Artificial Seeds-Regulated Femtosecond Laser Plasmonic Nanopatterning

Surface plasmon polaritons (SPPs), being localized at nanoscale and coherent with driving field, are attractive for large-scale surface nanopatterning. Under femtosecond laser irradiation, the interference between incident light and excited SPPs is efficient to produce periodic nanostructures. However, it generally relies on self-initiated seeds, which are random and uncontrollable, leading to irregular patterns. Here, controllable laser plasmonic nanopatterning is experimentally illustrated in terms of artificial seeds that are pre-structured by laser direct writing. The approach is demonstrated on bilayer ultrathin films, consisting of a 50-nm-silicon coating on a 100-nm-platinum (Pt) or silver (Ag) film. The artificial seeds are in form of silicon oxide. The Pt is utilized to support SPPs, and the nanopatterning occurs in Si film via laser-induced periodic oxidation. The underlying mechanisms of this approach are numerically investigated and experimentally verified. The typical problems, such as bifurcation, distortion, wavy, and poor splicing are all solved by the artificial seeds. Therefore, large-scale nanogratings with extremely high uniformity are readily produced. Furthermore, manipulating the orientation of periodic nanostructures by the artificial seeds associated with controlled light polarization is illustrated. When using circularly polarized lasers, the artificial seeds can facilitate a diverse range of periodic patterns with arbitrary while controllable orientation.

Automated summary

This article demonstrates controllable laser plasmonic nanopatterning using pre-structured artificial seeds. By utilizing these artificial seeds on bilayer ultrathin films, the problem of irregular patterns is solved, and large-scale nanogratings with extremely high uniformity are easily produced. Furthermore, the orientation of periodic nanostructures can be manipulated by controlling the light polarization.