Abstract

Kerr Lens Mode-Locking (KLM) [ 1 ] provides a versatile means to generate ultrashort pulses from solid-state lasers without compromising tunability and without the need for complex electronics or active components. In general KLM lasers are not self-starting but require some supplementary mode-locking mechanism to develop the high intracavity intensities necessary to access the optical Kerr effect. Recently, however, Cerullo et al [2] demonstrated that, by careful optimisation of the laser cavity, it is possible to maximise the nonlinear amplitude modulation of the KLM mechanism such that the lasers will spontaneously mode-lock with no additional starting mechanism. We have successfully applied this optimisation to Pr:YLF lasers in the visible spectral region and to Ti:sapphire Cr:Forsterite and Cr:YAG in the near infrared. We have also initiated KLM in a Pr:YLF laser using a moving mirror and have generated visible femtosecond pulses for the first time from a solid- state laser, obtaining pulses as short as 400 fs using the 613 nm transition.

© 1996 Optical Society of America