title: Sub-diffractional volume-confined polaritons in the natural hyperbolic material hexagonal boron nitride.
abstract: Strongly anisotropic media, where the principal components of the dielectric tensor have opposite signs, are called hyperbolic. Such materials exhibit unique nanophotonic properties enabled by the highly directional propagation of slow-light modes localized at deeply sub-diffractional length scales. While artificial hyperbolic metamaterials have been demonstrated, they suffer from high plasmonic losses and require complex nanofabrication, which in turn induces size-dependent limitations on optical confinement. The low-loss, mid-infrared, natural hyperbolic material hexagonal boron nitride is an attractive alternative. Here we report on three-dimensionally confined 'hyperbolic polaritons' in boron nitride nanocones that support four series (up to the seventh order) modes in two spectral bands. The resonant modes obey the predicted aspect ratio dependence and exhibit high-quality factors (Q up to 283) in the strong confinement regime (up to λ/86). These observations assert hexagonal boron nitride as a promising platform for studying novel regimes of light-matter interactions and nanophotonic device engineering.
authors.affiliation: U.S. Naval Research Laboratory, 4555 Overlook Ave, S.W., Washington, District of Columbia 20375, USA.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Caldwell
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Rd, Manchester M13 9PL, UK.
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Kretinin
authors.affiliation: 1] The Blackett Laboratory, Imperial College London, London SW7 2AZ, UK [2] Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore.
authors.forename: Yiguo
authors.initials: Y
authors.lastname: Chen
authors.affiliation: The Blackett Laboratory, Imperial College London, London SW7 2AZ, UK.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Giannini
authors.affiliation: Department of Physics, University of California San Diego, 9500 Gilman Dr, La Jolla, California 92093, USA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Fogler
authors.affiliation: The Blackett Laboratory, Imperial College London, London SW7 2AZ, UK.
authors.forename: Yan
authors.initials: Y
authors.lastname: Francescato
authors.affiliation: NRC Postdoctoral Fellow (residing at NRL), Washington, District of Columbia 20375, USA.
authors.forename: Chase T
authors.initials: CT
authors.lastname: Ellis
authors.affiliation: U.S. Naval Research Laboratory, 4555 Overlook Ave, S.W., Washington, District of Columbia 20375, USA.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Tischler
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Rd, Manchester M13 9PL, UK.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Woods
authors.affiliation: NRC Postdoctoral Fellow (residing at NRL), Washington, District of Columbia 20375, USA.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Giles
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore.
authors.forename: Minghui
authors.initials: M
authors.lastname: Hong
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.affiliation: The Blackett Laboratory, Imperial College London, London SW7 2AZ, UK.
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Maier
authors.affiliation: School of Physics and Astronomy, University of Manchester, Oxford Rd, Manchester M13 9PL, UK.
authors.forename: Kostya S
authors.initials: KS
authors.lastname: Novoselov