Graphene plasmons embedded in a gain medium

Graphene plasmonics has attracted much attention because of its remarkable properties such as tunable conductivity and extreme confinement. However, one of the major drawbacks to develop more efficient devices based on graphene plasmons remains losses. Here we study how the introduction of a gain medium surrounding graphene can affect plasmonic modes, both in 1D and 2D settings. We show the presence of a critical gain in 1D structures when the losses are entirely compensated. Furthermore, using numerical simulations and analytical models, we demonstrate a resonant gain leading to enhanced absorption in 2D graphene ribbons.