Fig. 3: DFT-based phonon signatures on the population inversion for mono- and bilayer WSe2.
From: High-purity and stable single-photon emission in bilayer WSe2 via phonon-assisted excitation
a Calculated phonon dispersion in mono- and bilayer WSe2 around the Γ point. For the bilayer, the equilibrium value dW-W = 6.5 Å is used for the vertical distance between W atoms in different layers. The inset shows the phonon dispersion across the full Brillouin zone. b Energy of interlayer SMs and BM at Γ as a function of the interlayer W-W distance dW-W. c Calculated population inversion in the presence of LA phonon coupling, as a function of wavelength detuning λlaser − λX from the exciton and pulse area Θ. The laser pulse has a FWHM of 0.30 nm (tp = 2.65 ps in our notation). d Same as in (c), including also the coupling to SMs and BM. Here, we use dW-W = 6.1 Å for the interlayer W-W distance, and the dimensionless BM coupling weight is set to ξBM = 5 (see the “Methods” section). Dashed orange and red lines are placed at detunings of −2.7 nm and −0.3 nm, respectively.
