High-aspect-ratio crack-free microstructures fabrication on sapphire by femtosecond laser ablation. (December 2020)

• Record Type: Journal Article
• Authors: Liu, Huagang; Li, Yang; Lin, Wenxiong; Hong, Minghui
• Is Part Of: Optics & laser technology. Volume 132(2020)
• Publication Date: 2020-12
• Subjects: Femtosecond laser -- Sapphire -- High aspect ratio -- Laser ablation -- Transparent materials -- Crack free; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2020.106472
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: Optimized strategy for absorption enhancement of laser on transparent materials. Precise control of laser ablation at critical fluence, avoiding cracks formation. Taper free, high-aspect-ratio microstructures fabrication on sapphire. Capability of varieties of microstructures fabrication on transparent materials. Abstract: We report a novel laser processing strategy to realize high-aspect-ratio crack-free microstructures fabrication on sapphire substrates by combining femtosecond laser-induced plasma-assisted ablation and subsequent direct laser ablation. The laser-induced plasma assisted ablation allows us to create a precursor for microstructure generation on smooth sapphire at a low laser fluence. Then we demonstrate a precise control of the direct laser ablation operating at a critical fluence to deepen the previous microstructures. The precise control and optimization of the processing parameters are able to effectively reduce laser heating and avoid crack formation inside the substrate. Crack-free and taper-free micro-grooves are achieved on sapphire with a maximum high-aspect-ratio up to 10:1. The capability of this method to fabricate a variety of functional microstructures is also experimentally demonstrated.