Abstract
This work proposes a physically consistent numerical model to simulate ultrashort laser absorption by a metallic workpiece at the water–metal interface when optical breakdown of the dielectric occurs. The simulation couples the framework of the finite difference time-domain method used in computational electromagnetics with the constitutive relation derived from both the model of direct ablation of metals and the first-order model of water breakdown. The simulation is used to describe interface ablation processes such as laser-induced plasma micromachining (LIPMM). Applied to the water–aluminum interface, the model is able to describe the metal absorption and the dielectric breakdown threshold in three-dimensional (3D) geometry. It is an extensible monolithic approach in which the absorption by different materials can be described by simply changing the constitutive relations.