Nonlinear plasmonics at high temperatures

TL;DR

This paper models high-temperature nonlinear plasmonic effects in metal nanoparticles by self-consistently solving Maxwell and heat equations using experimental permittivity data, revealing significant deviations from linear predictions and emphasizing the importance of accurate thermal property data.

Contribution

It introduces a self-consistent modeling approach using experimental permittivity data to better understand high-temperature nonlinear plasmonics, especially for refractory metals.

Findings

Thermal nonlinearity causes significant deviations from linear models.

Incompleteness of thermal property data limits quantitative accuracy.

The approach aids in identifying physical mechanisms of thermo-optical nonlinearity.

Abstract

We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW) illumination. Unlike previous studies, we rely on {\em experimentally}-measured data for the metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution, and thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modelling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high temperature nonlinear plasmonics, especially for refractory metals, both for CW and pulsed illumination.