Optical frequency combs based on a perioddoubling mode-locked Er-doped fiber laser

Mode locked fiber lasers are designed to switch from basic period mode locking (FML) to PD-ML with similar output pulses by simply changing the pump. The experimental results show that the new comb generated in PD-ML has a strong correlation with the original teeth, and has a consistent carrier envelope offset (CEO) frequency.

Therefore, the carrier envelope offset frequency and repetition frequency of the PD-ML laser can be locked by controlling the pump and cavity length. In the same f-2f heterodyne system and locking circuit, the phase locking of optical combs of PD-ML and FML with two repetition rates and the switching between them can be realized only by changing the pump.