An open-loop RFOG based on harmonic division technique to suppress LD's intensity modulation noise

Abstract

A harmonic division technique is proposed for an open-loop resonator fiber optic gyro (RFOG) to suppress semiconductor laser diode's (LD's) intensity modulation noise. The theoretical study indicates the RFOG with this technique is immune to the intensity noise. The simulation and experimental results show this technique would lead to a diminished linear region, which still could be acceptable for an RFOG applied to low rotation rate detection. The tests for the gyro output signal are carried out with/without noise suppressing methods, including the harmonic division technique and previously proposed signal compensation technique. With the harmonic division technique at the rotation rate of 10deg/s, the stability of gyro output signal is improved from 1.07deg/s to 0.0361deg/s, whose noise suppressing ratio is more than 3 times as that of the signal compensation technique. And especially, a 3.12deg/s signal jump is significantly removed with the harmonic division technique; in contrast, a residual 0.36deg/s signal jump still exists with the signal compensation technique. It is concluded the harmonic division technique does work in intensity noise suppressing under dynamic condition, and it is superior to the signal compensation technique.