Experiments by PM spectroscopy in resonator fiber optic gyro

Resonator fiber optic gyro (R-FOG) is a promising candidate for the next generation inertial rotation sensor whose resonant frequency is changed due to the Sagnac effect. Observed from the resonance curve, the free spectral range of the resonator, the full width at half maximum of the resonance curve, the finesse of the resonator, and the resonance depth are 35.7 MHz, 2.21 MHz, 16.2, and 0.95, respectively. In the experiment, there is an acoustic-optical modulator (AOM) in each light loop. When the frequency of the fiber laser is locked to the resonance frequency in the counterclockwise direction, the frequency difference between the driving frequencies of the two AOMs is equivalent to the frequency deviation caused by the gyro rotation. In this locked condition, the gyro dynamic range calculated from the demodulation curve in the clockwise direction is from 13.5 to −13.5 rad/s. From the signal-to-noise of the average intensity arriving in the photodiode, it can be estimated that the shot-noise-limited sensitivity of mis system will be 4×10−7 rad/s.