  We review the transmission of Dirac electrons through a potential barrier in
the presence of circularly polarized light. A different type of transmission is
demonstrated and explained. Perfect transmission for nearly head-on collision
in inffnite graphene is suppressed in gapped dressed states of electrons. We
also present our results on enhanced mobility of hot Dirac electrons in
nanoribbons and magnetoplasmons in graphene in the presence of the energy gap.
The calculated carrier mobility for a graphene nanoribbon as a function of the
bias field possesses a high threshold for entering the nonlinear transport
regime. This threshold is a function of both extrinsic and intrinsic
properties, such as lattice temperature, linear density, impurity scattering
strength, ribbon width, and correlation length for the line-edge roughness.
Analysis of non-equilibrium carrier distribution function confirms that the
difference between linear and nonlinear transport is due to sweeping electrons
from the right to left Fermi one through elastic scattering as well as moving
electrons from low to high-energy ones through field-induced heating. The
plasmons, as well as the electron-hole continuum are determined by both energy
gap and the magnetic field, showing very specific features, which have been
studied and discussed in details.
