▎ 摘　　要

We report a single- and dual-wavelength switchable mode-locked dissipative soliton in an ytterbium-doped fiber laser based on graphene/WS2 nanocomposites saturable absorber. The graphene/WS2 nanocomposites film possesses efficient saturable absorption characteristics with large modulation depth (45.1%), which results in the stable single-wavelength mode-locking operation with pulse duration of 450 ps. By carefully rotating the polarization controller, the mode-locking operation can be switched to a dual-wavelength at both 1066.4 nm and 1069.2 nm due to the modulation of the intracavity birefringence. Our work extends the studies for 2D nanomaterials and supplies potential applications in the multi-wavelength fiber laser. (C) 2019 The Japan Society of Applied Physics