Effect of RF Plasma Etching on Surface Damage in CsLiB6O10 Crystal

The laser-damage resistance of the CsLiB 6 O 10 (CLBO) surface for UV generation was successfully improved after removing the polishing compound by rf plasma etching. The ZrO 2 used as CLBO polish was found to be embedded in the crystal surface to a depth of 60 nm. We could remove the polishing compound without degradation of the surface condition when the applied rf power was less than 100 W. For the ∼7 W fourth-harmonic generation (266 nm) of a Nd:YAG laser (100 Hz), the surface lifetime of a 4HG crystal could be increased more than 10 times compared with that of an as-polished surface. No surface damage was observed over 160 h of operation.