Ablative microstructuring with plasma-based XUV lasers and efficient processing of materials by dual action of XUV/NIR–VIS ultrashort pulses

We report on a single-shot micropatterning of an organic polymer achieved by ablation with demagnifying projection using a plasma-based extreme ultraviolet (XUV) laser at 21 nm. A nickel mesh with a period of 100 μ m was 10×demagnified and imprinted on poly(methyl methacrylate) (PMMA) via direct ablation. This first demonstration of single-shot projection, single-step lithography illustrates the great potential of XUV lasers for the direct patterning of materials with a resolution scalable down to the submicrometer domain. In the second part, we present a novel experimental method for improving the efficiency of surface processing of various solids achieved by simultaneous action of XUV, obtained from high-order harmonic generation, and near-infrared (NIR)–VIS laser pulses. The NIR–VIS pulse interacts with free charge carriers produced by the energetic XUV photons, so that its absorption dramatically increases. Laser-induced periodic surface structures were effectively produced using this technique.