Electrostrictive Mechanism of Nanostructure Formation at Solid Surfaces Irradiated by Femtosecond Laser Pulses

The significance of the mechanical pressure of light in creation of laser-induced periodic surface structures (LIPSSs) is investigated. Distributions of the electrically induced normal pressure and tangential stress at the illuminated solid surface, as well as the field of volume electrostrictive forces, are calculated taking into account surface plasmon polariton (SPP) excitation. Based on these calculations, we predict surface destruction and structure formation due to inelastic deformations during single femtosecond pulses. The calculated fields of the electromagnetic forces are found to agree well with the experimental ripple structures. We thus conclude that the electrostrictive forces can explain the origin of the periodic ripple structures.