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A dual-band transmissive polarization conversion metastructure based on the toroidal dipole-assisted EIT effect
Li Zeng1, Tao Zhang1, Hai-Feng Zhang1
1College of Electronic and Optical Engineering and the College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing, 210023, China. hanlor@njupt.edu.cn.
Nanoscale
|February 26, 2025
Summary
This study introduces a novel metastructure for polarization conversion (PC) using electromagnetically induced transparency (EIT). The device achieves efficient linear-to-circular polarization conversion with low loss and stability for various applications.
Area of Science:
- Metamaterials and Nanophotonics
- Electromagnetics and Optics
- Terahertz Technology
Background:
- Transmissive polarization manipulation devices are crucial for satellite radar and wireless communication.
- Electromagnetically induced transparency (EIT) offers a pathway for high-transmission, low-loss optical phenomena.
- Toroidal dipoles play a key role in advanced electromagnetic responses.
Purpose of the Study:
- To demonstrate a new metastructure design for polarization conversion (PC).
- To achieve efficient linear-to-circular polarization conversion in transmission mode.
- To explore applications in polarization manipulation and optical filtering.
Main Methods:
- Designing a metastructure based on toroidal dipoles and EIT.
- Simulating the metastructure's response to normally incident x- and y-polarized waves to identify EIT windows.
- Analyzing the device's performance under 45° linearly polarized incidence for linear-to-circular PC.
- Investigating robustness against wide-angle incidence.
Main Results:
- The metastructure exhibits two distinct EIT windows with a maximum transmittance of 0.94.
- Achieved efficient linear-to-circular polarization conversion at 0.935 THz and 1.182 THz.
- Obtained low axial ratios (1.22 dB and 1.18 dB) and maintained performance under wide-angle incidence.
- Demonstrated low loss and stability under large incident angles.
Conclusions:
- The proposed metastructure effectively combines toroidal dipoles, EIT, and linear-to-circular PC.
- This design offers a low-loss, stable, and efficient method for transmissive polarization manipulation.
- The innovative approach provides new possibilities for optical filtering, multipole electromagnetics, and multifunctional devices.
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