Fig. 1. Combined laser fields as a function of time. (a) IR and EUV laser electric fields; (b) vector potential of the combined laser fields. The IR pulse has the wavelength 800 nm and the intensity I₁=1.5 × 10¹⁵ W/cm². Time delay is t_d=-17 a.u.

Fig. 2. Correlated information of the electrons. (a) and (b) denote wave functions at time t=323 a.u. when the electron-electron repulsion is excluded or included, respectively; (c) momentum distribution of correlated double ionization in (a); (d) momentum distribution of correlated double ionization in (b); (e) and (f) denote the single electron momentum distribution after integrating the signals marked by the triangles in (c) and (d) along the vertical axis, respectively

Fig. 3. Correlated information of the electrons. Photoelectron wave function in (a) space and (b) momentum representations at time t=344 a.u.; (c) electron-electron joint energy spectrum; (d) sum energy of two electrons obtained by integrating the signals in (c) along the lines E₁+E₂=const. The IR wavelength is 1200 nm, and the intensity I₁=8.3×10¹⁴ W/cm². The time delay is

Fig. 4. Ratio (anticorrelated double ionization probability to correlated double ionization probability) as a function of the screening parameter m_ee. Other parameters for the line with open circles are the same as those used in Fig. 3. For the line with crosses and line with stars, MIR intensities are I₁=5×10¹⁴ W/cm² and 5.3×10¹⁴ W/cm². MIR wavelengths are both 1500 n

Fig. 5. Anticorrelated joint electron-electron energy spectra. (a), (b) and (c) are joint electron-electron energy spectra for anticorrelated double ionization in the second and fourth quadrants at m_en=20, 10, 5, respectively; (d) potentials at different screening parameters (m_en=20, 10, 5). The MIR laser parameters are λ₁=2000 nm, I₁=3×10¹⁴ W/cm². Time delay t