Observation of the spatiotemporal multiscale evolution mechanism for the interaction between nanosecond pulsed laser and fused silica

Abstract

The issue of damage to fused silica by nanosecond pulsed lasers represents a significant challenge to enhancing the output capacity of high-power laser devices, and thus requires further investigation. The interaction between a laser and fused silica is a complex phenomenon that typically involves interactions across multiple spatiotemporal scales and physical fields. In this paper, a coupled macro-micro multiscale simulation technique based on temperature field is proposed. This method permits the observation of the spatiotemporal multiscale evolution mechanism underlying the interaction between a nanosecond pulsed laser and fused silica. The temperature distributions at various locations at the laser energy, obtained from a heat conduction model, are employed as inputs for laser energy in microscopic molecular dynamics simulations. This approach is employed to elucidate the atomic structure changes induced by laser radiation in fused silica, thereby providing a rapid dynamic correspondence of the processes occurring in fused silica irradiated by nanosecond pulsed laser. The results of the macroscopic and microscopic simulations demonstrate that the damage mechanism in fused silica can be divided into three distinct regions: the solid, melting, and ablation regions. The damage behavior is primarily ascribed to the internal atomic phase transition mechanism. Additionally, the laser fluence has a pronounced impact on the structural alterations occurring within fused silica. It was observed that fused silica undergoes thermal melting at a laser fluence of 1.0 J/cm², at 3.0 J/cm² the melting state coexists with ablation, and above 4.0 J/cm² a large amount of atomic ablation is observed.