Improved circuit model for plasmonic resonance of single split-ring resonators

Abstract

In this work, an improved circuit model is presented for the single split ring resonator (SRR), taking into account non-uniform distribution of conduction current and surface charges. To determine the circuit elements of the SRR, the electron kinetic, electric, and magnetic energy have been derived theoretically. Moreover, in addition to gap and surface capacitances, coupling capacitance is introduced to characterize the electric coupling effect between them. A formula for the fundamental resonance wavelength has been obtained, which shows good agreement with numerical simulations in both optical and microwave frequency ranges. The model will be instructive for engineering resonant properties of the SRRs and provide valuable insight into other complex plasmonic structures.