Experimental demonstration of artificial dielectrics with a high index of refraction

Recently, it has been suggested that metamaterials with high refractive index can be constructed using metal gratings with periodic subwavelength slits [J. T. Shen , Phys. Rev. Lett 94, 197401 (2005)]. We designed such metamaterials and investigate their transmittance and reflectance in the terahertz frequency range. The spectra can be directly compared to that of a conventional dielectric slab with effective refractive index of n similar or equal to 5.5. As theoretically predicted, the effective index of refraction only depends on the ratio of the width of the slits to the periodicity of the gratings. Existing small differences to the dielectric slab are discussed.