Mode properties in metallic and non-metallic plasmonic waveguides.

Non-metallic plasmonic materials have recently attracted research interest due to their adjustable plasmonic material properties and the potential low loss, which is important to plasmonic waveguides with ultrahigh mode confinement. In this paper, we analyzed the mode properties of four types of plasmonic waveguides based on noble metals, aluminum-zinc-oxide (AZO), and TiN, where the propagation length and mode size are chosen to compare the figures of merit. It is found that AZO has the smallest imaginary part of permittivity in the near-infrared region, while AZO waveguides have propagation lengths comparable to those of Cu waveguides but shorter than those of Au and Ag waveguides. Furthermore, due to the larger real part of permittivities, the mode sizes of the AZO and TiN waveguides are smaller than those of the metal waveguides, in particular, for the insulator-metal-insulator waveguide and dielectric-loaded plasmonic waveguide. AZO/ZnO films with tunable carrier density between 1.8×10/cm and 8.6×10/cm were grown by pulsed-laser deposition. Metal-like properties, i.e., negative real part of permittivity around 1550 nm, were observed, predicting an interesting candidate in the plasmonic optical interconnect.