Two-dimensional imaging of energy bands from crystal orientation dependent higher-order harmonic spectra in h−BN

摘要: High-order harmonic generation (HHG) from hexagonal boron nitride is simulated by solving extended multiband semiconductor Bloch equations under strong laser fields. By changing the angle of polarization with respect to crystal orientation, we find that spectra present a double-plateau structure and HHG dominantly emitted along \ensuremath{\Gamma}-M direction in first plateau, but special anisotropic distribution observed secondary plateau. In-depth analyses reveal two plateaus originate different pair conduction band valence band, shapes dispersion transition dipole moment determine emission $h$-BN crystal. Furthermore, show energies high-lying unoccupied bands low-lying occupied ones can be directly extracted dependent high spectra. This paves way image two-dimensional information solid materials using laser-induced HHG.