Laser-induced plasma-assisted ablation (LIPAA): fundamental and industrial applications

The laser-induced plasma-assisted ablation (LIPAA) process developed by our group, in which a single conventional pulsed laser is only used, makes it possible to perform high-quality and high-speed glass microfabrication. Up to the present, this process has been widely applied for micromachining of various transparent hard and soft materials. In this process, the laser beam first passes through the glass substrate since the laser beam has no absorption by the substrate. Then, the transmitted beam is absorbed by a solid target (typically a metal), located behind the substrate so that the target is ablated, resulting in plasma generation. Due to the interaction of the laser beam and the laser-induced plasma, significant ablation takes place at the rear surface of the substrate. Recently, we have developed the proto-type LIPAA system using a second harmonic of diode pumped Q-switched Nd:YAG laser for the practical use. In this paper, we demonstrate micromachining, crack-free marking and color marking of glass materials. Additionally, selective metallization of glass and polyimide by the LIPAA process followed by metal chemical-plating is investigated. A possible mechanism of LIPAA is also discussed based on the results from double pulse irradiation using near-IR fs laser, transient absorption measurement and plasma-conductivity measurement.