Active terahertz beam deflection based on a phase gradient metasurface with liquid crystal-enhanced cavity mode...

Area of Science:

• Optics and Photonics
• Materials Science
• Electrical Engineering

Background:

• Terahertz (THz) beam manipulation is crucial for applications like wireless communication, radar, and remote sensing.
• Existing methods for THz beam control often lack active tunability and high efficiency.

Purpose of the Study:

• To demonstrate an active THz beam deflection device.
• To achieve efficient polarization mode conversion and intensity modulation of THz beams.
• To explore the integration of phase-gradient metasurfaces and liquid crystals for THz wavefront control.

Main Methods:

• Integration of phase-gradient metasurfaces with tunable liquid crystal materials.
• Formation of a photonic cavity using a double-layer metasurface and anisotropic liquid crystals.
• Utilizing polarization mode conversion for beam deflection and active modulation via liquid crystal axis rotation.

Main Results:

• Achieved 47.5° beam deflection with 50% diffraction intensity at 0.69 THz (x-to-y polarization conversion).
• Demonstrated ultrahigh intensity modulation depth of 99.6% by rotating liquid crystal optical axis.
• Obtained 32.5° deflection at 0.94 THz (y-to-x polarization conversion) with 38% diffraction intensity and 97.8% modulation depth.

Conclusions:

• The developed device offers active control over THz beam deflection and intensity.
• The integration of liquid crystals with metasurfaces provides a novel approach for THz wavefront manipulation.
• This technology holds promise for advanced THz communication, sensing, and imaging systems.