Fig. 3: Exciton nonlinearity in MoS2 bilayers.

RC spectra measured with the NB (FWHM=28 nm) excitation for the XA (a) and hIX (b), and with the BB (FWHM = 50 nm) excitation (c) at different fluences. The dashed curves are guide for the eye. d The energy shift ΔE (top) and normalized integrated RC intensity (bottom) as a function of the exciton density for the hIX (left) and XA (right). Solid (open) symbols show the results for the BB (NB) excitation. For the normalized RC we divide the spectrally integrated RC at each laser fluence by its maximum value measured for the whole power dependence. Schematic diagram showing exciton generation under the NB (e) and BB (f) excitation. In (e) only generation of hIX is shown. In (f), the holes of the two excitonic species share the same valence band.