Compact four-way wavelength demultiplexers based on conformal surface plasmon waveguides

Abstract

We propose a compact planar four-way wavelength demultiplexer (WDM) with double gratings that support conformal surface plasmons (CSPs) in the microwave frequency range. The transversal size of the entire structure is less than one wavelength. A coplanar waveguide (CPW) is employed to feed electromagnetic waves to excite the CSPs on the four output waveguides. Simple band-pass filters are introduced in front of the output branches to improve the isolation between ports at lower frequencies. The simulation and measurement results in the microwave frequency range agree very well. A conformal flexible four-way WDM is also designed. These compact multiway WDMs can integrate conventional microwave devices with surface plasmonic devices very well.