Nanosecond-laser-induced damage in potassium titanyl phosphate: pure 532 nm pumping and frequency conversion situations.

Nanosecond-laser-induced damage measurements in the bulk of KTiOPO4 (KTP) crystals are reported using incident 532 nm light or using incident 1064 nm light, which pumps more or less efficient second harmonic generation. No damage threshold fatigue effect is observed with pure 532 nm irradiation. The damage threshold of Z-polarized light is higher than the one for X- or Y-polarized light. During frequency doubling, the damage threshold was found to be lower than for pure 1064 or 532 nm irradiation. More data to quantify the cooperative damage mechanism were generated by performing fluence ramp experiments with varying conditions and monitoring the conversion efficiency. All damage thresholds plotted against the conversion efficiency align close to a characteristic curve.