title: Mode Modification of Plasmonic Gap Resonances Induced by Strong Coupling with Molecular Excitons.
abstract: Plasmonic cavities can be used to control the atom-photon coupling process at the nanoscale, since they provide an ultrahigh density of optical states in an exceptionally small mode volume. Here we demonstrate strong coupling between molecular excitons and plasmonic resonances (so-called plexcitonic coupling) in a film-coupled nanocube cavity, which can induce profound and significant spectral and spatial modifications to the plasmonic gap modes. Within the spectral span of a single gap mode in the nanocube-film cavity with a 3 nm wide gap, the introduction of narrow-band J-aggregate dye molecules not only enables an anticrossing behavior in the spectral response but also splits the single spatial mode into two distinct modes that are easily identified by their far-field scattering profiles. Simulation results confirm the experimental findings, and the sensitivity of the plexcitonic coupling is explored using digital control of the gap spacing. Our work opens up a new perspective to study the strong coupling process, greatly extending the functionality of nanophotonic systems, with the potential to be applied in cavity quantum electrodynamic systems.
authors.affiliation: State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China.
authors.forename: Xingxing
authors.initials: X
authors.lastname: Chen
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, University of Otago , P.O. Box 56, Dunedin 9016, New Zealand.
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Qin
authors.affiliation: State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China.
authors.forename: Ding
authors.identifier: 0000-0001-9084-1521
authors.initials: D
authors.lastname: Zhao
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, University of Otago , P.O. Box 56, Dunedin 9016, New Zealand.
authors.forename: Boyang
authors.identifier: 0000-0002-6299-5010
authors.initials: B
authors.lastname: Ding
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Dodd-Walls Centre for Photonic and Quantum Technologies, Department of Physics, University of Otago , P.O. Box 56, Dunedin 9016, New Zealand.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Blaikie
authors.affiliation: State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University , Hangzhou 310027, China.
authors.forename: Min
authors.initials: M
authors.lastname: Qiu
keywords: J-aggregates; Strong coupling; far-field patterns; gap resonances; nanoparticles; spatial mode modification