Figure 3
THz driven reflectivity changes.
(a) Pump electric field temporal profile measured by electro optical sampling. (b) Transient reflectance induced by electric fields of different intensities (γ is the Keldysh parameter, see text for details). (c) Normalized relative variation of the reflectivity at 900 nm (1.38 eV) for highest (red) and lowest (blue) pump intensities. The absolute value of the THz field, whose phase content is independent of the intensity of the pump, is reported for comparison (dashed black curve). (d) Maximum value of 
as a function of pump amplitude. The red line is a guide for the eyes.
