Singularity-driven Second and Third Harmonic Generation in a {\epsilon}-near-zero nanolayer

TL;DR

This paper demonstrates a novel method to achieve epsilon near-zero materials without metal-based metamaterials, leading to significant enhancement of second and third harmonic generation through singularity-driven electric field amplification.

Contribution

It introduces a new approach to realize epsilon near-zero materials using Lorentz oscillators, enabling enhanced nonlinear optical effects without traditional metamaterials.

Findings

Enhanced second harmonic generation in epsilon near-zero nanolayers

Significant third harmonic generation observed in thin epsilon near-zero layers

Lowered thresholds for nonlinear phenomena due to electric field singularities

Abstract

We show a new path to {\epsilon}~0 materials without resorting to metal-based metamaterial composites. A medium that can be modeled using Lorentz oscillators usually displays {\epsilon}=0 crossing points, e.g. {\epsilon}=0 at {\lambda}~7{\mu}m and 20{\mu}m for SiO2 and CaF2, respectively. We show that a Lorentz medium yields a singularity-driven enhancement of the electric field followed by dramatic lowering of thresholds for a plethora of nonlinear optical phenomena. We illustrate the remarkable enhancement of second and third harmonic generation in a layer of {\epsilon}~0 material 20nm thick, and discuss the role of nonlinear surface sources.