  A plasmonic coupled-cavity system, which consists of a quarter-wave coupler
cavity, a resonant Fabry-Perot detector nanocavity, and an off-resonant
reflector cavity, is used to enhance the localization of surface plasmons in a
plasmonic detector. The coupler cavity is designed based on transmission line
theory and wavelength scaling rules in the optical regime, while the reflector
cavity is derived from off-resonant resonator structures to attenuate
transmission of plasmonic waves. We observed strong coupling of the cavities in
simulation results, with an 86% improvement of surface plasmon localization
achieved. The plasmonic coupled-cavity system may find useful applications in
areas of nanoscale photodetectors, sensors, and an assortment of
plasmonic-circuit devices.
