Cooperative Enhancement of Solid-State High-Harmonic Generation by Strain and Donor-Like Local Potentials

Motivated by the realistic scenario in which impurity incorporation can induce lattice deformation, we investigate the cooperative control of solid-state high-harmonic generation (HHG) by external strain and donor-like local potential modulation within a one-dimensional time-dependent Schr & ouml;dinger equation (TDSE) framework. Strain reshapes the electronic structure by modifying the band gap, effective mass, and transition dipole moment, leading to substantial changes in HHG intensity and chirp. To provide qualitative comparison with realistic materials, strain effects are further analyzed using first-principles-based semiconductor Bloch equation calculations. We identify two distinct strain classes: tensile strain narrows the band gap in wurtzite ZnO, whereas compressive strain narrows it in monolayer black phosphorus, resulting in opposite strain dependences of the HHG response. Resolving the spectrum relative to the minimum band gap reveals three regimes: intraband-dominated subgap harmonics, dephasing-sensitive band-edge harmonics, and strain-enhanced above-gap emission. The dephasing time T2 primarily affects the band-edge region, while strain robustly governs the plateau intensity. Impurity-induced local potential modulation introduces additional excitation channels that cooperate with strain, particularly enhancing higher-order harmonic emission. These results clarify the complementary roles of strain, impurity-induced local potential modulation, and dephasing in tailoring strong-field emission in solids.