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Negative RefractionLight bends the wrong way in materials where both e and m are negative as was pointed out in 1968 by Victor Veselago, A but the absence of natural materials with this property led to neglect of the subject until 1999 when it was shown how to make artificial materials, metamaterials, with negative m by exploiting the concept of a 'split ring resonator' Since then the subject has advanced rapidly. A key turning point was the publication of the first negative refraction experiment (R. A. Shelby, D. R. Smith, S. Schultz, Science 292, 77 (2001)). In the figure below we see one of the negatively refracting structures made at UCSD exploiting the 'split ring resonator' concept to give a negative magnetic response and incorporating thin metallic wires which give a negative electrical response. See also David Smith's website. B
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One other property that follows from figure A is that the velocity of the rays (or the group velocity) and the velocity of the waves must be oppositely directed leading to the curious situation illustrated below. C |
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