Suppression of residual intensity modulation noise in resonator integrated optic gyro

This study investigated residual intensity modulation (RIM) noise inducing offset error of the first harmonic demodulation in resonator integrated optic gyros. This offset error at the resonance point is susceptible to light intensity variation and induces frequency locking error with gyro output drift. We propose a correction for the zero error reference technique to optimize tracking resonant frequency performance, utilizing the RIM effect to correct the proportional integral servo zero error reference. Differential output from two loops is used as the rotation rate to eliminate RIM and light intensity noise, and frequency locking was compared experimentally with and without correction for the zero error reference technique. Frequency locking accuracy of 2.279∘/h and long term bias stability of 27.14∘/h (3600 s) were obtained, which is the current best result for the packaged resonator integrated optic gyro prototypes employing a semiconductor laser diode.