Wavelength Plasmonic Demultiplexer Based on Square-disk Resonators in MIM Waveguide

Abstract A palsmonic demultiplexer based on cascading square nanodisk resonators in a metal-insulator-metal (MIM) plasmonic waveguide is proposed in this paper. The basic structure of the proposed demultiplexer is a plasmonic filter which consists of two waveguides, a middle cavity and two square nanodisk resonators. According to the simulation results the transmission spectra Full Width at Half-Maximum (FWHM) in the proposed structure reaches about 10 nm.With appropriate choice of refractive index (RI) and geometrical parameters the proposed structure can be adjusted and modified. The prposed structure has low FWHM, high sensitivity and acceptable figure of marit (FoM). By putting three filters with the same dimensions together, a triple-channel demultiplexer with three different wavelengths in each of the channels is designed. The effect of cross talk in the designed demultiplexer is less than -25 dB. The proposed structure can be used in the large-scale photonic integration, ultra-compact demultiplexer devices, nanosensors, integrated plasmonic devices and the development of optical integrated circuits. These structures numerically studied using Finite- Different Time- Domain (FDTD) simulations.