Strong field ionization by ultrashort laser pulses: Application of the Keldysh theory

Analytical expressions and numerical results describing ionization of atoms by intense linearly polarized ultrashort laser pulses are obtained in the frame of the Keldysh approach. Photoelectron spectra and total ionization probabilities are presented for several analytical models of a single-cycle laser pulse. In particular, strong left–right asymmetry of the spectra is shown for the case of odd pulses.