Characteristics of a Vertical Metal-Insulator-Metal Microring Cavity

We propose a vertical metal-insulator-metal (MIM) plasmonic cavity that comprises top Ag and bottom InGaAsP microring structures on an Ag substrate. A full vectorial numerical simulation was used to characterize the fundamental optical properties of the transverse-magnetic-like plasmonic whispering-gallery-modes (WGMs) excited in a variety of MIM plasmonic cavities. In addition, we exploit the controllability of far-field radiations using the single MIM microring cavity and successfully demonstrate strong directional and localized vertical radiations from the plasmonic WGMs by introducing a number of nanoscale disks along the circumference of the cavity. Our plasmonic cavity can be applied as a component of nanoscale photonic integrated circuits as well as spatially localized out-of-plane optical sensors.