Fabrication of Highly Uniform Laser-Induced Periodic Structures on Polycarbonate Via Uv Femtosecond Pulses

Abstract

In this work, we report on the fabrication of highly uniform laser-induced periodic surface structures (LIPSS) on bulk polycarbonate (PC) with 258 nm femtosecond laser pulses where PC exhibits high absorptivity and a significantly large (~10-2) extinction coefficient. A systematic approach was pursued to demonstrate the influence of laser parameters such as fluence, energy dose and polarisation on the LIPSS size and orientation. Results revealed that the employment of linearly polarised beams generate the formation of periodic structures parallel or perpendicular to the laser polarisation depending on the excitation level attained similarly to LIPSS produced on dielectrics. Furthermore, observations showed that low excitation levels can lead to the fabrication of LIPSS with remarkably improved uniformity. By contrast, circularly polarised beams resulted into the development of microscale topographies covered with protruded nanodot-like structures of sizes dependent on the laser conditions. The impact of the features of the induced patterns were evaluated by analysing the wetting and optical properties that manifested a more hydrophilic behaviour over time and a slight increase of optical absorbance retaining their absorbance peak resonances.

Keywords: Laser material interaction, Laser-induced Self-organization, Polymer patterning, UV femtosecond pulses, Modelling of polymer patterning