Negative Index of Refraction
|Combining "magnetic atoms" with "electric atoms" in a suitable design can finally result in metamaterials which simultaneously exhibit negative values for the electric permittivity ε and the magnetic permeability μ. V. G. Veselago theoretically investigated this situation allready forty years ago. He predicted that the wave vector of a wave propagating through such a medium is antiparallel to its Poynting-vector. In other words, the phase velocity of the wave is negative.
This remarkable property has far-reaching consequences. For example, consider a light wave impinging from vacuum onto the surface of the medium under an angle with respect to the surface normal. According to Veselago's calculations the wave is refracted towards the "wrong" side of the normal, i.e., we obtain negative refraction. This unusual behavior is still compatible with Snell's law of refraction. However, one has to assign a negative index of refraction n<0 to the material under consideration.
Using a ray-tracing approach (POV-ray), we have calculated photorealistic images of the same object in materials with positive and negative indices of refraction. The images demonstrate that the geometrical optics of negative-index materials is full of surprises.