Analysis of Optimal Frequency Bias of Frequency-lock in Passive Ring Resonator Optic Gyro

The frequency-lock (FL) accuracy of a passive ring resonator optic gyro (PROG), which is closely related to the frequency bias, determines the ultimate measurement precision of the gyro system; therefore it is particularly important to choose a proper frequency bias for the PROG to achieve excellent performance. The best performance of the PROG comes from the optimal signal-noise ratio (SNR), rather than the highest sensitivity. The relations among the SNR affected by the photon shot noise of the photodetector, sensitivity and the frequency bias of the PROG are analyzed in detail for both transmission-type and reflection-type PROGs under Lorentz function approximation in this paper, and the optimal FL frequency bias ranges are discussed. This work provides explicit theoretical guidance for the systematic optimization of the PROG.