Group theory based design of isotropic negative refractive index metamaterials

Novel isotropic planar and three-dimensional negative refractive index (NRI) metamaterial (MTM) designs consisting of periodically arranged cross structures are developed in the terahertz (THz) frequency regime using group theory. The novel designs not only avoid magnetoelectric coupling but also enable a simplified fabrication process. Using Finite-difference Time-Domain (FDTD) simulations, the design exhibits an NRI passband which is in good agreement with the S-parameters obtained from Fresnels equation. Cross-polarized fields are used to characterize the magnetoelectric coupling mechanism and determination of material properties of the medium via group theory aid in the characterization of the isotropy of the structure. Numerical simulations of a wedge composed of the proposed metamaterials prove the negative refractive index of the models.