Mechanism of nanostructure defects coupled with organic contamination on optical components: adsorption kinetics and laser cleaning effects

The low damage threshold of optical components severely limits the performance of high-intensity laser systems, in which the coupling effect between defects and organic contaminants is particularly significant. However, the interaction mechanism between organic contaminants and nanostructure defects remains to be elucidated. To address this issue, this study established a coupling model of the interaction between three typical defects, organic contaminants and lasers through molecular dynamics simulations from adsorption kinetics to laser removal. The study commenced with an examination of the geometric characteristics of defects, followed by a quantitative analysis of the volume fraction and surface energy distribution under a series of defect parameters. It was determined that there was a significant positive correlation between the geometric parameters of defects and contaminant adsorption capacity. Specifically, II defects exhibit the highest contaminant adsorption due to their large volume coefficient. III defects have been observed to exhibit the strongest contaminant adsorption binding energy, a phenomenon that can be attributed to their elevated surface energy. During the laser cleaning process, the removal force field strength of III defects reaches 368 eV Å⁻¹, which is 2.14 and 2.32 times that of II and I defects, respectively. This discrepancy can be attributed to the pronounced interaction between contaminants and the substrate in III defects, which necessitates the utilization of laser energy to surmount a heightened potential barrier to achieve efficacious removal. This result provides a theoretical basis for cleaning strategies for contaminants on nanostructured defect surfaces.