Study On Polarization Characteristics Of Fiber Ring In Fiber Optical Gyroscope

Fiber optical gyroscope(FOG) is an angle rate sensor based on Sagnac effect. Ever since the FOG developed, it is aimed at improving the accuracy. Polarization maintaining optical fiber(PMF)is the important component of FOG and its performance directly affects the output precision of FOG.This paper discusses the polarization characteristics of linearly polarized light and partially polarized light in the PMF ring and the impacts on the null shift of FOG result from nonreciprocal phase shift error caused by the nonlinear optical effects. The mathematical model of the partially polarized light propagating in the fiber is established by Jones matrix method and coherence matrix method. The change of the polarization state of the partially polarized light under propagation is investigated. The coupled-mode theory is put forward to analyze the polarization characteristics of linearly polarized light in the high birefringence PMF and the impacts on the angular velocity measurement accuracy of FOG caused by the nonlinear phase shift result from cross-phase modulation is obtained. The modulation instability is researched of PMF in anomalous dispersion regime and in normal dispersion regime under the conditions of different polarization direction and different light power when the angel of the polarized direction and the birefringence axes is arbitrary. Besides, the Kerr effect and Faraday effect that bring about nonreciprocal phase drift are analyzed and the eliminating approach is given. The above research results can be used for improving the performance of FOG.