High-harmonic phase spectroscopy using a binary diffractive optical element

We report on high-order harmonic generation (HHG) using a Ti:sapphire laser beam phase shaped with a binary diffractive optical element (DOE) to create two spatially separated synchronized HHG sources at the focus of a lens. Using full three-dimensional computations, we show numerically that the harmonic dipole phase is imprinted in the resulting far-field fringe pattern. Using the corresponding experimental arrangement, we measure HHG phase in aligned carbon dioxide. This arrangement is robust, extremely stable, simple to use, and gives highly resolved fringes. It thus opens new perspectives for combined and refined HHG phase measurements in excited samples.