MODE-LOCKING WITH SLOW AND FAST SATURABLE ABSORBERS - WHATS THE DIFFERENCE

We investigate the differences in the dynamics of lasers mode-locked b y fast and slow saturable absorbers. Slow saturable absorbers can alre ady generate almost transform limited pulses much shorter than the rec overy time of the absorber. If soliton-like pulse shaping is present i n addition the pulses can be further compressed below the resulting ne t gain window until either the continuum breaks through or the pulses break up into multiple pulses, which sets a limit to the shortest puls ewidth achievable. Given a certain amount of saturable absorption, a c omparison is made that results in an estimate for the shortest pulse a chievable for a solitary laser stabilized by a fast or a slow saturabl e absorber, The theoretical results are compared with experiments.