Improvements of Depolarized FOG by Intra Coil Birefringent Modulating

Depolarized fiber optic gyroscopes (DFOG) can achieve high accuracy and have cost advantages, making them the preferred choice for applications that require both high performance and low cost, such as seismic rotation measurement. To further clarify its error sources and improve its performance, this paper first established an output spectral modulation model of the typical depolarized Sagnac interference assembly based on the principle of polarization interference, and conducted simulation research and experimental verification. To suppress the influence of spectral modulation, an intra coil birefringence modulation method was proposed and the optimized modulation parameters were obtained through experiments and the degree of spectral modulation is well suppressed. An experimental DFOG was built and its performance was tested, the results show that using this method can almost eliminate spectral modulation, and performances of bias instability and angular random walk are both improved by about 4 dB.