Plasmonic enhancement of the third order nonlinear optical phenomena: figures of merit

TL;DR

This paper develops a simple theory for plasmonic enhancement of third order nonlinear optical effects, revealing that while significant nonlinear index enhancement is possible, the phase shift per absorption length remains low, limiting certain applications.

Contribution

It introduces a transparent theoretical framework for understanding the limits of plasmonic enhancement in third order nonlinear optics, highlighting the practical constraints.

Findings

High nonlinear index enhancement achievable

Phase shift per absorption length remains low

Limited suitability for high-efficiency nonlinear applications

Abstract

Recent years have seen increased interest to plasmonic enhancement of nonlinear optical effects, yet there remains an uncertainty of what are the limits of this enhancement. We present a simple and physically transparent theory of plasmonic enhancement of third order nonlinear optical processes achieved in plasmonic structures and show that while huge enhancement of effective nonlinear index can be attained, the most relevant figure of merit, the of phase shift per one absorption length remains very low. This means that while on one hand nonlinear plasmonic materials are not well suitable for applications requiring high efficiency, e.g. all-optical switching and wavelength conversion, on the other hand they can be very useful for the applications where the overall high efficiency is not a must, such as sensing.