Single shot femtosecond laser nano-ablation of CVD monolayer graphene.

We investigate ablation of CVD monolayer graphene by femtosecond pulses in the single shot regime. We show that the ablation probability of flat graphene drastically reduces for small illumination diameters even if the ablation threshold is exceeded. However, the presence of graphene wrinkles enhances the ablation probability. This is interpreted in terms of electron and energy diffusion within the graphene layer. This differentiated behavior is a drawback for single shot laser nanopatterning. The morphology of the holes with minimal diameter depends on the fluence distribution at ablation threshold. Strong fluence gradients due to strong focussing produce an explosive folding of graphene during ablation.