Asymmetric molecular gating for supercontinuous high harmonic generation in the plateau.

Molecular wave packets provide an alternative route to steer the high harmonic generation (HHG). Here we present a new method for isolated attosecond pulse generation from high harmonics in the plateau with asymmetric molecules. It is shown that the photoionization depends on the molecular structure. Through steering the ionization, HHG is controlled with the asymmetric molecule and supercontinuous high harmonics are produced in the plateau, from which an isolated 95-attosecond pulse is generated. In contrast to the cutoff which declines sharply, the plateau shows almost a constant intensity, indicating a higher yield. Moreover, the plateau covers a very broad bandwidth, thus is preferable to produce an isolated attosecond pulse with a rather short duration.