The Research On Key Technologies Of New Optical Fiber Micro Electric-field Sensor

In view of the increasingly complex requirements of modern environmental detection,we need comprehensive and multi-means composite detection.Following the magnetic field and sound field,electric field monitoring becomes more and more important.Fiber optic weak electric field sensor is one of the most potential weak electric field sensors.In order to find out which measurement method is most suitable for the detection of weak electric field,three kinds of all-fiber electric field sensors are proposed,including Fabry-Perot interferometric cavity weak electric field sensor,grating optical fiber electric field sensor and D-type electric field sensor based on graphene.By comparing the sensitivity and fabrication difficulty of these three kinds of electric field sensors,it is concluded that Fabry-Perot interferometric cavity weak electric field sensor is more suitable.The main contents of this paper are as follows:1.Firstly,the spectral characteristics of F-P cavity with different reflectivity are simulated and analyzed.The results show that the transmission spectrum has high precision at high reflectivity and the reflection spectrum has high precision at low reflectivity.When one end of the F-P cavity has low reflection,the brightness contrast of the fringes increases first and then decreases with the increase of the reflectivity of the other end.When the reflection of one end of the F-P cavity is high,with the increase of the reflectivity of the other end,the brightness contrast of the fringes increases,and the sharpness of the dark fringes is quite high,but it is not conducive to determining the corresponding wavelength at the bright fringes.2.An F-P cavity with different reflectivity at both ends is proposed and an electric field transducer is fabricated.The phase demodulation of F-P cavity is based on fringe counting method.A weak electric field calibration system is designed and built.The detection experiments are carried out.The experimental results show that the cavity length changes 61.14 nm for every voltage rise and 57.14 nm for every voltage decrease.3.The transmission coupled mode equation of FBG is deduced,and then the theoretical model of FBG transmission is established by using the transfer matrix method.The reflection spectra of FBG with different structural parameters are simulated.Then the piezoelectric ceramics are analyzed,and a fiber Bragg grating voltage sensor based on piezoelectric ceramics is designed.The experimental results show that the voltage sensitivity of the sensor reaches 5.27pm/V.4.The photoelectric properties of graphene and the principle of D-type optical fiber evanescent field are studied,and the relationship between the applied electric field and the output light intensity is deduced.A D-type electric field detector based on graphene was designed.The system was fabricated and built.The experimental data were measured and the electro-optical characteristics of graphene were verified.The experimental results show that the light absorption of graphene decreases gradually at first,then decreases sharply,and finally increases slowly until it tends to be stable.