Research On The Characteristics And Application Of Optical Fiber Sensor Based On Double-cone Mach - Zehnder

Sensor technology is an important pillar of modern information technology,while providing a more safe and convenient way of life for human beings.With the development of optical fiber and optical devices,the application of the characteristics of optical fiber in sensing direction is more and more extensive,among which the application of strain sensing based optical fiber sensor is particularly prominent.Since the early 1980 s,fiber optic sensing has been commercialized from the laboratory.After a long period of commercialization,more mature optical fiber sensing products such as fiber optic gyroscope,DAS system and fiber Bragg grating(FBG)were born.With the continuous progress and development of science and technology,ordinary single-mode fiber(SMF)transmission capacity and rate has been developed to the extreme.Multi-core fiber(MMF)integrated the technology of module division multiplexing and air division multiplexing,which greatly improves the capacity and rate of single fiber transmission.In the communication transmission,multi-core fiber has a large development space because of its multi-channel,large capacity and high rate not less than single-mode fiber.In the field of sensing,multi-core fiber has a high sensitivity to bending strain,which makes it widely studied.The main research work in this paper is as follows:1.Through Furukawa S178 A fiber fusion machine,the Mach-Zehnder fiber interferometer with mismatched fiber core was constructed and its interference principle was analyzed by using conical fiber microstructure processing method.The optimal parameters for tapered fusion of triangular lattice four-core fiber and ordinary single-mode fiber are studied.2.The FBG cascaded double thick tapered four-core fiber(FCF)Mach-Zehnder interferometer(MZI)fiber sensor is constructed and its sensing characteristics are analyzed.The FCF length suitable for MZI sensing part is selected to obtain the transmission spectrum that can be easily monitored.Based on the sensitivity of MZI to curvature,refractive index and temperature in the cascade sensor,the sensor is applied to the measurement of these three parameters.The experiment shows that FBG in the sensor is sensitive to temperature but not to curvature and refractive index,so the sensor can eliminate the influence of temperature when monitoring curvature and refractive index respectively.3.FBG cascade twin tapered four-core fiber MZI fiber sensor was constructed and its sensing characteristics were analyzed.It is different from the sensor structure mentioned above,so the physical quantity measured here is also selected differently.The MZI part of the sensor USES a fine cone as a beam splitter and coupler,and the FCF length as the MZI sensing part is selected to obtain the transmission spectrum for easy monitoring.The three physical quantities of axial stress,refractive index and temperature were tested respectively,including the sensing system,operation process,data processing and result analysis for each physical quantity test.The results show that MZI is sensitive to all three parameters,FBG is sensitive to axial stress and temperature but not to refractive index.