High harmonic generation with circularly polarized fields in solid: a quantum trajectory perspective

We investigate the high harmonic generation (HHG) in solids driven by laser fields with different ellipticities. The HHG spectra show a two-plateau structure within the energy gap between the valence band and the first conduction band. These two plateaus depend distinctly on the laser ellipticity. The first plateau is decreased while the second plateau is enhanced with increasing the laser ellipticity. To understand these phenomena, we develop an intuitive Reciprocal-Space- Trajectory (RST) method, with which HHG in solids is explained by a trajectory-ensemble from different initial states and different ionization times in the reciprocal space. In the framework of RST, we can not only quantitatively reproduce the HHG spectra, but also well understand the underlying physics of these phenomena, providing a deep insight into the mechanism of HHG in solids.