Plasmonic wavelength demultiplexers based on tunable Fano resonance in coupled-resonator systems

We investigate a plasmonic waveguide system using a 2-dimension finite element method, which consists of a metal-insulator-metal waveguide coupled with a stub resonator and a baffle. Numerical simulations results show that the sharp and asymmetric Fano-line shapes can be created by placing a baffle into the waveguide, and the main dependent factors of Fano-like spectra response are discussed. Based on the above results, we design three kinds of plasmonic waveguides with possible applications in wavelength demultiplexing. An analytic model based on the transfer matrix formalism is utilized to describe and explain this phenomenon. These results could be applied for developing ultra-compact wavelength division multiplexing devices in highly all-optical integration system.