Research Of Tapered Fiber Bragg Grating Magnetic Field Sensor Based On Magnetic Fluid

Nowadays,with the rapid development of magnetic field sensing method,the traditional magnetic sensing method is susceptible to electromagnetic interference,so the traditional magnetic sensing method has been restricted in many fields.It can be found that it is important to design a new type of magnetic field sensor with new functional material.The optical fiber is a kind of insulation material in essent,so there are many unique characteristics in the magnetic field sensor,it is not sensitive to electromagnetic interference,and some other advantages such as light weight,corrosion resistance,small size.The tapered fiber Bragg grating is a new type of optical waveguide devices with nanometer and micron in diameter,it is a combination of evanescent field of the tapered optical fiber transmission characteristics and the choice of the wavelength of fiber Bragg grating optical properties,it has so many advantages,such as,the fast response speed,high reliability.In addition,the high temperature regenerated fiber grating has the advantages of not easy to be erased in the high temperature environment,the high temperature stability is essentical to the magnetic field.Especially,the most important is that it is not subject to electromagnetic interference,even in the flammable and explosive work environment,it can also work safely without accident risk.The High temperature regenerated fiber grating has a strong temperature stability and can be considered from low temperature and high temperature.The high temperature stability of the high temperature regenerated fiber Bragg grating can ensure that the grating area is intact and not erased.The sensitivity of the low temperature segment decreases with the normal fiber grating,but the stability is greatly improved.Compared with the same temperature,the common single-mode fiber Bragg grating has been erased.The magnetic field sensor combined with magnetic liquid used for sensing,and magnetic liquid as a kind of new functional material,it has a liquidity but it also retained solid magnetic,it is particularly important that the refractive index of liquid is affected by the strength of the magnetic field.Based on the above three points,this paper propose a novel tapered fiber grating magnetic field sensor based on magnetic fluid,including magnetic fluids as out layer of tapered regenerated fiber Bragg grating,the index of magnetic fluid has been controlled by changing the variable magnetic field intensity,and then realize the magnetic field sensor measurement.The main contents are listed as follows:(1)The development of optoelectronic sensing technology has been summarized,this paper introduces the classification of fiber optic sensor,analyzes the characteristics of magnetic liquid,including some of the main properties of magnetic fluids,it should be focused on performance indicators in the experiment,and its development and application of magnetic control index of focused on the magnetic properties.(2)The relationship between the refractive index and the effective refractive index of the tapered fiber grating is calculated in theory,the tapered fiber gratings of different structural parameters is be analyzed by using Rsoft software.the conclusion of simulation is the smaller the diameter of the taper waist,the higher sensitivity of the refractive index of fiber grating to external environment,and chirp in the shape of tapered fiber grating for external environment,the sensitivity of the refractive index is higher than the tapered area of uniform type tapered fiber Bragg grating.(3)The experimental system has been set up for the high temperature regenerated grating,and the regenerated fiber grating is placed into the high temperature furnace,the temperature characteristic and repeatability experiments are tested after doing the high temperature experiment.There are some problems in it when considering the operation in every detail and the experiment system.A new type of high temperature experiment system is designed(4)The new type of tapered experiment system has been designed based on fused biconical taper,choose the method of local heating resistance wire heating of regenerated fiber grating,which protects the tapered fiber grating effectively and makes it not easy to be damaged.(5)The magnetic field sensor based on tapered regenerated fiber Bragg has been set up.The studies have shown that with the increase of magnetic field intensity,the wavelength center of the tapered fiber Bragg grating towards long wave length direction,the sensitivity of the sensor is 731 pm/mT.In this paper,the characteristics of the refractive index of the tapered fiber Bragg grating sensor from the aspects of theory and experiment,and a new type of magnetic field of the tapered fiber Bragg grating sensor based on magnetic fluids has been designed.