All-fiber mode-locked ytterbium-doped fiber laser with a saturable absorber based on the nonlinear Kerr beam cleanup effect.

We theoretically and experimentally demonstrate a novel, to the best of our knowledge, mode-locked ytterbium-doped fiber laser with a saturable absorber based on the nonlinear Kerr beam cleanup effect. The saturable absorber was formed by a 2-m graded-index multimode fiber, and a single-mode fiber segment served as a diaphragm. With an all-normal-dispersion-fiber configuration, the laser generated dissipative soliton pulses with pulse duration of 26.