Tailoring the surface morphology of Ni at the nanometric scale by ultrashort laser pulses

Ultrafast-laser irradiated surfaces are self-organizing systems that form intricated micropatterns and nanopatterns. Different shapes of randomly and periodically dispersed nanostructures emerge from a homogenous metal surface, resulting in a remarkable display of dissipative structures. Under femtosecond laser irradiation with a controlled amount of energy, the formation of nanobreath-figure, nanocrosshatch, nanopeaks, nanohumps, nanobumps, nanocavities and nanolabyrinthine patterns are reported. The fabrication of these 2D different nanostructures may allow for novel surface functionalizations aimed at controlling mechanical, biological, optical, or chemical surface characteristics on a nanometric scale. We demonstrate that using crossed-polarized double laser pulses adds a new dimension to the nanostructuring process since the laser energy dose and multi-pulse feedback modify the energy gradient distribution, crossing key levels for surface self-organization regimes.