Impedance generalization for plasmonic waveguides beyond the lumped circuit model

TL;DR

This paper introduces a rigorous impedance ratio expression for photonic structures, extending the concept beyond simple circuit models, and demonstrates its application to plasmonic waveguides and Bragg reflectors.

Contribution

It generalizes impedance to a reciprocity-based overlap measure of eigenmodes, applicable beyond traditional circuit models in photonics.

Findings

Derived a universal impedance ratio expression for photonic structures.

Validated the approach with radiofrequency and optical domain cases.

Successfully modeled a plasmonic waveguide termination using the new impedance concept.

Abstract

We analytically derive a rigorous expression for the relative impedance ratio between two photonic structures based on their electromagnetic interaction. Our approach generalizes the physical meaning of the impedance to a measure for the reciprocity-based overlap of eigenmodes. The consistence with known cases in the radiofrequency and optical domain is shown. The analysis reveals where the applicability of simple circuit parameters ends and how the impedance can be interpreted beyond this point. We illustrate our approach by successfully describing a Bragg reflector that terminates an insulator-metal-insulator plasmonic waveguide in the near-infrared by our mpedance concept.