Surface Plasmon Excitation of Second Harmonic light: Emission and Absorption

TL;DR

This paper investigates how absorption affects second harmonic generation in metallic nanostructures, revealing that absorption often dominates emission and emphasizing the importance of understanding absorption for designing efficient plasmonic devices.

Contribution

It introduces a figure of merit to evaluate nanostructures' ability to enhance or hinder second harmonic generation, linking absorption to emission efficiency.

Findings

Absorption energy often exceeds emitted harmonic energy.

Enhancing local fields does not necessarily improve emission efficiency.

Understanding absorption is crucial for designing effective plasmonic frequency mixers.

Abstract

We aim to clarify the role that absorption plays in nonlinear optical processes in a variety of metallic nanostructures and show how it relates to emission and conversion efficiency. We define a figure of merit that establishes the structure's ability to either favor or impede second harmonic generation. Our findings suggest that, despite the best efforts embarked upon to enhance local fields and light coupling via plasmon excitation, nearly always the absorbed harmonic energy far surpasses the harmonic energy emitted in the far field. Qualitative and quantitative understanding of absorption processes is crucial in the evaluation of practical designs of plasmonic nanostructures for the purpose of frequency mixing.