Transient electron excitation in laser-induced plasma-assisted ablation of transparent materials

We investigate the mechanism of laser-induced plasma-assisted ablation (LIPAA), by which high-quality and high-efficiency ablation of transparent materials, such as glass, can be performed with a single conventional pulsed laser. The laser-induced plasma induces transient absorption of the laser beam (532 nm) by the glass substrate. The origin of the transient absorption is electron excitation by ions with kinetic energy more than approximately 10 eV in the plasma, which is observed by measuring transient polarization change in the glass substrate applied with a high external pulsed electric field during the plasma-assisted electron excitation (plasma-conductivity measurement). A possible mechanism of LIPAA is proposed based on the results obtained. (c) 2006 American Institute of Physics.