Non-adiabatic cluster expansion after ultrashort laser interaction

Abstract

We used X-ray spectroscopy as a diagnostic tool for investigating the properties of laser-cluster interactions at the stage in which non-adiabatic cluster expansion takes place and a quasi-homogeneous plasma is produced. The experiment was carried out with a 10 TW, 65 fs Ti:Sa laser focused on CO(2) cluster jets. The effect of different laser-pulse contrast ratios and cluster concentrations was investigated. The X-ray emission associated to the Rydberg transitions allowed us to retrieve, through the density and temperature of the emitting plasma, the time after the beginning of the interaction at which the emission occurred. The comparison of this value with the estimated time for the "homogeneous" plasma formation shows that the degree of adiabaticity depends on both the cluster concentration and the pulse contrast. Interferometric measurements support the X-ray data concerning the plasma electron density

Ultrashort laser subsurface micromachining of three–dimensional microfluidic structures inside photosensitive glass

“…This absorption mechanism, with non-adiabatic cluster expansion in ultrashort laser interaction (Yu et al, 2007) and the intense local plasma heating (Faenov et al, 2008), makes it possible to carry out photomodification inside the glass at the focal spot of fs IR laser (Davis et al, 1996;Fernandez et al, 2005;Lam et al, 2007;Kasperczuk et al, 2008;Bagchi et al, 2008). Direct fabrication of a three-dimensional (3D) microstructure inside transparent glass using fs laser offers great potential for the manufacture of 3D integrated microchips without the need for the cumbersome alignment and assembly processes of individual components.…”