T-rays could probe materials at unprecedented level of detail

A team of researchers from France and the UK have built a T-ray laser that is around 10,000 times more powerful than any similar device and can emit in separate pulses rather than a continuous stream.

Terahertz radiation — which refers to the far-infrared and microwave portion of the electromagnetic spectrum — is an area of increasing interest to scientists and engineers.

The technology was first developed by astronomers for detecting cosmic T-rays, but in the past decade or so there has been considerable progress in producing and detecting T-rays from terrestrial sources.

Active systems that emit T-rays then detect and image the resulting absorption and reflection patterns are now commercially available, while passive systems that can detect endogenous T-rays from various objects are also under development.

The method used by the current team is based on quantum cascade lasers that use a semiconductor as an active medium. They devised a way of ‘mode locking’ the laser by modulating its bias current with a radio-frequency synthesiser. The result was a powerful train of laser pulses that could be detected as a spectral signature.