Sum frequency generation from touching wires: A transformation optics approach

TL;DR

This paper uses transformation optics to analytically study nonlinear wave mixing in touching plasmonic wires, revealing that second-harmonic generation is most efficient due to field overlap at the singularity.

Contribution

It provides an analytical solution for nonlinear wave mixing in a singular geometry, highlighting the optimal efficiency of second-harmonic generation in this context.

Findings

Optimal efficiency occurs at second-harmonic generation.

Field overlap near the singularity explains efficiency behavior.

Analytic solutions for near-field and far-field properties are derived.

Abstract

We employ transformation optics to study analytically nonlinear wave mixing from a singular geometry of touching plasmonic wires. We obtain the analytic solution of the near-field and complement it with a solution of the far-field properties. We find, somewhat surprisingly, that optimal efficiency (in both regimes) is obtained for the degenerate case of the Second-harmonic generation. We exploit the analytic solution obtained to trace this behaviour to the spatial overlap of the input fields near the geometric singularity.