Femto-Second Laser Direct Writing Vertical Microholes in FOTURAN Glass
Y. Wu and Qingyue Wang
Vertical micro-holes were produced in a photosensitive glass (FOTURAN) using a focused femto-second laser irradiation at 775 nm, followed by a heat treatment and wet chemical etching in 8% hydrofluoric acid solution for 50 minutes. The micro-holes were analysed by optical and scanning electron microscopy. It is observed that the micro-holes have a circular cross-section and clear edge. Currently, micro-holes with an aspect ratio of about 7:1 can be achieved. By varying the incident laser fluence over a range of 2.3–36.2 J/cm2 and a laser writing speed of 100–1000μm/s, it is possible to produce and characterize micro-holes. It is found that writing speeds hardly affect the micro-hole diameter whereas relatively lower laser fluences result in smaller diameters and the cross-section is more circular.
Keywords: Microholes, microfabrication, femto-second laser, FOTURAN, photosensitive glass, laser fluence, aspect ratio