All-Dielectric Tunable Terahertz Metagrating for Diffraction Control.

Area of Science:

• Photonics and Metamaterials
• Electromagnetics and Optics
• Terahertz Technology

Background:

• Metagratings offer flexible control over electromagnetic waves but often suffer from ohmic losses in metallic components.
• All-dielectric designs overcome ohmic losses but present design challenges, particularly in the terahertz (THz) spectrum for 6G applications.
• Efficient manipulation of THz waves is crucial for next-generation wireless communications and sensing.

Purpose of the Study:

• To demonstrate a novel all-dielectric tunable terahertz metagrating for efficient beam steering.
• To investigate the performance of the metagrating in the 6G communication window.
• To develop and validate a metalens based on these metagratings for THz imaging.

Main Methods:

• Theoretical design and optimization of an all-dielectric unit cell for THz metagrating.
• Experimental fabrication and characterization of the metagrating for p- and s-polarized light.
• Integration of metagratings into a metalens and evaluation of its focusing and imaging capabilities at 0.14 THz.

Main Results:

• The metagrating achieved high energy concentration (>72.46% for p-polarization, >66.60% for s-polarization) into the T-1 diffraction order.
• Demonstrated tunability of the metagrating via angular deflection.
• Fabricated a metalens with NA=0.39, achieving a subwavelength focal spot (2.0 mm x 2.0 mm) and successful transmission imaging.

Conclusions:

• The all-dielectric tunable metagrating offers a promising solution for efficient THz wave manipulation, overcoming limitations of traditional designs.
• The developed metalens demonstrates significant potential for THz communication, sensing, and super-resolution imaging applications.
• Experimental results validate the theoretical design, paving the way for practical all-dielectric THz devices.