Reconfigurable Graphene-Metasurface Analysis via an Eigenmode-Free Method-of-Lines Formulation

We present an eigenmode-free (EF) method-of-lines (MoL) formulation for the fast synthesis of reconfigurable graphene metasurfaces (MS). As the complexity of MSs increases, analysis by full-wave methods becomes challenging. The MoL is a considerably faster semi-analytical method where the electromagnetic equations are solved analytically along the direction perpendicular to the MS layers and numerically on the MS plane, thereby substantially decreasing the degrees of freedom (DoFs). In existing MoL formulations, the eigendecomposition of the system matrix is calculated numerically, which becomes computationally demanding for MSs with larger cross-sections. To overcome this limitation, we introduce an EF MoL that calculates the S-parameter matrix by analytical closed-form expressions. We demonstrate the potential of the EF MoL by analyzing a reconfigurable graphene MS absorber. The EF MoL shows excellent agreement in the absorbance and is two orders of magnitude faster than the finite element method.