The novel tunable terahertz (THz) meta-device that allows for signal delivery to specific receivers has been developed by City University of Hong Kong (CityU).
The widespread adoption of such a device, made using advanced 3D printing technology, has implications for saving energy and protecting privacy. It offers many benefits for 6G communications, wireless power transfer and remote sensing. The low-cost fabrication method is also highly promising for industrial-level components in 6G communication.
The CityU team behind the discovery is led by Professor Chan Chi-hou, Acting Provost, Chair Professor in the Department of Electrical Engineering (EE) and the Director of the State Key Laboratory of Terahertz and Millimeter Waves (SKLTMW), Professor Tsai Din-Ping, Chair Professor in EE, Dr Chen Mu-Ku, Assistant Professor in EE, Dr Wu Gengbo, a postdoctoral fellow of the SKLTMW; and Zhang Jingcheng, a PhD student in EE.
During the research, the team demonstrated how rotary metasurface technology can fully control the THz beam’s radiation direction and coverage area based on 6G communication requirements.
The metasurface, which is 30 mm in diameter, comprises over 15,000 artificial minute meta-antennas fabricated through 3D printing. The THz wave can be projected onto an arbitrary spot in a 2D plane or even a 3D space. Only a user located in a specific spot can receive the signal.
“This arbitrary manipulation of the THz focused beams allows the signal to track the specific receivers without wasting power on nearby receivers and impairing privacy,” said Professor Tsai. “The research offers great benefits for advanced communication systems, including security, flexibility, and signal concentration.”
Extensive and accurate computing was required to design the meta-device for focal spot manipulation in a 2D plane and 3D space to produce the precise location of each spot.
“This was the most challenging part of the discovery,” said Zhang Jingcheng. “We made the varifocal meta-devices by incorporating and rotating several phase profiles, i.e., the cubic, gradient, and focusing phases while performing various projections within two or three metasurfaces.”
As a proof of concept, the team used two kinds of varifocal meta-devices to manipulate the wavefront and focus arbitrarily. The doublet meta-device is designed for steering the Airy beam focusing in a 2D plane, while the triplet meta-device is used for manipulating the Gaussian focal spot in 3D space. The design of the meta-devices was tested and validated in SKLTMW.
The findings have been published in the prestigious journal Science Advances titled “A 6G meta-device for 3D varifocal”.
Professor Tsai and Professor Chan are the corresponding authors. The co-first authors are Zhang Jingcheng, Dr Wu and Dr Chen. The research was supported by the Research Grants Council under the University Grants Committee; the Shenzhen Science and Technology Innovation Commission; and the Department of Science and Technology, Guangdong Province.