Applied Surface Science, Vol.493, 231-238, 2019
One-step fabrication of bi- and quad-directional femtosecond laser-induced periodic surface structures on metal with a depolarizer
With femtosecond (fs) laser pulse irradiation, a simple but efficient technique to fabricate bi- and quad-directional low spatial frequency laser-induced periodic surface structures (BD- and QD-LSFLs) is suggested on metals. By inserting a quartz wedge achromatic depolarizer prior to the focusing optics, we change the polarization of fs laser pulses periodically in one dimension within the laser spot, and find that this method leads to the creation of BD- and QD-LSFLs by simply raster scanning fs laser pulses on Ni. It is also demonstrated that the interval of orientation change of BD-LSFLs can be manipulated with defocus.