Polarization non-reciprocity error suppression in dual-polarization fiber optic gyroscopes

Abstract

The dual-polarization interferometric fiber optic gyroscope is distinguished by the fact that both orthogonal polarized light beams in the fiber coil are simultaneously sensitive to the rotation rate. The relative intensity noise can be effectively suppressed due to the strong correlation between the two polarized light beams. However, the system exhibits significant polarization non-reciprocity errors, which worsen the bias instability. In this paper, we demonstrate how modulation depth affects the angular random walk and the bias instability. Polarization non-reciprocity errors can be efficiently mitigated while the angular random walk approaches optimal value by adjusting the modulation depth to π/2rad rather than 2.7 rad. It is confirmed that the bias instability and angular random walk can be simultaneously improved by optimizing the modulation depth without increasing the complexity of the optical path. Experimental results indicate that for a 500-m-long fiber coil, the bias instability is improved from 0.025∘/h (2.7 rad) to 0.010∘/h (π/2rad) while the angular random walk remains at 0.001∘/h through modulation depth optimization, which advances its application in navigation.