Abstract

Kerr-lens mode-locked (KLM) solid-state lasers emitting femtosecond-duration pulses in the infrared region of the spectrum are now finding widespread use in scientific applications. For applications in the visible or ultraviolet, frequency doubling of an infrared laser can be employed. Avoidance of broadening femtosecond pulses in harmonic generation requires the use of, thin (typically <l-mm) nonlinear crystals because of the group-velocity mismatch (GVM) between the fundamental and the harmonic pulses. The use of thin crystals to preserve the input pulse duration limits the conversion efficiency of ultrashort pulses to low values: for the peak powers typically available from mode-locked lasers (<100 kW) conversion efficiencies below 5% are obtained with 100-fs pulses.

© 1995 Optical Society of America