Detector can view objects invisible to naked eye

A new ultra-thin detector holds promise as an instrument to view below the surface of bodies, beyond walls and other objects invisible to the human eye.

The detector could find applications in emerging fields such as mobile communications, medical imaging, chemical sensing, night vision and security, researchers said.

They used the special properties of graphene, a two-dimensional form of carbon that is only one atom thick, to see an extraordinarily broad band of wavelengths: Terahertz waves.

"Using a new operating principle called the hot-electron photothermoelectric effect, we created a device that is as sensitive as any existing room temperature detector in the terahertz range and more than a million times faster," explained Michael Fuhrer, a professor of physics from the University of Maryland and the Melbourne-based Monash University.

Graphene is uniquely suited to use in a terahertz detector because when light is absorbed by the electrons suspended in the honeycomb lattice of the graphene, they do not lose their heat to the lattice but instead retain that energy.

"Few technological applications for terahertz detection are currently realized, however, in part because it is difficult to detect light waves in this range," informed lead author Xinghan Cai, a physics graduate student from the University of Maryland.

The paper appeared in the journal Nature Nanotechnology.