High-order harmonics generated by 1.5 mu m parametric source

We investigated the generation of XUV high-order harmonics in argon by a passively carrier-envelope phase stabilized, few-cycle IR parametric source. Exploiting the tunability of the driving pulses provided by the parametric amplification process, we demonstrate the possibility to continuously tune the soft-X emission in the energy region above 25 eV. By properly tailoring the driving electric field in a two-color configuration, we generated continuous XUV spectra showing a spectral extension beyond 100 eV.