Formation of 2D laser-induced periodic surface structures on metal and phase change materials

The laser-induced periodic surface structures (LIPSS) represent an effective technique to modify optical, mechanical, and chemical surface characteristics. While most studies focus on one-dimensional (1D) LIPSS formation on bulk and thin-film materials with orientation direction depending on laser polarization state, more complex morphologies are highly demanded for advanced applications. Here, we demonstrate the formation of two-dimensional (2D) square and hexagonal LIPSS on metal (Cr, Hf) and phase-change material (Ge₂Sb₂Te₅) thin films, driven by thermochemical and plasmonic mechanisms, respectively. These findings expand the potential for applications in tunable photonic devices, diffractive optical elements, and structurally colored metals with 2D anisotropic optical properties.