Strong-coupling of WSe2 in ultra-compact plasmonic nanocavities at room temperature

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Kleemann, M-E 
Alexeev, EM 
Carnegie, C 

Strong-coupling of monolayer metal dichalcogenide semiconductors with light offers encouraging prospects for realistic exciton devices at room temperature. However, the nature of this coupling depends extremely sensitively on the optical confinement and the orientation of electronic dipoles and fields. Here, we show how plasmon strong coupling can be achieved in compact robust easily-assembled gold nano-gap resonators at room temperature. We prove that strong coupling is impossible with monolayers due to the large exciton coherence size, but resolve clear anti-crossings for greater than 7 layer devices with Rabi splittings exceeding 135 meV. We show that such structures improve on prospects for nonlinear exciton functionalities by at least 104, while retaining quantum efficiencies above 50%, and show evidence for superlinear light emission.

room temperature strong-coupling, 2D materials, TMDs, plasmons, polaritons, plexcitons, nanoparticle on mirror
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Nature Communications
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Springer Nature
Engineering and Physical Sciences Research Council (EP/G037221/1)
European Research Council (320503)
Engineering and Physical Sciences Research Council (EP/K028510/1)
Engineering and Physical Sciences Research Council (EP/L027151/1)
Engineering and Physical Sciences Research Council (EP/G060649/1)
EPSRC (1648373)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (676108)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (696656)
We acknowledge support from EPSRC grants EP/G060649/1, EP/L027151/1, EP/G037221/1, EPSRC NanoDTC, and ERC grant LINASS 320503. J.M. acknowledges support from the Winton Programme of the Physics of Sustainability. R.C. acknowledges support from the Dr Manmohan Singh scholarship from St John’s College, University of Cambridge. AIT and EMA acknowledge support from EPSRC grant EP/M012727/1, Graphene Flagship grant 696656, and ITN Spin-NANO 676108. CC acknowledges support from the UK National Physical Laboratory. CG acknowledges support by the A. v. Humboldt Foundation.
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