Improving the Scale Factor Thermal Stability of Resonant Fiber-Optic Gyroscopes by Tracking the Half-Wave Voltage of the Phase Modulator

In this paper, a novel method for detecting and tracking the half-wave voltage of the phase modulator in a resonant fiber-optic gyroscope (RFOG) is proposed and demonstrated. A theoretical model is first developed to illustrate the effect of phase modulator half-wave voltage fluctuations on the stability of the RFOG scale factor. A novel method for detecting the half-wave voltage fluctuations is then proposed by applying an additional sawtooth modulation signal. Based on this, a double closed-loop RFOG system scheme employing a half-wave voltage servo loop is designed to simultaneously eliminate the sawtooth wave reset voltage error during the RFOG operation. The performance of the RFOG was tested under variable temperature conditions. The experimental results indicated that the reset voltage errors could be controlled within 1 mV, and the scale factor thermal stability was improved from 95.97 ppm/°C to 9.39 ppm/°C.