British researchers announce breakthrough in controlling terahertz radiation

British researchers have announced a breakthrough in the harnessing of electromagnetic terahertz waves (T-rays) that could make detecting disease far easier.

Researchers at Bath University said they have found a way to control the flow of terahertz radiation down a metal wire, whose frequency is around 1,000 billion cycles a second, bridging the gap between the microwave and infrared parts of the electromagnetic spectrum, according to a press release by the university on Thursday.

Materials interact with radiation at T-ray frequencies in different ways than with radiation in other parts of the spectrum, making T-rays potentially important in detecting and analyzing chemicals by analyzing how they absorb T-rays fired at them.

This would allow quality control of prescribed drugs and detection of explosives to be carried out more easily, as many complex molecules have distinctive signatures in this part of the electromagnetic spectrum.

T-ray applications are presently limited by the relatively poor ability to focus the rays, which is achieved using the conventional means of lenses and mirrors to focus the radiation. This limits the spot size of focused T-rays to a substantial fraction of a millimeter and this has made studies of small objects such as biological cells with high resolution virtually impossible.

However, the researchers found that although ordinary metal wire would not guide T-rays very well, if a series of tiny grooves were cut into the wire, it would do so much more effectively. If such a corrugated metal wire is then tapered to a point it becomes possible to very efficiently transport radiation to a point as small as a few millionths of a meter across.

This might lead to breakthroughs in examining very small objects such as the interior of biological cells where it might be possible to detect diseases or abnormalities, the researchers said.

T-rays could also be directed to the interior of objects which could be useful in applications like endoscopic probing for cancerous cells or explosive detection.

"This is a significant development that would allow unprecedented accuracy in studying tiny objects and sensing chemicals using T-rays," Stefan Maier, who leads the research, was quoted as saying.

Metal wire ordinarily has a limited ability to allow T-rays to flow along it, but the researchers tried to overcome this by corrugating its surface with a series of grooves, in effect creating an artificial material or "meta-material" as far as the T-rays are concerned, Maier said, adding that in this way, the T-rays can be focused to the tip of the wire and guided into confined spaces or used to detect small objects, with important implications for disease detection or finding hidden explosives.

The researchers hope to produce a working model within a year.

Source: Xinhua