Fig. 2: Pump-probe measurement of valley-selective optical Stark shift.
From: Valley-selective optical Stark effect of exciton-polaritons in a monolayer semiconductor
a Pump-induced differential reflectance when pump and probe are co-circularly polarized. The sharp signal at t = 0 is attributed to a optical Stark shift of both upper and lower polaritons. b Differential reflectance when pump and probe are cross-polarized, lacking sharp signal at t = 0. c Background-subtracted ΔR/R signal at zero delay for increasing pump intensities (dots) and fits (solid) to a transfer matrix model. d Stark shift magnitude extracted from fits to data in c showing expected linear trend. Error bars in pump intensity represent uncertainty in the measured pump power and spot size. Error bars in Stark shift magnitude represent uncertainty from the fit procedure (see Supplementary Information).
