Paris, France--Researchers from Denis Diderot University, the French National Centre for Scientific Research (CNRS; Palaiseau) and the University of Leeds (England) have produced pulses of terahertz radiation from a quantum-cascade (QC) laser.1 This is the first time that such a high-powered source of terahertz radiation has been made to emit separate pulses rather than a continuous beam.
The work could open up new ways for terahertz radiation to image natural and synthetic materials. Terahertz radiation can be used to detect impurities in chemical and biological materials, generating characteristic spectral fingerprints that are used to identify different substances. Terahertz time-domain spectroscopy is a particularly sensitive way of probing materials using pulses of terahertz radiation. Hoever, up until now, these pulses have been made using laser sources with low peak power (around a microwatt).
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 QC laser (almost 10,000 times higher peak power) to create a train of terahertz pulses. They also devised a way of detecting the full pulse train--confirming that the technique could be used for probing materials.
"The potential for terahertz radiation to provide new imaging and spectroscopy techniques for a range of applications such as chemical and atmospheric sensing, or medical imaging, is immense," said Linfield. "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 more info, contactPaula Gould, University of Leeds press office: Tel 0113 343 8059, email [email protected].
1. S. Barbieri et al., Nature Photonics (doi: 10.1038/NPHOTON.2011.49).
Subscribe now to Laser Focus World magazine; it’s free!
Follow OptoIQ on your iPhone. Download the free App here