Abstract

Recent experiments succeeded in sub-100fs pulse generation from solid-state lasers by use of a saturable single-quantum-well absorber (SQW) yielding self-starting 34 fs pulses in a ti:sapphire laser [1] as well as 90fs pulses in a diode pumped CnLiSAF laser [3]. These experimental findings can hardly be explained by the common theoretical understanding of passive mode locking in solid-state lasers which requires a fast saturable loss for stable pulse generation. The relaxation of the absorption bleaching in a GaAs quantum well at room temperature exhibits a bitemporal behaviour where the fast component of about 200fs owing to thermal ionisation of the excitons is remarkably slower than the meanwhile achieved pulse width in the experiments.

© 1996 Optical Society of America