A New Method to Analyse the Role of Surface Plasmon Polaritons on Dielectric-Metal Interfaces

At nano-scale new phenomena have been discovered, allowing devices’ miniaturisation, energy harvesting, and power reduction. The Extraordinary Optical Transmission (EOT) phenomenon was reported in 1998 by Ebessen, who stated that the resonant peaks in the response of metallic nano antennas were more intense than predicted by classical diffraction theories. Years later, the main reason for this behaviour was attributed to the Surface Plasmon Polaritons (SPP), at least in ultraviolet and visible regions. In this article, a new method to model the radiation-matter interaction on a dielectric-metal interface is proposed, based on Maxwell’s equations and Fresnel Coefficients in absorbing media. Transmission percentage, angle and propagation length are obtained for a rigorous sweep on incident angle and wavelength. The results taken using some noble metals allow us to observe the presence of surface phenomena at expected SPP resonances. First, it is noticeable huge values of transmission in ultraviolet and visible regions, meaning that the metal does not reflect all the radiation. Also, the transmission angle tends to be higher, meaning huge surface components. Furthermore, the transmission length is on orders of 50-100 nm, meaning that phenomena as EOT only occurs at the nano-scale, since waves should arrive at another interface before being absorbed.