Home – Home – Jornals – Atmospheric and Oceanic Optics 2013 number 9

The results of numerical simulation of the nonlinear propagation of high-power pulsed laser radiation at a wavelength of 10.6 microns in air upon Kerr self-focusing and filamentation are presented. The optical model of air involves cubic and higher optical nonlinearity, plasma nonlinear absorption and refraction, and air linear absorption. The single-filamentation regime of the laser pulse with peak power of up to few terawatts and pulse duration of one picosecond is studied. For the first time we show that in contrast to the filamentation in the near-infrared wavelength range, the specific feature of long wavelength radiation self-action in air is the formation of abnormally elongated and wide intense light channel followed by nearly continuous along the propagation direction plasma column. The peak electron density of the formed plasma column is comparable to that created by a femtosecond radiation in the near-infrared spectral range. The physical cause for these peculiarities is the change of air ionization regime by picosecond CO₂-laser pulses in favor of bound electrons tunneling through the atomic potential barrier and the progressive development of the electron avalanche.