Unipolar pulse assisted generation of the coherent XUV pulses

A promising method to generate the attosecond XUV sources has been theoretically investigated when the Ne atom is driven by the multi-cycle two-color field combined with the unipolar pulse. The results show that with the introduction of the unipolar pulse, not only the harmonic cutoff is remarkably extended, but also the single short quantum path has been selected to contribute to the harmonics. Further, by optimizing the laser parameters, a supercontinuum with the 406 eV bandwidth can be obtained, which results in a series of sub-40as XUV pulses.