Proof-of-principle experiment on quasi-phase matching of high-order harmonic generation via the selected-zoning...

We demonstrate the proof-of-principle experiment on all-optical quasi-phase matching (QPM) of high-order harmonic generation (HHG) via the transverse selective-zoning method. The dephasing length and the out-of-phase region in the interacting medium are identified in advance by applying a tomographic diagnosis of the generation process. Then a transverse disruptive pulse is employed to suppress the harmonic emission in the out-of-phase region to achieve QPM. The final output is enhanced by 35% with just one QPM zone. This proof-of-principle result provides the feasibility of ion-based HHG for higher cut-off energies, where phase matching is difficult to achieve.