Incoherence suppression method of optical noises in a resonant fiber optic gyro based on the circularly polarized light propagation mechanism in a resonator

Resonant fiber optic gyros (RFOGs) generally use fiber ring resonator propagating linearly polarized light, so it is inevitably affected by coherent optical noises between two counterpropagation beams such as nonlinear effect and backscattering noise. So, we propose the incoherent suppression method of optical noises in a RFOG based on the circularly state of polarization (CSOP) light. The spun-fiber is used to fabricate a resonator that can realize the reciprocal transmission of CSOP light for the first time, and the highly reciprocal signal processing scheme is applied in RFOG based on the Faraday effect. We demonstrate that the designed resonator realizes orthogonal separation of backscattered light thereby suppressing the backscattering noise, and we confirm that the reciprocal CSOP light can greatly reduce the nonlinear effect due to incoherence. With the closed-loop method based on the Faraday effect and spun-fiber resonator, whose finesse is 6.6 with a length of 11-meter spun-fiber and 6-meter single-polarization fiber, the long-term stability and short-term stability of a RFOG have been greatly improved. The incoherence method based on a reciprocal CSOP light propagation mechanism has great potential in the suppression of coherence optical noises in a RFOG, which provides a new, to the best of our knowledge, idea to solve the problem. (C) 2021 Optical Society of America