Suppression of beam breakup in self-mode-locked Ti:sapphire lasers

We show that thermal aberration in optically pumped solid-state lasers can lead to the breakup of the beam profile. Kerr lensing present in the self-mode-locked regime tends to reduce the beam size in the laser material; such a beam is less sensitive to the thermal aberration, and its shape becomes free of secondary lobes. The thermal aberration has also the effect of moving the optimal operation point for self-mode locking. Experimental results obtained with a Ti:sapphire laser support our theoretical results.