Measurement Of Birefringence And Its Temperature Coeffitient Of Polarization-maintain Fibers Based On Brillouin Optical Domanin Analysis Technique

The fiber-ring of Fiber Optic Gyroscope(FOG) plays a key factor affecting the accuracy of FOG. As the temperature coefficient of birefringence of polarization maintaining fibers(PM fibers) have a great impact on the measurement accuracy of FOG, measurement of birefringence and its temperature coefficient of PM fibers has a very important significance for quality inspection of FOG ring. In this thesis, a series of studies that focusing on measuring birefringence and its temperature coefficient of PM fiber have been done, and the details are as follows:(1) The basic principles and characteristics of PM fibers comprised in FOG are introduced and the influence of birefringence and its temperature coefficient of PM fiber that affect the accuracy of FOG is analyzed.(2) Based on the stimulated Brillouin scattering three-wave coupling equations, the principle of measuring birefringence and its temperature coefficient of PM fiber by means of differential pulse-width pair optical time domain analysis technology(DPPBOTDA) is introduced. In addition, the experimental setup of DPP-BOTDA is built, and the derivative and correlation are used to process experimental data.(3) The birefringence of three different types of PM fibers at different temperatures are measured. Two methods to obtain temperature coefficient of PM fiber are proposed: one is based on the measurement of birefringence of PM fiber; another is based on the measurement of refractive of fast and slow axes of PM fiber.(4) Measurement errors caused by PM fiber outside the oven, temperature-induced changes of fiber length and sampling rate are discussed.