Optical Passive Ring-Resonator Gyro with Various Countermeasures for Performance Deterioration Factors

本研究的目的是通过对影响光学无源环形谐振陀螺性能的各种因素采取对策的实验研究，并对这些因素进行详细的分析，阐明提高光学无源环形谐振陀螺性能的途径。此外，新的方法已经发明，以大大减少所造成的瑞利后向散射在光纤谐振腔中的噪声，这已被应用在设置。详细分析了谐振腔中偏振态的起伏对噪声的影响。在保偏光纤谐振腔中，即使光纤接头处的微小错位也会导致较大的漂移。通过将光纤偏振器放置在谐振腔的引出端，或在接头处将偏振轴旋转90 °，可以减小这种漂移，并利用我们自己的分析方法进行了详细的估算。在实验中首次观察到了光克尔效应，并对干涉仪在光外差光纤陀螺、相干函数合成高分辨率反射测量、光纤传感器复用/解复用、高性能相干检测等方面的应用进行了研究。通过以上研究，在实验中获得了优于地球自转速率的陀螺分辨率和与地球自转速率相当的零点稳定度，这是迄今为止所获得的最高水平，同时也充分阐明了对主要机头因素的对策。因此，本研究的目的已经成功实现。

The purpose of this study is to clarify the manner for increasing the Performance of the Optical Passive Ring-Resonator Gyro, through the experimental studies using the setup having the various countermeasures for performance deterioration factors, and through the detailed analyses on the factors.First of all, the experimental setup has been constructed having the countermeasures, which we had been investigating. Moreover, the novel method has been invented to drastically reduce the noise caused by the Rayleigh backscattering in the fiber resonator, that has been applied in the setup. The polarization fluctuation in the resonator has been detailedly analyzed as one of the dominant noise factors. Even a small misalignment at the fiber splice in the polarization maintaining fiber resonator has been analyzed to cause a large drift. This drift can be reduced by putting the fiber polarisers at the lead portions of the resonator, or rotating the polarization axis by 90 degree at the splice, which have been estimated detailedly using our own analysis method. Optical Kerr effect has also been observed, at the first time, in the experiment.Besides the above studies, interferometer applications related have been investigated, such as the optical heterodyne fiber gyro, high resolution reflectometry by synthesis of the coherence function, fiber sensor multi/demultiplication and high performance coherent detection schemes. Requirements from the system including the gyro have also been investigated.From the above studies, the gyro resolution better than the earth rotation rate and the zero point stability comparable to that rate have been achieved in the experiment, which are in the highest level among the data presented so far, and the countermeasures for the dominant nose factors have been enough clarified. Thus, the purpose of this study has been successfully achieved.