The Design And Experimental Study Of Interferometric Microstructure Fiber 0ptic Sensor

Since the emergence of optical fiber in the 1970 s,with the continuous in-depth study of optical fiber technology,people have gradually realized that not only does optical fiber have good light transmission characteristics,but also can be used for information transmission without the need for other intermediate media.Measurements are linked to the characteristics of light in the fiber.Compared with traditional sensing technology,fiber optic sensors use light as a sensitive information carrier and optical fiber as a medium for transmitting information.Therefore,it has the characteristics of both optical fiber and optical measurement.It has a small size,high sensitivity and strong resistance to electromagnetic interference.It has many advantages such as radiation resistance,small energy attenuation,and integration of information sensing and transmission.This also makes fiber-optic sensing an extremely important part of modern sensing.Among them,fiber optic Mach-Zehnder interferometer(MZI)sensors and fiber optic Michelson interferometer(MI)sensors have been the focus of research on fiber optic sensors because of their compact structure and high sensitivity.This paper focuses on the design and experiments of fiber-optic sensors based on the above two interferometer structures.The main research contents are as follows:1.It mainly analyzes the principle of optical fiber sensing.Firstly,the physical mechanism of the optical fiber sensor is introduced,that is,the modulation principle of the sensor.Then,the principles of Mach-Zehnder interferometer and Michelson interferometer are analyzed in detail.The principle and advantages of Mach-Zehnder interferometer and Michelson interferometer with optical fiber structure are discussed through traditional optical structures.The sensor design and experimental research provide theoretical guidance.2.A temperature fiber optic sensor based on Mach-Zehnder interferometer is proposed.A single-mode fiber is fused on both ends of the tapered ring-shaped fiber to form a Mach-Zehnder interferometer structure.The influence of high refractive index ring layer(HIRL)on spectral interference and mode evolution is studied.The high refractive index ring layer is used to separate the fundamental mode and the cladding mode to complete the high-sensitivity detection of temperature by the optical fiber sensor.Through theory and experiments The feasibility of the interferometer as a temperature sensor was proved,and the maximum temperature sensitivity of 186.6 pm / ° C was obtained through experiments.3.Propose temperature fiber optic sensor based on Michelson interferometer.A small section of hollow fiber is connected to one end of the single-mode fiber,and the tail of the hollow fiber is discharged to form a ball lens to form a Michelson interferometer structure.The spherical lens has different focal points in different positions and different modes,so that it can distinguish different positions to complete the highly sensitive detection of displacement by the fiber optic sensor.The feasibility of the interferometer as a temperature sensor is proved by theory and experiments.The experiment obtained the maximum displacement sensitivity of 4nm.