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

This paper explores graphene's quasi-normal modes (QNMs) by developing a finite element method 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 non-reciprocal 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 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.