title: Plasmonic control of nonlinear two-photon absorption in graphene nanocomposites.
abstract: Nonlinear two-photon absorption in a quantum dot-graphene nanoflake nanocomposite system has been investigated. An external laser field is applied to the nanocomposite to simultaneously observe two-photon processes in the quantum dot and excite localized surface plasmons in the graphene nanodisk. This resonance condition can be achieved by tuning the plasmon resonance frequency in the graphene nanoflake via electrostatic gating. It is found that the strong local field of the graphene plasmons can enhance and control nonlinear optical processes in the quantum dot. Specifically, we show that the two-photon absorption coefficient in the quantum dot can be switched between single- and double-peaked spectra by modifying the graphene-quantum dot separation. Two-photon processes in the quantum dot can also be switched on or off by slightly changing the gate voltage applied to the graphene. Our findings indicate that this system can be used for nonlinear optical applications such as all-optical switching, biosensing and signal processing.
authors.affiliation: Department of Physics and Astronomy, The University of Western Ontario, London, N6A 3K7, Canada.
authors.forename: Joel D
authors.initials: JD
authors.lastname: Cox
authors.forename: Mahi R
authors.initials: MR
authors.lastname: Singh
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Antón
authors.forename: Fernando
authors.initials: F
authors.lastname: Carreño
mesh_terms: D000042:Absorption; D004560:Electricity; D006108:Graphite / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D017711:Nonlinear Dynamics; D045663:Quantum Dots; D055672:Static Electricity
chemical_list: D006108:Graphite