Optical breakdown of air triggered by femtosecond laser filaments

We report experiments on the generation of dense plasma channels in ambient air using a dual laser pulse excitation scheme. The dilute plasma produced through the filamentation of an ultraintense femtosecond laser pulse is densified via avalanche ionization driven by a co-propagating multi-Joule nanosecond pulse. (C) 2011 American Institute of Physics. [doi:10.1063/1.3651279]