RESUMEN
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.
RESUMEN
An accurate computation of the near-field enhancement is a key factor for the optimization of nanostructures in plasmonics. This problem has been addressed for Green's dyadic method but remains open for finite element method (FEM) where the use of non-Cartesian meshes is known to be the most efficient. We present a new adaptive mesh process based on the a posteriori error indicator estimation on the physical solution. This new procedure accelerates drastically the convergence of the solution and minimizes both the memory requirement and the computational time.