Improving Sensitivity of Broadband Source-Driven Resonant Fiber Optic Gyroscopes by Optical Cancellation

Resonant fiber-optic gyroscopes (RFOGs) driven by broadband light sources represent a critical pathway toward high-precision fiber optic gyroscopes. However, in conventional broadband source-driven RFOGs, the self-interference components of clockwise and counterclockwise propagating light do not carry rotation information, yet contribute to undesired DC intensity. This introduces additional optical noise, thereby degrading the system's angular random walk (ARW). In this paper, a broadband source-driven RFOG with optical cancellation is implemented, where a 2×2 coupler replaces traditional circulators and Y-branch splitters. The$\pi$/2-phase between transmitted and coupled waves in the 2×2 coupler enables optical cancellation. Theoretical and experimental results demonstrate that this method effectively suppresses spurious DC components, significantly reducing both shot noise and relative intensity noise. Finally, a prototype RFOG was developed with a 130 m-long and 18.3 cm-diameter fiber ring resonator. Static tests were performed under both optical cancellation and non cancellation configurations. The one-hour static test results demonstrated a 2.85 dB reduction in ARW with optical cancellation enabled, this confirms the scheme's significant contribution to gyroscope precision enhancement. Furthermore, the optical cancellation approach simplifies the optical path configuration and reduces signal processing circuit complexity, thereby enhancing the prospects for future compact RFOG integration.