Light scattering by a system of nanoparticles upon a thin gold film based on the Discrete Sources Method.

Light scattering by system of nanoparticles has become a subject of great interest due to a vast field of their potential applications. In particular considerable attention has been paid to the analysis of light scattering properties of optical antennas, which are usually systems of noble metal nanoparticles deposited at an interface. Due to the unique properties of noble metal nanostructures at optical frequencies optical antennas allow to enhance the interaction between light and matter and provide a desired directivity of the radiation. The extreme scattering effect (ESE) that has been reported recently [1] appears in the evanescent wave region and consists in a sharp increase of the energy transmitted through thin noble metal film with an irregularity inside or near the film. It has been demonstrated that ESE doesn’t depend on the thickness of the film, as well as on the shape and material of the irregularity, but is strongly affected by the film’s material. The discrete sources method (DSM) is known to be one the most flexible and inexpensive techniques for solving boundary value problems for Maxwell equations [2]. The DSM is a semi-analytical surface based meshless method and doesn’t require any integration procedure over the scatterer surface. In the frame of the DSM the approximate solution for scattered field everywher