Figure 1
Illustration of the non-rescattering trajectories and the back-scattering trajectories.
(a) There are two kinds of the non-rescattering trajectories in each laser cycle, i.e., the direct trajectory released before the field maximum (green) and the indirect trajectory released after the field maximum (blue). The indirect trajectory is initially emitted along the positive z direction and finally obtains a negative momentum. (b) According to the excurse time between the ionization and the rescattering, there are two types of backward rescattering trajectories, i.e., the long trajectory (black) and the short trajectory (magenta). In the bottom parts of (a) and (b), the arrows indicate the instant of the electron release. The scattering angle is assumed to be 180° in (b). The laser field is shown by the red curves in arbitrary units.
