  We study the response of graphene to high-intensity 10^11-10^12 Wcm^-2,
50-femtosecond laser pulse excitation. We establish that graphene has a fairly
high (~3\times10^12Wcm^-2) single-shot damage threshold. Above this threshold,
a single laser pulse cleanly ablates graphene, leaving microscopically defined
edges. Below this threshold, we observe laser-induced defect formation that
leads to degradation of the lattice over multiple exposures. We identify the
lattice modification processes through in-situ Raman microscopy. The effective
lifetime of CVD graphene under femtosecond near-IR irradiation and its
dependence on laser intensity is determined. These results also define the
limits of non-linear applications of graphene in femtosecond high-intensity
regime.
