Arrays of plasmonic nanocavities for non-linear light interactions

Here we present a plasmonic metamaterial consisting of a large-scale array of gold coaxial rod-tube (CRT) nanocavities. The CRT nanocavities were fabricated using an anodized alumina template. The etching process used in the fabrication process can create 5nm cavities, smaller than conventional top-down techniques. The large electric-field enhancements associated with nanometer-sized gaps and the tunability of the modes excited in the structure show potential for applications in non-linear optics including second harmonic generation (SHG) and surface enhanced Raman spectroscopy (SERS).