Experimental verification of negative refraction for a wedge-type negative index metamaterial operating at terahertz

We report on angle-resolved time domain spectroscopy (TDS) carried out on a prismlike negative index metamaterial operating around 0.5 THz. The wedge-type devices are constituted of hole arrays etched in gold thin films, which are stacked according to a sequential mask shift. By means of a goniometric TDS setup and subsequent analysis of the temporal waveforms, negative refraction is demonstrated with values close to n=-1 around 0.5 THz. The dispersion of refractive index retrieved from the Snell-Descartes law shows comparable trends in comparison with the dispersion deduced from complex transmission and reflection measurements on slab-type samples. (C) 2010 American Institute of Physics. [doi:10.1063/1.3511540]