Dept. of Physics, University of Utah, Salt Lake City, UT 84112, U.S.A.
Recently there has been growing interest in the creation of lenses with unusually sharp foci. These lenses come in two varieties.
The original proposal by Moscow physicist Victor Veselago dates back to 1967.1 Veselago studied a medium where for some hypothetical reason both electric permittivity ε and magnetic permeability μ are negative at some frequency ω0. Since the εμ product is positive, the light velocity remains real and the wave equation is unchanged. However, the vectors k, E, H of a plane wave now form a left-handed rather than a right-handed set, so that the Poynting vector S points opposite to the wavevector k. This anomaly is not forbidden by any general principle and such a medium is often called a left-handed medium (LHM). Veselago predicted negative refraction (minus sign in Snell’s law) at the interface of the LHM and a regular medium (RM) and some other interesting manifestations of the LHM.
It is important to understand that the negative refraction is a property of the interface that follows from the regular boundary conditions. One should be cautious in ascribing a negative value to the bulk refractive index n of the LHM2,3 even though this definition would restore a positive ...