T-ray laser pulses advance imaging

U. LEEDS (UK) — Researchers have produced terahertz ray pulses from a quantum cascade laser, the first time rays have been made to emit separate packets of radiation, rather than in a continuous beam.

The work, published online in Nature Photonics, could open up new ways for T-rays to image natural and synthetic materials.

T-rays, a band of radiation in the electromagnetic spectrum that falls between radio waves and visible light, can be used to detect impurities in chemical and biological materials, generating characteristic spectral fingerprints that are used to identify different substances.

Researchers have been working with a technique known as terahertz time-domain spectroscopy, a particularly sensitive way of probing materials using pulses of T-rays. Up until now, these pulses have been made using laser sources that generated very little power (around one millionth of a watt).

Harnessing the power of a quantum cascade laser that is almost 10,000 times more powerful, researchers created a t-ray pulse train, an advance that confirms the technique can be used for probing materials.

“The potential for T-rays to provide new imaging and spectroscopy techniques for a range of applications such as chemical and atmospheric sensing, or medical imaging, is immense, says Edmund Linfield, professor of electronic and electrical engineering at the University of Leeds. “This breakthrough provides a significant advance in the underpinning technology.”

Giles Davies from Leeds and Stefano Barbieri from Denis Diderot University in Paris contributed to the work, which was supported by the Délégation Générale pour l’Armement, the National Agency for Research, the UK Engineering and Physical Sciences Research Council, and the European Research Council.

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