Designing polarization insensitive negative index metamaterial for operation in near infrared

Hexagonal arrays of gold nanoelements with C₃ symmetry are studied as a metamaterial slab of reduced anisotropy. Tri-dimensional (3D) finite-difference time domain (FDTD) simulations are used to calculate the reflected and transmitted electromagnetic field for two waves normally incident to the slab with mutually perpendicular polarizations. S-parameter method is used to retrieve the constitutive parameters for each polarization. While dipolar plasmonic resonance in the case of one layer metamaterial slab leads only to negative values of permittivity, using two layers of asymmetric nanoelements leads to a negative refractive index metamaterial in the near infrared range (158–172 THz) as a result of hybridized plasmonic states inversion.