Ultrashort hard X-ray pulse driven by cylindrical vector beam

Maxwell equations determine that a shaped electromagnetic pulse in vacuum can be an azimuthally polarized (ap) cylindrical vector (CV) beam. High-order harmonics generation (HHG) by the ap–CV beam can effectively yield hard X-ray photons (ℏω∼103−4eV). By controlling relative positions of atoms to the axis of driving laser pulse, we can adjust the generated HHG spectrum and the temporal shape of the driven pulse. Calculations confirm that the duration of driven pulse can be achieved to sub-femtosecond level.