Transmissive metasurface with 3.5-μm-thick liquid crystals for subterahertz-wave dynamic beamforming

Area of Science:

• Physics
• Materials Science
• Electrical Engineering

Background:

• Subterahertz (sub-THz) wave propagation control is crucial for next-generation wireless systems.
• Liquid crystal (LC) metasurfaces offer a promising route due to their large aperture and manufacturability.
• Existing LC metasurfaces face challenges in independent thickness control and broad frequency design.

Purpose of the Study:

• To propose and demonstrate a dual-linear polarization unit cell for LC metasurfaces.
• To enable independent control of LC layer thickness for broad frequency design (microwave to sub-THz).
• To achieve efficient propagation control, including beam steering and focusing, in the sub-THz range.

Main Methods:

• Design of a dual-linear polarization unit cell with an independently tunable LC layer.
• Fabrication of a transmissive metasurface comprising 47,524 cells with a sub-λ/8 cell size.
• Experimental characterization of the metasurface's insertion loss, bandwidth, and beam steering capabilities at 115 GHz.

Main Results:

• The prototype metasurface demonstrated an insertion loss of 2.5 dB and a 3-dB bandwidth of 10%.
• Experimental results showed 2D beam steering up to 30 degrees.
• Variable focusing was achieved through aperture amplitude modulation.

Conclusions:

• The developed LC metasurface facilitates effective propagation control for subterahertz waves.
• The design's compatibility with display manufacturing technologies promotes industrial adoption.
• This advancement is expected to accelerate the use of sub-THz bands in future mobile communication networks.