Negative capacitors and inductors in optical plasmonic nanocircuits

Optical plasmonic nanocircuits are a heuristic route inspired by electronics for light manipulation in deep-subwavelength scales at optical frequencies with lumped capacitors and inductors. Here, a class of negative capacitors and inductors is discovered in the paradigm of optical plasmonic nanocircuits based on a modified model of a plasmonic nanoparticle. In this model, the global electromagnetic response of a Drude-dispersive plasmonic nanoparticle is imitated by a parallel pair of a capacitor and an inductor by involving the host medium of the plasmonic nanoparticle. We theoretically and numerically demonstrated the performance of such negative optical elements for extremely wideband impedance matching. A comprehensive lumped-element map for optical plasmonic nanocircuits is thus constructed including positive/negative inductors/capacitors with series/parallel configurations, which will inspire more possibilities in nanocircuit design.