Abstract

Self-mode-locking of solid-state lasers is now established as the most powerful method to generate femtosecond optical pulses.^1-4 Best results reported so far^3,4 were obtained with Ti:sapphire lasers where pulse durations down to 10 femtoseconds were achieved. Self-modelocking is attributed⁵ to Kerr lensing (selffocusing) in the gain medium or in other intracavity materials; in properly designed cavities, Kerr lensing has the effect of reducing the diffractional losses or of improving the overlap between the pump and laser beams. Under such circumstances, Kerr lensing produces a nonlinear gain favoring the growth of intense short pulses at the expense of multimode (cw) oscillations. It is known experimentally³ that high-power, self-mode-locked lasers switch from one-pulse to two-pulse emission. In this paper, we analyze the large-signal response of nonlinear cavities in order to understand the stability range for one- and two-pulse emission.

© 1994 IEEE