Generation of even harmonics with a small redshift in an asymmetric nonhomogeneous laser field

Abstract

We theoretically investigate the high-order harmonic generation (HHG) of the H2 + molecule in an asymmetric nonhomogeneous laser field by solving the one-dimensional time-dependent Schrödinger equation within the non-Born–Oppenheimer approximation. The results show that even harmonics with a small redshift can be observed in an asymmetric nonhomogeneous laser field. We also investigate the spatial distribution of the HHG spectra to explain the appearance of the even harmonics with a small redshift. The HHG was separated into two parts according to the electronic coordinate z (z > 0 and z < 0) to illustrate the contributions to the HHG from the two nuclei. Furthermore, the underlying physical mechanism of the generation of even harmonics with a small redshift is illustrated by the interference term of the HHG spectra.