Extreme-Thickness Meta-Membrane for Controlling Terahertz Vectorial Beams

Area of Science:

• Terahertz (THz) optics
• Metasurface (MS) engineering
• Wave manipulation

Background:

• Conventional terahertz (THz) beam manipulation devices are bulky and not suitable for optical integration.
• Transmission-mode metasurfaces (MSs) typically require significant thickness for effective phase modulation.

Purpose of the Study:

• To propose and demonstrate a new type of flexible metasurface (MS) for efficient transmission-mode manipulation of terahertz (THz) beams.
• To achieve wide-range phase and polarization control of THz waves using an ultra-thin meta-system.

Main Methods:

• Proposed a flexible metasurface (MS) composed of two metallic screens with tailored air slits.
• Utilized near-field coupling of two slit resonances for wave manipulation, enabling an extremely thin structure (∼λ/30).
• Employed leaky eigenmode theory for analysis and full-wave simulations for experimental validation.

Main Results:

• Demonstrated that the phase and polarization of transmitted THz waves can be modulated by altering slit geometries and orientations.
• Successfully constructed three THz MSs using coupled air-slits as meta-atoms.
• Generated scalar and radially polarized vectorial Bessel beams at 0.39 THz illumination.

Conclusions:

• The proposed ultra-thin, flexible metasurface (MS) offers a novel approach for transmissive terahertz (THz) beam manipulation.
• This technology is suitable for integration into compact optical systems.
• Potential applications include biosensing, communications, and advanced display technologies.