Hybrid approach for graphene modeling in numerical simulations of graphene based plasmonic devices with COMSOL

We present a hybrid approach for graphene modeling in the finite element method numerical simulations of graphene based plasmonic devices with COMSOL. The surface conductivity approach for modeling graphene or other two-dimensional materials needs less number of meshing elements if compared to the volumetric permittivity approach; however, it is less intuitive and less compatible with the boundary mode analysis, which provides a very efficient way for the excitation of boundary ports. We adopt the surface conductivity approach in the scattering domain and the volumetric permittivity approach in the boundary ports. A triangular connector with a spatially varying permittivity is introduced to achieve reflection-less coupling between the surface conductivity and the volumetric permittivity. The hybrid model enables the numerical simulation of graphene based devices with COMSOL to be benefited from less storage and calculation time, keeping compatibility with the boundary mode analysis.