Generation of extended-area femtosecond laser induced periodic nanostructures on TiO2 by moving samples through a line focus

TLDR: In this paper, the combination of sample translation and line focusing by cylindrical optics is shown to be a convenient and highly effective way of generating laser induced coherent periodic surface structures (LIPSS) in TiO2 over significantly longer areas.

Abstract: The combination of sample translation and line focusing by cylindrical optics is shown to be a convenient and highly effective way of generating laser induced coherent periodic surface structures (LIPSS) in TiO2 over significantly extended areas. Compared to known techniques based on a sample translation relative to a circular symmetric focus, the approach is much less time consuming and requires only a single translation stage. The capability of the method to form both high and low spatial frequency LIPSS (HSFL, LSFL) at the second harmonic wavelengths of a Ti:sapphire-laser (around 400 nm) at properly chosen scanning velocity and laser pulse energies is demonstrated. Structured multi-mm2 areas with periods of 80 nm and 325 nm were obtained corresponding to distinct sets of optimized parameters. Furthermore, the appearance of nano-bumps on 30 nm scale on the surface of the LSFL is reported. Basic technical issues are discussed and potential applications of LIPSS in rutile-type TiO2 like superwetting, friction control, catalysis and photovoltaic are proposed.