Long-Term Stabilization of Fiber Laser Using Phase-Locking Technique With Ultra-Low Phase Noise and Phase Drift

We investigated the phase noise performance of a conventional phase-locking technique in the long-term stabilization of a mode-locked fiber laser (MLFL). The investigation revealed that the electronic noise introduced by the electronic phase detector is a key contributor to the phase noise of the stabilization system. To eliminate this electronic noise, we propose an improved phase-locking technique with an optic-microwave phase detector and a pump-tuning-based technique. The mechanism and the theoretical model of the novel phase-locking technique are discussed. Long-term stabilization experiments demonstrated that the improved technique can achieve long-term stabilization of MLFLs with ultra-low phase noise and phase drift. The excellent locking performance of the improved phase-locking technique implies that this technique can be used to stabilize fiber lasers with a highly stable H-maser or an optical clock without stability loss.