Tailoring Sub-micrometer Periodic Surface Structures via Ultrashort Pulsed Direct Laser Interference Patterning

TL;DR

This paper investigates the fundamental mechanisms of creating complex sub-micrometer surface structures on stainless steel using combined ultrashort pulsed direct laser interference patterning, supported by experimental and theoretical analysis.

Contribution

It introduces a multiscale physical model linking interference parameters and laser pulses to resulting surface morphologies, advancing understanding of laser-matter interactions in this context.

Findings

Identification of key parameters influencing surface topographies

Development of a physical model correlating interference and morphology

Enhanced control over hierarchical sub-micrometer structures

Abstract

Direct laser Interference Patterning (DLIP) with ultrashort laser pulses (ULP) represents a precise and fast technique to produce tailored periodic sub-micrometer structures on various materials. In this work, an experimental and theoretical approach is presented to investigate the previously unexplored fundamental mechanisms for the formation of unprecedented laser-induced topographies on stainless steel following proper combinations of DLIP with ULP. DLIP is aimed to determine the initial conditions of the laser-matter interaction by defining an ablated region while double ULP are used to control the reorganisation of the self-assembled laser induced sub-micrometer sized structures by exploiting the interplay of different absorption and excitation levels coupled with the melt hydrodynamics induced by the first of the double pulses. A multiscale physical model is presented to correlate the interference period, polarization orientation and number of incident pulses with the induced morphologies. Special emphasis is given to electron excitation, relaxation processes and hydrodynamical effects that are crucial to the production of complex morphologies. Results are expected to derive new knowledge of laser-matter interaction in combined DLIP and ULP conditions and enable enhanced fabrication capabilities of complex hierarchical sub-micrometer sized structures for a variety of applications.