Influence of layer eccentricity on the resonant properties of cylindrical active coated nano-particles

We report on the influence of the layer eccentricity on the resonant properties of active coated nano-particles made of a silver core and gain impregnated silica shell illuminated by a near-by magnetic line source. For a fixed over-all size of the particle, designs with small and large cores are analyzed in terms of their far- and near-fields, as well as power flow properties. They demonstrate that the super-resonant states of the concentric particles are significantly influenced by introducing the eccentricity. In particular their amplitude responses are found to diminish significantly, this being more profound for the larger core nano-particles. The present results are useful from a from a practical viewpoint since slight displacements of the centers of the core and shell parts in these configurations are likely to occur in standard fabrication processes.