Fig. 2

Polariton anti-crossing and Raman characterization. a Transmission response of bare arrays featuring different nanoantenna lengths. The vertical dashed line (labelled “lat”) marks the position of the lattice mode at around 9.8 THz (see below and Supplementary Note 6 for further details). b Same as in (a), when the arrays are covered with a single layer of NCs (dashed line: FR phonon resonance). c, d Experimental (c) and numerical (d) 2D maps of the polariton branches dispersion. The colour bar corresponds to the values of the extinction E, extracted from the transmission T as E = 1−T. The blue (red) solid lines are the trends of the high-energy (low-energy) polariton branch, as estimated by a three-coupled-oscillator model (see below and Supplementary Note 7), while the purple dashed line marks the lattice mode position. e Raman spectra of the NCs taken in a nanocavity region for different values of L. f Raman spectra of the NCs taken: in different positions along the nanoantennas composing a nanocavity (black lines), in the nanocavity region (red line) and just outside the cavity on the silicon substrate (blue line). The spectra are vertically shifted for clarity