Nanosecond-laser induced damage at 1064 nm, 532 nm, and 355 nm in LiB3O5

LiB 3 O 5 , short LBO, is an important nonlinear optical material for frequency conversion. As efficient frequency conversion requires high intensities nonlinear optical crystals are often subject to laser induced damage even in commercial laser systems. In this work we studied nanosecond laser induced damage in LBO at the three harmonic wavelengths of the Nd:YAG laser: 1064nm, 532nm and 355nm. Similarly to KTP and RTP a polarization dependent anisotropy of the laser induced damage threshold has been found, being strongest at 1064nm wavelength. The weakest point of this material regarding the three tested wavelengths is the bulk damage threshold at 355nm. The fatigue effect was found to be negligible at the UV wavelength and most important for the IR light. Despite the fact that the green light has been generated by external frequency doubling, it caused an intermediate fatigue effect. Our measurements also confirmed the high bulk laser damage threshold for the IR wavelength being approximately a factor 1.5 higher than the one of synthetic fused silica.