Asymmetric response in a line of optically driven metallic nanospheres

We describe the dipole-dipole interactions between a linear array of optically driven silver metallic nanospheres (MNSs). These model calculations incorporate the full electric field generated by an oscillating dipole and predict several interesting effects due to the retardation of the field. The distribution of the power associated with MNSs along the array shows a strong variation on a scale smaller than the wavelength of the driving light. For a given geometry, there is a small range of frequencies where the relative power in the last MNS compared to the first dramatically changes, suggesting a simple device for wavelength discrimination in this frequency range. Moreover, small changes in the driving frequency can completely change the direction of the scattered light when only a single nanosphere is driven.