Dependence of nonsequential double ionization of He on intensity ratio of orthogonal two-color field

Using classical ensemble model, the dependence of nonsequential double ionization of He on intensity ratio of orthogonal two-color field is investigated. It is shown that this dependence is related to the relative phase(phi) of two-color pulse. When phi = 0.25 pi, with intensity ratio increasing, correlated momentum distribution along the polarization of long wavelength field changes from correlation to anticorrelation pattern; when phi = 0.35 pi, 0.45 pi, correlated momenta are mainly distributed, in the first and third quadrants, correlation pattern is nearly unchanged with the variation of intensity ratio. Back analyses of recollision time, recollision angle, recollision momentum of double ionization trajectories are responsible for the above results, and reveal the control of recollision time and the recollision angle in NSDI by orthogonally polarized two-color field.