Interplay of mutual electric and magnetic couplings between three-dimensional split-ring resonators.

We experimentally and theoretically study the interplay between capacitive electric and inductive magnetic couplings in infrared metamaterials consisting of densely-packed three-dimensional (3D) meta-atoms. The meta-atom is made of metal-stress-driven assembled 3D split-ring resonators to exhibit strong bi-anisotropy, where electric and magnetic resonances occur simultaneously. By varying the spatial arrangement of the arrayed meta-atoms, the mutual coupling between meta-atoms dramatically modifies their mode profiles and resultant spectral responses. The corresponding numerical simulations evidently retrieved current densities and magnetic field strengths, as well as the transmittance, to reveal the important resonant behavior in the coupled meta-atom systems. We conclude that the mutual electric coupling between the neighboring meta-atoms plays a crucial role to the scattering behaviors of the bi-anisotropic metamaterials.