Figure 2: Observation of the optical Stark effect in few-layer ReS2.
From: Selectively tunable optical Stark effect of anisotropic excitons in atomically thin ReS2

(a) Absorption spectrum with light polarization angle of θ=70°. (b) Schematic illustration of DT spectrum (black line) due to Stark shift for an exciton state. Gray and blue lines indicate unperturbed and blue-shifted absorption resonances, respectively. (c,d) Transient DT dynamics with a co-polarized pump–probe configuration (θ=70°) (c) and time traces at two different probe photon energies (d).