Multimodal Plasmonics in Fused Colloidal Networks

TL;DR

This paper demonstrates the creation of fused gold nanoparticle networks that support low-energy, tunable surface plasmon modes capable of long-range propagation, advancing nanoscale optical information processing.

Contribution

It introduces a method to produce fused colloidal gold networks with controlled plasmonic properties using electron beam-induced fusion, enabling nanoscale waveguides with tunable modes.

Findings

Fused nanoparticle networks support low-energy, spectrally tunable SP modes.

The networks enable long-range plasmon propagation at the nanoscale.

The morphology and crystallinity are preserved after fusion.

Abstract

Harnessing the optical properties of noble metals down to the nanometer-scale is a key step towards fast and low-dissipative information processing. At the 10-nm length scale, metal crystallinity and patterning as well as probing of surface plasmon (SP) properties must be controlled with a challenging high level of precision. Here, we demonstrate that ultimate lateral confinement and delocalization of SP modes are simultaneously achieved in extended self-assembled networks comprising linear chains of partially fused gold nanoparticles. The spectral and spatial distributions of the SP modes associated with the colloidal superstructures are evidenced by performing monochromated electron energy loss spectroscopy with a nanometer-sized electron probe. We prepare the metallic bead strings by electron beam-induced interparticle fusion of nanoparticle networks. The fused superstructures retain the native morphology and crystallinity but develop very low energy SP modes that are capable of supporting long range and spectrally tunable propagation in nanoscale waveguides.