Laser-induced defect reactions governing damage initiation in DKDP crystals.

We investigate the interaction of high-power nanosecond-laser pulses at different frequencies with damage initiating defect structures in bulk KD(x)H(2-x)PO(4) (DKDP) crystals in order to enhance the understanding of a) the nature and behavior of the defects involved and b) the laser-induced defect reactions leading to improvement to the material performance. The experimental results indicate that there is more than one type of defect structure giving rise to damage initiation over two different spectral ranges. Moreover, within one set of defects we observe two different damage behaviors depending on the pre-irradiation parameters, pointing to more than one defect reaction pathway.