  Injection or optical generation of electrons and holes in graphene bilayers
(GBLs) can result in the interband population inversion enabling the terahertz
(THz) radiation lasing. The intraband radiative processes compete with the
interband transitions. We demonstrate that remote doping enhances the indirect
interband generation of photons in the proposed GBL heterostructures. Therefore
such remote doping helps surpassing the intraband (Drude) absorption and
results in large absolute values of the negative dynamic THz conductivity in a
wide range of frequencies at elevated (including room) temperatures. The
remotely doped GBL heterostructure THz lasers are expected to achieve higher
THz gain compared to previously proposed GBL-based THz lasers.

Mesoscale and Nanoscale Physics