Effects of γ-ray irradiation on optical absorption and laser damage performance of KDP crystals containing arsenic impurities

Abstract

The effects of γ-irradiation on potassium dihydrogen phosphate crystals containing arsenic impurities are investigated with different optical diagnostics, including UV-VIS absorption spectroscopy, photo-thermal common-path interferometer and photoluminescence spectroscopy. The optical absorption spectra indicate that a new broad absorption band near 260 nm appears after γ-irradiation. It is found that the intensity of absorption band increases with the increasing irradiation dose and arsenic impurity concentration. The simulation of radiation defects show that this absorption is assigned to the formation of AsO₄⁴⁻ centers due to arsenic ions substituting for phosphorus ions. Laser-induced damage threshold test is conducted by using 355 nm nanosecond laser pulses. The correlations between arsenic impurity concentration and laser induced damage threshold are presented. The results indicate that the damage performance of the material decreases with the increasing arsenic impurity concentration. Possible mechanisms of the irradiation-induced defects formation under γ-irradiation of KDP crystals are discussed.

Traceless mitigation of laser damage precursors on a fused silica surface by combining reactive ion beam etching with dynamic chemical etching

“…Since laser-induced damage (LID) on fused silica surfaces radically limits the lifetime of optics in high-power fusion-class laser systems such as the National Ignition Facility, 1 the Megajoule laser 2 or SG-III, 3 damage precursors have been investigated extensively aiming at improving the laser-induced damage threshold (LIDT) of fused silica. [4][5][6][7][8][9] Although recent efforts in HF-based chemical etching have succeeded in dramatically improving the damage resistance of fused silica, [10][11][12] they remain limited to the surface quality aer etching. 13,14 The root cause of the surface quality degradation is chemical treatment leaving etching traces (scratches and pits are opened and extended into geometrical structures), which lead to the increase of surface roughness and gure errors.…”

Nonlinear Optical and Laser Damage Properties of KDP Crystal with Trace Impurities in Bulk

“…Both samples exhibit an absorption peak at 222 nm and a shoulder around 270 nm. In previous studies, such features were supposed to be ascribed the absorption of impurities defects such as Al, Fe, As, etc . The lattice imperfect caused by impurity incorporation could possibly cause additional absorption.…”

Recent Advances in Laser-Induced Surface Damage of KH2PO4 Crystal

“…At present, a series of studies on the damage mechanism and the damage threshold of fused silica and other optical elements in ICF devices under laser irradiation have been carried out. The bulk damage of KDP crystal materials has been mostly studied by Ogorodnikov et al [21,22]. However, the impurity particles inside the crystal have been avoided gradually due to the improvement of the growth technology of KDP crystal materials.…”