Enhanced four-wave mixing with nonlinear plasmonic metasurfaces

TL;DR

This paper demonstrates that nonlinear plasmonic metasurfaces with film-coupled silver nanostripes significantly enhance four-wave mixing efficiency, enabling compact, high-power optical sources with directional emission and relaxed phase matching.

Contribution

The work introduces a novel nonlinear metasurface design using film-coupled silver nanostripes with Kerr material, achieving unprecedented FWM enhancement and practical visible and THz source applications.

Findings

FWM efficiency increased by nineteen orders of magnitude.

Generated FWM waves exhibit directional radiation patterns.

Output power is relatively insensitive to incident angles.

Abstract

Plasmonic metasurfaces provide an effective way to increase the efficiency of several nonlinear processes while maintaining nanoscale dimensions. In this work, nonlinear metasurfaces based on film-coupled silver nanostripes loaded with Kerr nonlinear material are proposed to achieve efficient four-wave mixing (FWM). Highly localized plasmon resonances are formed in the nanogap between the metallic film and nanostripes. The local electric field is dramatically enhanced in this subwavelength nanoregion. These properties combined with the relaxed phase matching condition due to the ultrathin area lead to a giant FWM efficiency, which is enhanced by nineteen orders of magnitude compared to a bare silver screen. In addition, efficient visible and low-THz sources can be constructed based on the proposed nonlinear metasurfaces. The FWM generated coherent wave has a directional radiation pattern and its output power is relatively insensitive to the incident angles of the excitation sources. This radiated power can be further enhanced by increasing the excitation power. The dielectric nonlinear material placed in the nanogap is mainly responsible for the ultrastrong FWM response. Compact and efficient wave mixers and optical sources spanning different frequency ranges are envisioned to be designed based on the proposed nonlinear metasurface designs.