Velocity-tunable exciton-photon hybridization in cathodoluminescence

TL;DR

This paper demonstrates a novel, tunable exciton-photon hybridization in suspended films using electron energy variation, eliminating the need for structural modifications and enabling dynamic control of light-matter interactions.

Contribution

It introduces a free-electron-driven platform for tunable exciton-photon hybridization by controlling electron energy, film thickness, and electron velocity.

Findings

Hybrid resonances depend on film thickness and electron velocity.

Electron energy variation allows continuous tuning of exciton-photon detuning.

The method provides a dynamic, structural modification-free approach to exciton-light interactions.

Abstract

Exciton-photon hybridization is typically realised in geometrically defined optical cavities, where tunability is achieved by modifying either the cavity or the excitonic medium. Here we investigate transition-radiation interferences in suspended subwavelength films resembling a free-electron-defined resonance and explore their interaction with excitons in transition metal dichalcogenides. We demonstrate that these resonances hybridize with excitonic transitions and can be tuned continuously by varying the electron energy. The resulting detuning depends on both film thickness and electron velocity, establishing the latter as an external and continuous knob for exciton-photon coupling. This approach enables tunable hybridization without structural modification and provides a free-electron-driven nanoscale platform for studying exciton-light interactions.