基于寄生次波追溯的高精度光纤陀螺偏振非互易性研究

Fiber optic gyroscope (FOG) is a new inertial instrument to implement carrier's autonomic guidance, high precision (HP) FOG is its trend of development, but polarization non-reciprocity (PNR) is a key factor affecting HP FOG's bias stability, restricting the improvement of its performance. Due to the fact that traditional analyzing method of PNR error is not able to reach each parasitic secondary wave, the research promotes parasitic secondary wave tracking method. With the method, the historical information of each major secondary wave in HP FOG is computed and recorded, and their interference result is analyzed,Based on this, the mechanism of PNR error is disclosed with overall consideration of coherence detection and closed-loop feedback, the effect of temperature and step wave on PNR error is clarified, the suppression method is promoted from the aspect of amplitude and phase, and the testing system is established to verify the mechanism's exactness and suppression method's effectiveness. Therefore, the research supplies theoretical foundation for the improvement of HP FOG's bias stability. On the other hand, based on the relationship between polarization non-reciprocity and coupling intensity of polarization crossover,PNR error is applied to real-time monitoring of two coupling points in the process of direct-coupling between fiber coil and integrated optic chip (IOC),through amplifying polarization non-reciprocity. Therefore, the research also supplies a new method for solution of key problems in the engineering implementation of HP FOG.

光纤陀螺是实现载体自主导航的新型主流惯性仪表，高精度光纤陀螺是其发展趋势，偏振非互易性（PNR）是影响高精度光纤陀螺零偏稳定性的一个关键因素，制约了其性能的提高。针对PNR误差传统分析方法不能深入到每个寄生次波的缺陷，本课题提出寄生次波追溯方法，以高精度光纤陀螺为研究对象，明确其光路中每个主要寄生次波的历程信息，分析其干涉结果，综合考虑相干检测和闭环反馈，揭示PNR误差机理，阐明温度和阶梯波对PNR误差的影响，从相位和幅值两方面提出抑制方法，搭建PNR误差定量测试系统以验证，从而为高精度光纤陀螺零偏稳定性的提高奠定理论基础。同时，基于偏振非互易效应与光路偏振交叉耦合强度直接相关的特性，通过放大偏振非互易效应，应用PNR误差大小来实时监测光纤环与集成光学芯片直接耦合过程中的耦合点串音变化，从而也为解决高精度光纤陀螺工程实现中的关键技术问题提供新思路。

光纤陀螺是实现载体自主导航的新型主流惯性仪表，高精度光纤陀螺是其发展趋势，偏振误差是影响高精度光纤陀螺零偏稳定性的一个关键因素，制约了其性能的提高。针对偏振误差传统分析方法不能深入到每个寄生次波的缺陷，本课题提出了寄生次波追溯方法，以高精度光纤陀螺为研究对象，明确了其光路中主要寄生次波的历程信息，揭示了一阶和二阶偏振误差机理，阐明了偏振误差对标度因数非线性和零偏稳定性的影响，提出了基于双折射环节匹配的偏振误差抑制方法，使得0.001°/h光纤陀螺偏振误差理论值小于精度一个数量级，同时，搭建了一套陀螺偏振误差测试系统，验证了偏振误差机理分析的正确性和抑制方法的有效性，以及基于放大的偏振非互易效应的直接耦合点偏振串音监测方法可行性，从而不仅为高精度光纤陀螺零偏稳定性的提高奠定了理论基础，而且为解决高精度光纤陀螺工程实现中的关键技术问题提供了思路。