Transmission measurements in wedge-shaped absorbing samples: an experiment for observing negative refraction

We report on experiments of light transmissivity, at wavelengths of 532 nm and 400 nm, through an Au film with a wedge shape. Our results exhibit a resemblance with those reported for observing negative refraction in proposed left-handed materials. This resemblance is present even though the medium that we used is well known to be right handed with its refractive index, therefore, having a positive real part. Analogous results are obtained with a glass wedge at 320 nm where absorption dominates. The experiment is explained by the wave losses that dominate over propagation, as in the already reported observation of negative refraction in developed metamaterial wedges. We design and propose an experiment with metamaterials by using thicker wires and parallel face slabs, in correspondence with light measurements that we have carried out in positive refractive index samples. This experimental configuration should conclusively determine whether refraction is positive or negative.