Abstract

Significant progress has recently been made in the generation of femtosecond dye laser pulses, in particular by means of the colliding pulse technique [1]. Some observed features of the mode-locked (ML) lasers still remain largely unexplained, however. In a few cases, for instance, a strong negative frequency chirp has been experimentally observed [2] and attributed to a phenomenon of self-phase-modulation (SPM) arising from the saturation of the saturable absorber [3]. In other cases, the choice of the cavity mirrors [4] and their layout in the laser cavity [5] have been shown to influence the pulse duration.

© 1984 Optical Society of America