Electromagnetic dipole coupling mechanism in layered terahertz metamaterials

Interplay between adjacent dipoles is an experimental priori for designing artificially-engineered structure because the dipole coupling is one critical factor for determining the electromagnetic response in metamaterials. Although numerous investigations have been performed to study the coupling effect of the split-ring resonator (SRR), the interlayer dipole coupling of its complementary SRR, called C-SRR, has been largely unexplored. Here, we present experimental and theoretical investigations on the electromagnetic coupling effect in the two stacks of layered C-SRR structures. By adjusting the relative lateral distance between the two-dimensionally stacked meta-structures, we observe that the confined magnetic dipole plays an important role in determining the resonance frequency and the bandwidth broadening of the C-SRR, exhibiting an exactly opposite behavior to the SRR structure. Our investigation provides experimental basis for developing frequency tunable three-dimensional metamaterial devices.