Fig. 4: Strong coupling of two- and three-molecule excitons with single AuNDs.

a, b Representative scattering spectra of the hybrid AuNDs interacting with (a) two and (b) three MB-molecule excitons. The insets show the SEM images (upper) of the measured samples and the schematics (bottom) of two and three CB[7]@single MB emitters embedded in the gap of the hybrid AuND. The dashed black lines represent the Lorentzian fits of the upper and lower plexcitonic states of the measured SRSs. c SRS observed in scattering spectra associated with different individual hybrid AuNDs, including (upper panel) two and (lower panel) three MB molecules. d Statistics of the experimentally measured SRSs as a function of the exciton number (N). The orange square with error bars (standard deviations, SDs) represents the statistics of the measured SRSs and the number of the sampled structures (40, 15, and 10, for exciton numbers N = 1, 2, and 3, respectively). The colored histogram represents the average values of the measured SRSs for N = 1, 2, and 3. The theoretical result (orange curve) was calculated using Eq. (1) with \({g}_{{{{{{\rm{dc}}}}}}}\) = 56.2 meV, \({\bar{{\varGamma }}}_{{{{{{\rm{d}}}}}}}\) = 135 meV, and \({{\varGamma }}_{{{{{{\rm{c}}}}}}}\) = 85 meV; the green stars represent SRSs simulated using the finite element method (FEM) for the hybrid AuNDs integrated with one, two, and three MB molecules, respectively. The dashed gray line is calculated according to \(\hslash {\Omega }_{R}=({{\varGamma }}_{{{{{{\rm{d}}}}}}}+{{\varGamma }}_{{{{{{\rm{c}}}}}}})/2\).