Suppression of backscattering-induced noise in a resonator optic gyro by the dual-frequency modulation method

Abstract

Backscattering noise is one of the main noises affecting the accuracy of resonant optical gyroscope (ROG) systems. A method of suppressing backscattering noise in a ROG is demonstrated using a dual frequency modulation technique. On the premise of obtaining the Sagnac frequency difference, the frequency interval between the forward and backward beams is increased. Among them, high frequency modulation is used in the frequency-locked circuit, low-frequency modulation is used in the output path and the modulated optical components have a certain frequency difference. Firstly, the frequency difference between the clockwise and counterclockwise optical paths is increased by high and low frequency modulation to increase the carrier rejection ratio, and the noise generated by backscattering and signal light is suppressed. Then, bandpass filtering is used to eliminate the noise caused by the backscattering itself. Through theoretical analysis and experiment, the feasibility and effectiveness of the scheme are verified. The method effectively improves the output precision of the gyro, and the final output of the gyroscope reaches 0.0054∘/s (10 s integration time).