Grid search algorithm applied to auto-lock of ultra-stable laser

Abstract

Ultra-stable laser with PDH (Pound-Drever-Hall) frequency stabilization technology is an indispensable tool in optical atomic clocks, gravitational wave detection, and optical fiber optical frequency transfer. As the demand for space and transportable science missions rises, the ultra-stable laser is required to have an auto-lock function. During auto-lock, the PZT is scanned in pre-set steps to find the resonance point with the optical reference cavity. To determine steps for the first lock automatically and update steps when pre-set steps are changed by long-term drift, the Grid Search algorithm with priori knowledge is utilized. To verify the reliability of the algorithm, the system out of lock is simulated 904 times. The relock with the parameters determined by the Grid Search algorithm is achieved with a success rate of 100% and a mean relock time of about 0.9s. The Grid Search algorithm with priori knowledge proposed in this paper can optimize the hyperparameters in auto-lock.