A compact wavelength demultiplexing structure based on arrayed MIM plasmonic nano-disk cavities

A compact plasmonic wavelength demultiplexing structure based on arrayed metal-insulator-metal (MIM) plasmonic nano-disk cavities is proposed and numerically investigated by utilizing finite-difference time-domain (FDTD) method. The structure consists of a bus waveguide perpendicularly coupled with a series of nano-disk cavities through slit-waveguides. A model based on resonator theory is used to design the operating wavelength of the structure. Simulation results show that compared with the directly side-coupled nano-disk structure, the narrower transmission linewidth of each channel could be obtained through the coupling between fore-end slit-waveguide and nano-disk cavity. The transmission wavelength and bandwidth of the structure can be tuned by adjusting the geometrical parameters and the refractive index of cavities. The proposed structure will be useful in ultra-compact optical devices for optical communications and computing. (C) 2012 Elsevier B.V. All rights reserved.