Switchable multi-functional broadband polarization converter in terahertz band

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Terahertz (THz) technology requires efficient polarization control for various applications.
• Metamaterials offer unique electromagnetic properties, but achieving tunable and multi-functional polarization conversion remains a challenge.

Purpose of the Study:

• To propose and demonstrate a novel graphene-VO2 hybrid metamaterial for multi-functional broadband terahertz polarization conversion.
• To enable switchable functionalities between transmissive and reflective polarization conversion modes.
• To investigate the tunability of polarization conversion using temperature and graphene's Fermi energy.

Main Methods:

• Design and theoretical analysis of a graphene-VO2 hybrid metamaterial structure.
• Simulation of terahertz wave interaction with the metamaterial under varying temperature and Fermi energy conditions.
• Analysis of polarization conversion efficiency and bandwidth for different operational modes.

Main Results:

• Achieved broadband transmissive linear-to-linear polarization conversion from 0.39-1.22 THz at 298K, with tunable conversion angles.
• Demonstrated switchable reflective linear-to-circular polarization conversion at 358K, covering distinct frequency bands for left-circular (1.57-2.74 THz) and right-circular (1.13-1.59 THz) polarization.
• Showcased tunability of polarization states by adjusting graphene's Fermi energy in both operational modes.

Conclusions:

• The proposed graphene-VO2 hybrid metamaterial exhibits switchable multi-functional broadband polarization conversion capabilities.
• The device's performance is effectively controlled by temperature and graphene's Fermi energy, offering design flexibility.
• This work holds potential for developing compact and integrated terahertz devices and circuits.