Circuit analysis in metal-optics

► We provide electrical circuit descriptions for bulk plasmons, single surface plasmons, and parallel-plate plasmons. ► Simple circuits can reproduce the exactly known frequency versus wave-vector dispersion relations for all these cases, with reasonable accuracy. ► The capacitance/unit length and the Faraday inductance/unit length, of a flat metal surface, are C′ = 2(okW, and L′ = (o/2kW, respectively (where k is the wave-vector, and W is the width of the flat metal surface). ► The circuit paradigm directly provides a characteristic wave-impedance, Zo, that is rarely discussed in the context of plasmonics. ► The wave-impedance, Zo, is found to diverge at the nanoscale, thus allowing for optical voltage transformer action.