Resonator fiber optic gyro using digital serrodyne modulation

A resonator fiber optic gyro using digital serrodyne modulation for control the input lightwave frequency is proposed. In the system, phase modulators in an integrated waveguide circuit are used, instead of an acousto-optical modulator (AOM) frequency shifters with bulky shapes. With operating the signal digitally, it becomes easy to track the resonant frequency by the feedback with a higher accuracy. Errors due to nonideal digital serrodyne waveform are analyzed and are shown to be small enough. Performances of this system are experimentally demonstrated, under open-loop and closed-loop operation. The proposed scheme can implement the ways to reduce the noises without increasing the number of optical elements.