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Tunable circular conversion dichroism of single-layer twisted graphene-patterned metasurface
Yali Zeng1, Qilin Duan1, Jinying Xu2
1Department of Physics and Institute of Electromagnetics and Acoustics, Xiamen University, Xiamen 361005, China.
Iscience
|February 28, 2023
Summary
Researchers developed a tunable terahertz metasurface using twisted graphene with elliptical holes. This structure achieves chirality-induced asymmetric transmission and reflection, offering new possibilities for polarization control devices.
Area of Science:
- Optics and Photonics
- Materials Science
- Condensed Matter Physics
Background:
- Two-dimensional (2D) chirality-induced asymmetric transmission/reflection is crucial for polarization applications.
- Circular conversion dichroism (CCD) typically arises from chiral metasurfaces.
Purpose of the Study:
- To theoretically reveal tunable CCD in a single-layer twisted graphene-patterned metasurface in the terahertz (THz) region.
- To demonstrate achieving tunable CCD by altering structural 2D chirality in an achiral unit cell.
Main Methods:
- Utilizing a single-layer metasurface composed of twisted graphene with tilted elliptical hole arrays.
- Investigating terahertz (THz) wave interaction with the metasurface at normal incidence.
- Analyzing the role of structural anisotropy and graphene's tunability for active control.
Main Results:
- Achieved tunable circular conversion dichroism (CCD) by modifying the in-plane orientation of elliptical holes.
- Demonstrated that reflection phase can intuitively indicate metasurface anisotropy, complementing CCD measurements.
- Showcased active CCD control enabled by graphene's tunability.
- Observed multiband enhancement of CCD spectra due to Fabry-Pérot resonance, controllable via dielectric layer thickness.
Conclusions:
- The proposed metasurface offers a novel approach to achieve tunable CCD in the THz region.
- Structural chirality in an achiral unit cell provides a flexible method for polarization manipulation.
- Graphene's tunability allows for active control of CCD, paving the way for advanced THz devices.
