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

We report a passively mode-locked Er-doped fiber laser based on WS2, graphene, and graphene/WS2 (G/WS2) nanocomposites saturable absorber (SA), respectively. These materials were easily prepared by liquid phase epitaxy (LPE) method with isopropanol (IPA). Compared with pure graphene or pure WS2, the film of G/WS2 nanocomposites possesses low nonsaturable loss (31%) and low saturable intensity (12.78 MW/cm2), which is of benefit to achieve passive mode-locked fiber laser. Stable traditional soliton pulses were generated with central wavelength of 1566.7 nm, spectral width of 7.3 nm, pulse duration of 357 fs, and repetition rate of 22.86 MHz. Further, we present the bound-state soliton mode-locked based on G/WS2-SA with a modulation period of 4.9 nm, soliton spacing of 1.67 ps and pulse width of 353 fs. Our work extends the studies for G/WS2 nanocomposites in ultrafast photonics applications.