Reduction of backscattering noise in a resonator integrated optic gyro by double triangular phase modulation

A high carrier suppression level is required to reduce the backscattering noise of a resonator integrated optic gyro (RIOG). This paper proposes a double triangular phase modulation (DTPM) technology for backscattering noise reduction. The principle of the DTPM is described and the carrier suppression of the DTPM is theoretically analyzed and simulated. Based on the numerical simulations, the modulation parameters of the DTPM are optimized. Compared with single triangular phase modulation technology, the DTPM can not only achieve higher carrier suppression but also relax the requirements of modulation amplitude accuracy and temperature stability. The advantage of the DTPM for carrier suppression is validated by experiments, demonstrating that the DTPM is helpful in backscattering noise reduction. As a result, the experimental setup of the RIOG based on the DTPM is established: a bias stability of 0.22 deg/s (10 s integrated time) is achieved for 1 h. To our knowledge, this is the best long-term bias stability of an RIOG reported to date.