Probing laser-driven structure formation at extreme scales in space and time

TL;DR

This paper reviews how ultrashort, high-intensity laser pulses can induce and study the formation of surface structures like LIPSS at extreme spatial and temporal scales using advanced free electron laser sources.

Contribution

It highlights recent experimental advances enabled by 4th-generation light sources to investigate the fundamental mechanisms of laser-induced surface patterning.

Findings

Ultrafast laser pulses can create both transient and permanent surface structures.

Recent methods allow nm-scale spatial resolution combined with femtosecond temporal resolution.

Understanding the transition from chaotic to periodic surface structures is advancing with new experimental techniques.

Abstract

Irradiation of solid surfaces with high intensity, ultrashort laser pulses triggers a variety of secondary processes that can lead to the formation of transient and permanent structures over large range of length scales from mm down to the nano-range. One of the most prominent examples are LIPSS - Laser Induced Periodic Surface Structures. While LIPSS have been a scientific evergreen for of almost 60 years, experimental methods that combine ultrafast temporal with the required nm spatial resolution have become available only recently with the advent of short pulse, short wavelength free electron lasers. Here we discuss the current status and future perspectives in this field by exploiting the unique possibilities of these 4th-generation light sources to address by time-domain experimental techniques the fundamental LIPSS-question, namely why and how laser-irradiation can initiate the transition of a "chaotic" (rough) surface from an aperiodic into a periodic structure.