rapidly developed based on electronic device technology,optical fiber communication technology,and computer technology.It plays a very important role in the development and application of optoelectronic technology and is an important indicator to measure the level of informatization of a country.optical fiber sensors,with the advantages of compact structure,small size,anti-electromagnetic interference,and fast response,can accurately measure external physical quantities such as strain,humidity,and air pressure.They are widely used in aerospace satellites,meteorological forecasting,industrial manufacturing,and other fields.However,the current production of optical fiber sensors tends to rely on new materials and requires high production processes and procedures,which increase the production cost of sensors and may pose certain limitations to their mass production and popularization.Therefore,this thesis proposes an air-cavity-based Optical fiber Fabry-Perot sensor,which is made and optimized using fusion splicing technology.The strain and humidity sensing characteristics of the sensor are analyzed.The main research contents of this thesis are as follows:1.An optical fiber Fabry-Perot sensor based on air cavity is proposed and fabricated.This sensor uses chemical etching to corrode the optical fiber end face,and analyzes the effects of different fusion splicing parameters on fiber fusion based on the principle of arc discharge.After multiple experimental tests,suitable fusion splicing parameters are obtained.By splicing multimode fibers(MMF)that have undergone different chemical etching times,three optical fiber Fabry-Perot sensors with different air cavity lengths(54.35 μm,70.63 μm,and 100.52 μm)are obtained for strain sensing characteristic analysis.The experimental results show that within the range of 0 ～ 8750 με strain,all three sample sensor can achieve strain measurement with good sensing characteristics: the linearity is 1.26%,2.5%,and 1.27% respectively,and the sensitivity is 490.42 nm/ε,373.14 nm/ε,and 335.66 nm/ε respectively.At the same time,they exhibit good stability.2.To address the problem that chemical etching can result in a certain curvature of the aircavity reflective surface,the effect of reflective surfaces with different curvature radii on reflection intensity,interference contrast,and fringe fineness is studied.Furthermore,a method for optimizing the air-cavity reflective surface using arc discharge is proposed.The experimental results show that the sensor optimized by arc discharge reduces the interference loss of light in the optical fiber core,allowing more light to participate in interference,thereby improving the interference contrast and fringe fineness.The interference contrast can reach 26 dB.To expand the application range of the sensor,on the basis of the previous structure,one end of the multi-mode fiber is cut flat and a layer of Polyvinyl Alcohol(PVA)film with a thickness of 14 μm is coated on the end face.Within the range of ambient relative humidity of 29.1% to 81.8% RH,the average sensitivity of the sensor can reach 73.24 pm/%RH,and it exhibits good stability.In summary,the optical fiber Fabry-Perot sensor made by welding technology has the advantages of low cost,compact structure and simple preparation process,and has a good application prospect in the field of strain and humidity detection.