Time-resolved measurement of single pulse femtosecond laser-induced periodic surface structure formation

TL;DR

This study uses time-resolved diffraction microscopy to observe the formation dynamics of laser-induced periodic surface structures on copper, revealing sequential ripple formation and modeling electron heating and surface plasmon excitation.

Contribution

It introduces a time-resolved microscopy approach to directly observe LIPSS formation and proposes a 1-D analytical model explaining the underlying physical mechanisms.

Findings

LIPSS ripples form sequentially from the groove edge.

First ripple appears after 50 ps.

The analytical model qualitatively explains the formation dynamics.

Abstract

Time-resolved diffraction microscopy technique has been used to observe the formation of laser-induced periodic surface structures (LIPSS) from the interaction of a single femtosecond laser pulse (pump) with a nano-scale groove mechanically formed on a single-crystal Cu substrate. The interaction dynamics (0-1200 ps) was captured by diffracting a time-delayed, frequency-doubled pulse from nascent LIPSS formation induced by the pump with an infinity-conjugate microscopy setup. The LIPSS ripples are observed to form sequentially outward from the groove edge, with the first one forming after 50 ps. A 1-D analytical model of electron heating and surface plasmon polariton (SPP) excitation induced by the interaction of incoming laser pulse with the groove edge qualitatively explains the time-evloution of LIPSS formation.