Origin of second-harmonic generation enhancement in optical split-ring resonators

TL;DR

This paper investigates the mechanisms behind second-harmonic generation enhancement in optical split-ring resonators, revealing that electric properties, not magnetic ones, are primarily responsible for the observed nonlinear effects.

Contribution

It introduces a hydrodynamic model that explains the nonlinear response in metal-based metamaterials, clarifying the role of electric versus magnetic contributions in SHG enhancement.

Findings

SHG enhancement is driven by electric properties.

The hydrodynamic model aligns with experimental data.

Magnetic effects are less significant in SHG enhancement.

Abstract

We present a study of the second-order nonlinear optical properties of metal-based metamaterials. A hydrodynamic model for electronic response is used, in which nonlinear surface contributions are expressed in terms of the bulk polarization. The model is in good agreement with published experimental results, and clarifies the mechanisms contributing to the nonlinear response. In particular, we show that the reported enhancement of second-harmonic in split-ring resonator based media is driven by the electric rather than the magnetic properties of the structure.