SESAM and SWCNT Mode-Locked All-Fiber Thulium-Doped Lasers Based on the Nonlinear Amplifying Loop Mirror

We report on thulium-doped all-fiber lasers based on the nonlinear amplifying loop mirror and mode-locked with a semiconductor saturable absorber (SESAM) or single-walled carbon nanotubes (SWCNTs). An intracavity and external dispersion management was realized with the aid of a passive germanium-silicate fiber. The SESAM mode-locked laser generates as short as 230-fs pulses with a maximum average output power of 106 mW, corresponding to a 3.7 kW peak power and almost 2 nJ pulse energy. In contrast to the SESAM-based laser, the SWCNT mode-locked laser generates 450-fs pulses of mW-level average output power.