Macroscopic generation of attosecond-pulse trains in strongly ionized media

The characteristics of attosecond-pulse trains (APT) obtained from high-order harmonics are investigated by using a nonadiabatic three-dimensional model. A time-dependent phase matching approach is used in order to analyze the macroscopic formation of the APT. Under high ionization conditions, the process of APT formation is found to be the result of an interlace among the driving laser field, single atom response, phase matching effects in the near field and burst interference in the far field.