Related Experiment Video
Updated: Aug 5, 2026
10:54
Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters
Published on: July 8, 2013
Bidirectional terahertz frequency conversion via structural resonances at a plasma time boundary
Yindong Huang1, Bin Zhou1,2, Aijun Xuan1,3
1Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing 100071, China.
Science Advances
|July 31, 2026
Summary
Researchers created an ultrafast time boundary using laser-induced plasma, achieving bidirectional frequency conversion for terahertz waves. This breakthrough enables new possibilities in dynamic terahertz photonics and light-matter interactions.
Area of Science:
- Physics
- Optics
- Materials Science
Background:
- Time boundaries offer dynamic spectral control by altering material refractive index.
- Previous studies in Drude-like materials resulted in limited, unidirectional frequency shifts.
Purpose of the Study:
- To experimentally realize an ultrafast time boundary for terahertz waves using a laser-induced plasma.
- To investigate bidirectional frequency conversion and its underlying mechanisms.
Main Methods:
- Created a time boundary by converting air into a cylindrical plasma column within 100 femtoseconds.
- Utilized terahertz waves interacting with a plasma exhibiting a Lorentzian resonant response.
- Employed a model coupling tunneling ionization with Lorentzian dispersion to analyze results.
Main Results:
- Observed unconventional bidirectional frequency conversion (simultaneous red- and blue-shifted) at a single time boundary.
- Confirmed time refraction as a fundamental sub-cycle effect by resolving spectral evolution.
- Demonstrated strong, sub-cycle refractive index modulation.
Conclusions:
- Lorentzian time boundaries provide a platform for advanced temporal light-matter interactions.
- This research lays the foundation for dynamic terahertz photonics, including reconfigurable spectral elements and photonic time crystals.
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