Study On The Fabrication Of All-fiber Vibration Sensor Based On A Fabry-Perot Cavity And Its Applications

In recent years,with the rapid development of optical fiber sensing technology,the optical fiber vibration sensors have been widely used in aerospace science,deep-sea because of their advantages such as good electromagnetic compatibility,high sensitivity,passive front end,miniaturization,easy to carry,easy to chime,facilitate the composition of sensor networks and remote monitoring.In the field of measurement,medical equipment,chemical and chemical industry,national security and other fields.It is believe that in the future development,The fiber optic vibration sensing technology is developing towards integrated and multi-functional direction.In this paper,based on the mechanism of optical fiber acoustic and ultrasonic sensing,a kind of vibration sensors probe based on micro Fabry-Perot cavity structure based on optical fiber is designed and fabricated,and the acoustic response characteristics of the all fiber structure sensor are studied in detail.In addition,we also use this all optical fiber vibration sensing probe to analyze and discuss the ultrasonic transmission characteristics of optical fibers in detail.The contents of the paper include the following six chapters.The details of each chapter are as follows:The first chapter mainly introduces the research background and significance of all optical fiber vibration sensors,the sensing mechanism and research status of optical fiber vibration sensors.Finally,this chapter is a summary of this chapter,and discusses the significance of the all optical fiber Fabry-Perot sensor developed in this paper.The second chapter mainly introduces the basic principle of all fiber microstructured optical fiber EFPI type vibration sensor.The interference principle of optical fiber sensor based on FP cavity is analyzed theoretically,and the distribution of light field in the structure of fiber FP cavity is simulated.Finally,the acoustic,ultrasonic detection and transmission characteristics of this sensor structure are analyzed.The third chapter mainly introduces the fabrication and temperature stability test of all fiber micro structure EFPI type vibration sensor.In this chapter,we first introduce the fabrication process of our all fiber structure Fabry-Perot cavity sensor.Then,the design and optimization,we finally realized a all fiber sensor with good temperature stability,with a cavity length of 208 um and a extinction ratio of 31 dB.The fourth chapter mainly introduces the acoustic detection research of all fiber micro structured optical fiber EFPI sensor.The acoustic response characteristic of the Fabry-Perot cavity sensor with all fiber structure is experimentally studied.The minimum detectable sound pressure under the noise restriction is 38.9 uPa/Hz1/2,and the sensitivity of the highest sound pressure response is 520 mV/Pa.Furthermore,we also analyze and discuss the directional selection characteristics of the acoustic response of the fiber sensor probe.The fifth chapter mainly introduces the ultrasonic testing system of all fiber micro structure optical fiber EFPI sensor.We use the FP cavity sensor we made respectively to study the ultrasonic transmission and coupling characteristics in the optical fiber.The characteristics of the coupling between the optical fiber and the PZT under different bonding conditions are obtained,and the parameters of the splicing point and the coating layer are analyzed.The transmission characteristics of ultrasonic wave in optical fibers are of practical significance for the application of these optical fiber ultrasonic sensors in practical engineering.The sixth chapter summarizes and summarizes the main contents of this thesis.This paper summarizes the characteristics of optical fiber vibration sensors,further summarizes the problems,enumerates the problems found in the experiment,finds and makes up the shortcomings of the experiment and puts forward the future prospect of the fiber vibration sensors.