Elliptical High-Order Harmonic Generation from H₂⁺ in Linearly Polarized Laser Fields

We investigate the elliptical high-order harmonic generation (HHG) from the ground state of H₂⁺ subjected to linearly polarized laser fields, by numerically solving the three-dimensional (3D) time-dependent Schr?dinger equation (TDSE) and using the strong-field approximation (SFA) models. Highly elliptical HHG is yielded at intermedial alignment angles from the TDSE, while the standard SFA model fails to predict this. By including the coulomb potential and the stark shift corrections, we yield qualitative agreement results with the TDSE. The comparisons show that in the description of elliptical HHG, both the coulomb potential and the stark-shift are necessary.