From ripples to spikes: a hydro-dynamical physical mechanism to interpret femtosecond laser induced self-assembled structures

TL;DR

This paper proposes a coupled electrodynamics and hydrodynamics model to explain the formation of self-assembled nanostructures on conductive materials induced by femtosecond laser pulses, advancing understanding of light-matter interactions.

Contribution

It introduces a novel physical mechanism combining surface plasmon excitation and Marangoni convection to interpret laser-induced self-assembled structures.

Findings

The model explains the formation of nano-ripples, micro-grooves, and micro-spikes.

Applicable to various conductive materials.

Provides a unified framework for sub-ablation laser structuring.

Abstract

Materials irradiated with multiple femtosecond laser pulses in sub-ablation conditions are observed to develop various types of self-assembled morphologies that range from nano-ripples to periodic micro-grooves and quasi-periodic micro-spikes. Here, we present a physical scenario that couples electrodynamics, describing surface plasmon excitation, with hydrodynamics, describing Marangoni convection, to elucidate this important sub-ablation regime of light matter interaction in which matter is being modified, however, the underlying process is not yet fully understood. The proposed physical mechanism could be generally applicable to practically any conductive material structured by ultrashort laser pulses, therefore it can be useful for the interpretation of further critical aspects of light matter interaction.