Two teams of US researchers have got their eye on graphene to advance the state of the art in medical imaging, communications and security screening, thanks to its strong response to the terahertz region of the electromagnetic spectrum.
Writing in Nature Nanotechnology, scientists from Lawrence Berkeley National Laboratory and the University of California at Berkeley, explain how nanoribbons of graphene could form the "beginnings of a toolset" for working with terahertz radiation.
Physics World describes their approach: "The graphene is arranged in arrays of extremely narrow ribbons, called nanoribbons. The terahertz response of the array can be tuned by varying the width of the ribbons and the number of charge carriers (electrons and holes) in the structures. In fact, varying these two parameters allows the researchers to control the collective oscillations of electrons (plasmons) in the graphene ribbons, and it is these plasmons that couple strongly to the terahertz light."
Meanwhile, at the University of Notre Dame in Indiana another team is looking at graphene’s potential in terahertz radiation. Writing in an article accepted for publication in Applied Physics Letters, the researchers describe how graphene can be used to tune terahertz radiation, offering better control of the frequency range.
The team was interested in learning how to modulate terahertz radiation, because control of the wave heights of radiation allows us to use it to carry information.
The current state of the art is based on small, semiconductor transistor-like structures, according to the press release. These structures rely on a thin layer of metal to actually tune the radiation, but this also reduces the signal strength and limits how much of the signal can be modulated. Replacing this "metal gate" with graphene means the signal is not disrupted anything like as much, leaving more of the wave open for modulation.