Enhanced Broadband Source-Driven Whispering Gallery Mode Microcavity Gyroscope With Optical Cancellation

This study presents a comparative investigation between the conventional Y-branch phase modulator (Y-PM) scheme and a novel optical cancellation scheme for resonant micro-optic gyroscopes (RMOGs), both employing the same 9.5-mm-diameter, ultrahigh-Q (equivalent Q of 4.6×10⁸) multimode whispering gallery mode (WGM) microcavity supporting 134 nondegenerate modes as the sensing element. A theoretical and numerical analysis of noise was performed for both architectures. By implementing the novel optical cancellation scheme with a directional coupler, most of the rotation-unresponsive self-interference component was effectively suppressed, leading to a significant reduction in the detected optical power and associated noise while fully preserving the amplitude of the rotation signal. Experimental results demonstrate the superiority of the optical cancellation scheme, which achieves an angular random walk (ARW) of 0.13°/√h—a substantial improvement over the 0.76°/√h ARW of the conventional Y-PM scheme. This approach establishes a new technical pathway toward integrated high-precision optical gyroscopes.