BROADLY TUNABLE FEMTOSECOND CR-LISAF LASER

We demonstrate wavelength tunability of femtosecond pulses over a rang e of more than 50 nm from a diode-pumped Cr:LiSAF laser. The mode-lock ing mechanism can be explained by soliton mode locking that is started and stabilized by a broadband semiconductor saturable-absorber mirror designed for low loss over the full reflection bandwidth of the under lying Bragg mirrors, which ultimately limits tunability. We obtain 45- fs pulses at 105-mm average output power and a maximum mode-locked ave rage output power of 125 mW with 60-fs pulses. (C) 1997 Optical Societ y of America.