Plasmonic wavelength splitter based on a metal-insulator-metal waveguide with a graded grating coupler.

A plasmonic wavelength splitter based on a sub-wavelength metal-insulator-metal (MIM) periodic rectangle wrinkle waveguide with a graded grating coupler is theoretically analyzed and experimentally demonstrated. The surface plasmon polaritons (SPPs), excited in the metal grating with wavelength selection, are deflected by the graded difference according to the aplanatic parametric principle. The wave vector of the deflected SPPs meets the phase-matching condition and couples into the periodic rectangle wrinkle waveguide with a plasmonic bandgap.