Study On Closed-loop Modulation And Frequency-locking Technique Of Resonant Optical Gyroscope

The resonant integrated optical gyro represents one of the developing trends of the inertial sensor due to its high precision and integration feasibility.In this thesis,the processes of the direct laser-frequency modulation,the phase modulation,and the demodulation are analyzed,and it is verified that there are various sidebands in the modulated signal.Fourier transform is used to analyze the effect of laser frequency noise in the modulation.It is shown that the laser frequency noise with an frequency,which is even times of the modulation frequency,may introduce a first-order harmonic signal in the output of the resonator,and cause the measurement error of the gyroscope.For a particular gyro system,the modulation signal parameters are optimized.It is studied to depress the backscattering noise in the integrated optical gyro by introducing a difference frequency between two acousto-optic frequency shifters.It is shown that the power imbalance of the two acousto-optic frequency shifters leads to a difference in the slope of the demodulation curves of the CW and the CCW circuits and will eventually leads to a measurement error of the gyroscope.By compensating the output power of the acousto-optic frequency shifters,the influence of the acousto-optic frequency shifters' power bandwidth is effectively overcome.The frequency noise performance of the laser is detected on the resonant optical gyro platform.It is further shown that the power compensation of acousto-optic frequency shifters can improve the stability of gyro.The basic performance of RIOG is measured also.