Controlling harmonic distributions from H2+ driven by linearly and circularly polarized laser fields

The spatial distributions of the high-order harmonics from H2+ driven by the linearly and the circularly polarized laser fields have been theoretically investigated. It is found that when the molecular axis parallels to the polarized direction of the linearly polarized laser field, the contributions of the harmonics are mainly from the negative-H and the positive-H for the cases of E(t) > 0 and E(t) < 0, respectively. As the angle between the molecular axis and the linearly polarized laser field increases, the contributions of the harmonics from the negative-H are enhanced and play the main role in the harmonic spectrum. Further, with the introduction of the controlling circularly polarized laser field, the intensity enhancement of the harmonics from the positive-H can be achieved. Moreover, the contributions of the harmonics from the two-H nuclei are sensitive to the ellipticity of the laser field. Finally, the time-frequency analyses of the harmonics and the time-dependent electron locations have been given to explain the physical mechanism behind the spatial distributions of the harmonics from the two-H nuclei of H2+.