Tailoring submicrometer periodic surface structures via ultrashort pulsed direct laser interference patterning

Direct laser interference patterning (DLIP) with ultrashort laser pulses (ULPs) represents a precise and fast technique to produce tailored periodic submicrometer structures on various materials. In this work, an experimental and theoretical approach is presented to investigate the fundamental mechanisms for the formation of unprecedented laser-induced topographies on stainless steel following proper combinations of DLIP with ULPs. The combined spatial and temporal shaping of the pulse increases the level of control over the structure while it brings insights into the structure formation process. The aim of DLIP is to determine the initial conditions of the laser-matter interaction by defining an ablated region while double ULPs are used to control the reorganization of the self-assembled laser-induced submicrometer 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 knowledge of laser-matter interaction in combined DLIP and ULP conditions and enable enhanced fabrication capabilities of complex hierarchical submicrometer sized structures for a variety of applications.

Automated summary

This study investigates the fundamental mechanisms for the formation of laser-induced topographies on stainless steel using DLIP and ULP, enhancing control over the structure and providing insights into the formation process.