Multiphoton interaction of coherent electromagnetic radiation with 2Dmetallic carriers confined on the surface of the 3D topological insulator isconsidered. A microscopic theory describing the nonlinear interaction of astrong wave and metallic carriers with many-body Coulomb interaction isdeveloped. The set of integrodifferential equations for the interbandpolarization and carrier occupation distribution is solved numerically.Multiphoton excitation of Fermi-Dirac sea of 2D massless carriers is consideredfor a THz pump wave. It is shown that in the moderately strong pump wave fieldalong with multiphoton interband/intraband transitions the intense radiation ofhigh harmonics takes place.
展开▼