propBG: A program for calculating the intensity and the far-field profile of harmonics emitted by a dilute gas irradiated by an intense Gaussian or Bessel–Gauss laser beam Original Research Article

Using the Greenʹs function of the scalar wave equation, the program propBG computes and analyzes the far-field amplitude of the harmonics generated when a linearly polarized Gaussian or Bessel–Gauss beam of order zero passes through a dilute gaseous atomic target. The user must supply the relevant atomic data, namely the intensity-dependent atomic dipole moments, linear atomic susceptibilities (both at the fundamental and the harmonic frequencies), and photoionization rate. Target depletion and phase-mismatch due to photoionization are taken into account.