Graphene Plasmonic Circuits Take a Critical Step Foward

Graphene-based optical antennas could help create photonic logic circuits

2 min read
Graphene Plasmonic Circuits Take a Critical Step Foward
Graphic representation of the refraction of graphene plasmons—launched by a tiny gold antenna—when passing through a one-atom-thick prism.
Illustration: nanoGUNE

When one takes into account the rough and tumble world for electrons in electronic devices, one would think it might make more sense just to use photons instead. The problem has been that light takes up a lot of space. The components for such a photonic system can’t get any smaller than a wavelength of light, which would translate to devices many times larger than today’s.

However, the field of plasmonics, which takes advantage of the surface plasmons that are generated when photons hit a metal structure, has looked to be a way forward for confining electromagnetic energy to subwavelength scales and create smaller photonic logic circuits. Recent research has shown that graphene and other two-dimensional materials produce plasmons too. These so-called graphene plasmons have an advantage over surface plasmons because their confinement of electromagnetic energy at subwavelength scales can be tuned and controlled by a gate voltage.

Now Spanish researchers at CIC nanoGUNE outside of San Sebastian, the Institute of Photonic Sciences (ICFO) near Barcelona, and the company Graphenea located at the CIC nanoGUNE research center have demonstrated that an optical antenna made from graphene can capture infrared light and transform it into graphene plasmons.

The research, which was recently published in the journal Science, demonstrated that a metal rod on graphene can act as an antenna for infrared light and transform it into graphene plasmons in much the same way a radio antenna converts radio waves into electromagnetic waves in a metal cable.

“We introduce a versatile platform technology based on resonant optical antennas for launching and controlling of propagating graphene plasmons, which represents an essential step for the development of graphene plasmonic circuits”, said team leader Rainer Hillenbrand in a press release.

The researchers believe that the graphene-based optical antennas provide a number of advantages. “The excitation of graphene plasmons is purely optical, the device is compact and the phase and wavefronts of the graphene plasmons can be directly controlled by geometrically tailoring the antennas,” said Pablo Alonso-González, who performed the experiments at nanoGUNE, in a press release. “This is essential to develop applications based on focusing and guiding of light.”

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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