Spectroscopic investigation of metamaterials across the effective medium threshold

We spectroscopically investigate the scaling properties of a metamaterial consisting of a square array of gold cylindrical dots. The electromagnetic response of the gold-dot array is found to scale in relation to the ratio of the incident wavelength over the array spacing, in agreement with general predictions of metamaterial theory. The appropriateness of an effective medium description of the array is analyzed in terms of the resonant polarizability of the array components, and the onset of van der Hulst backscattering at higher frequencies.