Formation of Laser-induced Periodic Surface Structures During Femtosecond Laser Ablation of Highly Oriented Pyrolytic Graphite (HOPG)
W. Zhang, M. Zhou, G. Amoako, Y-L. Shao, B-J. Li, J. Li and C-Y. Gao
Formation of laser-induced periodic surface structures (LIPSS) during femtosecond laser ablation of highly oriented pyrolytic graphite (HOPG) is investigated. Using a 1 kHz femtosecond pulses (pulse width 130 fs, centre wavelength 800 nm) for micro-processing on HOPG, the calculated ablation threshold is 0.19 J/cm2. Two kinds of different periodic nanostructures were seen through scanning electron microscopy (SEM) characterization of the ablated material surface. These were low-spatial-frequency structures with period of about 400 nm and high-spatial-frequency structures with period of about 100 nm. Formation conditions of the nanostructures are analysed by changing the parameters such as laser energy and pulse number. This result would make femtosecond laser direct-write technologies of carbon nanostructures possible.
Keywords: Femtosecond laser, ablation, laser-induced periodic surface structures (LIPSS), highly oriented pyrolytic graphite (HOPG), high-spatial-frequency LIPSS (HSFL), low-spatial-frequency LIPSS (LSFL), carbon nanostructures