title: Negative refractive index in left-handed materials.
abstract: The real part of the refractive index n(omega) of a nearly transparent and passive medium is usually taken to have only positive values. Through an analysis of a current source radiating into a 1D "left-handed" material (LHM)-where the permittivity and permeability are simultaneously less than zero-we determine the analytic structure of n(omega), demonstrating frequency regions where the sign of Re[n(omega)] must, in fact, be negative. The regime of negative index, made relevant by a recent demonstration of an effective LHM, leads to unusual electromagnetic wave propagation and merits further exploration.
authors.affiliation: Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0319, USA. drs@sdss.ucsd.edu
authors.forename: D R
authors.initials: DR
authors.lastname: Smith
authors.forename: N
authors.initials: N
authors.lastname: Kroll