Surface plasmon polaritons on rough metal surfaces: Understanding the formation of laser induced periodic surface structures in metals

TL;DR

This paper investigates the formation of laser-induced periodic surface structures (LIPSS) on metals, especially copper, revealing deviations from standard models and proposing a new SPP-based model considering surface roughness to better explain experimental results.

Contribution

The paper introduces a novel SPP propagation model on rough surfaces that accounts for surface roughness effects, improving understanding of LIPSS formation in metals.

Findings

Significant deviations in LIPSS period from standard model predictions at high laser incidence angles.

The new rough surface SPP model aligns well with experimental data.

Enhanced understanding of LIPSS formation mechanisms in metals.

Abstract

The formation of self-organized laser induced periodic surface structures (LIPSS) in metals, semiconductors and dielectrics upon pulsed laser irradiation is a well-known phenomenon, receiving increased attention due to its huge technological potential. For the case of metals, a major role in this process is played by surface plasmon polaritons (SPPs) propagating at the interface of the metal with the medium of incidence. Yet, simple and advanced models based on SPP propagation sometimes fail to explain experimental results, even of basic features as the LIPSS period. We experimentally demonstrate, for the particular case of LIPSS on Cu, that significant deviations of the structure period from the predictions of the standard model are observed, which are very pronounced for elevated angles of laser incidence. In order to explain this deviation, we introduce a model based on the propagation of a SPP on a rough surface that takes into account the influence of the specific roughness properties on the SPP wave vector. Good agreement of the modelling results with the experimental data is observed, which highlights the potential of this model for the general understanding of LIPSS in other metals.