Generating liquid nanojets from copper by dual laser irradiation for ultra-high resolution printing

Qingfeng Li (1) , A.P. Alloncle (1) , David Grojo (1) , P. Delaporte (1)

1 LP3 - Laboratoire Lasers, Plasmas et Procédés photoniques

When the energy of a short laser pulse is localized in a fluid material, a flow motion is induced that can lead to the generation of free-surface jets. This nozzle-free jetting process is exploited to print conductive materials, typically metal nanoparticle inks, but this approach remains limited to the transfer of low viscosity fluids with a minimum feature size of few microm-eters. We introduce a dual-laser method to achieve reproducible high-aspect-ratio jets from thin solid films. A first laser irradiation induces the melting of copper thin films and a second synchronized short pulse irradiation initiates the jetting process. Using time-resolved microscopy, we investigate the influence of the film thickness on the flow motion mechanisms and the ejection dynamics. For a wide range of laser fluences, we present observations similar to those obtained when the jets are generated by a single laser pulse from liquid donor films. The use of a solid film allows reducing the film thickness and then the volume of transferred material. Finally , we analyze these results in the perspective of using this double pulse LIFT technique for additive manufacturing of nano-micro-structures. Stable jets are formed from the copper films over distances exceeding 50-μm and are exploited to demonstrate periodic printing of 1.5-μm diameter droplets.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Optique [physics.optics]; Physique des plasmas [physics.plasm-ph]

Qingfeng Li, A.P. Alloncle, David Grojo, P. Delaporte. Generating liquid nanojets from copper by dual laser irradiation for ultra-high resolution printing. Optics Express, 2017, 25 (20), pp.24164. ⟨10.1364/OE.25.024164⟩. ⟨hal-02138435⟩