Graphene breaks light confinement limit

Confining light to small spaces is a fundamental challenge for computing using light rather than electric current. The smaller the space into which a pulse of light can be confined, the more compact a device using this technology, such as sensors or nanoscale lasers can be. Up to now, light has been confined to a space smaller than its own wavelength using the atomic lattices of metals to trap and guide photons. Now, researchers from the European Graphene Flagship, led by a team from ICFO (the Institute of Photonic Sciences in Barcelona), have found that this is yet another property that can be accessed using the single atom thick form of elemental carbon

“Graphene keeps surprising us: nobody thought that confining light to the one atom limit would be possible,” said research leader Prof Frank Koppens. In a paper published in Science, Koppens and colleagues at the University of Minho, Portugal, and MIT describe how they fabricated a composite nano-optical device starting with a layer of graphene, topped with an insulating hexagonal boron nitride layer, which was in turn topped with an array of metallic rods. Graphene is already known to have the ability to guide light in the form of plasmons, which are oscillations of electrons within the material structure that interact strongly with light.