Local field enhancement and thermoplasmonics in multimodal Aluminum structures

TL;DR

This study explores the optical and thermal properties of aluminum nanostructures, demonstrating their potential for controlled field enhancement and thermoplasmonic applications through experimental and theoretical analysis.

Contribution

It reveals high-order plasmonic resonances in aluminum structures and demonstrates polarization-controlled field and heat distribution, advancing aluminum's use in thermoplasmonics.

Findings

Polarization-sensitive electric field concentration in Al structures

Quantitative agreement between experimental and theoretical temperature increase

Potential for aluminum-based thermoplasmonic nanosources

Abstract

Aluminum nanostructures have recently been at the focus of numerous studies due to their properties including oxidation stability and surface plasmon resonances covering the ultraviolet and visible spectral windows. In this article, we reveal a new facet of this metal relevant for both plasmonics purpose and photo-thermal conversion. The field distribution of high order plasmonic resonances existing in two-dimensional Al structures is studied by nonlinear photoluminescence (nPL) microscopy in a spectral region where electronic interband transitions occur. The polarization sensitivity of the field intensity maps shows that the electric field concentration can be addressed and controlled on-demand. We use a numerical tool based on the Green dyadic method to analyze our results and to simulate the absorbed energy that is locally converted into heat. The polarization-dependent temperature increase of the Al structures is experimentally quantitatively measured, and is in an excellent agreement with theoretical predictions. Our work highlights Al as a promising candidate for designing thermal nanosources integrated in coplanar geometries for thermally assisted nanomanipulation or biophysical applications.