Macroscopic High Harmonic Generation with Gouy and Gaussian Phase Distributions

We study the effects of the Gouy and Gaussian phase distributions on phase matching in macroscopic high harmonic generation (HHG) for different locations of a gas jet with respect to the focus of a laser pulse. The macroscopic HHG signal is computed by first interpolating results of \emph{ab initio} simulations of the time-dependent Schrodinger equation at the microscopic level over both intensity and carrier envelope phase. Then, we approximate the macroscopic build-up assuming point-like field emitters. We develop several measures to qualitatively discuss the strength and width of the harmonic line and the relevance of off-harmonic radiation.