Numerical simulations on self-focusing and filamentation of multi-terawatt picosecond CO2-laser pulse in air

At present, CO₂-laser is the only actual source of high-power 10-μm radiation traditionally used in various atmospheric optics applications where the extreme power at joule energy in laser pulse is crucial. The advent of high-pressure CO₂:N₂O gas mixture lasers involves a significant increase of the output pulse power up to multiterawatt level due to laser pulse shortening down to few picoseconds and even to hundreds of femtoseconds. The mid-IR spectral region is attractive because at the relatively low continual absorption the atmosphere can linearly transfer light power up to several terawatts. Further increase of laser power gives rise to nonlinear losses of propagating radiation, which is mostly due to ionization and optical breakdown of air against the background of Kerr self-focusing and filamentation of a laser beam.