Ultra-high repetition-rate-selectable passive harmonic mode locking of a fiber laser

The pursuit towards higher repetition rate pulse sources has accelerated recently, due to the strong need, in numerous applications, of pulse trains with gigahertz repetition rates. Considering their versatility and scalability, passively mode-locked fiber lasers present interesting potentialities in that respect. Especially promising for the development of ultra-high repetition rate lasers is the exploitation of the multi-pulsing operation under intense pumping power through the collective dissipative soliton dynamics of harmonic mode-locking (HML) [1]. Passively HML fiber lasers have reached 10 GHz [2]. Still, many factors affecting the regular distribution of multiple pulses all along the cavity remain unclear. In particular, the role of a continuous wave background to act as an efficient interaction mediator between pulses has been advanced [3].