Impact of pre-patterned structures on features of Laser Induced Periodic Surface structures

TL;DR

This study investigates how pre-patterned surfaces and laser polarization influence the formation of laser-induced periodic surface structures (LIPSS) on nickel, revealing polarization-dependent effects and electromagnetic mode interference in pattern formation.

Contribution

It demonstrates the role of pre-patterned structures and laser polarization in controlling LIPSS features, supported by a multi-scale physical model explaining electromagnetic interference effects.

Findings

LIPSS form perpendicular to pre-pattern when polarization is parallel to ridges.

LIPSS periodicity is independent of ridge spacing for parallel polarization.

LIPSS periodicity correlates with ridge spacing when polarization is perpendicular.

Abstract

The efficiency of light coupling to surface plasmon polariton (SPP) represents a very important issue in plasmonics and laser fabrication of topographies in various solids. To illustrate the role of pre-patterrned surfaces and impact of laser polsarisation in the excitation of electromagnetic modes and periodic pattern formation, Nickel surfaces are irradiated with femtosecond laser pulses of polarisation perpendicular or parallel to the orientation of the pre-pattern ridges. Experimental results indicate that for polarisation parallel to the ridges, laser induced periodic surface structures (LIPSS) are formed perpendicularly to the pre-pattern with a frequency that is independent of the distance between the ridges and periodicities close to the wavelength of the excited SPP. By contrast, for polarisation perpendicular to the pre-pattern, the periodicities of the LIPSS are closely correlated to the distance between the ridges for pre-pattern distance larger than the laser wavelength. The experimental observations are interpreted through a multi-scale physical model in which the impact of the interference of the electromagnetic modes is revealed.