Single- and bound-state soliton mode-locked Er-doped fiber laser based on graphene/WS2 nanocomposites saturable absorber

•In this paper, we report a passively mode-locking Er-doped fiber laser based on WS2, graphene, and graphene/WS2 nanocomposites saturable absorber, respectively. Compared to pure WS2 and pure graphene, the pulse width based on graphene/WS2 is the narrowest and the output power is the highest.•WS2, graphene, and graphene/WS2 nanocomposites were prepared by liquid phase epitaxy method, which is low cost and massive production for large-scale application. Compared with other references in which saturable absorbers prepared by the same method, the pulse width of our laser is the narrowest.•A bound-state soliton mode-locked Er-doped laser based on graphene/WS2 nanocomposites saturable absorber is reported for the first time. Its spectral modulation period is 4.9 nm, soliton spacing is 1.67 ps, and pulse width is 353 fs.