Graphene doping inhomogeneities: plasmonic taper applications

Combining plasmonics and graphene is a new promising application for optoelectronic circuits since graphene supports low-loss plasmons and is tunable via doping. Therefore, a study of these graphene plasmons with various doping profiles is proposed. We show that the reflection at abrupt doping interfaces is a simple function of the doping difference. Improved transmission is obtained with a tapered interface and an optimal size for the transition zone is found. Finally, localized inhomogeneities are considered. A Fabry-Perot cavity leading to an absorption above 60% is described and a 6nm length cavity achieving 100% absorption is proposed. These results may lead to novel optical switches or nano-sensors.