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Toward Optimum Coupling between Free Electrons and Confined Optical Modes
Valerio Di Giulio1, Evelijn Akerboom2, Albert Polman2
1The Barcelona Institute of Science and Technology, Institut de Ciencies Fotoniques-ICFO, 08860 Castelldefels (Barcelona), Spain.
ACS Nano
|May 22, 2024
Summary
Researchers explored how free electrons excite nanoscale optical fields. They found high excitation probabilities using low-energy electrons and small structures, enabling new applications in quantum optics and microscopy.
Area of Science:
- Nanophotonics
- Quantum Optics
- Electron Microscopy
Background:
- Free electrons are vital for probing and manipulating nanoscale optical fields.
- Exciting single optical modes with individual free electrons has low probability, limiting applications.
Purpose of the Study:
- To theoretically investigate electron-driven excitation probability for various optical modes.
- To identify conditions for optimizing electron-photon coupling for nanoscale applications.
Main Methods:
- Theoretical analysis of electron-driven excitation probabilities.
- Investigation across a broad spectral range (UV to IR).
- Study of plasmons, Mie resonances, and waveguide modes.
Main Results:
- Order-unity coupling achieved with <100 eV electrons and eV polaritons in nanometer-scale structures.
- Conventional dielectric cavities show maximum few-percent probability.
- Waveguide modes generated with higher-than-unity efficiency using grazing electrons.
Conclusions:
- Low-energy electrons and small structures are key for efficient electron-photon coupling.
- Artificial atoms offer strong coupling potential.
- Waveguide mode generation provides an alternative route for enhanced excitation.
Keywords:
cathodoluminescenceconfined optical modeselectron energy-loss spectroscopyelectron-beam spectroscopiesfree-electron−light interactiongeneration of guided lightstrong light–matter interactionMore Related Videos
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