Amplification and spontaneous emission of plasmons in photo-inverted graphene — Metamaterials 2015

Graphene, as a sheet conductor, supports surface plasmon modes, which, due to the zero band gap of its electronic stucture, can be absorbed and re-emitted by the creation or anihilation of electron/hole pairs. This opens up the question, whether plasmons with gain can be supported by partially inverting the carrier system. We show that, by calculating the exact complex-frequency plasmon dispersion (CFPD) of such inverted systems, plasmons can be amplified by stimulated emission even in cases of finite scattering rates, finite temperatures, and extrinsic chemical doping. From here, given these non-equilibrium carrier distributions, we investigate the rates of electron-hole recombination via plasmonic channels and find they are a factor of 5 faster than previously predicted.