  AB-stacked bilayer graphene with a tunable electronic bandgap in excess of
the optical phonon energy presents an interesting active medium, and we
consider such theoretical possibility in this work. We argue the possibility of
a highly resonant optical gain in the vicinity of the asymmetry gap. Associated
with this resonant gain are strongly amplified plasmons, plasmons with negative
group velocity and superluminal effects, as well as directional leaky modes.
