The Tilted Fiber Bragg Grating(TFBG) Magnetic Field Sensor Based On Magnetic Fluid

There are many areas that require magnetic field detection,such as engineering structure safety detection,aerospace and ship sensing,electric power industry,petrochemical industry and so on.The traditional magnetic field detection device mainly integrates electronic components into the sensing system,converts the magnetic signals into electrical signals and then carries out inversion sensing and detection.The main sensor parts are Gauss meter and Fluxgate.However,the traditional magnetic field sensor has many disadvantages,such as poor signal conversion efficiency,and the result is susceptible to electromagnetic interference generated by the electronic components themselves.In this paper,a new magnetic field measurement method is proposed,which is based on magnetic-fluid-based tilted fiber Bragg grating magnetic field sensor.As an essentially insulated material,optical fiber has unique advantages in magnetic field sensing.In addition to being free from electromagnetic interference,it also has the advantages of light weight,small volume,high precision and easy to form distributed measurement.Tilted fiber Bragg grating is a kind of fiber Bragg grating,whose grating fringe is at an Angle with the fiber core in the axial direction.It not only has the characteristic of common fiber Bragg grating,but also has the characteristic of long period fiber Bragg grating sensitive to the outside environment,it can realize multi-parameter simultaneous measurement,effectively solve the cross-sensitive problem,and can realize the magnetic field direction measurement.As a new type of functional material,magnetic fluid has both the magnetism of solid and the fluidity of liquid.It has magnetooptic effect,magneto-birefringence effect,adjustable index of refraction and Faraday effect,especially its adjustable index of refraction,which makes it possible to measure magnetic field by combining magnetic fluid with optical fiber.The main research contents and innovation points of this paper are as follows:(1)The principle,characteristics,writing method and application prospect of fiber Bragg grating are introduced,and the principle,fabrication method,characteristics and application field of magnetic fluid are introduced.(2)The theory of mode coupling,writing method and sensing principle of TFBG are introduced,and the principle of optical fiber surface plasmon resonance technology and its application in the field of optical fiber sensing are introduced.(3)The effect of magnetic fluid film thickness on the wavelength shift and peak value of fiber Bragg grating transmission spectrum was studied.The influence of temperature and external environment on magnetic field measurement was solved by means of compensation method.(4)Summary and prospect:it is proposed to produce SPR effect on the surface of optical fiber to increase the sensitivity of optical fiber surface.In addition,an asymmetric magnetic fluid coating on the surface of the optical fiber is proposed to obtain a magnetic field sensor with the best comprehensive performance.