Accurate Extraction of Graphene Scattering Properties via a Robust Formulation for Fundamental Modes

This article explores graphene’s quasinormal modes (QNMs) by developing a finite-element method (FEM) solver, which addresses an augmented eigenvalue problem where graphene is represented as an equivalent surface current. This representation correlates with the surface conductivity of the material through a Debye frequency dispersion model. Initially, the straightforward intraband term is considered, while the study delves into the interband contributions to graphene’s conductivity, described via a complex conjugate series of Debye terms. Also, it examines the magneto-optical properties of graphene, which can be tuned by an external magnetic field to produce nonreciprocal effects. Finally, the proposed formulation covers the normalization of graphene QNMs and the reconstruction of scattered fields, providing a complete analysis tool that handles graphene as a scattering surface. The featured methodology is successfully validated by comparing the evaluated absorption cross section (ACS) due to scattering from graphene sheets with the corresponding outcomes of a commercial full-wave solver. Graphene attributes are selected properly to model high-quality-factor resonances indicating the remarkable accuracy of the proposed scheme.