French & British Researchers produce Terahertz pulses from quantum cascade laser

http://www.biosciencetechnology.com/News/Feeds/2011/04/sections-international-news-t-ray-laser-produces-pulses/

Researchers from Denis Diderot University in Paris, the French National Centre for Scientific Research (CNRS) and the University of Leeds, have produced T-ray ‘pulses’ from a quantum cascade laser.

This is the first time that such a high-powered source of terahertz rays (T-rays) has been made to emit separate 'packets' of terahertz radiation, rather than one continuous T-ray beam.

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

The term 'T-rays' describes a band of radiation in the electromagnetic spectrum that falls between radio waves and visible light. T-rays can be used to detect impurities in chemical and biological materials, generating characteristic 'spectral fingerprints' that are used to identify different substances.

Researchers have recently become interested in 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).

In this latest work, Stefano Barbieri and colleagues from Paris, together with Edmund Linfield and Giles Davies from the University of Leeds' School of Electronic and Electrical Engineering harnessed the power of a quantum cascade laser (almost 10,000 times more powerful) to create a train of T-ray pulses.  They also devised a way of detecting the full pulse train - confirming that the technique could be used for probing materials.

Professor Edmund Linfield said: "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.  This breakthrough provides a significant advance in the underpinning technology." 

The research was supported by the Délégation Générale pour l'Armement (contract no. 06.34.020), the National Agency for Research (ANR) (contract HI-TEQ), the UK Engineering and Physical Sciences Research Council (EPSRC), and the European Research Council programmes 'NOTES' and 'TOSCA'.

For further information:

Paula Gould, University of Leeds press office: Tel 0113 343 8059, email mailto:www.leeds.ac.uk/news/article/1690/p.a.gould@leeds.ac.uk