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Nonvolatile chirality switching in terahertz chalcogenide metasurfaces
Jiaxin Bao1, Xieyu Chen2, Kuan Liu1
1School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, 116024 P. R. China.
Microsystems & Nanoengineering
|October 4, 2022
Summary
Chiral metamaterials with active germanium antimony telluride components enable tunable terahertz wave polarization control. This breakthrough offers nonvolatile optical activity for advanced terahertz spectroscopy and metadevices.
Area of Science:
- Metamaterials
- Terahertz (THz) optics
- Chiroptics
Background:
- Controlling terahertz (THz) wave polarization is crucial for polarization-sensitive spectroscopy.
- Existing THz polarization modulators are limited, hindering spectroscopy development.
- Chiral metamaterials offer potential for manipulating THz polarization.
Purpose of the Study:
- To demonstrate nonvolatile and continuously tunable optical activity in the THz region.
- To integrate conjugated bilayer chiral metamaterials (CMMs) with Ge2Sb2Te5 (GST225) for active THz polarization control.
- To explore the potential of GST225's phase transition for tunable chiroptical responses.
Main Methods:
- Theoretical and experimental demonstration of CMMs with GST225.
- Utilizing THz time-domain spectroscopy for device characterization.
- Investigating the effect of GST225's amorphous (AM) to crystalline (CR) phase transition on optical activity.
Main Results:
- Achieved tunable ellipticity (‒36° to 0°) and polarization rotation (32° to 0°) at 0.73 THz.
- Demonstrated a continuously tunable chiroptical response by partially crystallizing GST225.
- Verified the nonvolatile nature of GST225 for retaining its structural state without energy input.
Conclusions:
- Conjugated bilayer chiral metamaterials integrated with GST225 provide nonvolatile, tunable THz optical activity.
- This technology enables the development of advanced THz metadevices, including circular polarizers and polarization modulators.
- The findings pave the way for enhanced THz spectroscopy and imaging applications.
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