Multidimensional Hybridization of Dark Surface Plasmons

Abstract

Synthetic three-dimensional (3D) nanoarchitectures are providing more control over light-matter interactions and rapidly progressing photonic-based technology. These applications often utilize the strong synergy between electromagnetic fields and surface plasmons (SPs) in metallic nanostructures. However, many of the SP interactions hosted by complex 3D nanostructures are poorly understood because they involve dark hybridized states that are typically undetectable with far-field optical spectroscopy. Here, we use experimental and theoretical electron energy loss spectroscopy to elucidate dark SPs and their interactions in layered metal-insulator-metal disc nanostructures. We go beyond the established dipole SP hybridization analysis by measuring breathing and multipolar SP hybridization. In addition, we reveal multidimensional SP hybridization that simultaneously utilizes in-plane and out-of-plane SP coupling. Near-field classic electrodynamics calculations provide excellent agreement with all experiments. These results advance the fundamental understanding of SP hybridization in 3D nanostructures and provide avenues to further tune the interaction between electromagnetic fields and matter.

Unprecedented efficient electron transport across Au nanoparticles with up to 25-nm insulating SiO2-shells

“…Plasmonic dark modes are pure near-field modes that can arise from the plasmon hybridization in a set of interacting nanoparticles. And this mode does not couple to light and are difficult to measure with light 25–27 . The dark mode plasmonic effect occurs in the dark, and upon light irradiation, light-excited plasmon modes will couple to the dark mode and enhances the plasmonic effect, which result in an increase of the current.…”

3D Imaging of Gap Plasmons in Vertically Coupled Nanoparticles by EELS Tomography

“…From an application point of view, going from 2D to 3D structures by vertically stacking nanoparticles opens a wealth of new opportunities. 16 − 18 First, coupling between two particles is no more limited to be mediated by single corners or edges but can extend over the whole structure. Second, very small gaps between two separate particles are possible in a vertical arrangement, as thin film deposition can be readily controlled with subnanometer accuracy.…”

Electron Beam Interrogation and Control of Ultrafast Plexcitonic Dynamics

“…This is one of the main reasons why EELS is widely used to characterize plasmonic devices, because electrons can map high order resonances that are difficult to couple to from the far-field, using for example dark-field microscopy. 26,[39][40][41][42] For faster electrons (v ≈ 0.2 c), energy is coupled more efficiently into the radiative lowest order mode (l = 1) than higher-order dark plasmons, which leads to a competitive behavior dependent on the electron velocity, nanoparticle size and impact parameter. For even faster and relativistic electrons (v > 0.5 c), the coupling coefficients C M,E lm gradually reduce in value, which is evident in both the radiative and loss spectra.…”