CC BY
20LM-I-41
Functional surfaces for industrial applications due to direct laser texturing
G. Mincuzzi1, L. Gemini1, A. Sikora1, A. Bourtereau1, S. Nourry1, M. Faucon1, R. Kling3
1- Alphanov Technology Center, Rue François Mitterrand, 33400 Talence, France
Main author email address: rainer.kling@alphanov.com
Materials processing with femtosecond lasers in often accompanied by a self-organization-effecl creating regular patterns on the surface first discovered by Birnbaum in 1965 [1]. The effect has been intensively studied in the meantime to understand the fundamental mechanisms and to be able to conti their shape. The nanoscale surface structures appear on most type of materials in particular metals, semiconductors and even crystalline dielectric material s. Due to their regular nature the patterns are called laser induced periodic surface structures - LIPSS. As the creation mechanism does not rely on conventional material ablation, their shape and height are not a direct mapping of the laser intensity profile but are moreover principally determined by the laser wavelength, polarization, fluence and the number of consecutive pulses. As the orientation of the nano textures is known to be influenced by the polarization of the laser pulse [2] we engage various polarization converters and double pulses with variable delay to manipulate the shape of the periodic structures. With different combinations of these influential parameters different topographies can be created to serve different applications with speciifc functions and surface properties, which are briefly introduced below.
Nano sized patterns on surfaces have a major influence on optical and mechanical surface properties. On metal surfaces grating structures diffract the light and can serve as coloriztion, decoration and anti-counterfeit. On reflective noble metals spike structures generate light trapping effects and therefore increase the absorptivity to more than 9 5% over a wide wavelength range [3]. For microfluidics the increase of surface energy eads to hydrophobicity exhibiting lotus effects [4]To generate antimicrobia surfaces, nanopillars with a periodicity close thesize of the respective bacteria have been demonstrated to be most effective [5]. We believe ourhigh-throughput approach will contribute to transfer lasei functionalized surfaces into industrial applications.
All these texturations are typically generated by applying femtosecond laser pulses with fluencies nea the ablation threshold. Scientific publications mostly rely on low power Ti:Sapphire lasers for LIPSS creation. In contrast to this we demonstrate high repetition rate processing (up to 15 MHz) based on femtosecond lasers with an average of up to 300W. Examples of different scales, different topologies and accordingly different surface fun ctions are presented along with their application. The characterization of the surfaces is performed by means of optical microscopy, SEM images, absorptivi measurements, and contact angle measurements.
[1] M. Birnbaum J. Appl. Phys. 36, 3688-3689 (1965)
[2] U. Klug, J. F. Dusing, T Sato, K. Washio and R. Kling, , Proc. SPIE 7590, (2010)
[3] A. Y. Vorobyev and C Guo, J. Appl. Phys. Vol. 110, 043102 (2011 )
[4] X. Zhang, F. Shi, J. Niu, Y. Jiang and Z. Wang, J. Mater. Chem., 18, 621633. (2008)
[5] A. Lutey, L. Gemini, L. Romoli, G. Lazzini, F. Fuso, M. Faucon, and R. Kling. "Towards laser-textured antibacterial surfaces." Scientific reports 8, no.1, pp. 1-10 (2018)
