Propagation of few-cycle laser pulses through a linear gas medium

We investigate the ultrashort pulse propagation through a linear gas medium by direct solution of the wave equation beyond the often used lowest orders of the dispersion approximation and the assumption of a slowly varying envelope. The dispersion effects and the effective absorption of the pulse energy by the medium are shown to result in a strong dispersive broadening of the initial pulse in the time and space domains. New features of the polarization response of the medium resulting from essentially nonadiabatic ramps of the pulse envelope are found. The possibility of using the two-pulse experimental scheme to partly compensate for the dispersion is discussed.