Modulator Coefficient Tracking Method of Resonant Integrated Optical Gyroscope Based on Novel Four-State Modulation

A modulator coefficient tracking system (MCTS) with the novel four-state modulation technique is proposed to improve the stability of scale factor for resonant integrated optical gyroscope (RIOG). Firstly, we analyze the influence mechanism of integrated optical phase modulator (IOPM) coefficient on the scale factor stability of RIOG. Then, the novel four-state modulation technique is proposed to synchronously detect angular velocity information and IOPM coefficient without additional optical devices, which consists of the basic triangular modulation signal and the triangular signal for demodulating modulator coefficient. Finally, MCTS based on the novel four-state modulation technique is designed to real-timely track the modulator coefficient and adjust loop-gain to be constant for improving the scale factor stability of RIOG. The experimental results show that the tracking error of MCTS is 0.23% from −40 °C to +60 °C and the scale factor stability of RIOG is optimized to 163.37 ppm. The proposed MCTS with the novel four-state modulation technique can significantly improve the performance of RIOG, which contributes to promoting the applications of RIOGs.