Investigation of the high-order harmonic generation for a solid with a defect by Bohmian trajectories

We theoretically investigate the high-order harmonic generation (HHG) for a solid by solving the one-dimensional time-dependent Schrodinger equation. The numerical results with the potential well depth of the defect V-1 = 0.35 a.u. and V-1 = 0.31 a.u. are demonstrated. The intensity of the second plateau of the harmonic spectra can be enhanced with the small potential well depth of the defect. We investigate the emission time of harmonics in terms of the time-frequency analysis, which shows that with the potential well depth of the defect V-1 = 0.31 a.u., one emission peak is weakened and the other is enhanced. By analyzing the time evolution of the electronic probability density distribution and the Bohmian trajectories, the electrons ionized in the negative-x direction will pass directly through the defect to the positive-x direction, which is different from the potential well depth of the defect V-1 = 0.35 a.u. In addition, we show a velocity curve to illustrate further the movement process of the ionized electrons. Copyright (C) 2022 EPLA.