Product Code: JLA_26_1_012001

Authors:
Bin Liu
Wenjun Wang
Gedong Jiang
Xuesong Mei
Kedian Wang
Jiuhong Wang
Zibao Wang
State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an 710054, China

The characteristics of laser-induced periodic surface structures are investigated after laser irradiation with a pulse duration (10 ps) under a certain laser fluence (0.27 J/cm²) and pulse number (N = 50–2000). In the experiments, at the lowest number of pulses, ultrafine ripples are observed with sub-200-nm spatial periods and an orientation parallel to laser polarization direction. With the increasing pulse number, a chain of events that has been observed consists of ultrafine ripples followed by a transformation towards regular ripples with an orientation perpendicular to laser polarization direction and holes finally breaking regular ripples. Although the generation of ultrafine and regular ripples upon laser irradiation is a universal phenomenon, the origin behind the transition is discussed here to help understand the exact physical mechanism and their occurrence with their dependence on the irradiation parameters.