Two-dimensional terahertz beam scanning with a programmable liquid crystal metasurface

Area of Science:

• Optics and Photonics
• Metamaterials
• Terahertz Technology

Background:

• Terahertz (THz) metasurfaces are crucial for beam steering.
• Existing liquid crystal (LC) metasurfaces have limited continuous phase coverage, hindering precise phase pattern synthesis.
• A need exists for advanced metasurfaces with enhanced phase control for 2D beam steering.

Purpose of the Study:

• To demonstrate a programmable terahertz (THz) metasurface enabling two-dimensional (2D) beam steering.
• To overcome the limitations of existing LC-based THz metasurfaces.
• To provide a scalable route toward intelligent THz apertures.

Main Methods:

• Proposed an orthogonally addressable architecture using dual H-shaped resonators in a metal-LC-metal stack.
• Utilized hybridized stacked resonators to form an electric quadrupole mode, localizing the field in the LC.
• Integrated a Fabry-Pérot (FP) cavity using a coupled bilayer and backside reflector to increase phase difference.

Main Results:

• Achieved 300° continuous phase tuning via voltage control.
• Demonstrated 2D phase gradients using an orthogonal coding scheme.
• Experimentally realized beam scanning with 5° steps up to an angular range of ±40°.

Conclusions:

• The proposed metasurface architecture enables precise 2D beam steering.
• This technology offers a scalable solution for intelligent THz apertures.
• The findings advance THz communication and sensing capabilities.