Broadband all dielectric high refractive index metamaterials in the terahertz region

We design an all-dielectric broadband terahertz-band high-refractive metamaterial sensor. The structure is composed of a single-layer square column structure based on ultra-high dielectric constant materials, and exhibits a square periodic arrangement. The S-parameter inversion algorithm calculates that the effective refractive index is above 15 in the 2.48THz similar to 2.97THz band, and the peak value is above 16. At the same time, we reveal the effects of cell size, cell height, period, etc. on the effective permittivity, permeability, impedance, refractive index, and frequency bandwidth of the structure and their changing trends. We further propose a metamaterial structure with four square pillars of different sizes within the unit structure. The effects of square pillar size, square pillar height and cell base height on the effective refractive index of the metamaterial structure were studied respectively. This square-pillar composite structure metamaterial has more degrees of freedom, and can control the effective refractive index of the metamaterial, and the peak refractive index can reach more than 18.