Superluminescence During the Filamentation of 950-nm Femtosecond Laser Pulses in Carbon Dioxide

Abstract

Directional superluminescence on a large number of spectral lines in the wavelength range of 310–470 nm has been obtained during the filamentation of 950-nm femtosecond radiation from a Ti:sapphire laser in carbon dioxide. The lines have been identified as transition lines between the vibrational levels of electron-excited A²Π_u and X²Π_g states of CO\(_{2}^{ + }\) ions. The effect of the pressure on the radiation spectrum has been studied and mechanisms of the observed phenomenon are discussed.