Extreme Nonlinear Optical Response From Al‐Doped ZnO

As a direct consequence of the nonlinear optical response, high‐harmonic generation (HHG) from zinc oxide (ZnO) doped with aluminum (Al) is investigated. Two main mechanisms lead to HHG from shallow donor impurity, interband, and intraband emission. Similar to gas phase, interband HHG is described by saddle point analysis. A comparison of the semiclassical trajectories of both dopant HHG and atomic HHG is shown. The nonparabolic conduction band (CB) dispersion can be considered as the main origin of the difference between the two cases when the field becomes high enough to let the electron reach the nonquadratic part of the band. In addition, the simulated high harmonic spectral intensity of ZnO:Al is also presented.