Effects of multi-layer stacking along the propagation direction of an infrared metamaterial on the electromagnetic response of the structure

We numerically study a metamaterial structure with unit cells composed of two silver rods standing on a silver plate. While no left-handed behaviour is observed in the case of a single-layer structure, a multi-stacked-layer structure represents a left-handed behaviour at 300 THz. The electromagnetic response is different for different number of stacked layers along the propagation direction, however when the number of stacked layers is large enough, increasing the number of layers has no influence on the EM response of the structure. We also investigate the influence of the lattice constants along different directions on the LH (left-handed) behaviour of the structure.