Fig. 2

Linear response of exciton surface plasmon polaritons. a Calculated real (gray) and imaginary (blue) parts of the dispersion relation for exciton surface plasmon polaritons, E-SPPs. The inset shows the dispersion near the exciton resonance (1.737 eV), whose location is depicted by dashed boxes on the main figure. b Measured transmission at the exciton resonance as a function of the effective WSe2 sample length on the waveguide