Radiation direction mutation in a spherical plasma filled multilayered core–shell particle

An actively tunable Fano resonance and the radiation direction mutation are supported in a multilayered core–shell particle composed of a spherical plasma-core and three-layered dielectric shells through varying plasma frequency. The simulated and theoretical results reveal that the Fano resonance relies on the interference between a narrow band electric dipole resonance and a broad band magnetic dipole resonance. The electric and magnetic dipole resonances can be controlled independently. The radiation direction mutates between forward and backward scatterings at Fano resonance frequency with lower plasma frequency, but there is a “delay” of the mutation in frequency with higher plasma frequency. The reasons for generating the mutation and delay are explained by using scattering amplitudes. The research results can be applied to antenna, directional emission control, and sensor areas.