Strong Plasmon-Exciton Coupling with Directional Absorption Features in Optically Thin Hybrid Nanohole Metasurfaces
Artikel i vetenskaplig tidskrift, 2018

Plasmons and excitons can interact to form new hybridized light-matter states, with a multitude of potential applications including optical logic circuits and single-photon switches. Here, we report the first observation of strong coupling based on optically thin plasmonic nanohole films. The absorptive plasmon resonances of these nanohole films lead to suppressed transmission and Fano-shaped extinction peaks. We prepared silver nanohole films by colloidal lithography, which enables large-scale fabrication of nanoholes distributed in a short-range order. When coated with J-aggregate molecules, both extinction and absorption spectra show clear formation of two separated polariton resonances, with vacuum Rabi splitting on the order of 300 meV determined from anticrossing experiments. In accordance with strong coupling theory, the splitting magnitude increases linearly with the square root of molecular concentration. The extinction peak positions are blue-shifted from the absorption polariton positions, as explained by additional Fano interference between the hybridized states and the metal film. This highlights that absorption measurements are important not only to prove strong coupling but also to correctly determine hybridized polariton positions and splitting magnitudes in hybrid plasmonic nanohole systems. The polariton absorption peaks also show strong dependence on illumination direction, as found related to inherent directionality of the plasmonic nanohole metasurface and differences in light interaction with nonhybridized molecules. Importantly, optical simulations could successfully reproduce the experimental results and all coupling features. Furthermore, simulated spatial distribution of the absorption provides additional evidence of strong coupling in the hybrid nanohole system. The work paves the way toward strong coupling applications based on optically thin nanohole systems, as further promoted by the scalable fabrication.

strong coupling

polaritons

metasurfaces

Fano interferences

nanoholes

J-aggregates

plasmonics

directional absorption

Författare

Evan S. H. Kang

Linköpings universitet

Shangzhi Chen

Linköpings universitet

Samim Sardar

Linköpings universitet

Daniel Tordera

Linköpings universitet

Nerijus Armakavicius

Linköpings universitet

Vanya Darakchieva

Linköpings universitet

Timur Shegai

Chalmers, Fysik, Bionanofotonik

Magnus P. Jonsson

Linköpings universitet

ACS Photonics

2330-4022 (eISSN)

Vol. 5 10 4046-4064

Ämneskategorier

Atom- och molekylfysik och optik

Annan fysik

Den kondenserade materiens fysik

DOI

10.1021/acsphotonics.8b00679

Mer information

Senast uppdaterat

2018-12-10