Theoretical investigation of the electron dynamics in high-order harmonic generation process from the doped periodic potential

The electron dynamics in the harmonic emission process from the doped periodic potential have been investigated by numerically solving the time-dependent Schrodinger equation. The results show that the harmonic efficiency of the second plateau can be enhanced almost six orders of magnitude for the doped potential. Moreover, the corresponding doping rate dependence changes from enhanced to suppressed rather than a linear tendency. It can be ascribed to two excitation channels, i.e. the direct excitation channel and the step-by-step excitation channel. By means of the time-dependent electron imaging picture, time-frequency maps and the energy-band structure, the underlying physical mechanism is revealed.