Surface damage and radiation resistance of lithium tetraborate single crystals

The surface damage thresholds of Li2B4O7 crystals, nonlinear crystals used in ultraviolet (UV) solid-state lasers, were measured and found to be 8.4 G W/cm(2) at 1064 nm, 1.9 GW/cm(2) at 532 nm, and 0.83 GW/cm(2) at 266 nm. Th e damage threshold at 1064 nm was 1.5 times higher than that of fused silic a. In addition, the direction dependence of the damage threshold was {1 1 0 } > {0 0 1} > {1 0 0}. No color center was generated in the crystal after 2 0 W/cm(2), 10(7) shots irradiation of KrF and ArF excimer lasers. The excel lent damage threshold and radiation resistance of Li2B4O7 were attributable to its wide band gap and relatively few defects in the crystal. (C) 1999 E lsevier Science B.V. All rights reserved.