SINGLE-SHOT BULK DAMAGE THRESHOLD AND CONVERSION EFFICIENCY MEASUREMENTS ON FLUX-GROWN KTIOPO4 (KTP)

The single shot bulk laser damage threshold was measured on thirteen different flux grown KTP crystals. The measurements were made with the KTP oriented for type II phase matched second harmonic generation (SHG) at 1064 nm. The width of the Q-switched Nd:YAG laser pulses was 8.5 ns. The crystals were grown under different experimental conditions. Some of the crystals were measured topographically in order to find possible differences in the damage thresholds between different growth sectors and to check the crystals for optical homogeneity. The measured average threshold for dielectric breakdown of KTP is 31.5+/-4 GW/cm2. Topographic measurements showed, that the samples have a good optical homogeneity with the exception of trivalent cation doped KTP. The presence of Sc3+ and Cr3+ lowers the damage threshold of KTP and areas with preferential chromium incorporation in KTP show a lowered damage threshold in comparison with areas containing less chromium. The conversion efficiency for type 11 phase matching of the 1064 nm beam of a Nd:YAG laser has a maximum value of 55%. The measured d(eff) was 3.1 pm/V.