Closed-Loop Broadband Source-Driven Resonant Optical Gyroscope Using Multimode Microcavity and Multimode Detection

The broadband source-driven resonant optic gyroscope (ROG) based on a multimode microcavity, as a new type of chip-scale gyroscope, demonstrates impressive advantages in both detection sensitivity and long-term bias stability. To address practical application requirements, this paper presents the first study on closed-loop multimode microcavity-based ROG to enhance dynamic range and scale factor linearity. Firstly, an equivalent analytical model of a broadband source-driven ROG using a multimode microcavity is developed. Based on this model, the feasibility of implementing closed-loop operation via serrodyne modulation is analyzed. Subsequently, the theoretical scale factor nonlinearity of the multimode microcavity-based closed-loop ROG is calculated. Finally, a closed-loop ROG incorporating a 28.5-mm-diameter multimode whispering-gallery-mode microcavity is constructed for experimental validation. Test results indicate that after compensation for inherent residual errors, the scale factor nonlinearity reaches 50 ppm—two orders of magnitude lower than the theoretical limit. In static long-term tests, the bias instability was reduced to below 0.5°/h.