Unidirectional light scattering by electric dipoles induced in plasmonic nanoparticles

Abstract

We proposed and demonstrated that unidirectional light scattering, usually realized by utilizing induced electric and magnetic dipole moments, can also be achieved via only electric dipole moments induced in an assembly of plasmonic nanoparticles. The condition for such kinds of unidirectional scattering has been derived in the dipole approximation. Calculated with the coupled dipole method, a contrast between the forward and backward scattering has been demonstrated with nearly five orders of magnitude for a dimer of gold nanospheres. It can be attributed to the destructive interference of scattered far field from the induced electric dipole moments with similar magnitudes and a relative phase of about π. Such properties are general for an assembly of electric dipole moments, and a trimer structure has been demonstrated to realize unidirectional light scattering as well as steering. Our results suggest a simple but yet versatile platform for manipulating light scattering.