Emission-Programmed Femtosecond Bessel Beams for Fabricating Micro–Nano Hierarchical Structures

TL;DR

A new laser technique creates complex micro and nano structures on silicon with potential uses in optoelectronics and biomedicine.

Contribution

A rapid drilling strategy using emission-programmed femtosecond Bessel beams for hierarchical structure fabrication.

Findings

The method combines subtractive drilling and additive nanostructuring in one process.

Areal scanning allows precise control over the geometry of the structures.

The approach is applicable for infrared photodetection and drag-reduction surfaces.

Abstract

Ultrafast laser-induced micro–nano hierarchical structures show broad applicability in optoelectronics, functional surfaces, and biomedicine. However, precisely controlling their formation through light field manipulation remains a relatively unexplored area. This work demonstrates a rapid drilling strategy on silicon using an emission-programmed, high-repetition-rate femtosecond Bessel beam. This spatiotemporal modulation enables a unique manufacturing synergy that integrates subtractive drilling and thermo-fluidic redistribution by the central lobes with additive nanostructuring by the peripheral lobes, directly fabricating a micro–nano hierarchical structure comprising tapered micro-holes, elevated micropillars, and dense nanocoatings. Meanwhile, areal scanning enables programmable geometry control through line interval adjustment. This approach offers new insights into laser-matter interactions and facilitates applications in infrared photodetection or drag-reduction surfaces.

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