Little teras

A UK project plans to bring terahertz (THz) imaging capability to low-power portable equipment, thanks to optoelectronic technology first used in the telecoms industry.

Researchers working on the four-year initiative hope it will pave the way for a new generation of miniature THz devices that are as small and easy to use as torches and cameras.

THz has potential applications ranging from disease diagnosis to weapons detection, and devices could eventually appear in doctors’ surgeries and customs halls.

Those taking part in the project include Essex University, NPL and the government’s communications R&D division. Also involved is Teraview, the UK company pioneering commercial applications for THz which has already made considerable strides in miniaturising the technology.

Prof Ian Henning, principal investigator on the £1.2m EPSRC-backed project, said the aim is to apply well-established optoelectronic technology to the particular needs of THz imaging.

Positioned between the infrared and microwave regions of the electromagnetic spectrum, radiation in the ‘THz gap’ can reveal otherwise hidden information about objects being scanned. But the gap has proved challenging for those developing systems to generate and detect THz light, usually requiring the use of bulky and expensive lasers.

To develop the ‘torches’ and ‘cameras’ the group plans to use semiconductor lasers fitted with indium phosphide detectors that have been optimised for speed. This would bring the same output from less power input, opening the way for handheld THz devices.

According to Henning, the small devices will allow THz radiation to be used in applications such as airport security to screen for explosives or drugs, pollution monitoring, or by GPs to aid diagnosis.

‘You could get very large hospital systems into a GP environment,’ he said. ‘It is like an X-ray, but more sensitive to molecular structure so provides more information.’ Henning added:

‘The thing about portability is it opens up investigations in different areas. If you are relying on a laboratory system, which requires a big power supply and is bulky, everything has to be brought in. If you have low power and it is portable, you can take it wherever you go and it opens up new possibilities. It could be cheaper as well.’

Background work has been done at Essex and UCL, and the initial phase of the project will be to extend this to develop knowledge of the THz range, said Henning. He added that there had already been commercial interest in the work.