Automated suppression of polarization-fluctuation in resonator fiber optic gyro by a resonator with twin 90º polarization-axis rotated splices- theoretical analysis

We present the theoretical analysis on the effectiveness of the polarization-fluctuation suppression feedback control in resonator fiber optic gyro (R-FOG) with twin 90o polarization-axis rotated splices. Previously reported experimental results have shown that this feedback scheme is effective in improving the long-term bias stability of R-FOG by keeping the length difference of the fiber segments between two 90o polarization-axis rotated splicing points (Δl) to a half of the beat-length of the polarization maintaining fiber (B/2). In this paper, the effectiveness of the feedback loop is verified theoretically using Jones transfer matrix. Simulation results indicate that: (1) the error signal of the feedback loop (the yaxis polarized component in the output of the resonator) changes linearly with Δl; (2) the error signal diminishes as Δl is adjusted to the ideal condition of B/2, which are in good accordance with our experimental results.