Microscopic nonlinear quantum theory of absorption of strong electromagnetic radiation in doped graphene

Microscopic quantum theory of nonlinear stimulated scattering of two-dimensional (2-D) massless Dirac particles in doped graphene on the Coulomb field of impurity ions at the presence of an external strong coherent electromagnetic radiation is developed. We consider high Fermi energies and low frequencies (actually terahertz radiation) to exclude the valence electrons excitations. The Liouville-von Neumann equation for the density matrix is solved analytically, taking into account the interaction of electrons with the scattering potential in the Born approximation. With the help of this solution, the nonlinear inverse-Bremsstrahlung absorption rate for a grand canonical ensemble of 2-D Dirac fermions is calculated. It is shown that one can achieve the efficient absorption coefficient by this mechanism. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)