Analysis of electron trajectories with two-color strong-field ionization

Two-color ionization of atoms with a strong 800-nm fundamental component and a weak 400-nm component with perpendicular polarization gives detailed insight into the ionization dynamics. When the delay between the two colors is varied on a subcycle scale, the slow-electron signal shows an oscillatory structure due to intracycle interference between different ionization times. Using a trajectory-based interference model, we extract the relative strength of the two contributing pathways. Ionization times can be read directly from the delay scan, and the times for the long trajectories agree well with the quantum-orbit model. The fast electrons arise predominantly from long rescattering trajectories.