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It is well known that refraction of light at interfaces leads to a beam displacement for oblique incidence of light onto a slab of material. In ray optics and for homogeneous isotropic materials, the sign of this beam displacement is strictly identical to the sign of the refractive index. Our numerical calculations reveal negative beam displacements from state-of-the-art double-fishnet-type photonic metamaterials. This holds true for the "main" polarization corresponding to a negative phase velocity for normal incidence as well as for the "secondary" polarization with positive phase velocity. To understand and interpret these results, we also present exact analytical calculations for thin metal films showing that, in wave optics, the sign of the beam displacement (i.e., the sign of refraction) is generally not identical to the sign of the refractive index.

The literature regarding the influence of the hole shape on the performance, especially on the losses, of negative-index metamaterials on the basis of the so-called double-fishnet structure is unclear. We investigate this aspect in a systematic theoretical study showing that the figure of merit can differ by as much as a factor of 2.5 between rectangular and circular holes, respectively.

We modify a recently theoretically suggested multilayer negative-index photonic metamaterial design and fabricate corresponding structures with up to three functional layers (seven actual layers) for the first time to our knowledge. Measured transmittance and reflectance spectra agree well with theory.

We further miniaturize a recently established silver-based negative-index metamaterial design. By comparing transmittance, reflectance, and phase-sensitive time-of-flight experiments with theory, we infer a real part of the refractive index of -0.6 at a 780 nm wavelength--which is visible in the laboratory.

We fabricate and characterize a low-loss silver-based negative-index metamaterial based on the design of a recent theoretical proposal. Comparing the measured transmittance and reflectance spectra with theory reveals good agreement. We retrieve a real part of the refractive index of Re(n)= -2 around 1.5 microm wavelength. The maximum of the ratio of the real to the imaginary part of the refractive index is about three at a spectral position where Re(n)= -1. To the best of our knowledge, this is the best figure of merit reported for any negative-index photonic metamaterial to date.

Using a ray-tracing approach, we calculate photorealistic images and simple movies of objects in a material with negative index of refraction. Our results show several surprising and drastic effects, for example reversal of apparent object velocity, extreme distortions of object shape, and even apparent loss of connectivity of simple objects. The material presented aims at giving both researchers and laymen an intuition and visual understanding for the unusual optical properties of negative-index materials.

We study the optical properties of metamaterials made from cut-wire pairs or plate pairs. We obtain a more pronounced optical response for arrays of plate pairs, a geometry that also eliminates the undesirable polarization anisotropy of the cut-wire pairs. The measured optical spectra agree with simulations, revealing negative magnetic permeability in the range of telecommunications wavelengths. Thus nanoscopic plate pairs might serve as an alternative to the established split-ring resonator design.