High Quality Content by WIKIPEDIA articles! A photoionization mode is a mode of interaction between a laser beam and matter, giving rise to a photoionization pattern, having very specific characteristics in terms of photoionization spatial distribution and density, as well as relative yields of photolytic species. A particular photoionization mode is also very specific in terms of the ultimate chemical and structural effects induced to a given dielectric material. The concept of photoionization mode refers to very distinct interaction regimes of a laser beam, normally a pulsed laser beam, with a dielectric material, which are governed by a specific set of laws, and controlled by a specific set of parameters. For this reason, this concept is very well defined.