Incidence angle and polarization-insensitive multi-band absorption and an all-reflective dual-function switchable...

Area of Science:

• Metamaterials and Nanophotonics
• Terahertz (THz) Technology
• Graphene-based Devices

Background:

• Metasurfaces offer novel ways to control electromagnetic waves.
• Tunable absorption and reflection are critical for advanced optical systems.
• Graphene and Vanadium Dioxide (VO2) are promising materials for dynamic control of THz waves.

Purpose of the Study:

• To design and demonstrate a reconfigurable metasurface with dual functionality: tunable perfect absorption and total reflection.
• To achieve wide incidence angle and polarization insensitivity for robust performance.
• To enable amplitude modulation of terahertz waves for potential 6G applications.

Main Methods:

• Utilizing a resonant ring structure composed of graphene and vanadium dioxide (VO2).
• Tuning the metasurface's properties by adjusting the graphene's Fermi level.
• Exploiting the phase transition of VO2 (insulating to metallic) to switch between absorption and reflection.

Main Results:

• Achieved near-perfect wave absorption (>90%) in two distinct frequency bands when VO2 is in its insulating state.
• Demonstrated tunable absorption bands by altering the graphene's Fermi energy level.
• Observed a transition to a total reflection state when VO2 becomes metallic at elevated temperatures.

Conclusions:

• The proposed metasurface exhibits reconfigurable dual functionality (absorption/reflection) with wide angle and polarization independence.
• The device is easy to fabricate and integrate, showing significant potential for 6G terahertz communications.
• This work advances the development of dynamic metasurfaces for versatile terahertz wave manipulation.