Effect of Rayleigh backscattering in an optical passive ring-resonator gyro

Abstract

Resonance characteristics of Rayleigh backscattering in an optical passive ring-resonator gyro (OPRG) are theoretically formulated taking the temporal coherence of the optical source into account. This resonance has two peaks with separation equal to the Sagnac phase shift when rotation is induced. This phenomenon degrades the gyro’s linearity in a configuration to obtain the frequency output. Rayleigh backscattering also can induce an enhanced noise at specific input rotation rates. The methods of solving these problems are discussed. The theoretical limit of rotation sensing, given by the detector shot noise, is also computed taking into account the optical source coherence. A spectrum width narrower than several tens of kHz is required to realize the OPRG for navigation use.