Recollision dynamics analysis of high-order harmonic generation in solids

We theoretically investigate the dynamic processes of solid harmonics generation using the one-dimensional time-dependent density functional theory and the three-band recollision model. Compared with gas harmonics, more quantum paths contribute to the generation of solid harmonics. Moreover, the number of quantum paths further increases as the laser vector potential increases. Analysis indicates that the multiple velocity reversals of electrons play an important role in the generation of solid harmonics, which induces multiple collisions of electrons and holes and forms more quantum paths. Besides, we find that the dephasing effect cannot reduce the number of quantum paths. Finally, the relationship between harmonic order and the electron migration distance is also studied. It is found that there is no unified dependence between harmonic order and the electron migration distance because this relationship is path dependent. Our work can contribute to a considerable understanding of the recollision dynamics of solid harmonic generation, which provides the possibility of manipulating the generation of solid harmonics in the future.