Interference effect between high-order harmonics generated by degenerate current-carrying orbitals of cyclic triatomic molecular ion H ₃²⁺ in intense laser fields

We investigate theoretically the interference effect between high-order harmonics generated by degenerate current-carrying orbitals of cyclic triatomic molecular ion <i>H</i>32+ driven by bichromatic linearly polarized laser pulses. The results show that the interference can be manipulated by adjusting the relative phase between the two laser fields in the bichromatic linearly polarized laser pulses. By utilizing the interference and at specific relative phase <i>ϕ</i> = 0.5<i>π</i>, we achieve the large intensity differences between right-circularly polarized high harmonics (RCPHH) and left-circularly polarized high harmonics (LCPHH), which are the two counter-rotating components projected by the harmonic radiation. This large intensity difference is beneficial for the synthesis of elliptically polarized attosecond pulses. Moreover, we demonstrate that, by using a special absorbing layer to extract the contribution of the short trajectories, the interference between different trajectories is reduced, which enhances the interference effect between harmonics generated by the degenerate current-carrying orbitals, and the elliptically polarized attosecond pulse with large ellipticity can be obtained. Our results offer a way to generate an isolated near-circularly polarized attosecond pulse radiation.