3D morphology of laser-induced bulk damage at 355 and 1064nm in KDP crystal with different orientations

Abstract

In this study, wet etch process was applied to expose the bulk damage sites in the Z-cut and X-cut KDP crystals to the surface, which gave us the direct access to the modified material for scanning electron microscopy (SEM) and optical microscopy. It's found that the morphology of damage site initiated with 1064nm laser was consisted of three distinct regions: a core, some oriented cracks spreading from the core, and a region of modified material surrounding the core. The 3D pattern of the crack was constructed from three distinct 2D projections, which were perpendicular to each other. The 355nm laser damage morphology was also investigated, and the wavelength dependence of laser damage morphology was presented. A simple model was proposed to explain the damage morphology, and the relation between the 3D crack patterns and crystal structure was discussed.