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Asymmetric Backscattering from the Hybrid Magneto-Electric Meta Particle

The optical theorem relates the total scattering cross-section of a given structure with its forward scattering, but does not impose any restrictions on other directions. Strong backward-forward asymmetry in scattering could be achieved by exploring retarded coupling between particles, exhibiting both electric and magnetic resonances. Here, a hybrid magneto-electric particle (HMEP), consisting of a split ring resonator acting as a magnetic dipole and a wire antenna acting as an electric dipole, is shown to possess asymmetric scattering properties. When illuminated from opposite directions with the same polarization of the electric field, the structure has exactly the same forward scattering, while the backward scattering is drastically different. The scattering cross section is shown to be as low as zero at a narrow frequency range when illuminated from one side, while being maximal at the same frequency range when illuminated from the other side. Theoretical predictions of the phenomena are supported with both numerical and experimental conformations, obtained at the GHz frequency range, and all are in a good agreement with each other. HMEP meta-particles could be used as building blocks for various metamaterials assembling solar cells, invisibility cloaks, holographic masks and more.