Work

Evolution of Cone-Shaped Damage Channels in Aluminum Nanofilm Induced by Repeated High-Power Subpicosecond Terahertz Pulses

Year: 2026

Type: article

Abstract: We investigate the formation of surface periodic structures during ablation of a 20 nm aluminum film on a glass substrate by high-power terahertz pulses. Using subpicosecond pulses in the 0.5–3 THz range with a field strength of 15 MV/cm (fluence 0.3 J/cm2) generated in a DSTMS crystal pumped by a femtosecond Cr:Forsterite laser, we observe discrete growth of cone-shaped damage channels with a period of 20 µm at an energy density below the single pulse ablation threshold (Fa≈0.15 J/cm2). The channel length increases from pulse to pulse (for 8, 20, and 100 pulses) due to local current density enhancement at the channel tip. This enhancement scales inversely with the square root of the tip radius and reaches an order of magnitude. Surface morphology analysis reveals a thermomechanical mechanism governing film destruction. The observed self-organized periodic structures, whose orientation is strictly perpendicular to the THz electric field, hold promise for functional devices in the terahertz band, such as polarizers, near-field sensors, and spatially selective absorbers, provided the formation process can be regulated.

Source: Nanomaterials

DOI: 10.3390/nano16120760

Authors: Sergey I. Ashitkov, Oleg V. Chefonov, Andrey V. Ovchinnikov

Institution: Joint Institute for High Temperatures

Language: English

Topic: Laser Material Processing Techniques

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,896

Funders: Ministry of Science and Higher Education of the Russian Federation, Russian Academy of Sciences