Figure 19: (a) The relative change in gap, recorded at 4.3 K for various intensities in mJ/. The dashed lines are fits to the data with (1). (b) The dependence of on intensity at 4.3 K. The dashed line is a fit to the simple saturation model; the solid line is the linear fit. Inset: the temperature dependence of the saturation energy density, , compared to the -dependence of (dashed line). Panel (c) shows the -dependence of the superconducting recovery time, , for several intensities (in mJ/cm). Inset: recorded at 4.3 K. For low intensities the relaxation rate increases linearly with (dashed line) (after ).