Femtosecond laser-assisted three-dimensional microfabrication in silica

Abstract

We demonstrate direct three-dimensional (3-D) microfabrication inside a volume of silica glass. The whole fabrication process was carried out in two steps:(i) writing of the preprogrammed 3-D pattern inside silica glass by focused femtosecond (fs) laser pulses and (ii) etching of the written structure in a 5% aqueous solution of HF acid. This technique allows fabrication of 3-D channels as small as 10mum in diameter inside the volume with any angle of interconnection and a high aspect ratio (10mum -diameter channels in a 100mum -thick silica slab).

Progress in ultrafast laser processing and future prospects

“…In this way, internal modification and 3D processing of transparent materials can be performed. Such processing, unique to ultrafast lasers, includes refractive index modification [7], nanovoid formation, [8], valence state change of doped ions [79], elemental redistribution in materials [80], atom precipitation [81], particle crystallization [82], and enhancement of the chemical etching rate [83].…”

“…Microfluidics is a key component for biochips, which are essentially miniaturized laboratories used for reactions, detection, analysis, separation, and the synthesis of biochemical materials with benefits of high sensitivity, short analysis time, low reagent consumption, and low waste production. There are two methods available for the fabrication of 3D microfluidics structures using ultrafast lasers, which are femtosecond laser-assisted etching (FLAE) [83,96] and water-assisted femtosecond laser drilling (WAFLD) [97].…”

Advances and opportunities of ultrafast laser synthesis and processing

“…18 -20 This densifi ed region has a different refractive index and can be used for guiding light. 21 It can also be used to create regions where chemical attack/etching is greatly enhanced for producing microfl uidic and microelectromechanical system (MEMS) devices 22 (see the Jiang et al article in this issue). Each of these fundamental mechanisms for material removal or transformation has allowed or enhanced a large number of applications envisaged by creative researchers around the world.…”

Hybrid waveguide-bulk multi-path interferometer with switchable amplitude and phase

“…An improved version of the hybrid interferometer would, therefore, aim at decoupling transmission and phase switching from each other. One possibility would be a Mach-Zehnder configuration with cavities, e.g., etched into the glass after laser structuring, 29,30 into which shutters and phase shifters can be inserted separately. This would have the additional benefit of smaller moving masses and, therefore, higher feasible switching rates.…”