Optical Gain Through Metallic Electro-Optic Effects

Two-dimensional (2D) materials are rapidly being integrated into technologies ranging from optical sensors to fiber optics. Most often, these 2D materials can only couple with the transverse-magnetic field mode, limiting their scope of impact. In this theoretical study, we find a resonant transverse-electric (TE) mode in biased two-dimensional metallic systems which leads to optical gain. We do so by first modeling the system's optical response using Boltzmann non-equilibrium transport theory and then analyzing its light transmission. In our model, we include non-reciprocal responses governed by the Berry curvature dipole (BCD) and previously overlooked magnetoelectric terms which arise from the interplay between the Berry curvature and the orbital magnetic moment of Bloch electrons. After analyzing each response separately, we find that the resonant TE mode is only accessed when responses due to the BCD and magnetoelectric terms are both present. Further studies are necessary to find materials with suitably large magnetoelectric terms, in order to realize the predictions within this study. This study paves the way for novel applications of 2D materials in optical technologies.