Control of high-order harmonic generation in solids by orthogonally polarized laser fields

We theoretically investigate the high-order harmonic generation (HHG) from ZnO crystals driven by orthogonally polarized two-color (OTC) laser fields. By solving the semiconductor Bloch equation (SBE) in two dimensions, it is found that the HHG yields show a high sensitivity to the relative phase between the two fields. By changing the laser intensity, the yields of HHG show two maxima in the high-order region. To reveal the physical origin of these phenomena, we analyze the behavior of the electron-hole pair in the real and reciprocal spaces by the recollision model, respectively. It could qualitatively interpret the results by SBE simulations. Our analysis demonstrates that the OTC laser fields could control the electron-hole dynamics and HHG processes efficiently.