Ultra-high field enhancing in Split Ring Resonators by azimuthally polarized excitation

TL;DR

This paper demonstrates that azimuthally polarized light significantly enhances field intensity in split-ring resonators compared to linear polarization, and introduces a simple method to tune resonance frequencies by adding gaps.

Contribution

It reveals the superior enhancement effect of azimuthal polarization and proposes a straightforward resonance tuning method by structural modifications.

Findings

Azimuthal polarization increases intensity enhancement by over an order of magnitude.

Adding gaps to the SRR allows resonance tuning with minimal impact on enhancement.

Design parameter effects differ notably from linear polarization cases.

Abstract

We study the field enhancement and resonance frequencies in split-ring resonators (SRR) illuminated by azimuthally polarized light. We find that compared to linearly polarized illumination, the azimuthally polarized illumination increase the intensity enhancement by more than an order of magnitude. We attribute the increase in the intensity enhancement to the improved overlap between the SRR geometry and the direction of the electric field vector in each point. In addition, we present and explore a method to tune the resonance frequency of the SRR (for azimuthal polarization) by introducing more gaps to the structure. This approach allows for simple and straightforward tuning of the resonance frequency with small impact on the intensity enhancement. The impact of the design parameters on the intensity enhancement under azimuthally polarized illumination is also studied in details, exhibiting clear differences to the case of linear polarized illumination.