Research On An Interferometric Fiber Optic Gyroscope Not Limited By Intrinsic Frequency

In the process of mankind’s continuous exploration of the mysterious space domain,the navigation system has played an important role.Where the Beidou satellite navigation system,Global Positioning System and Global Navigation Satellite System are three satellite navigation systems certified by United Nations Satellite Navigation Committee.However,the core component of the inertial navigation system is the gyroscope,and the performance of the gyroscope directly affects the index of the inertial navigation system.Therefore,this paper proposes a structure,which can solve the problem that the modulation frequency of the traditional interferometric fiber optic gyroscope is limited to the intrinsic frequency,obtains a medium-high precision fiber optic gyroscope that is not based on the intrinsic frequency.The specific research content is as follows:Firstly,by summarizing the development of interferometric fiber optic gyroscopes from China to abroad,we found that the modulation frequency is limited by the intrinsic frequency.Combining the Sagnac effect and the minimum irreversible structure,the two main modulation methods of the interferometric fiber optic gyroscope are analyzed.And then the influence of the optical path system and circuit system on the performance indicators of the fiber optic gyroscope is obtained.Secondly,the optical path structure of the spatially non-reciprocal fiber optic gyroscope with an intermediate phase modulator is designed.This structure fundamentally overcomes the inherent frequency limitation of the traditional Sagnac interferometer,and has the advantage of overcoming the backscattered noise.Thirdly,the Jones matrix analysis model of optical path structure was established,and the expression of interference signal was obtained according to the Jones matrix.The polarization coupled noise was analyzed in detail from multiple perspectives,and the simulation rule of polarization coupled noise was obtained according to the actual optical device parameters.The analysis results show that the fiber optic gyroscope with the central structure of phase modulator can effectively suppress the polarization coupling noise.Finally,an experimental prototype was established,and the non-linearity of the scale factor,zero-bias stability and random walk coefficient were tested through experiments.Experimental results show that the above-mentioned parameters of this fiber optic gyroscope with an intermediate phase modulator structure have reached a mid-to-high level.For the accuracy requirements of the gyroscope,the above research provides a basis for the optimization of the system parameters of the fiber optic gyroscope in the next step.