Supermode noise mitigation and repetition rate control in a harmonic mode-locked fiber laser implemented through the pulse train interaction with co-lased CW radiation

We report on new, to the best of our knowledge, techniques enabling both the mitigation of supermode laser noise and highly precise setting of the pulse repetition rate (PRR) in a soliton harmonically mode-locked (HML) fiber laser employing nonlinear polarization evolution (NPE). The principle of operation relies on resonant interaction between the soliton pulses and a narrowband continuous wave (CW) component cooperatively generated within the same laser cavity. In contrast to our recent findings [ Opt. Lett. 46 , 5747 ( 2021 ) 10.1364/OL.441630 and Opt. Lett. 46 , 5687 ( 2021 ) 10.1364/OL.443042 ], the new methods are implemented through the specific adjustment of the HML laser cavity only and do not require the use of an external tunable CW laser source.