A Poincaré's approach for plasmonics: the plasmon localization.

A Poincaré's approach is employed to characterize the excitation of a plasmon, which in essence corresponds to a zero of a complex S-matrix. Throughout this work we study the plasmonic behaviour of gold, as this metal not only is frequently used in experimental arrays, but also requires an accurate dispersion model to properly excite plasmons. We investigate the plasmonic behaviour of gold nanogratings by means of Born's approximation and the Finite-Elements Method. Also, a method based on the Poincaré's approach is proposed to optimize this kind of structures.