A Comprehensive Theoretical Study of the Guided Modes in a Five-Layer Hybrid-Metal/Dielectric/Metal Waveguide

We theoretically investigate the hybrid guided modes in a five-layer symmetrical hybrid-metal-dielectric-metal (MDM) plasmonic waveguide. It is a modified-MDM structure that consists of five layers with three-layer (low/high/low) dielectric cladded symmetrically by metal. The hybrid guided mode is characterized and analyzed based on the results obtained from the mode characteristics equations. Such a waveguiding structure can support different types of hybrid-MDM modes at different dielectric thicknesses. Consequently, the optical performance of the hybrid MDM plasmonic waveguide can be controlled by the geometrical parameters and the refractive indices of the dielectric layers, which could be useful for emerging applications in ultracompact nanophotonics.