An efficient plasmonic waveguide mode solution using rational function fitting of Green’s function

A novel approach to find plasmonic waveguide modes is presented in this paper. The method is based on rational function fitting of spectral Green’s function (RFF-SGF) of slab waveguide with the use of modified VECTFIT algorithm. Dispersion equation solutions including complex modes of structures with material/metal loss can be obtained with no extra complexity during the poles and residues extraction in the fitting approach. Moreover, this method can be used in multilayered plasmonic waveguides straightforwardly which are widely utilized in nanophotonic devices. The main advantage of this method lies in its simple implementation, speed as well as controllable accuracy. Surface plasmon and also surface wave modes of various plasmonic slab waveguides are investigated, and excellent agreements with rigorous methods are shown.