First-principles study of metallic impurities induced 355 nm UV laser absorption in fused silica

To date, it is controversial which metallic impurities play crucial role in the laser induced degradation and damage of fused silica at 355 nm. In this work, a First-principles study for the influences of impurities in fused silica are presented, which are usually contaminated during manufacture and post-processing processes. Our results show that Ca, K, Fe and Ce can lead to obvious optical absorption near 355 nm. Moreover, we find that, for K and Ca, the absorption intensity near 355 nm is highly sensitive to the concentration. Our results indicate that K and Ca can easily induce degradation and damage of fused silica at 355 nm. These two impurities should be concerned during manufacture and post-processing pro-cesses. The detailed theoretical study reveal that Ca and K can induce obvious impurity states in band gap and the optical absorption near 355 nm is originated from the transition between impurity states to conduction band. Our results also reveal that, for fused silica with Ca impurity, the exciton effect plays an important role for the optical absorptions near 355 nm, while it is not significant for K. Our work helps to explore laser damage mecha-nism and improve manufacture and post-processing techniques of fused silica. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study investigates the influence of impurities in fused silica on its optical absorption at 355 nm using first-principles calculations. The results show that impurities such as Ca and K can cause significant absorption near 355 nm, and the absorption intensity is highly sensitive to concentration. It is found that K and Ca are particularly concerning as they can easily induce degradation and damage of fused silica at 355 nm. The study reveals that the optical absorption is attributed to the transition between impurity states and the conduction band, and the exciton effect plays a role in the optical absorption for fused silica with Ca impurity. This work contributes to understanding the laser damage mechanism and improving the manufacturing and post-processing techniques of fused silica.