The Atomistic Perspective of Nanoscale Laser Ablation

Abstract

Materials irradiated by ultrashort laser pulses can undergo a variety of surface relief and structural modifications due to melting, spallation, and ablation processes. The possibility of instant and localized energy deposition into materials makes the short laser pulses a perspective tool in precise material modifications under controlled conditions. Thus, with certain laser irradiation parameters, the absorbed energy can trigger one or several laser-induced phase transition processes in the solid leading to material ejection, generation of subsurface voids, or nanostructures growth on the surface. The resulting material modifications can change its topographical, morphological, magnetic, and optical properties. While the ablation and spallation processes were utilized in laser welding and drilling technology, the functionalized surfaces have found a number of applications in micro-optics, waveguides, Raman spectroscopy, and biosensors. Generation of material modifications in a designed way, however, requires a detailed understanding of the dynamics of fast, nonequilibrium, and interrelated laser-induced processes at nanoscale. In this work, a combined particle-based mesoscopic numerical approach suitable for the investigation of ablation and nanostructuring mechanism of solids on the experimental scale is proposed. The combined model is applied to investigate the laser-induced processes and their dependences on the surrounding media and laser irradiation parameters: wavelength, pulse duration, and fluence. Good agreement between the modeling and the experimental results justifies the proposed approach as a powerful numerical tool revealing the fundamental physics of the underlying the ablation and nanostructuring processes. This will pave the way toward predesigned topography for functionalized surfaces on the nanoscales.