Laser-induced circular nanostructures in fused silica assisted by a self-assembling chromium layer

Nanostructures have a widespread field of applications and are of growing industrial importance. However, the economic fabrication of nanostructures poses a critical challenge. In this work, a fundamental research of a laser-induced surface nanostructuring of fused silica using the dynamic self-assembling structure formation in metal layers is presented. This method may offer promising opportunities for nanostructuring of dielectrics. This new approach is demonstrated by the formation of randomly distributed concentric nanostructures into fused silica. The irradiation of chromium-covered fused silica samples with a KrF excimer laser results in melting, partial ablation, restructuring, and resolidification of both the metal layer and the dielectric surface. In this way, concentric circular structures into the dielectric were formed with dimensions that can be controlled by the laser fluence Φ and by the pulse number N. The distance of the concentric rings increases with increasing laser fluence. The experimental results were compared with simulated structure dimensions taking into account the heat equation and the Navier–Stokes equation. Despite the currently applied decoupled approach for the simulations, i.e. separating the heat equation and the fluid flow, a good agreement of simulation results with experimental data was achieved.