Research On Fiber Grating Differential Vibration Sensing Method Based On Fiber Laser

With the rapid development of modern science and technology,vibration detection plays an increasingly important role in the field of modern engineering.The existing vibration measurement methods include mechanical method,electrical method and optical method;Electrical measurement method is easy to be affected by electromagnetic interference,which limits the application of the above two methods in some special occasions;Optical measurement can make up for these defects by reflecting vibration signals with optical parameters,which is widely used.As a widely used sensor in optical measurement,fiber grating sensor has the advantages of high sensitivity,insensitivity to electromagnetic interference,easy reuse and so on.It can measure a variety of physical quantities such as temperature,strain,vibration and fluctuation,and plays an important role in the sensing field.In this project,fiber laser technology and grating vibration sensing technology are combined,and the fiber grating differential vibration sensing method based on fiber laser is deeply studied.Firstly,this paper introduces the research background and significance of the subject,and summarizes the research status of fiber laser and fiber grating vibration sensing based on fiber laser.On this basis,the theory of erbium-doped fiber laser and fiber grating sensing is analyzed.Secondly,a fiber Bragg grating differential vibration sensing system based on fiber laser is designed,which uses fiber laser as light source to improve the utilization of optical power;The double matched fiber Bragg grating structure is used for differential adjustment of the sensing system,which can double the detection sensitivity and reduce the temperature effect adaptively in theory.At the same time,OptiSystem software is used to optimize the length of erbium-doped fiber and the splitting ratio of coupler,which improves the performance of the sensing system.The characteristics of single matched grating vibration sensing system and double matched grating differential vibration sensing system are analyzed and compared by using OptiSystem software.The simulation results show that the sensitivity of double matched grating differential vibration sensing system is higher than that of single matched grating vibration sensing system.Finally,according to the design scheme of FBG vibration sensing system,the FBG cantilever vibration sensing experimental system is built,and the influence of wavelength and bandwidth matching of FBG on the output of the system is analyzed to realize the vibration signal sensing detection;The acoustic vibration sensing experimental system is built,and the output characteristics of the sensing system at different acoustic frequencies are analyzed to realize the acoustic signal sensing detection.