title: Three-dimensional negative index of refraction at optical frequencies by coupling plasmonic waveguides.
abstract: We identify a route towards achieving a negative index of refraction at optical frequencies based on coupling between plasmonic waveguides that support backwards waves. We show how modal symmetry can be exploited in metal-dielectric waveguide pairs to achieve negative refraction of both phase and energy. Control of waveguide coupling yields a metamaterial consisting of a one-dimensional multilayer stack that exhibits an isotropic index of -1 at a free-space wavelength of 400 nm. The concepts developed here may inspire new low-loss metamaterial designs operating close to the metal plasma frequency.
authors.affiliation: Center for Nanophotonics, FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, 1098 XG, Amsterdam, The Netherlands. ewold.verhagen@epfl.ch
authors.forename: Ewold
authors.initials: E
authors.lastname: Verhagen
authors.forename: René
authors.initials: R
authors.lastname: de Waele
authors.forename: L
authors.initials: L
authors.lastname: Kuipers
authors.forename: Albert
authors.initials: A
authors.lastname: Polman