Enhancement of the laser breakdown of simple gaseous and liquid materials under intense picosecond double-pulse excitation

We report the breakdown behaviors of simple gaseous and liquid materials un der double-pulse excitation from an intense picosecond Nd:YAG laser. With a n increasing in the separation time of the pulse pair, a sharp increase in the intensity and decay time of a white-light emission from the breakdown p lasma was observed. The further excitation of the preformed. plasma by the second pulse explains the origin of the phenomenon.