Optical Gain Through Metallic Electro-Optical Effects

TL;DR

This theoretical study predicts that biased low-symmetry 2D metallic systems can exhibit optical gain via a resonant TE mode without stimulated emission, influenced by Berry curvature dipole and Magnetoelectric tensor effects.

Contribution

It introduces a novel mechanism for optical gain in metallic systems through resonant TE modes affected by Berry curvature dipole and Magnetoelectric effects.

Findings

Resonant TE mode depends on both BCD and MET effects.

Optical conductivity varies with bias direction.

Both effects are necessary for the TE mode to occur.

Abstract

Optical gain is a critical process in today's semiconductor technology and it is most often achieved via stimulated emission. In this theoretical study, we find a resonant TE mode in biased low-symmetry two-dimensional metallic systems which may lead to optical gain in the absence of stimulated emission. We do so by first modeling the optical conductivity using Boltzmann non-equilibrium transport theory and then simulating the scattering problem using a scattered-wave formalism. Assuming that the system may possess a Berry curvature dipole (BCD) and a non-zero Magnetoelectric tensor (MET), we find that the optical conductivity has a non-trivial dependence on the direction of the applied bias, which allows for probing the TE mode. After analyzing the system with one of each of the effects, we find that the resonant TE mode is only accessible when both effects are present. Further studies are necessary to find materials with a suitably large BCD and MET, in order to realize the predictions within this study.