Theory of strong-field injection and control of photocurrent in dielectrics and wide bandgap semiconductors
We propose a theory of optically-induced currents in dielectrics and wide-gap semiconductors exposed to a non-resonant ultrashort laser pulse with a stabilized carrier-envelope (CE) phase. In order to describe strong-field electron dynamics, equations for density matrix have been solved self-consistently with equations for the macroscopic electric field inside the medium, which we model by a one-dimensional potential. We provide a detailed analysis of physically important quantities (band populations, macroscopic polarization, and transferred charge), which reveals that carrier-envelope phase control of the electric current can be interpreted as a result of quantum-mechanical interference of multiphoton excitation channels. Our numerical results are in good agreement with experimental data.