Ellipticity dependence of the near-threshold harmonics of H2 in an elliptical strong laser field

We study the ellipticity dependence of the near-threshold (NT) harmonics of pre-aligned H-2 molecules using the time-dependent density functional theory. The anomalous maximum appearing at a non-zero ellipticity for the generated NT harmonics can be attributed to multiphoton effects of the orthogonally polarized component of the elliptical driving laser field. Our calculation also shows that the structure of the bound-state, such as molecular alignment and bond length, can be sensitively reflected on the ellipticity dependence of the near-threshold harmonics. (C) 2013 Optical Society of America