Abstract
Metal-insulator-metal (MIM)-based plasmonic microcavity has attracted widespread interest due to its ability in manipulating and concentrating photons on the sub-wavelength scale. However, noble metals suffer from large intrinsic loss and lack active tunability. Here, a micro-cavity structure of quantum well sandwiched between periodic top contact of graphene grating and bottom contact graphene was proposed. Graphene plasmons provide a suitable alternative for metal plasmons and provide the advantage of being highly tunable by electrostatic gating. Effect of changes in both graphene physical and device structural parameters on optimized absorption performance was systematically analyzed through the calculation of reflectivity curves of incident light. Our results indicate that intersubband absorption of device can be improved by adjusting parameters of both graphene material and device structure. Furthermore, cavity resonant mode excited by surface plasmon polariton can be tuned to response frequency of quantum well under optimized parameters. Intersubband absorption is almost 1.5 times higher than that of a micro-cavity structure that uses metal grating.
Polarization Effects on Intersubband Absorption in GaN/ZnGeN2 Quantum Wells