Maxwell-Vlasov-Uehling-Uhlenbeck (VUU) Simulation for Coupled Laser-Electron Dynamics in a Metal Irradiated by Ultrashort Intense Laser Pulses

TL;DR

This paper extends a semiclassical Vlasov approach to include electron-electron scattering via the VUU equation, coupled with Maxwell's equations, to simulate ultrashort laser interactions with metals, revealing polarization-dependent energy absorption and extended energy transport.

Contribution

The novel integration of the VUU equation with Maxwell's equations provides a new, cost-effective method to model laser-metal interactions including fermionic collisions.

Findings

Electron-electron scattering influences energy absorption more under p-polarization.

Energy transport extends beyond optical penetration depth.

Surface potential affects scattering and absorption behavior.

Abstract

The description of electron-electron scattering presents challenges in the microscopic modeling of the interaction of ultrashort intense laser pulses with solids. We extend the semiclassical approach based on the Vlasov equation [Phys. Rev. B 104, 075157(2021)] to account for dynamic electron-electron scattering by introducing the Vlasov-Uehling-Uhlenbeck (VUU) equation. We further couple the VUU equation with Maxwell's equations to describe the laser pulse propagation. We apply the present approach to simulate laser-electron interactions in bulk and thin-film aluminum, focusing on energy absorption and transport. Our calculation results reveal that electron-electron scattering affects energy absorption more significantly under p-polarization than under s-polarization, highlighting the role of the non-uniform surface potential. Our simulations also show that the energy transport extends beyond the optical penetration depth, which is consistent with observations in previous laser ablation experiments. The developed Maxwell-VUU approach is expected to advance the understanding of intense laser-material interactions not only as a cost-effective alternative to the time-dependent density functional theory (TDDFT), but also by incorporating fermionic two-body collisions whose description is limited in TDDFT.