Harmonic mode locking of bound-state solitons fiber laser based on MoS₂ saturable absorber

We present a kind of harmonic mode locking of bound-state solitons in a fiber laser based on molybdenum disulfide (MoS₂) saturable absorber (SA). The mode locker is fabricated by depositing MoS₂ nanosheets on a D-shaped fiber (DF). In the fiber laser, two solitons form the bound-state pulses with a temporal separation of 3.4 ps, and the boundstate pulses are equally distributed at a repetition rate of 125 MHz, corresponding to 14th harmonics of fundamental cavity repetition rate (8.968 MHz). Single-and multiple-pulses emissions are also observed by changing the pump power and optimizing the DF based MoS₂ SA. Our experiment demonstrates an interesting operation regime of mode-locked fiber laser, and shows that DF based MoS₂ SA can work as a promising high-power mode locker in ultrafast lasers.