Plasmonic crystal demultiplexer and multiports.

We report the realization of two-dimensional optical wavelength demultiplexers and multiports for surface plasmons polaritons (SPPs) based on plasmonic crystals, i.e., photonic crystals for SPPs. These SPP elements are built up of lithographically fabricated gold nanostructures on gold thin films. We show by direct imaging of laterally confined SPP beams in the visible spectral range by leakage radiation microscopy that SPPs of different wavelengths are efficiently rerouted into different directions. In addition we demonstrate the generation of three output SPP beams from one input beam.