Dynamics of Ultrafast Laser Ablation of Water

Abstract

Ultrafast laser ablation is an extremely precise and clean method of removing material, applied in material processing as well as medical applications. And due to its violent nature, it tests our understanding of the interplay between optics, condensed matter physics and fluid dynamics. In this manuscript, we experimentally investigate the femtosecond laser induced explosive vaporization of water at a water/gas interface on the micron-scale through several time-scales. Using time-resolved microscopy in reflection mode, we observe the formation of a hot electron plasma, an explosively expanding water vapor and a shockwave propelled into the surrounding gas. We study this fs-laser induced water vapor expansion dynamics in the presence of different atmospheres, i.e. Helium, air and tetrafluoroethane. We use the Sedov-Taylor model to explain the expansion of the water vapor and estimate the energy released in the process.