Effects of excimer laser irradiation on the KDP crystal

Abstract

The progress in the development of powerful solid state lasers depends to a great extent on the laser damage threshold of KDP single crystal used for harmonics generation of laser radiation. However, the bulk damage threshold of crystal is low.In order to condition KDP crystal, the effects of laser pre-irradiation on the KDP crystals were investigated in this paper. The KDP crystals were irradiated by excimer laser with 308-nm wavelength 35 ns pulsewidth, and we observed that the 215 nm absorption band disappeared, which is correlated with the electronic center charged oxygen vacancy. It is shown that P + and K + ions shifting became slow after excimer laser pre-irradiation by means of the electron probe measurement, which further demonstrated the electronic defects to be repaired. In addition, a single mode Nd:YAG laser with 10 ns pulsewidth was used in the laser damage experiments. Damage thresholds of the KDP crystals increase by a factor of 2-3.