Strong Light-Matter Coupling between Plasmons in Individual Gold Bi-pyramids and Excitons in Mono- and Multilayer WSe2
Journal article, 2018

Monolayer transition-metal dichalcogenides (TMDCs) have attracted a lot of research attention recently, motivated by their remarkable optical properties and potential for strong light-matter interactions. Realization of strong plasmon-exciton coupling is especially desirable in this context because it holds promise for the enabling of room-temperature quantum and nonlinear optical applications. These efforts naturally require investigations at a single-nanoantenna level, which, in turn, should possess a compact optical mode interacting with a small amount of excitonic material. However, standard plasmonic nanoantenna designs such as nanoparticle dimers or particle-on-film suffer from misalignment of the local electric field in the gap with the in-plane transition dipole moment of monolayer TMDCs. Here, we circumvent this problem by utilizing gold bi-pyramids (BPs) as very efficient plasmonic nanoantennas. We demonstrate strong coupling between individual BPs and tungsten diselenide (WSe2) monolayers at room temperature. We further study the coupling between multilayers of WSe2and BPs to elucidate the effect of the number of layers on the coupling strength. Importantly, BPs adopt a reduced-symmetry configuration when deposited on WSe2, such that only one sharp antenna tip efficiently interacts with excitons. Despite the small interaction area, we manage to achieve strong coupling, with Rabi splitting exceeding ∼100 meV. Our results suggest a feasible way toward realizing plasmon-exciton polaritons involving nanoscopic areas of TMDCs, thus pointing toward quantum and nonlinear optics applications at ambient conditions.

Strong coupling

WSe 2

gold bi-pyramid

plasmon resonance

TMDC

exciton

Author

Michael Stührenberg

Chalmers, Biology and Biological Engineering, Chemical Biology

Battulga Munkhbat

Chalmers, Physics, Bionanophotonics

Denis Baranov

Chalmers, Physics, Bionanophotonics

Jorge Cuadra

Chalmers, Physics, Bionanophotonics

Andrew Yankovich

Chalmers, Physics, Eva Olsson Group

Tomasz Antosiewicz

Chalmers, Physics, Bionanophotonics

University of Warsaw

Eva Olsson

Chalmers, Physics, Eva Olsson Group

Timur Shegai

Chalmers, Physics, Bionanophotonics

Nano Letters

1530-6984 (ISSN) 1530-6992 (eISSN)

Vol. 18 9 5938-5945

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics

DOI

10.1021/acs.nanolett.8b02652

More information

Latest update

12/10/2018