ULTRA-VIOLET LIGHT GENERATION AT 205 NM BY 2 FREQUENCY-DOUBLING STEPSOF A CW TITANIUM-SAPPHIRE LASER

We have built a source at 205 nm from a CW titanium-sapphire laser at 820 nm. Two successive frequency doubling steps are made in LBO and BB O crystals. The difficulties encountered with the BBO crystal account for the low output power. In a quasi-continuous regime we obtain 1 mW (peak power) at 205 nm for a fundamental power at 820 nm of 2.2 W. In these conditions, the life time of a point of the BBO crystal is sever al hours.