Evaluation and Suppression of the Effect of Laser Frequency Noise on Resonant Fiber Optic Gyroscope

This article provides a novel method to analyze and calculate the effect of laser frequency noise on a resonant fiber optic gyroscope (RFOG). The output signal of the fiber ring resonator is expressed as the sum of various harmonic responses. It is found that the laser frequency noise at certain noise frequency would be demodulated together with the rotation-induced frequency signal, and thus deteriorating the gyro output stability. A theoretical model is then setup. The effect of laser frequency noise on the RFOG based on the separate modulation-demodulation technique is numerically evaluated and the effectiveness of the reciprocal modulation-demodulation technique is verified both theoretically and experimentally. The measured angular random walk of the reciprocal RFOG improves as the detected light power at the photodetector increases, which indicates that the measured angular random walk reaches the theoretical shot-noise limited sensitivity in the RFOG. The best value is 0.0021 °/√h when the light power arrived at the photodetector is 69 μW.