Residual Intensity Modulation Induced Error in Resonator Fiber Optic Gyroscopes With Reciprocal Detection

In the resonator fiber optic gyroscope (RFOG), both the residual intensity modulation (RIM)-induced error and backscattering-induced noise need to be effectively suppressed. When the clockwise and counterclockwise resonance detection adopt the same phase modulation and demodulation scheme, namely reciprocal detection, the reciprocity of the RFOG is improved, and the error induced by the RIM of the phase modulator used for detection (PMD) can be effectively suppressed. However, it is inevitable to add a phase modulator used for frequency shift (PMFS) to suppress the backscattering-induced noise. In this paper, the influence of the RIM of the PMFS on the performance of the RFOG is analyzed, and the model of the RIM-induced error in the RFOG with reciprocal detection is established. The analysis shows that in order to reduce the bias to the level of the shot noise, it is necessary to suppress the error induced by the RIM of the PMFS, and reducing the modulation frequency of the PMFS can effectively suppress the RIM-induced error. When a phase modulator is added to the RFOG with reciprocal detection to further suppress the backscattering-induced noise, the RIM-induced error can still be effectively suppressed by reducing the frequency of the added phase modulation.