Promising Plasmonic Observations on GrapheneCategory: Science & Technology
Posted: June 25, 2012 08:42AM
Though not their goal, two teams of researchers have shown that great minds think alike by independently performing extremely similar experiments. The teams at the University of California, San Diego and Elhuyar Fundazioa in Spain have directly observed plasmons on sheets of graphene. Their data may lead to a new generation of advanced optoelectronics that can be tuned and operate at speeds similar to modern microchips.
Plasmons are a kind of quasiparticle that is actually a coupled electron and photon. This kind of coupling allows the energy and information of the photon to be confined to a size as much as 100 times smaller than the original photon. This is a very valuable ability as the wavelength of visible light is in the hundreds of nanometers, which is considerably larger than the 22 nm of modern silicon circuitry.
Both experiments used a laser aimed at a very sharp tip placed above the graphene. The laser and tip induced the plasmons to form and propagate along the graphene. As the plasmons traveled they were reflected off of the edges of the graphene and then interfered with other plasmons. This backscattering is what enabled the researchers to directly observe the existence and behavior of the plasmons.
The researchers also found it is possible to tune these plasmons by controlling an electric circuit on the graphene. This kind of control is something that will be needed for graphene to be used in technology for its optoelectric properties.