Optimization of second-harmonic generation from touching plasmonic wires

TL;DR

This paper uses transformation optics to significantly enhance second-harmonic generation in touching plasmonic wires, achieving up to 10 orders of magnitude increase in scattering cross-section and providing insights for nanostructured frequency-conversion devices.

Contribution

It introduces an analytic approach to optimize nonlinear wave interactions in complex nanostructures, surpassing previous methods in efficiency and accuracy.

Findings

10 orders of magnitude increase in scattering cross-section

5 orders of magnitude increase in efficiency

Critical comparison of theoretical approaches for nonlinear nanophotonics

Abstract

We employ transformation optics to optimize the generic nonlinear wave interaction of second-harmonic generation from a pair of touching metallic wires. We demonstrate a 10 orders of magnitude increase in the second-harmonic scattering cross-section by increasing the background permittivity and a 5 orders of magnitude increase in efficiency with respect to a single wire. These results have clear implications for the design of nanostructured metallic frequency-conversion devices. Finally, we exploit our analytic solution of a non-trivial nanophotonic geometry as a platform for performing a critical comparison of the strengths, weaknesses and validity of other prevailing theoretical approaches previously employed for nonlinear wave interactions at the nanoscale.