Probing the photonic local density of states with electron energy loss spectroscopy

TL;DR

This paper demonstrates that electron energy-loss spectroscopy (EELS) in transmission electron microscopes can directly measure the photonic local density of states with nanometer-scale spatial resolution, enhancing nanophotonics and plasmonics research.

Contribution

It establishes a direct link between EELS measurements and the photonic LDOS, with detailed analysis of specific 2D and quasi-planar structures, advancing nanoscale optical characterization.

Findings

EELS can directly probe the photonic LDOS at sub-nanometer resolution.

Analysis of 2D photonic structures with translational symmetry.

Insights into plasmonic structures under normal incidence.

Abstract

Electron energy-loss spectroscopy (EELS) performed in transmission electron microscopes is shown to directly render the photonic local density of states (LDOS) with unprecedented spatial resolution, currently below the nanometer. Two special cases are discussed in detail: (i) 2D photonic structures with the electrons moving along the translational axis of symmetry and (ii) quasi-planar plasmonic structures under normal incidence. Nanophotonics in general and plasmonics in particular should benefit from these results connecting the unmatched spatial resolution of EELS with its ability to probe basic optical properties like the photonic LDOS.