▎ 摘　　要

The response of high harmonics of a laser field to the change of Fermi surface topology in graphene-like nanostructures during the process of the high harmonic generation has been investigated. The microscopic nonlinear quantum theory of the interaction of intense coherent electromagnetic radiation with such systems near the critical Fermi level is used. The Liouville-von Neumann equation for the density matrix in the multiphoton excitation regime is solved numerically. The obtained results show that high harmonics are sensitive to the change of the topology of the Fermi surface which can be used for the determination of the Fermi energy in such systems.