HIGH-POWER 2ND-HARMONIC GENERATION WITH PICOSECOND AND HUNDREDTHS-OF-PICOSECOND PULSES OF A CW MODE-LOCKED TI-SAPPHIRE LASER

A cw mode-locked Ti:sapphire laser was efficiently frequency doubled w ith a lithium triborate crystal in an external enhancement cavity. Sec ond-harmonic output powers of 1.28 W and 860 mW have been generated at 399 nm with fundamental pulse widths of 1.5 and 320 ps, respectively. At the 1.5-ps pulse width the conversion efficiency was 75%. The spec tral width of the 320-ps pulses, produced by modification of a laser c avity, is as narrow as the bandwidth of a normal cw, multimode, narrow -bandwidth Ti:sapphire laser. The frequency-doubled output can be thus used as a high-power, narrow-bandwidth light source in the UV region.