title: 3D vertical nanostructures for enhanced infrared plasmonics.
abstract: The exploitation of surface plasmon polaritons has been mostly limited to the visible and near infrared range, due to the low frequency limit for coherent plasmon excitation and the reduction of confinement on the metal surface for lower energies. In this work we show that 3D--out of plane--nanostructures can considerably increase the intrinsic quality of the optical output, light confinement and electric field enhancement factors, also in the near and mid-infrared. We suggest that the physical principle relies on the combination of far field and near field interactions between neighboring antennas, promoted by the 3D out-of-plane geometry. We first analyze the changes in the optical behavior, which occur when passing from a single on-plane nanostructure to a 3D out-of-plane configuration. Then we show that by arranging the nanostructures in periodic arrays, 3D architectures can provide, in the mid-IR, a much stronger plasmonic response, compared to that achievable with the use of 2D configurations, leading to higher energy harvesting properties and improved Q-factors, with bright perspective up to the terahertz range.
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Malerba
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Alabastri
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Ermanno
authors.initials: E
authors.lastname: Miele
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Zilio
authors.affiliation: University of Pavia, Physics Department - Via Bassi, 6, I-27100 Pavia, Italy.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Patrini
authors.affiliation: University of Pavia, Department of Industrial and Information Engineering - Via Ferrata, 1, I-27100 Pavia, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Bajoni
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Gabriele C
authors.initials: GC
authors.lastname: Messina
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Dipalo
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Toma
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Remo
authors.initials: R
authors.lastname: Proietti Zaccaria
authors.affiliation: Istituto Italiano di Tecnologia - Via Morego, 30, I-16163 Genova, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: De Angelis