Flexible Terahertz Beam Manipulations Based on Liquid-Crystal-Integrated Programmable Metasurfaces

Area of Science:

• Optics and Photonics
• Materials Science
• Electrical Engineering

Background:

• Metasurfaces offer advanced control over electromagnetic waves, particularly in the terahertz (THz) spectrum.
• Phase manipulation using metasurfaces is crucial for developing novel THz devices.
• Liquid crystals (LCs) provide a tunable medium for dynamic control of metasurface properties.

Purpose of the Study:

• To develop a terahertz beam steering device utilizing a liquid-crystal-integrated programmable metasurface.
• To investigate the phase manipulation capabilities of a reflective-type 1-bit metasurface element.
• To demonstrate anomalous beam reflection and wide-angle beam steering using a fabricated metasurface array.

Main Methods:

• Design of a reflective-type 1-bit metasurface element using a multilayer structure (metallic back plate-LC-complementary split ring resonator).
• Numerical simulations to optimize the operation frequency and evaluate phase difference and reflection amplitudes.
• Fabrication of a 1D programmable metasurface array with 32 independently controlled subarrays using lithography technology.

Main Results:

• The designed metasurface element exhibited a nearly 180° phase difference between unbiased and biased states with comparable reflection amplitudes at 0.675 THz.
• Simulated and measured far-field scattering patterns confirmed anomalous beam reflection and wide-angle beam steering.
• Experimental results showed a slight red shift in the optimal operating frequency to 0.645 THz.

Conclusions:

• The developed LC-integrated programmable metasurface is effective for terahertz beam steering.
• This technology shows promise for advancing applications in terahertz beam manipulation.
• The study highlights the potential of tunable metasurfaces for dynamic control of THz waves.