Fabrication of plasmonic Au nano-void trench arrays by guided self-assembly

Plasmonic devices, which will enable on chip optical communication, rely on the interaction of light with free charges, and are key to optical sensing and waveguiding. Previous works have shown that spherical nanoscale voids in metal possess different, and potentially more useful, plasmonic modes than nanoscale metal particles. However, only by making linear arrays of such nanovoid structures it is possible to guide plasmons in specific geometric directions and fabricate plasmon waveguides which will enable on chip optical communication. In this work, single and multilayer arrays of gold voids have been fabricated through self assembly of sub-micron polystyrene spheres in V-shaped trenches in silicon, followed by selective area electrodeposition. Angle-dependent dispersion characteristics reveal the existence of localized plasmons. This is the first experimental evidence of linear plasmon arrays in templated self assembled structures. The gold nanovoid linear arrays are of high quality with respect to lateral symmetry and allow the detection of anisotropic plasmonic dispersion.