Chromatic aberrations correction of attosecond high-order harmonic beams by flat-top spatial shaping of the fundamental beam

Attosecond pulses created by high-order harmonic generation in gases often exhibit strong chromatic aberrations, arising from the broad bandwidth and wavelength-dependent nonlinear light-matter interaction. When driving laser intensity varies spatially, as for Gaussian beams, apparent source position of harmonics differs significantly one order to next, thus affecting achievable duration attosecond when they are focused on a target. We show that these aberrations can be reduced spatially shaping fundamental beam generate with driver having flat-top profile inside gas medium. By measuring both wavefront each plane, we access extreme ultra-violet (XUV) properties investigate near focus. observe controlling spatial strongly reduces variation XUV spectrum axis during propagation and, return, longitudinal sensitivity temporal profiles shifts pulses.