Propagation Characteristics of Symmetric and Asymmetric Multilayer Hybrid Insulator-Metal-Insulator and Metal-Insulator-Metal Plasmonic Waveguides

Propagation characteristics of symmetrical and asymmetrical multilayer hybrid insulator-metal-insulator (HIMI) and metal-insulator-metal (HMIM) plasmonic slab waveguides are investigated using the transfer matrix method. Propagation length (L-p) and spatial length (L-s) are used as two figures of merit to qualitate the plasmonic waveguides. Symmetrical structures are shown to be more performant (having higher L-p and lower L-s), nevertheless it is shown that usage of asymmetrical geometry could compensate for the performance degradation in practically realized HIMI waveguides with different substrate materials. It is found that HMIM slab waveguide could support almost long-range subdiffraction plasmonic modes at dimensions lower than the spatial length of the HIMI slab waveguide.