Constructive feedback for the growth of laser-induced periodic surface structures

TL;DR

This paper investigates the formation and growth of laser-induced periodic surface structures using FDTD simulations, introducing an inverse expansion mechanism to explain experimental observations that contradict traditional theories.

Contribution

It proposes a novel inverse expansion mechanism for LIPSS growth, addressing limitations of previous ablation-based models and clarifying discrepancies with experimental results.

Findings

Introduces an expansion-like mechanism for LIPSS growth.

Explains formation of structures on metals similar to dielectrics.

Reconciles experimental observations with theoretical models.

Abstract

We study the formation and growth of laser-induced periodic surface structures (LIPSSs) with the finite-difference time-domain (FDTD) method. We use a recently proposed inter-pulse feedback method to account for the evolution of the surface morphology between each laser pulse sent to the surface of the processed material. This method has been used with an ablation-like mechanism, by removing material exposed to a light intensity higher than a given threshold. We propose an inverse mechanism, an expansion-like mechanism, able to grow structures that the ablation-like process cannot. This allows us to introduce the notions of constructive and destructive feedback and explains a strong contradiction between the standard Sipe-Drude theory and the experimental observations, i. e. the formation on metals of structures usually linked to wide band gap dielectrics.