# Wavelength Dependence of Picosecond Laser-Induced Periodic Surface Structures on Copper

## TL;DR

This study investigates how the wavelength of picosecond laser pulses affects the formation of periodic surface structures on copper, revealing that hydrodynamic effects may play a key role in pattern development.

## Contribution

It provides experimental data on LIPSS wavelength dependence across UV, visible, and near-IR ranges and compares results with theoretical models, highlighting the importance of hydrodynamic mechanisms.

## Key findings

- LIPSS period varies with laser wavelength.
- Discrepancies with surface-scattered wave models.
- Hydrodynamic effects likely influence pattern formation.

## Abstract

The physical mechanisms of the laser-induced periodic surface structures (LIPSS) formation are studied in this paper for single-pulse irradiation regimes. The change in the LIPSS period with wavelength of incident laser radiation is investigated experimentally, using a picosecond laser system, which provides 7-ps pulses in near-IR, visible, and UV spectral ranges. The experimental results are compared with predictions made under the assumption that the surface-scattered waves are involved in the LIPSS formation. Considerable disagreement suggests that hydrodynamic mechanisms can be responsible for the observed pattern periodicity.