Gate-tuned graphene meta-devices for dynamically controlling terahertz wavefronts.

Area of Science:

• Optics and Photonics
• Materials Science
• Electrical Engineering

Background:

• Dynamical control of terahertz (THz) wavefronts is essential for numerous applications.
• Existing methods often rely on sub-micrometer tunable elements, which are challenging to implement in the THz spectrum.

Purpose of the Study:

• To propose and demonstrate a new approach for THz wavefront control using globally tuned graphene layers combined with metasurfaces.
• To overcome limitations of local-tuning mechanisms in THz meta-devices.

Main Methods:

• Utilizing coupled-mode-theory (CMT) to analyze the tunable loss mechanism of graphene.
• Designing and fabricating a graphene-based meta-device.
• Experimentally demonstrating THz wave reflection control with varying polarization.
• Numerically simulating the generation of vectorial THz beams with tunable polarization.

Main Results:

• Graphene acts as a tunable loss element, enabling phase transitions in the meta-device.
• Experimental validation of directional THz wave reflection control via gating voltages.
• Numerical demonstration of continuously tunable vectorial THz beam generation.

Conclusions:

• The proposed global tuning approach offers a viable alternative for THz wavefront control.
• This technology has significant potential for applications in THz sensing, imaging, and wireless communications.