The efficient finite element method with impedance transmission boundary condition for computing optical waveguide modes

In this paper, we propose an efficient finite element method with impedance transmission boundary condition (ITBC) to significantly improve the numerical solutions of the optical waveguide problems. It utilizes the curl-conforming linear tangential and quadratic normal (LT/QN) edge elements to expand the tangential component of the electric field, and the second order nodal-based scalar basis functions to expand the longitudinal component. Furthermore, to avoid the very fine spatial discretization of thin lossy sheet, ITBC has been proposed for the FEM formulations. The graphene plasmonic waveguide verify that the FEM with ITBC technique has high efficiency.