Using un-used spectrum …

Spectrum, the range of frequencies (and wavelengths) of an electromagnetic field, is usually considered as scarce, however it is not scarce per sé. What is scarce is the usable spectrum and its usability depends on a variety of factors: the propagation characteristics (the shorter the wavelength, i.e. the higher the frequency, the more information potentially carried but the more tricky the propagation, the longer the wavelength the longer the antenna needed to capture it and so on), the absorption in the ambient, and, of course, the technology required to manage it.
So far engineers have managed to deal with spectrum in the GHz (and below) range and in the 10-100 THz range (that is usually addressed in terms of nm wavelength …. since it is the range where light is involved). 
The range of THz has been neglected because of technical difficulties in managing these frequencies, laying between microwaves and infrared. This range is particularly interesting since the electromagnetic field in this range is able to go through matter although slightly interacting with it. As such it can be used to detect anomalies in materials, including body tissues leading, as an example to the detection of cancers.
Researchers at the University of Leeds have been able to develop an efficient laser, with an emission power around 1 W, representing a 100% increase in power with respect to the one previously developed at MIT, that can be used in practical applications.
The laser is embedded in a chip only a few square mm, made up by 1,000-2,000 layers, each one a few atoms thick. Actually, it is by finely controlling the thickness of each layer that it is possible to create the laser working at 3.1 THz. The production process is very complex and this explains why it took so long before creating such a laser.
The potential applications are many, from detecting specific chemicals (like traces of explosive) to specific micro structures, such as cancerous cells.
As it is the case with most sensors, the chip can provide raw data. It is up to the software to analyse them and make sense out of them.

About Roberto Saracco

Roberto Saracco fell in love with technology and its implications long time ago. His background is in math and computer science. Until April 2017 he led the EIT Digital Italian Node and then was head of the Industrial Doctoral School of EIT Digital up to September 2018. Previously, up to December 2011 he was the Director of the Telecom Italia Future Centre in Venice, looking at the interplay of technology evolution, economics and society. At the turn of the century he led a World Bank-Infodev project to stimulate entrepreneurship in Latin America. He is a senior member of IEEE where he leads the New Initiative Committee and co-chairs the Digital Reality Initiative. He is a member of the IEEE in 2050 Ad Hoc Committee. He teaches a Master course on Technology Forecasting and Market impact at the University of Trento. He has published over 100 papers in journals and magazines and 14 books.