Research Papers in Physics and Astronomy


Date of this Version



J. Phys. B: At. Mol. Opt. Phys. 46 (2013) 231001 (7pp)


Copyright 2013 IOP Publishing Ltd. Used by permission.


The interpretation of many high-order harmonic generation (HHG) experiments is based on the assumption that the HHG yield of an atom can be factorized into (i) a laser-dependent ‘electron wave packet’ with rather simple properties, including a nearly universal shape, and (ii) an atomic photorecombination cross section. We show that this factorization is restricted to linearly polarized laser fields and fails in two-colour laser fields with orthogonal polarizations. At the same time, we show how two-colour HHG spectroscopy using orthogonally polarized intense fundamental and relatively weak second harmonic fields makes a complete experiment possible that enables the retrieval of the angle-resolved photorecombination cross sections for atomic p states.