Optical response of two-dimensional electron fluids beyond the Kohn regime: strong non-parabolic confinement and intense laser light

TL;DR

This paper explores the linear and non-linear optical responses of 2D electron fluids under strong non-parabolic confinement, revealing higher-harmonic generation influenced by electron interactions and potential engineering.

Contribution

It demonstrates how anharmonic confinement potentials can be used to control optical responses in 2D electron systems, combining quantum and classical modeling approaches.

Findings

Higher harmonics are generated due to anharmonic confinement.

Electron-electron interactions diminish non-linear effects.

Classical hydrodynamics aligns with quantum results.

Abstract

We investigate the linear and non-linear optical response of two-dimensional (2D) interacting electron fluids confined by a strong non-parabolic potential. We show that such fluids may exhibit higher-harmonic spectra under realistic experimental conditions. Higher harmonics arise as the electrons explore anharmonicities of the confinement potential (electron-electron interactions reduce this non-linear effect). This opens the possibility of controlling the optical functionality of such systems by engineering the confinement potential. Our results were obtained within time-dependent density-functional theory, employing the adiabatic local-density approximation. A classical hydrodynamical model is in good agreement with the quantum-mechanical results.