LAUSR

The high-order harmonic generation process of ${\mathrm{H}}_{2}{}^{+}$ in a co-rotating two-color circularly polarized laser pulse was investigated by numerically solving the time-dependent Schr\"odinger equation. Compared with the target of the atom, the harmonic intensity of ${\mathrm{H}}_{2}{}^{+}$ is remarkably enhanced. Moreover, the harmonic intensity of ${\mathrm{H}}_{2}{}^{+}$ approaches its maximum when the electric field amplitude ratio of the fundamental frequency and the second one is approximately 1:2.3. By analyzing the evolution of the time-dependent wave packets, the enhancement of harmonic intensity may be attributed to an increase in the probability of the ionized electron recolliding with the parent ion. In addition, the dependence of harmonic intensity on the internuclear distance and the alignment angle of ${\mathrm{H}}_{2}{}^{+}$ is explored. We found that the ellipticity of the particular harmonic order changes with the molecular alignment angle, which provides a chance to generate an extreme ultraviolet coherent light pulse with controllable polarization.