Unidirectional scattering induced by the toroidal dipole moment in the system of plasmonic nanoparticles

TL;DR

This paper explores how toroidal dipole moments influence unidirectional scattering in plasmonic nanoparticle systems, revealing their significant role and potential for tunable nanoantenna design.

Contribution

It demonstrates the importance of toroidal dipole moments in unidirectional scattering, a factor often overlooked in previous studies, and shows how to achieve tunable scattering configurations.

Findings

Toroidal dipole moments interfere with conventional multipoles to cause unidirectional scattering.

Specific nanoparticle configurations enable tunable backward and forward scattering.

Results have potential applications in nanoantenna design.

Abstract

Unidirectional backward and forward scattering of electromagnetic waves by nanoparticles are usually interpreted as the interference of conventional multipole moments (i.e., electric and magnetic dipole, electric quadrupole, etc.). The role of toroidal dipole moments in unidirectional scattering is generally overlooked. In this work, we investigate the unidirectional scattering for the system of three plasmonic nanospheres. It is found that the unidirectional backward scattering is caused by the interference between the toroidal dipole moment and other conventional multipole moments. Tunable primary backward and forward scattering can be achieved under some specific configurations. Our results can find applications in the design of nanoantennas.