Zero-backward scattering by Metallo-Dielectric core-shell nanostructures

Abstract

Based on the Mie theory, we propose and investigate a “metal (M)-low-permittivity (LP)-high-permittivity (HP)” core-shell nanoparticle that possesses the high directional zero-backward scattering characteristics. We analyze the effect of the LP layer on the wavelength and strength of the electric or magnetic dipolar resonance, and reveal that the zero-backward scattering and dramatically enhanced forward scattering are easy to be obtained by modulating the thickness and refractive index of the middle LP layer, which can engineer the dipolar electric and magnetic modes in the M-LP-HP core-shell nanoparticles to coincide spectrally with the same strength, thus satisfying the first Kerker condition of zero backward scattering. We also demonstrate that the zero-backward scattering can be tuned over a wide range from the near-infrared to visible by varying the metal core size and the outer radius of the HP shell or by changing the refractive index of the HP shell. Our results can provide a scientific direction for designing the nanostructures and devices based on the zero-backward scattering.