In this paper, we have numerically investigated a novel kind of ultra-compact wavelength demultiplexing (WDM) in high-confined metal–insulator–metal (MIM) plasmonic waveguides. It is found that the drop transmission efficiency of the filtering cavity can be strongly enhanced by introducing a side-coupled cavity in the MIM waveguide. The theoretical analysis is verified by the finite-difference time-domain simulations. Through cascading the filtering units, a highly effective triple-wavelength demultiplexer is proposed by selecting the specific separation between the two coupled cavities of filtering units. Our results may find potential applications for the nanoscale WDM systems in highly integrated optical circuits and networks.
Surface plasmon modes of finite, planar, metal-insulator-metal plasmonic waveguides
