A conceptually general coherent X-ray attosecond pulse shaper

An optimal control technique for broadband spectral amplitude and phase control of light pulses produced in high-order harmonic generation (HHG) is presented. Weak intensity filtered regions of the HHG emission are coherently added to the intense IR driving pulse with optimal attenuation and time delay parameters in a computerized iterative scheme. We demonstrate that isolated attosecond pulses can be produced in a robust manner by using different spectral widths and central photon energies matching experimental values, such as a spectral width of 30 eV centered at 36 eV, well in the plateau, or 20 eV centered at 60 eV in the cutoff region.