Characterization of tunable graphene metasurfaces over an ultrawide terahertz band using a 1‐step leapfrog hybrid implicit‐explicit FDTD method

Abstract

An improved 1‐step leapfrog hybrid implicit‐explicit finite‐difference time domain method is developed for simulating tunable characteristics of graphene metasurfaces over an ultrawide terahertz band for different physical and geometrical parameters. The graphene conductivity is described by a closed‐form approximate expression and further expanded into a rational sum of complex‐conjugate pole‐residue pairs using the vector‐fitting technique. It is further implemented into the leapfrog hybrid implicit‐explicit finite‐difference time domain by an associated auxiliary differential equation formulation. Parametric studies are performed for capturing terahertz band responses of some typical graphene metasurfaces, with their tunabilities investigated and compared for different chemical potentials, layer numbers of graphene surface, operating temperatures, etc. When the results are compared with conventional finite‐difference time domain and analytical solutions, the proposed method demonstrates both high efficiency and good accuracy.

Applications of anisotropic one‐step leapfrog HIE‐FDTD method in microwave circuit and antenna

“…Compared to the ADI‐FDTD method, the HIE‐FDTD method has higher computational efficiency and accuracy, which has led to its rapid development . Recently, a novel one‐step leapfrog HIE‐FDTD (L‐HIE‐FDTD) method has emerged, with looser numerical stability condition compared to the existing HIE‐FDTD method, and its application has been extended to dispersive media, graphene, plasmonic structures, and rotationally symmetric structures . However, although the numerical dispersion of hybrid method is lower than that of other unconditionally stable FDTD methods, its performance deteriorates in some specific directions, which limits its application and development to some extent.…”