title: Negative refractive index in coaxial plasmon waveguides.
abstract: We theoretically show that coaxial waveguides composed of a metallic core, surrounded by a dielectric cylinder and clad by a metal outer layer exhibit negative refractive index modes over a broad spectral range in the visible. For narrow dielectric gaps (10 nm GaP embedded in Ag) a figure-of-merit of 18 can be achieved at lambda(0) = 460 nm. For larger dielectric gaps the negative index spectral range extends well below the surface plasmon resonance frequency. By fine-tuning the coaxial geometry the special case of n = -1 at a figure-of-merit of 5, or n = 0 for a decay length of 500 nm can be achieved.
authors.affiliation: Center for Nanophotonics, FOM-Institute for Atomic and Molecular Physics,Science Park 104, 1098 XG Amsterdam, The Netherlands. waele@amolf.nl
authors.forename: René
authors.initials: R
authors.lastname: de Waele
authors.forename: Stanley P
authors.initials: SP
authors.lastname: Burgos
authors.forename: Harry A
authors.initials: HA
authors.lastname: Atwater
authors.forename: Albert
authors.initials: A
authors.lastname: Polman