Analysis and Compensation for the Impact of IOC Half-Wave Voltage Thermal Dependence Errors on Scale Factor of IFOGs

Interferometric fiber optical gyroscopes (IFOGs) serve as rotation rate sensors operating on the Sagnac effect. The digital phase ramp feedback detection scheme is currently the global industry standard. However, the half-wave voltage of the integrated optical chip (IOC) used for phase modulation demonstrates high sensitivity to ambient temperature fluctuations, significantly impacting the IFOG scale factor. This study investigates the thermal dependence of the IOC half-wave voltage and its effect on scale factor accuracy. We further analyze how reset errors during digital phase ramp resets, induced by half-wave voltage variations, influence scale factor performance, establishing a quantitative relationship between reset error and scale factor inaccuracy. The principles of a secondary closed-loop system for tracking half-wave voltage fluctuations are presented, along with its operational limitations. Leveraging the thermal dependence model of a lithium niobate modulator's half-wave voltage, we propose a cost-effective half-wave voltage tracking method for scale factor compensation. Verification results demonstrate tracking accuracy exceeding 406 ppm.