Mechanism of quasi-phase-matching in a dual-gas multijet array

Abstract

Quasi-phase-matching in a dual gas (Ar-H2) multijet array has recently been demonstrated to be a promising way to enhance the yield of high-order harmonics (HH). Here, we investigate the HH produced individually from these two gases under identical conditions. Our results indicate that the quasi-phase-matching results from the much lower recombination cross section of H2 as compared to that of Ar in the energy range of interest, rather than from full ionization of H2 by the driving laser as proposed previously.