Laser Cleaning of Optical Components: Molecular Insights into Contaminant-Dependent Efficiency

Internal contamination significantly degrades the performance and lifetime of optical components in high-power laser systems, making surface cleanliness a critical challenge. In this study, molecular dynamics simulations were employed to investigate the interfacial adsorption behavior and laser-induced removal efficiency of representative organic contaminants on fused silica surfaces, focusing on various molecular structures and surface coverages. The results reveal that molecular architecture is a decisive factor in adhesion and cleaning. Dibutyl phthalate demonstrates the highest affinity through polar and conjugated intermolecular interactions, leaving a residual surface density 3.3 times higher than benzene for an absorbed laser fluence of 10 J/cm². In contrast, benzene desorbs easily at low fluence, whereas long-chain alkanes and phthalates exhibit pronounced retention. Surface coverage further exerts a significant influence on cleaning performance. At low coverage, enhanced adsorption density and interfacial energy enable removal efficiencies exceeding 84%. However, once the fractional coverage above 1.17, multilayer adsorption causes the residual density to increase to roughly 4.0 times that under low-coverage conditions, impeding complete desorption even under high-energy irradiation. These findings highlight how contaminant structure and surface coverage govern laser cleaning performance, and lay the foundation for parametrized contaminant data sets to optimize optical component cleaning.