Automodulations in Kerr-lens mode-locked solid-state lasers

Nonstationary pulse regimes associated with self-modulation of a Kerr-lens mode-locked Ti:sapphire laser have been studied experimentally and theoretically. Such laser regimes occur at an intracavity group delay dispersion that is smaller than or larger than what is required for stable mode locking and exhibit modulation in pulse amplitude and spectra at frequencies of several hundred kilohertz. Stabilization of such modulations, leading to an increase in the pulse peak power by a factor of 10, were accomplished by weak modulation of the pump laser with the self-modulation frequency. The main experimental observations can be explained with a round-trip model of the femtosecond laser, taking into account gain saturation, Kerr lensing, and second- and third-order dispersion. (C) 2000 Optical Society of America [S0740-3224(00)01502-2].