3D isotropic metamaterial based on a regular array of resonant dielectric spherical inclusions

The 3D regular lattice of bi-spherical dielectric resonant inclusions arranged in a cubic lattice as two sets of dielectric spheres having different radii and embedded in a host dielectric material with lower dielectric permittivity was carefully investigated. The magnetic resonance mode in smaller spheres gives rise to the magnetic dipole momentum and the electric resonance mode in bigger spheres is responsible for the electric dipole momentum. The magnetic resonance corresponding to the first Mie resonance in the spherical particles is followed by forming a regular array of effective magnetic dipoles, and the structure of the identical spherical dielectric resonators can be designed as an isotropic μ-negative 3D-metamaterial. At the same time, it was found experimentally and by the simulation that the resonant response of the electric dipole was weakly pronounced and the ɛ-negative behavior was remarkably suppressed. To enhance the electric dipole contribution, two different ways were considered: (i) using another kind of symmetry of the bi-spherical arrangement of the particles corresponding to the body-centered cubic symmetry instead of the symmetry of NaCl analog considered previously; (ii) using a strong coupling between the identical resonant dielectric spheres arranged in the simple cubic symmetry for creation of the structure exhibiting properties of the isotropic DNG medium.