Research on resonance splitting under sinusoidal modulation in resonant optic fiber gyro

•The RFOG simulation system is established, through which the relationship between resonance splitting and modulation frequency is obtained.•The resonance splitting is then explained based on sideband spectrum theory.•The feasibility of the sideband frequency locking technology is verified by resonance splitting based on sideband spectrum theory. In this study, the sinusoidal phase modulation and demodulation principle in resonant fiber optic gyro (RFOG) are introduced. The RFOG simulation system is established, through which the relationship between resonance splitting and modulation frequency of dual-frequency sawtooth and sinusoidal signal is obtained. The resonance splitting is then explained based on sideband spectrum theory. The experimental device is built and the results show that there are obvious resonance splitting and distortion in linear region of demodulation output, when the sinusoidal frequency is higher than FWHM/2. Finally, the feasibility of the sideband frequency locking technology is verified by resonance splitting based on sideband spectrum theory, providing theoretical support for this novel technology, which can suppress backscattering noise effectively.