Ablation enhancement of fused silica glass by femtosecond laser double-pulse Bessel beam

Abstract

In this study, the double-pulse Bessel beam ablation of fused silica glass is investigated. Compared to a conventional Bessel–Gauss beam, a double-pulse Bessel–Gauss beam can greatly enhance the photo-modification zone. As the time delay increases, the photo-modification zone first increases and then decreases. By optimizing the processing parameter, the photo-modification zone with a diameter in the range of 1.5–3 µm and an aspect ratio of about 1500:1 can be fabricated. Compared to the zone processed by a single-pulse Bessel–Gauss beam, the photo-modification zone of a double-pulse Bessel–Gauss beam increases by a factor of 500. Furthermore, the processing parameter of the pulse energy distribution ratio is also investigated to optimize fabrication. In addition, the experimental results show that the obtained etching rate of the photo-modification zone processed by the double-pulse Bessel–Gauss beam with a time delay of 50 ps is four times that of the single-pulse Bessel–Gauss beam. As an application example, a microreaction cell is fabricated using a femtosecond laser, double-pulse Bessel–Gauss beam to demonstrate the advantage of the proposed method in fabricating three-dimensional microfunctional structures.