1 KHZ SOLID-STATE LASER SYSTEM FOR THE GENERATION OF 50 FS PULSES TUNABLE IN THE VISIBLE

Tunable visible pulses with pulse lengths as short as 50 fs were gener ated with 1 kHz repetition rate and energies between 25 and 300 nJ by up-conversion of near infrared pulses. The latter were derived from th e 100 fs output pulses of a regeneratively amplified Ti:sapphire laser system by travelling wave parametric generation and amplification. Th e conversion scheme produces such short visible pulses with nearly Fou rier transform limited bandwidth because the initial parametric proces ses in the infrared possess extremely low group velocity mismatch even at the necessary crystal lengths of some millimeters and the subseque nt up-conversion proceeds in very thin crystals. It is argued that the total scheme can be scaled simultaneously to higher energies, even sh orter pulses, and a complete coverage of the visible spectral range.