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

Abstract

Microscopic quantum theory of nonlinear stimulated scattering of 2D massless Dirac particles in doped graphene on 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 2D Dirac fermions is calculated. It is shown that one can achieve the efficient absorption coefficient by this mechanism.

Microscopic nonlinear quantum theory of absorption of coherent electromagnetic radiation in doped bilayer graphene

“…(17)- (20), since the contribution of electron-holes intermediate states will be negligible for considered EM radiation intensities and Fermi energies. Taking into account anticommutation rules (18), (19) and Eqs. (17), (4)-(6), the second quantized Hamiltonian can be expressed in the form:…”

“…[43][44][45][46][47]. Multiphoton cross-sections for SB of conduction electrons in intrinsic SG have been obtained in the Born approximation over the scattering potential in the presence of an external EM radiation field in [17], [18].…”

High harmonic generation in triangular graphene quantum dots

“…In the last decade, there has been a growing interest to extend high harmonic generation (HHG) to twodimensional (2D) crystals and nanostructures, such as semimetallic graphene [1], and semiconductor transition metal dichalcogenidescite [2]. The role of graphene as an effective nonlinear optical material has been discussed in many theoretical [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], and experimental [23], [24] studies that consider various extreme nonlinear optical effects, in particular, HHG, which takes place in strong coherent radiation fields in the multiphoton regime at excitation of such nanostructures [25], [26]. On the other hand, apart from the remarkable and unique electronic and optical properties of graphene, the lack of an energy gap as a semimetal greatly limits their applicability, in contrast, for example, to bilayer graphene [27][28][29][30][31][32].…”

On the extreme nonlinear optics of graphene nanoribbons in the strong coherent radiation fields

“…Graphene and its analogs have attracted enormous interest in the last decade due to the unique electronic and optical properties of such 2D quantum systems 1 . The significance of graphene as an effective nonlinear optical material has triggered many theoretical [2][3][4][5][6][7][8][9][10][11] and experimental 12,13 investigations devoted to diverse extreme nonlinear optical effects, specifically, high-harmonic generation (HHG) taking place in the strong coherent radiation fields -at the multiphoton excitation of such nanostructures 14,15 . On the other hand, apart from the invaluable physical properties, two dimensional graphene can be patterned into narrow ribbon that causes the carriers to be confined in quasi-one-dimensional graphene nanoribbons (GNRs) (with the diverse topologies depending on the ribbon form) 16 .…”