光纤陀螺保偏光纤环几何轴向磁敏感性理论研究

Study on Geometrical Axial Magnetic Field Sensitivity in PM Optical Fiber Coil of Fiber Optic Gyroscope

在光纤陀螺中,磁场会造成法拉第相位误差。实验结果表明,轴向磁敏感性较径向更为明显。在轴向磁场作用下,在保编光纤中传播的正反两束光会产生一个与磁场有关的非互易相位差。研究了由光纤在光纤环上螺旋缠绕引起的几何轴向磁敏感性,利用耦合模方程和有限元分析法,从理论上推导出了保偏光纤陀螺在轴向磁场作用下,产生的几何法拉第非互易相位差的具体表达式,并对理论结果进行了仿真分析。研究表明,光纤环中光纤几何扭转引起的圆双折射是产生几何法拉第相位误差的主要原因。另外,轴向磁敏感性会随着半径的减小而增大。

The magnetic field in fiber optic gyroscope （FOG） will cause Faraday effect, resulting in Faraday phase error. Experimental results show that the axial magnetic field sensitivity is more obvious than the radial magnetic field sensitivity. The clockwise （CW） and coienter-clockwise （CCW） light which propagate in the polarization maintain （PM） fiber in Fiber-optic gyro will generate a nonreciprocal phase error associated with axial magnetic field. In this paper, the geometrical axial magnetic field sensitivity caused by helically wounded optical fiber is studied; coupled-mode theory and finite element analysis are used to induce the FOG＇s specific expression of Faraday nonreciprocal phase difference generated in axial magnetic field. The simulation analysis is given based on the theoretical results. Research show that circular birefringence caused by the geometrical torsion in the fiber of the fiber coil is the main causes of the geometry Faraday phase error. Furthermore, the study results show that axial magnetic field sensitivity will increase with decreasing radius.