Study On The Sensor Of Polarization Maintaining Fiber Bragg Gratings

Because of its many unique advantages,fiber Bragg grating has a broad application prospect in the fields of communication and sensing.In order to overcome the cross sensitivity of the fiber Bragg grating?FBG?the paper investigates the reflection spectrum characteristic of polarization maintaining fiber Bragg grating?PMFBG?influenced by temperature,axial tension,lateral pressure and twist.The phase-shifted PMFBG fabricated by the method of arc discharge is proposed and analyzed.The main research contents are as follows:1.The classification and writing methods of fiber Bragg gratings are introduced analyzes,the application status of fiber Bragg gratings in the sensing field is analyzed,the shortcomings of FBG in the application process are pointed out and thus investigates the characteristics and research progress of polarization maintaining fiber Bragg gratings.2.The basic principle of fiber Bragg grating is systematically studied,the influence of grating parameters on the reflection spectrum is analyzed and the principle and spectral characteristics of phase-shifted FBG are analyzed.On this basis,the spectral characteristics of polarization maintaining fiber Bragg grating are analyzed by four-mode coupled transmission matrix method.3.The spectral characteristics of PMFBG are studied for the temperature and axial tension,the reflection spectrum of the panda PMFBG is measured under lateral pressure.The four-mode coupling theory model is reconstructed to analyze the twist characteristics of the PMFBG.4.Based on arc discharge method and CO₂laser,the phase-shift polarization maintaining fiber Bragg grating?PMFBG?is fabricated successfully.The four-mode coupling theory model is reconstructed to analyze the twist characteristics of the PMFBG.The experimental and simulation results show that the intensity of the intersection region between the two principal Bragg reflections increases with the increase of the twisting rate,but it cannot determine the twisting direction.The phase-shifted PMFBG fabricated by the method of arc discharge make the phase-shifted PMFBG introduces an symmetric structure in the PMFBG which leads to a unique spectral response for the clockwise and anticlockwise twist of the PMFBG.The opposite intensity change of the intersection region between the two principal Bragg reflections for the clockwise and anticlockwise twist is used to measure the twisting amplitude and discriminate the twisting direction.