Suppression of residual intensity modulation induced error in resonator fiber optic gyroscopes with improved modulation technique

The carrier-suppressed phase modulation effectively suppresses backscattering induced noise in resonator fiber optic gyroscopes (RFOGs), but also introduces residual intensity modulation (RIM) induced error when determining the resonance line center. This paper proposes an improved modulation technique to suppress backscattering induced noise while reducing the zero offset induced by the RIM effect on the demodulation curve. The improved modulation technique is that the left and right working points are periodically located at the source frequency by the PZT to obtain the output signal of the RFOG, and the light waves are modulated by a triangular wave with the Y-branch modulator without demodulation. Theoretical analysis shows that the improved modulation technique can effectively reduce the RIM induced error. The experimental results show that the improved modulation technique can effectively suppress the backscattering induced noise while reducing the RIM induced error, and a gyro bias stability of 56°/h has been carried out.