Simultaneous Excitation of Electric and Magnetic Dipole Modes in a Resonant Core-Shell Particle at Infrared Frequencies to Achieve Minimal Backscattering

Plasmonic nanoparticles have been the focus of much interest in recent years, especially core-shell particles that pair a negative permittivity material with a dielectric layer to promote tunability of the resulting plasmon resonances. Nearly all nanoparticle designs have been considered in the optical regime where metals provide readily available negative permittivities, but where high-index dielectrics are uncommon. By moving to the infrared regime, high-index dielectrics can be used, which allow a greater variety of core-shell designs by admitting the appearance of magnetic resonances. By properly designing a core-shell nanoparticle to engineer the simultaneous excitation of both the magnetic and electric resonances with appropriate amplitudes, highly resonant particles with minimal backscattering can be achieved. Configurations that integrate these minimal backscattering designs with interfaces lead to potential thermal emission control surfaces.