Fano resonances in nanohole oligomers in a gold film

The optical properties of nanohole oligomers in a gold film have been investigated theoretically and experimentally. Helium focused ion beam milling was used to create arrays of close-packed heptamer-arranged nanoholes (HNH) in a gold film on a fused silica substrate. The holes are slightly elliptical about a nominal diameter of 100 nm and are separated by 15 nm Au regions (“bridges”) to form close-packed heptamer arrangements. Optical …