Reduction of angle random walk by in-phase triangular phase modulation technique for resonator integrated optic gyro.

In a resonator integrated optic gyro (RIOG) employing a planar optical waveguide ring, the interference between backreflected light and signal light will not only cause nonreciprocal drift of cw and ccw resonance frequencies, but also deteriorate the original signal waveform of the resonator output. If contra-phase triangular phase modulation (CPM) were applied, a cosine-like ripple, whose initial phase varies randomly, would superpose upon the quasi-square waveform of the resonator output, resulting in increment of noise and the gyro's angle random walk (ARW). Therefore, in-phase triangular phase modulation (IPM) technique is proposed and used to eliminate the ripple and improve the waveform quality of the resonator output, and the gyro's ARW is obviously reduced from 3 to 0.8 deg/h compared to that of CPM. This enlightens a new way to design the scheme of backreflection/backscattering suppression.