High-order-harmonic generation in an elliptically polarized laser field: analytic form of the electron wave packet

Abstract

An analytic expression for the electron wave packet (EWP) describing high-order harmonic generation (HHG) by atoms in an intense laser field with small ellipticity is derived quantum mechanically in the tunneling limit within the time-dependent effective range theory. This result is valid over a wide interval of returned electron energies in the HHG plateau region and generalizes the previous result for HHG rates obtained by Frolov M V et al (2012 Phys. Rev. A 86 063406) only for the HHG plateau cutoff region. It is shown that the most important difference from the case of a linearly polarized field originates from a nonzero electron energy at the moment of ionization in an elliptically polarized field that, in turn, results in the dependence of ionization factor in the EWP on the returning electron energy. Our analytic result for the EWP averaged over interference oscillations in the HHG spectrum is applied for analysis of the laser wavelength scaling of the HHG yield induced by an elliptically polarized midinfrared laser field as well as for the improvement of the recently suggested method of elliptic HHG spectroscopy for retrieving both the energy and angular dependence of the photorecombination cross section of the target atom (see Frolov M V et al 2016 Phys. Rev. A 93 031403).