Fano resonant plasmonic systems: Functioning principles and applications

Using a generalization of Fano formula that includes the intrinsic losses associated with metals, we retrieve the underlying modal structure that produces Fano resonances from the interference between a bright and a dark mode. This knowledge is used to determine the most efficient plasmonic system for a specific application by tuning its mode of operation from weak coupling to best energy storage or strong coupling. This approach is illustrated with examples from sensing.