By Nick Gilbert
Research groups in Spain have succeeded in imaging light confined on graphene. 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.
Nanoimaging of Graphene Plasmons (Credit : nanoGUNE, IQFR-CSIC, ICFO)
The study was a collaborative effort between ICFO at Barcelona, IQFR-CSIC at Madrid and nanoGUNE at San Sebastian.
Graphene exhibits interesting properties, particularly optical. It is assumed to consist of wave-like oscillations called plasmons in the midst of the vast expanse of conduction electrons. The wavelength of plasmons is extremely small and cannot be viewed using existing light microscopes. This is the reason for lack of experimental evidence for the existence of plasmons in graphene until now. The research team achieved the first ever visualization by using a near-field microscope that employs a pointed tip to focus the illumination light into a nano light spot. The illuminated tip launches 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 give way to nano optical switches and facilitate modulation of light at speeds on 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.