Efficient directional forward scattering by a single Cu@Si core-shell nanoparticle in visible regions

Efficient control of optical radiation at nanoscale dimensions have attracted considerable interests in nano antennas, sensors, and light-emitting devices. Herein, based on Mie theory and the Kerker condition, we have theoretically achieved directional forward scatterings realized through a single Cu@Si core-shell nanoparticle in visible regions. Importantly, the contributions of high-order electric and magnetic quadrupoles on directional scatterings beyond conventional dipolar modes have been demonstrated through multipole analysis of electromagnetic scattering. Moreover, by optimizing the structural parameters, such as the size of the core radius and the thickness of the shell, the directivity can be engineered readily. These findings provide guidance for designing structures capable of achieving signal enhancement, manipulation, and directional transmission.