Three-wave approximation for the modal field inside high-index dielectric rods of hybrid plasmonic waveguides

An approximate three-wave model is suggested for describing the modal field inside the high-index dielectric rod of a hybrid plasmonic waveguide. An evanescent wave, an uniform wave and a propagating wave are considered along the direction perpendicular to the metal surface. The superposition of these three waves forms the modal field inside the high-index rod. Through numerical tests, we find that this model is highly valid for a large range of waveguide sizes.