Surface Nanostructure Preparation By Femtosecond Laser-induced And Properties

As the unique properties of femtosecond lasers, femtosecond pulse lasers induced surface structure (LIPSS) attracted widely attention. In the paper, the effects of laser conditions in the structure formation process on materials is studied. We verified that the ablation area increases with the increases of pulse energy and confirmed that the cumulative effect of femtosecond laser pulses decreases with the increases of pulsed number. By compared the surface structures respectively formed by femtosecond laser’s dot mod and line mod, find that the formation of a large area LIPSS is mainly caused by the edge area of focusing spot.A method to prepared ITO thin films with nano-structure by femtosecond laser ablation is proposed. High spatial frequency laser induced period surface structure(HSFL) was achieved by using a femtosecond laser with ablation energy less than the ITO ablation threshold, repeated frequency of lkHz,pulse duration of 130fs ,wavelength of 775nm and with a ZnO film buffer layer. HSFL with period of about 176nm、237nm were achieved respectively at the laser energy of 20mW and 80mW.Through the studying of LIPSS cycle size on the ITO thin film and silicon substrate, the HSFL’s formation mechanism on the ITO film and the HSFL period size’s variation with the laser energy were analyzed. The research provides a basis studying for the preparation of ITO nano-structure with controlled size.Prepared a large area LIPSS on 304 stainless steel by the femtosecond laser with pulse duration of 130fs, repeated frequency of 1KHz, pulse energy of 200μJ, processing speed of 5mm/s, and a central wavelength of 775nm.The period of LIPSS is 670nm,and the depth is 340nm.Such a stainless steel with a large area LIPSS express a different colors at the different angles under natural light. We found that there is a linear relationship between reflected light’s peak corresponding wavelength and the angles through the study of the spectrometer measurements. Calculate that the change rate of reflection peak wavelength and the angles M are 5.0nm/deg. and 11.1nm/deg..Qualitative analysis of the optical properties of this colored stainless steel was studied. We believe that our work may play a very important role in the application of this stainless steel with large area LIPSS.