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M. Zhong and P. Fan
Fig. 2.9 SEM images of surface particle structures with different sizes fabricated by ultrafast
laser. a Nano particles; b sub-micro particles; c, d fine-micro particles; e, f micro particles; g,
h coarse-micro particles. Reproduced from [55] with permission from Elsevier
scanning intervals were equivalent to the focal spot, regularly distributed surface
structures began to form and uniform hole-array structures with dimension of ~20 µm
were produced (Fig. 2.11b). When scanning intervals were larger than the focal spot,
only a certain portion of the metal surfaces can be directly irradiated by laser, through
which arrayed bell mouth-like structures with plateau-like areas among them were
generated (Fig. 2.11c).
It can be seen that not only the dimensions but also the topological forms of SMNS
can be easily controllable by adapting the ultrafast laser processing parameters. Thus,
large flexibility is offered to us by the high repetition rate high power ultrafast lasers
for fabricating the desired SMNS for targeted optical performances.