High ellipticity of harmonics from molecules in strong laser fields of small ellipticity

We study high-order harmonic generation (HHG) from aligned molecules in strong elliptically polarized laser fields numerically and analytically. Our simulations show that the spectra polarization of HHG depend strongly on molecular alignment ellipticity. In particular, for small ellipticity, large ellipticity harmonics with high intensity is observed parallel alignment, forming a striking hump around threshold. interplay structure two-dimensional electron motion plays an important role here. This phenomenon can be used to generate bright elliptically-polarized EUV pulses.