Landau-quantized graphene in strong radiation field and high harmonic generation

Due to the exotic nonlinear electromagnetic (EM) properties of graphene, it is extensively considered as an active material for diverse nonlinear optical applications. Thanks to unusually high interaction parameter with EM radiation field, the graphene is an effective material for multiphoton interband excitation, wave mixing and high harmonic generation (HHG) processes. When a static uniform magnetic field is applied perpendicular to the graphene plane, the electron energy is quantized forming nonequidistant Landau levels. As a consequence, in the graphene the anomalous quantum Hall effect takes place. Under these circumstances the main works have concentrated on the static or linear optical properties of the Landau-quantized grapheme. In the present work, a microscopic theory of the Landau-quantized graphene interaction with strong coherent EM radiation is presented. The results of our investigations show that one can achieve efficient yield of HHG with strong radiation fields - when the work of the wave electric field on the magnetic length is much larger than pump photon energy. At that for the specific frequencies and gated level one can achieve considerable enhancement of HHG rate. (author)