Uniform periodic nano-patterning of metallic glass substrates via high-frequency nanosecond laser irradiation.

Abstract

Achieving high spatial uniformity in laser-induced periodic surface structures (LIPSS) has long remained elusive, as even femtosecond lasers, despite their nominally "cold" processing capability, cannot eliminate the stochastic defects that compromise long-range order. Here, we present a strategy that utilizes high-repetition-frequency nanosecond pulses, a regime traditionally deemed unsuitable for precision nano-patterning due to pronounced thermal dissipation, to fabricate one-dimensional (1D) LIPSS with uniform morphology on structurally homogeneous metallic glass (MG) substrates. This is achieved by exploiting strong inter-pulse correlation, which simultaneously moderates thermal fluctuations and sustains a coherent optical near-field to template deterministic pattern formation from stochastic seeds. Performing repeated scanning along the same single-line path transform these 1D patterns into regular two‑dimensional (2D) nanodot arrays. Finite-difference time-domain simulations reveal that a unified optical near-field interaction governs the entire structural evolution, from initial 1D ordering to subsequent 2D reconfiguration. The process preserves the MG substrate's amorphous state and chemical composition while being inherently scalable.