The localized surface plasmon resonance (LSPR) is a resonant oscillation of the free-electron gas confined within a metallic nanostructure driven by an incident electromagnetic (EM) wave. Physically, the charges displaced by the EM field experience a restoring force due to their mutual attraction; when the characteristic oscillation frequency o0 associated to the restoring force matches that of the EM field, the resonance condition is met for the plasma oscillation [1]. At the LSPR, the extinction of EM radiation is greatly enhanced as a result of an increase of both scattering and absorption cross sections. The enhanced scattering arises from the reradiation of the EM field that is induced in the metallic medium, whereas the absorption is related to the non-radiative decay of the plasma oscillations that typically leads to the dissipation of the power associated with the EM wave within the …