Resonant self-interaction of CO2 laser pulses in SF6

An experimental and numerical investigation was made of the transverse structure of nanosecond CO₂ laser pulses propagating in SF₆. It was found that resonant self-focusing leads to a considerable distortion in the transverse spatial distribution of the energy density in a pulse having an initial Gaussian profile, this being manifested as a stratification of the beam into concentric annular zones.