Research groups in Spain have succeeded in imaging light confined on graphene.
Researchers at the nanoGUNE lab
Graphene is a single-layered sheet of carbon atoms. The imaging confirms the long-standing theory that graphene can be used as a medium to confine and manipulate light efficiently and also provides scope for merging the fields of nano-optics and nano-electronics. The study was a collaborative effort between ICFO at Barcelona, IQFR-CSIC at Madrid and nanoGUNE at San Sebastian.
Graphene exhibits fascinating optical properties. It has been assumed for some time that wave-like oscillations called plasmons must exist on the surface of graphene, in the midst of the vast expanse of conducting electrons. The wavelength of the plasmons is extremely small, however, so they cannot be viewed using existing light microscopes. Because of this, no experimental evidence for the existence of plasmons in graphene has been found, until now. The research team achieved the first ever visualization of graphene plasmons by using a near-field microscope that employs a pointed tip to focus the illumination light into a nano-sized spotlight. The illuminated tip instigates plasmons, and also can be used to detect the presence of plasmons. Graphene plasmons can be likened to the electrons in a transistor for controlling light. While other plasmonic materials are not equipped with such capabilities, graphene plasmons can be used as nano-optical switches and facilitate modulation of light at speeds on a par with current generation microchips. The ability to confine small volumes of light makes it ideal for next generation nanoscale sensors and in quantum information processing.