title: Intensity dependences of the nonlinear optical excitation of plasmons in graphene.
abstract: Recently, we demonstrated an all-optical coupling scheme for plasmons, which takes advantage of the intrinsic nonlinear optical response of graphene. Frequency mixing using free-space, visible light pulses generates surface plasmons in a planar graphene sample, where the phase matching condition can define both the wavevector and energy of surface waves and intraband transitions. Here, we also show that the plasmon generation process is strongly intensity-dependent, with resonance features washed out for absorbed pulse fluences greater than 0.1 J m-2This implies a subtle interplay between the nonlinear generation process and sample heating. We discuss these effects in terms of a non-equilibrium charge distribution using a two-temperature model.This article is part of the themed issue 'New horizons for nanophotonics'.
authors.affiliation: Electromagnetic Materials Group, Department of Physics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4QL, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Constant
authors.affiliation: Electromagnetic Materials Group, Department of Physics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4QL, UK.
authors.forename: S M
authors.initials: SM
authors.lastname: Hornett
authors.affiliation: Institut de Ciències Fotòniques (ICFO), Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain.
authors.forename: D E
authors.initials: DE
authors.lastname: Chang
authors.affiliation: Electromagnetic Materials Group, Department of Physics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4QL, UK e.hendry@exeter.ac.uk.
authors.forename: E
authors.identifier: http://orcid.org/0000-0002-4848-9840
authors.initials: E
authors.lastname: Hendry
keywords: graphene; nonlinear optics; plasmonics