Elliptical high-order harmonic generation from H2+ driven by orthogonally polarized two-color laser fields

We theoretically investigate the elliptical high-order harmonic generation from the H${}_{2}^{+}$ molecule driven by the orthogonally polarized two-color laser field by numerically solving the two-dimensional time-dependent $\mathrm{Schr}\stackrel{\ifmmode \ddot{}\else \"{}\fi{}}{\text{o}}\mathrm{dinger}$ equation. The results show that the odd-order harmonics in the $x$ component and the even-order harmonics in the $y$ component can be generated with the specific alignment angle $\ensuremath{\theta}={0}^{\ensuremath{\circ}}$ for the different intensity ratios of the laser fields. The harmonic intensity distribution and ellipticity distribution at the different intensity ratios of the laser fields and the alignment angles differ significantly from each other. The result also shows that the ellipticity-tunable high-order harmonics can be generated through adjusting the intensity ratio of the laser fields and the alignment angles. Further analyses show that the amplitude ratio and the phase difference of the $x$ and $y$ components of the harmonics are the origin of the ellipticity of the harmonics in general. The two-center interference effect can also affect the ellipticity of the harmonics. The results show that the ellipticity of the harmonics can be used as a potential tool to probe the position of the minimum. The results we obtained can be useful for the optimization of elliptically polarized XUV radiation generation.