According to an article published this week in Nature Nanotechnology, new research involving graphene-based light detectors could revolutionize scanning technology in the next few years.. Lead author Xinghan Cai, a grad student at the University of Maryland, said a scaled-up new light detector of this type “could find applications in emerging terahertz fields such as mobile communications, medical imaging, chemical sensing, night vision and security.”
New light detector can detect tetrahertz waves
The new light detector is based on the special properties of graphene, a two-dimensional form of carbon that is just one atom thick. The researchers report that a prototype detector can see into an exceptionally wide range of wavelengths. Perhaps most importantly, the new detector can operate in the tetrahertz band of light wavelengths.
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Scientists and engineers say that that an ability to detect terahertz waves, which are invisible to the human eye, opens up a number of exciting possibilities in micro-level scanning. One example of a medical application might be the ability scan individual layers of skin or blood vessels, which cannot be done with current scanning technologies.
The long wavelengths and low frequencies of tetrahertz waves lie between microwaves and infrared waves. The light in these wavelengths can pass through materials normally considered solid or opaque, such as skin, plastics, cloth and wood. The new detector could also be used to identify chemical signatures only emitted in the terahertz range.
Very few applications for terahertz detection exist currently, largely because it is difficult to detect light waves in this range. Most tetrahertz detectors need to be kept extremely cold, as cold -452 degrees F., to perform efficiently. Other known room temperature tetrahertz detectors are large, slow and very expensive to build and operate.
Based on an operating principle named the “hot-electron photothermoelectric effect,” the team developed a device that is “as sensitive as any existing room temperature detector in the terahertz range and more than a million times faster,” according to Michael Fuhrer, professor of physics at the University of Maryland and Monash Univ.
The idea behind the detector is relatively simple, explain University of Maryland Physics Prof. Dennis Drew. “Light is absorbed by the electrons in graphene, which heat up but don’t lose their energy easily. So they remain hot while the carbon atomic lattice remains cold.”