Self-starting passive mode-locked ytterbium fiber laser with variable pulse width

We report a scheme for controlling pulse width in a robust self-starting mode-locked ytterbium fiber laser using a semiconductor saturable absorber mirror (SESAM). We demonstrate that the pulse width in a mode-locked laser made of all-normal-dispersive fiber can be adjusted by changing ump power to the laser or by adjusting the axial position of the SESAM with respect to a focusing beam. We have obtained optical pulse width of 7.4 ps and the adjustable range was 2 ps without dispersion compensators in the all-normal-dispersive cavity and provides a high reliability of turn-key operation. We have explained that the principle of position dependent pulse width change in a mode-locked laser with a SESAM and verified with numerical simulations.