Multimode interference demultiplexers and splitters in metal-insulator-metal waveguides.

Multimode interference (MMI) effect in metal-insulator-metal (MIM) waveguides is studied in this paper. Theoretical calculation based on the self-imaging principle and the finite element method (FEM) simulation are used to analyze the effect and further guide the design of plasmonic MMI devices. We show that wavelength-selective routing and splitting with high extinction ratios can be realized in the multimode waveguides, and active control by refractive index modulation is also demonstrated.