  Terahertz (THz) lasers on optically pumped multiple-graphene-layer (MGL)
structures as their active region are proposed and evaluated. The developed
device model accounts for the interband and intraband transitions in the
degenerate electron-hole plasma generated by optical radiation in the MGL
structure and the losses in the slot or dielectric waveguide. The THz laser
gain and the conditions of THz lasing are found. It is shown that the lasers
under consideration can operate at frequencies > 1 THz at room temperatures.
