Theory for heating of metals assisted by Surface Plasmon Polaritons

TL;DR

This paper develops a theoretical model combining surface plasmon polaritons with a two-temperature approach to explain how laser pulses induce periodic surface structures in metals by modulating energy transfer and lattice temperature.

Contribution

It introduces the TTM+P model that integrates SPP effects into the two-temperature framework for the first time, explaining laser-induced surface patterning mechanisms.

Findings

Demonstrates periodic lattice temperature modulation due to SPP interference

Shows potential for explaining laser-induced surface structures

Provides a numerical analysis on gold as a case study

Abstract

We propose a model accounting for plasmons within a two temperature description, to investigate the role of surface plasmon polaritons (SPP) in the energy redistribution between laser excited electrons and the lattice, leading to surface restructuring of the material. This energy transfer can lead to the creation of laser induced surface structures in metals illuminated by an ultrashort laser pulse. The Two Temperature Model + Plasmon (TTM+P) equations are constructed by applying perturbation theory on the energy-, momentum- and density conservation equations of free electrons in metals. We consider three subsystems: the lattice, the thermalized electrons and the SPP, subject to an external laser field irradiation. The interference between the laser and SPP fields leads to spatially modulated energy absorption by the electronic system, and, through electron-phonon collisions, periodically shapes the lattice temperature. A numerical analysis is performed on a 1D model for gold. We show the emergence of a periodic modulation of the lattice temperature, which may contribute to laser induced periodic surface structures (LIPSS).