title: Imaging and controlling plasmonic interference fields at buried interfaces.
abstract: Capturing and controlling plasmons at buried interfaces with nanometre and femtosecond resolution has yet to be achieved and is critical for next generation plasmonic devices. Here we use light to excite plasmonic interference patterns at a buried metal-dielectric interface in a nanostructured thin film. Plasmons are launched from a photoexcited array of nanocavities and their propagation is followed via photon-induced near-field electron microscopy (PINEM). The resulting movie directly captures the plasmon dynamics, allowing quantification of their group velocity at ∼0.3 times the speed of light, consistent with our theoretical predictions. Furthermore, we show that the light polarization and nanocavity design can be tailored to shape transient plasmonic gratings at the nanoscale. This work, demonstrating dynamical imaging with PINEM, paves the way for the femtosecond and nanometre visualization and control of plasmonic fields in advanced heterostructures based on novel two-dimensional materials such as graphene, MoS2, and ultrathin metal films.
authors.affiliation: Laboratory for Ultrafast Microscopy and Electron Scattering, ICMP, École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Tom T A
authors.initials: TTA
authors.lastname: Lummen
authors.affiliation: SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Lamb
authors.affiliation: Laboratory for Ultrafast Microscopy and Electron Scattering, ICMP, École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Berruto
authors.affiliation: Interdisciplinary Center for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: LaGrange
authors.affiliation: Department of Electrical and Computer Engineering and Photonics Center, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215, USA.
authors.forename: Luca
authors.initials: L
authors.lastname: Dal Negro
authors.affiliation: ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, 08860 Barcelona, Spain.|ICREA - Institució Catalana de Recerca i Estudis Avancats, Passeig Lluís Companys, 23, Barcelona 08010, Spain.
authors.forename: F Javier
authors.initials: FJ
authors.lastname: García de Abajo
authors.affiliation: SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Damien
authors.initials: D
authors.lastname: McGrouther
authors.affiliation: Department of Physics, Trinity College, 300 Summit Street, Hartford, Connecticut 06106, USA.
authors.forename: B
authors.initials: B
authors.lastname: Barwick
authors.affiliation: Laboratory for Ultrafast Microscopy and Electron Scattering, ICMP, École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Carbone