Plasmonic graphene breakthrough could yield next gen circuits

The team at the University of California says this is the first time plasmons have been observed on graphene and is an important step toward transmitting information in spaces too tight to use light. "Everybody suspected that plasmons should be there, but seeing is believing. We've imaged them and shown that they propagate. And we've demonstrated that we can control them," commented Dimitri Basov, professor of physics at UC San Diego. The team coated silicon dioxide chips with graphene, then launched plasmons by shining an infrared laser on the surface and measured the waves using an atomic force microscope. The scientists then showed the interference pattern could be altered by controlling an electrical circuit attached to the graphene surface and a layer of pure silicon beneath the chips. Much like light can carry complex signals through fibre optics, plasmons could be used to carry information within far tighter spaces. Scientists have generally found metals to be the best material for creating plasmons, but these have proved difficult to control. The team claims that it produced some of the shortest plasmon wavelengths measured in any material and that the waves propagated as far as they would in metals such as gold, with the addition that they were tuneable. "There also is entirely new, fundamental science coming out of this," added Basov. "By monitoring plasmons, we learn what electrons do in this new form of carbon; how fundamental interactions govern their properties. This is a path of inquiry."