Laser annealing characteristics of multiple bulk defect populations within DKDP crystals

Abstract

Laser annealing by pre-exposure to subdamage threshold laser pulses is a well-established method to increase the damage performance of bulk KH2PO4 and KDxH2−xPO4 nonlinear optical materials. The origin of laser-induced damage is believed to be localized absorption by a defect structure, either a light-absorbing foreign nanoparticle or a cluster of stoichiometric defects. It has been recently shown that there are at least three populations of such defect structures in these materials in which pre-exposure to laser pulses of specific fluence and wavelength results in a measurable reduction in their number density or decrease in their susceptibility to damage. In this work, we investigate the annealing characteristics of these three populations of defect structures in DKDP under variable irradiation conditions. The aim is to understand the similarities and differences between these populations in the way they interact with laser light. The results depict distinct behaviors that reveal information on the relationship between the defect populations and their modifications responsible for annealing.