Dispersion compensation-free fiber laser mode-locked and stabilized by a high-contrast saturable absorber mirror

We report here a compact diode-pumped fiber laser that represents a promising route to designing a portable picosecond light source that is rugged and compact. The laser design presented in this paper is based on a high-contrast semiconductor saturable absorber mirror (SESAM) and targets a reliable picosecond-range fiber laser. The cavity is simple, since no dispersion compensators are used, the SESAM-based mode locking mechanism is robust, and self-starting resulted in low-maintenance turn-key operation. We investigated pulse formation in a short-length fiber cavity and found that nonlinear effects in a near-resonant SESAM in combination with the large cavity dispersion are the predominant mechanism that causes self-starting and stabilization of mode-locking. The effect of the recovery time of the SESAM on the stretched-pulse width and spectrum for resonant-type absorber mirrors was also studied.