The future of super-fast 6G communications could lie in the use of flexible plates with eye-catching spirals of carbon nanotubes tuned to broadcast terahertz (THz) signals.
In a new study published April 30 in the journal Advanced Optical Materials, researchers explained how layers of spiral zone plates can act as optical components to manage a THz beam. This is electromagnetic radiation in the 1 trillion hertz spectrum that sits between the microwave and infrared frequency bands for use in 6G communications, microscopy and medicine.
The varifocal Fresnel zone plates – devices with transparent and opaque concentric rings used to focus light and other waveforms – were constructed of a thin film of carbon nanotubes arranged in a spiral pattern that can twist the waveform of a THz beam passing through it. The new component can be seen here.
By combining two plates and rotating them relative to each other, the researchers changed the distribution of the intensity of the THz beam and split it into several areas of different radiation intensities. This could be used to create several channels for high-speed information transfer.
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Maria Burdanova, a senior researcher at the Moscow Institute of Physics and Technology’s Laboratory of Nanooptics and Plasmonics, explained in a statement that the paper outlines a way to overcome the challenges of making instruments that can tap into the THz spectrum band — which will be essential for high-speed 6G in the future.
"One of the key features highlighting the prospects of carbon nanotubes is the possibility to create multifunctional devices with properties that can be fine-tuned by different effects through responses at the atomic, supramolecular, and micron levels," Burdanova said in the statement. "For the first time, our joint team has succeeded in introducing an additional effect: interaction of different nanotube patterns. This paves the way for future devices."
By creating plates with spiral patterns formed from thin carbon nanotubes on a flexible and stretchable substrate, the plates can then be stretched and orientated – tuning them for the specific manipulation of THz signals.
Tubular signals
6G is mostly in the early research stages at the moment, despite a predicted rollout slated for 2023 by trade body GSMA. Until now, manipulating signals in the THz spectrum has been difficult to accomplish at range and scale.
As such, there’s a need to create components that can modulate and generate terahertz vortex beams that carry data — or beams that can be used as a form of X-ray in medicine. That’s why developing a varifocal Fresnel zone plate, based on focusing THz radiation via nanotubes, is significant.
Because the plates can be layered, stretched and rotated, they may pave the way for THz control components that can be tuned for different applications rather than needing different parts for communications and medical applications.
Furthermore, using nanotubes means engineers can create components that are compact and lightweight as well as tunable, which will be essential if 6G networks are to be developed at scale. With the constant demand for more data at faster speeds for both business and pleasure, 6G must be sufficiently scalable to usher in the next generation of high-speed communication.
