Numerical investigation of terahertz polarization-independent multiband ultrahigh refractive index metamaterial by bilayer metallic rectangular ring structure

• Published in: RSC advances 2018-01, Vol.8 (4), p.22361-22369
• Main Authors: Fang, Bo, Chen, Lin, Deng, Yuqiang, Jing, Xufeng, Li, Xue
• Format: Article
• Language: English
• Subjects: Bilayers; Chemistry; Coupling; Diamagnetism; Metamaterials; Multilayers; Numerical analysis; Refractivity
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c8ra03758b

Multiband high index of refraction can be realized by thin ring-type terahertz metamaterials composed of multilayer coupled unit cells. We have focused on the numerical investigation of this type of a metamaterial. By drastically decreasing the diamagnetic effect with a thin metallic structure in the unit cell and by increasing the effective permittivity through strong capacitive coupling, a bandwidth of 1.5 THz with an index of more than 24 can be achieved using a single-layer thin brick-type metamaterial. The refractive index peak is 35. Then, we design a ring-type metamaterial structure, achieving a refractive index of 91 at about 0.45 THz, which is due to a decrease in the diamagnetic effect with smaller area surrounded by toroidal currents. Based on the coupling effects of double layer ring-type metamaterials or single-layer double ring-type structures, the refractive index peaks reach 43.2 and 18.68 at 0.43 THz and 0.92 THz, respectively. A three-layer ring-type metamaterial structure is proposed to obtain three band high index metamaterials. Multiband high index of refraction can be realized by thin ring-type terahertz metamaterials composed of multilayer coupled unit cells.