title: Toward Cavity Quantum Electrodynamics with Hybrid Photon Gap-Plasmon States.
abstract: Combining localized surface plasmons (LSPs) and diffractive surface waves (DSWs) in metallic nanoparticle gratings leads to the emergence of collective hybrid plasmonic-photonic modes known as surface lattice resonances (SLRs). These show reduced losses and therefore a higher Q factor with respect to pure LSPs, at the price of larger volumes. Thus, they can constitute a flexible and efficient platform for light-matter interaction. However, it remains an open question if there is, in terms of the Q/V ratio, a sizable gain with respect to the uncoupled LSPs or DSWs. This is a fundamental point to shed light upon if such modes want to be exploited, for instance, for cavity quantum electrodynamic effects. Here, using aluminum nanoparticle square gratings with unit cells consisting of narrow-gap disk dimers-a geometry featuring a very small modal volume-we demonstrate that an enhancement of the Q/V ratio with respect to the pure LSP and DSW is obtained for SLRs with a well-defined degree of plasmon hybridization. Simultaneously, we report a 5× increase of the Q/V ratio for the gap-coupled LSP with respect to that of the single nanoparticle. These outcomes are experimentally probed against the Rabi splitting, resulting from the coupling between the SLR and a J-aggregated molecular dye, showing an increase of 80% with respect to the DSW-like SLR sustained by the disk LSP of the dimer. The results of this work open the way toward more efficient applications for the exploitation of excitonic nonlinearities in hybrid plasmonic platforms.
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.|Dipartimento di Matematica e Fisica "Ennio De Giorgi" Strada Provinciale Lecce-Monteroni, Universitá del Salento , Campus Ecotekne, Lecce 73100, Italy.
authors.forename: Francesco
authors.identifier: 0000-0002-0188-6048
authors.initials: F
authors.lastname: Todisco
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.|Dipartimento di Matematica e Fisica "Ennio De Giorgi" Strada Provinciale Lecce-Monteroni, Universitá del Salento , Campus Ecotekne, Lecce 73100, Italy.
authors.forename: Marco
authors.identifier: 0000-0001-8170-6694
authors.initials: M
authors.lastname: Esposito
authors.affiliation: Center for Biomolecular Nanotechnologies@UNILE, Istituto Italiano di Tecnologia , Via Barsanti, Arnesano 73010, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Panaro
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.
authors.forename: Milena
authors.identifier: 0000-0002-4522-7933
authors.initials: M
authors.lastname: De Giorgi
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Dominici
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Ballarini
authors.affiliation: Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid Calle Francisco Tomás y Valiente , 7 Madrid E-28049, Spain.
authors.forename: Antonio I
authors.initials: AI
authors.lastname: Fernández-Domínguez
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.
authors.forename: Vittorianna
authors.initials: V
authors.lastname: Tasco
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.
authors.forename: Massimo
authors.identifier: 0000-0002-4934-3376
authors.initials: M
authors.lastname: Cuscunà
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.
authors.forename: Adriana
authors.initials: A
authors.lastname: Passaseo
authors.affiliation: Center for Biomolecular Nanotechnologies@UNILE, Istituto Italiano di Tecnologia , Via Barsanti, Arnesano 73010, Italy.
authors.forename: Cristian
authors.identifier: 0000-0003-3349-8389
authors.initials: C
authors.lastname: Ciracì
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.|Dipartimento di Matematica e Fisica "Ennio De Giorgi" Strada Provinciale Lecce-Monteroni, Universitá del Salento , Campus Ecotekne, Lecce 73100, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Gigli
authors.affiliation: CNR NANOTEC Istituto di Nanotecnologia, c/o Campus Ecotekne Via Monteroni Lecce, Lecce 73100, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Sanvitto
keywords: aluminum; plasmon; plasmon-exciton-polaritons; plasmonic crystals; plexciton; surface lattice resonance