Gain assisted harmonic generation in near-zero permittivity metamaterials made of plasmonic nanoshells

TL;DR

This paper demonstrates that gain-assisted near-zero permittivity metamaterials made of plasmonic nanoshells can significantly enhance harmonic generation, enabling extreme nonlinear optical phenomena at low irradiance levels.

Contribution

It introduces a novel gain-assisted metamaterial design that achieves near-zero permittivity and dramatically boosts harmonic generation efficiencies.

Findings

Enhanced second and third harmonic generation near zero permittivity

Presence of narrow-band features in optical transmission and reflection

Potential for extreme nonlinear phenomena at low irradiance levels

Abstract

We investigate enhanced harmonic generation processes in gain-assisted, near-zero permittivity metamaterials composed of spherical plasmonic nanoshells. We report the presence of narrow-band features in transmission, reflection and absorption induced by the presence of an active material inside the core of the nanoshells. The damping-compensation mechanism used to achieve the near-zero effective permittivity condition also induces a significant increase in field localization and strength and, consequently, enhancement of linear absorption. When only metal nonlinearities are considered, second and third harmonic generation efficiencies obtained by probing the structure in the vicinity of the near-zero permittivity condition approach values as high as for irradiance value as low as . These results clearly demonstrate that a relatively straightforward path now exists to the development of exotic and extreme nonlinear optical phenomena in the KW/cm2 range