Researchers Use Graphene to Confine Light to the One-Atom Limit

Graphene has been used by scientists to reduce a lightwave to just one atom thick, paving the way for ultra-small sensors and switches. 

Graphene, heralded by many as a super material has already provided many breakthroughs in science. Now, researchers from the Institute of Photonic Sciences (ICFO) in Barcelona, in collaboration with a team at the Graphene Flagship have published a study in which they explain how they managed to reduce light down to just a single atom thick. 

Their article, published in Science describes how they used graphene to confine the light. The discovery will open doors to the design of ultra-small optical sensors, detectors, and switches. The discovery comes after years of attempts to use metals to shrink light.

Graphene made breakthrough possible

Graphene overcomes the problems previously encountered. “Graphene keeps surprising us: nobody thought that confining light to the one-atom limit would be possible,” explains Professor Frank Koppens who led the research at ICFO. “It will open a completely new set of applications, such as optical communications and sensing at a scale below one nanometer."

“Graphene keeps surprising us: nobody thought that confining light to the one-atom limit would be possible.”

And while Graphene continues to surprise scientist, it appears the discovery too was a surprise. "At first we were looking for a new way to excite graphene plasmons,” says David Alcaraz Iranzo, lead author on the paper from ICFO. “On the way, we found that the confinement was stronger than before and the additional losses minimal. So we decided to go to the one atom limit with surprising results."

Scientists make discovery by accident

The team managed the phenomenal breakthrough by using stacks of two-dimensional materials called heterostructures to build up a nano-optical device. The researchers then used a graphene monolayer on top of which they added a hexagonal boron nitride monolayer to act as an insulator. They continued to stack, next adding an array of metallic rods.

Graphene was used because of its light-guiding properties, thanks to its oscillating electrons known as plasmons. The initial research was to see how plasmons propagated in between metal and graphene. The surprise discovery came after the scientists decided to reduce the gap between metal and graphene to see if energy would be lost if they confined the light.

Tiny devices still some time away

They discovered that by using a hexagonal boron nitride monolayer as a spacer, the graphene plasmons were still activated and able to propagate freely, even when confined to a space of just one atom thick.

“Having reached the ultimate limit of light confinement could lead to new devices with unprecedented small dimensions."

"The impressive results reported in this paper are a testimony to the relevance for the cutting-edge science of the Flagship work,” explained Professor Andrea C Ferrari, science and technology officer at Graphene Flagship. “Having reached the ultimate limit of light confinement could lead to new devices with unprecedented small dimensions."

While it may be some time before we see the applications of this research in consumer goods, this breakthrough is just another step closer to thinner, lighter and smaller drives in the future.

Science unlocked with Graphene

Graphene is the first material that is 2D. It has many unique properties that can be exploited for scientific research. Since its discovery in 2004 many breakthroughs in science have occurred. Its two inventors Prof Andre Geim and Prof Kostya Novoselov. were awarded the Nobel Prize for Physics in 2010.