Periodic Structure On The Surface Of Metal Induced By Femtosecond Laser Based On Electron Dynamics Control

This paper mainly focuses on the periodic structure on the surface of metal induced byfemtosecond laser based on electron dynamics control. Femtosecond laser, as afemtosecond magnitude of pulse laser, is an advanced micro/nano manufacturing toolbecause its advantages of small heat affected zone, high peak power and high machiningaccuracy compared with processing methods such as long pulse laser or continuous laser.Because of the unique advantages above, a lot of related work has been done by researchersaround the world in the field of femtosecond laser micro/nano fabrication. However, thereare still deficiencies in some ways. For instance, laser induced periodic surface structures(LIPSS) occur under certain conditions when the surface of material is modified byfemtosecond laser. The formation mechanism of LIPSS is yet under discussion, and thestudy on morphology control is not systematic enough. This subject research is proposedbased on the aforementioned background. This paper systematically discusses thefundamental mechanism of the interaction between femtosecond laser and metal. Based onthe theory of electron dynamics control (EDC), we finally achieve the aim of themodulation of LIPSS on metal surface efficiently and accurately by adjusting the laserprocessing parameters such as pulse energy, scanning speed, polarization direction andpulse delay.My main research work can be summarized as the following four parts:1. Briefly describe the research background. The latest research situation at home andabroad is also reported.2. Research on the mechanism of interaction between femtosecond laser and metal,summarize and conclude the theory of femtosecond laser fabricating LIPSS on metal.3. Experiments on femtosecond laser single pulse ablation of metal.1) Study the effectof laser fluence, number of pulse, scanning speed on the morphology of different materials(Al, Ni and Si) surface.2) Study the effect of laser polarization orientation on the surfacemorphology of different materials (Al, Ni and Si).4. Experiments on femtosecond laser pulse train ablation of metal.1) Study the effectof pulse delay on the morphology of LIPSS on Ni surface.2) Study the combination effectof pulse delay and polarization orientation on the morphology of LIPSS on Ni surface.Following conclusions are obtained through the experimental results: 1. Under femtosecond laser single pulse, we can get the slit structure with directionparallel to the polarization orientation by designing reasonable laser fluence and pulsenumber. When lines are written on the aluminum surface, polarization orientation has asignificant influence on the quality of surface morphology due to the erased morphology byabove slit structure.2. Under femtosecond laser single pulse, the formation of HSFL on nickel surface canbe controlled by designing laser fluence, scanning speed and polarization orientation.3. Under femtosecond laser pulse train, we can accurately control the period and linewidth of structure on nickel surface by designing pulse delay and polarization orientation.