Time–energy analysis of above-threshold ionization in the transverse direction of the linearly polarized laser pulses

Abstract

We use a Wigner-distribution-like function based on the strong field approximation to study the photoelectrons emitted in the direction perpendicular to the laser field polarization in the linearly polarized laser pulses with different pulse durations. The calculated time–energy distributions for few-cycle laser pulses show distinct interference structures with regular energy separation of 2ω, which are consistent with the corresponding energy spectra. Analysis shows that these interference structures can be attributed to the intracycle interference between electrons emitted at times when the laser field is close to its extreme, which is the main reason for the carpet-like pattern in the momentum spectrum. For the longer laser pulse, the energy spectrum shows a much more complicated structure consisting of main peaks with energy separation of 2ω and many subpeaks in between the main peaks. The time–energy distribution indicates that the main peaks and subpeaks are ascribed to intracycle and intercycle interferences.