One-shot phase image distinction of plasmonic and dielectric nanoparticles

TL;DR

This paper introduces a rapid, single-shot phase imaging method to distinguish plasmonic from dielectric nanoparticles, enabling precise nanostructure characterization and identification in nanophotonics.

Contribution

The authors develop a simple, single-shot phase imaging technique that quantitatively measures and differentiates the phase responses of plasmonic and dielectric nanoparticles.

Findings

Successfully measured the scattering phase of various nanomaterials.

Demonstrated spectral phase changes near pi at plasmon resonance.

Enabled direct identification of nanoparticle types from a single image.

Abstract

Nanoscale phase-control is one of the most powerful approaches to specifically tailor electrical fields in modern nanophotonics. Especially the precise sub-wavelength assembly of many individual nano-building-blocks has given rise to exciting new materials as diverse as metamaterials, for miniaturizing optics, or 3D assembled plasmonic structures for biosensing applications. Despite its fundamental importance, the phase-response of individual nanostructures is experimentally extremely challenging to visualize. Here, we address this shortcoming and measure the quantitative scattering phase of different nanomaterials such as gold nanorods and spheres as well as dielectric nanoparticles. Beyond reporting spectrally resolved responses, with phase-changes close to pi when passing the particles' plasmon resonance, we devise a simple method for distinguishing different plasmonic and dielectric particles purely based on their phase behavior. Finally, we integrate this novel approach in a single-shot two-color scheme, capable of directly identifying different types of nanoparticles on one sample, from a single widefield image.