Simultaneous nanoscale excitation and emission mapping by cathodoluminescence

TL;DR

This paper introduces a cathodoluminescence technique that simultaneously maps nanoscale excitation and emission, revealing detailed optical properties and energy transport in nanostructures beyond previous spatial resolution limits.

Contribution

The study presents a novel method for concurrent excitation and emission mapping at the nanoscale, enabling insights into optical mode delocalization and energy transport in nanophotonics.

Findings

Revealed sub-wavelength emission position modulation

Visualized electromagnetic energy transport in nanoplasmonic systems

Accessed previously inaccessible nanoscale optical properties

Abstract

Free-electron-based spectroscopies can reveal the nanoscale optical properties of semiconductor materials and nanophotonic devices with a spatial resolution far beyond the diffraction limit of light. However, the retrieved spatial information is constrained to the excitation space defined by the electron beam position, while information on the delocalization associated with the spatial extension of the probed optical modes in the specimen has so far been missing, despite its relevance in ruling the optical properties of nanostructures. In this study, we demonstrate a cathodoluminescence method that can access both excitation and emission spaces at the nanoscale, illustrating the power of such simultaneous excitation and emission mapping technique by revealing a sub-wavelength emission position modulation as well as by visualizing electromagnetic energy transport in nanoplasmonic systems. Besides the fundamental interest of these results, our technique grants us access into previously inaccessible nanoscale optical properties.