Tunability of subradiant dipolar and fano-type plasmon resonances in metallic ring/disk cavities: implications for nanoscale optical sensing.

Hao, Feng; Nordlander, Peter; Sonnefraud, Yannick; Van Dorpe, Pol; Maier, Stefan A · ACS Nano · 2009

basic_science · Level V

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Abstract

Plasmonic nanocavities consisting of the concentric arrangement of a disk and a ring sustain both subradiant and superradiant dipolar plasmon modes with large associated field enhancements and high refractive index sensitivities. In structures with broken symmetry, additionally a highly tunable Fano interference feature appears, which can be explained with a simple analytical harmonic oscillator model. The spectral tunability of these resonances from the visible to the mid-infrared is investigated, highlighting a potential for applications in surface enhanced spectroscopies.