Abstract

The field of laser-induced damage in transparent materials has been under investigation since optical breakdown was first observed by Maker et al. in 1963 [1]. The nonlinear absorption mechanisms responsible for optical breakdown and damage in transparent materials are strongly intensity-dependent. The femtosecond laser is therefore an ideal tool to study these processes as the high intensity necessary to produce breakdown (on the order of 10¹⁷ W/m²) can be reached with very little energy (as little as 5 nJ per pulse with a 100-fs pulse). Femtosecond lasers have therefore revolutionized the field of laser micromachining as the low energy per pulse yields minimal collateral damage and hence high resolution in micromachining applications. Furthermore, focusing the pulse with high numerical aperture microscope objectives allows machining of the bulk without affecting the surface, because the intensity is only above the breakdown threshold in the focal volume.

© 2002 Optical Society of America