Femtosecond laser-induced periodic surface structures

TLDR

The study investigates the formation of laser‑induced periodic surface structures in metals, semiconductors, and dielectrics using linearly polarized femtosecond laser pulses in air, combining experimental and theoretical approaches. The authors analyze how transient changes in optical properties influence LIPSS periods in semiconductors and examine the role of transient excitation stages in dielectrics, while characterizing LIPSS formation across materials with femtosecond pulses. They observe low‑frequency LIPSS with periods near the laser wavelength in metals, generate sub‑100‑nm high‑frequency LIPSS under specific conditions, and show that in dielectrics the LIPSS period decreases for double‑pulse delays shorter than 2 ps.

Abstract

The formation of laser-induced periodic surface structures (LIPSS) in different materials (metals, semiconductors, and dielectrics) upon irradiation with linearly polarized fs-laser pulses (τ ∼ 30–150 fs, λ ∼ 800 nm) in air environment is studied experimentally and theoretically. In metals, predominantly low-spatial-frequency-LIPSS with periods close to the laser wavelength λ are observed perpendicular to the polarization. Under specific irradiation conditions, high-spatial-frequency-LIPSS with sub-100-nm spatial periods (∼λ/10) can be generated. For semiconductors, the impact of transient changes of the optical properties to the LIPSS periods is analyzed theoretically and experimentally. In dielectrics, the importance of transient excitation stages in the LIPSS formation is demonstrated experimentally using (multiple) double-fs-laser-pulse irradiation sequences. A characteristic decrease of the LIPSS periods is observed for double-pulse delays of less than 2 ps.