title: Highly confined low-loss plasmons in graphene-boron nitride heterostructures.
abstract: Graphene plasmons were predicted to possess simultaneous ultrastrong field confinement and very low damping, enabling new classes of devices for deep-subwavelength metamaterials, single-photon nonlinearities, extraordinarily strong light-matter interactions and nano-optoelectronic switches. Although all of these great prospects require low damping, thus far strong plasmon damping has been observed, with both impurity scattering and many-body effects in graphene proposed as possible explanations. With the advent of van der Waals heterostructures, new methods have been developed to integrate graphene with other atomically flat materials. In this Article we exploit near-field microscopy to image propagating plasmons in high-quality graphene encapsulated between two films of hexagonal boron nitride (h-BN). We determine the dispersion and plasmon damping in real space. We find unprecedentedly low plasmon damping combined with strong field confinement and confirm the high uniformity of this plasmonic medium. The main damping channels are attributed to intrinsic thermal phonons in the graphene and dielectric losses in the h-BN. The observation and in-depth understanding of low plasmon damping is the key to the development of graphene nanophotonic and nano-optoelectronic devices.
authors.affiliation: ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain.
authors.forename: Achim
authors.initials: A
authors.lastname: Woessner
authors.affiliation: ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain.
authors.forename: Mark B
authors.initials: MB
authors.lastname: Lundeberg
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: Yuanda
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Principi
authors.affiliation: CIC nanoGUNE, 20018 Donostia-San Sebastian, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Alonso-González
authors.affiliation: 1] NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, 56126 Pisa, Italy [2] SPIN-CNR, Via Dodecaneso 33, 16146 Genova, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Carrega
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.affiliation: Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Vignale
authors.affiliation: 1] NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, 56126 Pisa, Italy [2] Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30 16163 Genova, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Polini
authors.affiliation: Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: James
authors.initials: J
authors.lastname: Hone
authors.affiliation: 1] CIC nanoGUNE and UPV/EHU, 20018 Donostia-San Sebastian, Spain [2] IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
authors.forename: Rainer
authors.initials: R
authors.lastname: Hillenbrand
authors.affiliation: ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain.
authors.forename: Frank H L
authors.initials: FH
authors.lastname: Koppens