Frequency Spectrum Separation Method of Suppressing Backward-Light-Related Errors for Resonant Integrated Optical Gyroscope

Abstract

With on-chip integration enabled, resonant integrated optical gyroscope (RIOG) is a promising choice of rotation rate sensor in the novel micro inertial navigation systems. However, various optical errors, especially the backward-light-related errors including backscattering error and back-reflection error caused by the manufacturing process and heterogeneous materials in the optical elements, limit the performance of RIOG. Here, we propose the frequency spectrum separation method to suppress the backward-light-related errors for improving the detection precision of RIOG. The method can separate the angular velocity signal from the backward-light-related errors in the frequency domain. And, we investigate the optimal strategy of modulation frequencies to obtain maximum spectrum gaps of clockwise and counter-clockwise light for suppressing the backward-light-related errors, and simultaneously maintain maximum demodulation gain and minimum nonlinearity of optical effect for improving detection sensitivity. With the frequency spectrum separation method, the long-term bias stability of RIOG achieves 0.3°/h based on Allan deviation, which is the best reported result to the best of our knowledge. The proposed method of backward-light-related errors suppression can significantly improve the detection precision of RIOG based on a photonic chip, which contributes to the application of RIOG in the novel micro inertial navigation field such as cluster unmanned aerial vehicles and micro-nano satellites.