Abstract

Approaching the gain-bandwidth-limit in Kerr-lens-mode-locked (KLM)¹ Ti:sapphire (Ti:S) and related vibronic solid state lasers has been primarily limited by the finite high-reflectivity bandwidth Δν_HR of quarterwave multilayer dielectric mirrors and the finite constant-group-delay-dispersion bandwidth Δν_GDD of prism pairs. Although the discovery of chirped multilayer dielectric mirrors² and their subsequent use in KLM Ti:S lasers³ improved the situation, several problems have remained to be solved: i) a quarterwave dichroic mirror used for pump beam coupling and a quarterwave output coupler were employed and hence limited Δν_HR also in mirror-dispersion-controlled systems,³ ii) initiating mode locking becomes more and more difficult for shorter pulse durations. This latter problem relates on the one hand to the low negative GDD required for sub-10fs pulses. On the other hand, self amplitude modulation can not be maximized as suggested before⁴ due to saturation problems at very short steady-state pulse durations.

© 1996 Optical Society of America