Circuit Analysis in Metal-Optics

TL;DR

This paper introduces a circuit-based approach to analyze various plasmonic phenomena in metal optics, providing simple models that accurately reproduce dispersion relations and introduce wave-impedance concepts.

Contribution

It presents a novel circuit paradigm for modeling bulk, surface, and parallel-plate plasmons, including the characteristic wave-impedance, applicable to diverse geometries.

Findings

Circuit models accurately reproduce dispersion relations.

Wave-impedance Z₀ is derived for plasmonic modes.

Single-surface plasmons can be modeled as transmission lines.

Abstract

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 circuit paradigm directly provides a characteristic wave-impedance, Zo, that is rarely discussed in the context of plasmonics. The case of a single-surface-plasmon is particularly interesting since it can be modeled as a transmission line, even though there is no return current conductor. The capacitance/unit length and the Faraday inductance/unit length, of a flat metal surface, are C'=2epsilon_okW, and L'=epsilon_o/2kW respectively, (where k is wave-vector, and W is the width of the flat metal surface). We believe that many other metal-optic geometries can be described within the circuit paradigm, with the prerequisite that the distributed capacitance and inductance must be calculated for each particular geometry