Frequency tracking and locking methods in resonator micro-optic gyro

As one of the new rotation rate sensing devices, resonator micro-optic gyro (RMOG), incorporating optical Sagnac effect and micro-electromechanical systems (MEMS) fabrication technique, makes essential sense in promoting miniaturized and sensitive gyros. Fast and accurate frequency tracking and locking technique is quite important to suppress the drift induced by environmental temperature and mechanical variations. Two frequency tracking and locking methods, based on single light path (single mode) and common part of both counter-propagating light paths (common mode), are presented and applied on established RMOG system. For the single mode method, signal from single light path is detected to feedback and control the light frequency, where the influence of nonreciprocal optical noise is neglectable. However, in the latter case, the common mode of the two counter-propagating lights is used, which is a constant during the rotating state variation, representing fast frequency tracking speed. Testing results show that the frequency tracking time of 0.09 ms·[(°)/s]^-1 under rotation rate variation and frequency locking precision of 0.07°/s for over 1h by single mode and common mode frequency tracking and locking methods for the RMOG system, respectively.