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Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters
Published on: July 8, 2013
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Broadband circularly polarized terahertz source based on free-electron radiation
Optics Letters
|November 14, 2025
Summary
We demonstrate a novel method using stacked bianisotropic metasurfaces to generate broadband circularly polarized (CP) radiation from free electrons. This technique enhances terahertz free-electron radiation sources with tunable polarization control.
Area of Science:
- Physics
- Metamaterials
- Electromagnetism
Background:
- Metasurfaces offer advanced control over electromagnetic waves.
- Free-electron radiation sources are crucial for various applications.
- Current methods have limitations in polarization control and bandwidth.
Purpose of the Study:
- To propose a new scheme for generating broadband circularly polarized (CP) radiation.
- To utilize stacked bianisotropic metasurfaces for manipulating free-electron radiation.
- To explore new degrees of freedom for tailoring free-electron radiation properties.
Main Methods:
- Interaction of free electrons with stacked bianisotropic metasurfaces.
- Analysis of polarizability shaping beyond spectral and angular control.
- Multipole analysis (electric, magnetic, toroidal dipoles and quadrupoles).
- Characterization using Stokes parameters.
Main Results:
- Achieved broadband CP radiation spanning the first-order diffraction of Smith-Purcell radiation (SPR).
- Demonstrated extended 3-dB axial ratio (AR) bandwidth through simple layered stacking.
- Identified bianisotropy as a key factor for enhanced polarization control.
Conclusions:
- The proposed scheme offers a novel pathway for generating broadband CP free-electron radiation.
- This method provides enhanced control over polarization states.
- Paves the way for compact, tunable, high-power terahertz free-electron radiation sources.
