Rational design of metallic nanocavities for resonantly enhanced four-wave mixing

TL;DR

This paper presents a rational design approach for metallic nanocavities that enhances four-wave mixing by resonating plasmonic modes, achieving high conversion efficiency comparable to bulk nonlinear crystals.

Contribution

The study introduces a method to optimize nanocavity shapes for resonant enhancement of four-wave mixing using Maxwell equations and FDTD simulations, demonstrating superior nonlinear optical performance.

Findings

Conversion efficiency surpasses that of BBO crystals of similar thickness.

Resonant nanocavities enable broadband and efficient nonlinear optical responses.

Electric field propagation inside cavities is effectively modeled by Maxwell's equations.

Abstract

Optimizing the shape of nanostructures and nano antennas for specific optical properties has evolved to be a very fruitful activity. With modern fabrication tools a large variety of possibilities is available for shaping both nanoparticles and nanocavities; in particular nanocavities in thin metal films have emerged as attractive candidates for new metamaterials and strong linear and nonlinear optical systems. Here we rationally design metallic nanocavities to boost their Four Wave Mixing response by resonating the optical plasmonic resonances with the incoming and generated beams. The linear and nonlinear optical responses as well as the propagation of the electric fields inside the cavities are derived from the solution of Maxwell equations by using the 3D finite-differences time domain method. The observed conversion-efficiency of near infra-red to visible light equals or surpasses that of BBO of equivalent thickness. Implications to further optimization for efficient and broadband ultrathin nonlinear optical materials are discussed.