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On-chip Cherenkov radiation tuning in 3.2-14 THz
Tianchang Li1, Fang Liu2, Yudi Chen1
1Department of Electronic Engineering, Tsinghua University, Beijing, China.
Nature Communications
|August 25, 2025
Summary
Researchers achieved tunable terahertz Cherenkov radiation using on-chip hyperbolic metamaterials made of graphene and hexagonal boron nitride. This breakthrough enables compact, tunable free-electron radiation sources in the terahertz domain.
Area of Science:
- Physics
- Materials Science
- Nanotechnology
Background:
- Cherenkov radiation is crucial for free electron radiation sources.
- On-chip free electron radiation sources have been limited to visible light and lacked tunability.
- Hyperbolic metamaterials enable Cherenkov radiation with low-energy electrons.
Purpose of the Study:
- To experimentally observe on-chip, free-electron-based Cherenkov radiation in the terahertz domain.
- To explore the frequency tunability of this terahertz Cherenkov radiation.
- To develop a compact and tunable terahertz free electron radiation source.
Main Methods:
- Fabrication of a hyperbolic metamaterial using graphene and hexagonal boron nitride.
- Excitation of Cherenkov radiation using low-energy electrons.
- Characterization of the emitted radiation's frequency and tunability.
Main Results:
- Successful observation of on-chip, free-electron-based terahertz Cherenkov radiation.
- Demonstration of a wide frequency tunable range from 3.2 to 14 THz.
- Achieved a hundred-micron-scale chip size, over three orders of magnitude smaller than other terahertz sources.
Conclusions:
- This work extends on-chip free-electron-based Cherenkov radiation to the terahertz spectrum.
- The developed device offers a highly tunable and compact terahertz radiation source.
- Highlights potential for advancements in compact free electron radiation sources.
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