Realization of ultrahigh refractive index in terahertz region by multiple layers coupled metal ring metamaterials

Abstract

We report a polarization-independent unnaturally high refractive index metamaterial. It is found that the effective permittivity of the designed metamaterial can be drastically increased by the capacitive coupling effect. Also, the effective permeability of metamaterial can be increased by reducing the diamagnetic effect by designing a thin structure. In our work, the single-layer multi-band high refractive index metamaterials with a peak achieving to 26.8 at 0.9 THz is demonstrated. Furthermore, the three-dimensional metamaterial possessing high refractive index more than 85 around 0.91 THz can be constructed by a double-layer tricyclic structure. Ultrabroadband and ultrahigh refractive index of designed metamaterials can be obtained by multilayer coupling effect. In addition, the polarization-independent property and wide-angle performance of high refractive index metamaterial are exhibited.