MAY 01, 2000
In a material with a negative dielectric constant and negative permeability, convex lenses are diverging and Cerenkov radiation is emitted backward.
According to Maxwell’s equations, lossless propagation of electromagnetic waves requires the index of refraction n, given by to be real, where ε is the electrical permittivity or dielectric constant and μ is the magnetic permeability. All familiar materials have a positive μ and, for the most part, positive ε. But at the March Meeting of the American Physical Society, held in Minneapolis, a group of researchers from the University of California, San Diego, led by David Smith and Sheldon Schultz, reported having built a composite medium with an effective μ that is negative. By combining that medium with one that has a negative ε, they have created a composite material that allows transmission of microwaves that would be blocked by either medium alone. But the propagation inside the composite is predicted to have unusual properties, such as a negative index of refraction.
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© 2000 American Institute of Physics
