Recent Advances in Laser-Induced Surface Damage of KH2PO4 Crystal

Abstract

As a hard and brittle material, KDP crystal is easily damaged by the irradiation of laser in a laser-driven inertial confinement fusion device due to various factors, which will also affect the quality of subsequent incident laser. Thus, the mechanism of laser-induced damage is essentially helpful for increasing the laser-induced damage threshold and the value of optical crystal elements. The intrinsic damage mechanism of crystal materials under laser irradiation of different pulse duration is reviewed in detail. The process from the initiation to finalization of laser-induced damage has been divided into three stages (i.e., energy deposition, damage initiation, and damage forming) to ensure the understanding of laser-induced damage mechanism. It is clear that defects have a great impact on damage under short-pulse laser irradiation. The burst damage accounts for the majority of whole damage morphology, while the melting pit are more likely to appear under high-fluence laser. The three stages of damage are complementary and the multi-physics coupling technology needs to be fully applied to ensure the intuitive prediction of damage thresholds for various initial forms of KDP crystals. The improved laser-induced damage threshold prediction can provide support for improving the resistance of materials to various types of laser-induced damage.

Unveiling sub-bandgap energy-level structures on machined optical surfaces based on weak photo-luminescence

“…The outer circle diameters of most Vickers indentations and the pitted defects are all in the range of 1-100 μm. 22 Moreover, Vickers indentations have been proven effective in modeling the surface defects on the machined fused silica surfaces to study the effects of surface defects in previous work. 24,31,32,52,53 Thus, Vickers indentations can be chosen to model the surface defects in this work.…”

“…Moreover, the crack widths of most Knoop indentations and the machined surface cracks on the optical surfaces are all in the range of 1-20 μm. 22 Thus, previous work 54,55 has prepared Knoop indentations to model the pre-cracks on material surfaces. Herein, we prepared Knoop indentations to model the surface cracks in this work.…”

“…19,20 Previous work concentrated on the physicochemical properties of surface defects to better understand their influence on the LIDTs of machined optical surfaces. [21][22][23] It has been generally accepted that surface-defect zones usually have different optical properties from non-defective zones, which would severely decrease the laser-induced damage resistance of the optical elements.…”

“…Previous work indicated that defect-induced optical field modulation and thermal absorption induced by the impurities within defect zones would decrease the laser-induced damage thresholds (LIDTs) of the optical surfaces. 22,23 However, some work showed that these two theories are still incompetent. 24,25 Shen et al etched optical surfaces in the presence of defects with different dimensions using hydrofluoric acid to eliminate the possible influence of impurities.…”

Molecular Dynamics Simulation of Laser Induced Heating of Silicon Dioxide Thin Films

“…Initially, the models describing LID were based on continual approaches including heat equations, kinetic equation, Boltzman equation, and so on [1,[7][8][9]. In recent decades, due to significant progress in high-performance computing, it has become possible to apply the methods of atomistic simulation for studying the laser radiation interaction with condensed matter [10][11][12].…”