14 DAY TRIAL // Experts at the Massachusetts Institute of Technology (MIT) announce the development of a new method of producing and fine-tuning terahertz quantum cascade lasers. The scientists argue that terahertz radiation has been on experts' minds for many years, but that elusive radiation could not be generated easily, using conventional lasers. These rays can be found between microwaves and infrared wavelengths, on the electromagnetic spectrum, the group reports.
The main ability that terahertz radiation has it that it is able to penetrate clothing, plastic, and human tissue, in addition to glass and other materials, without harming living things. This allows for it to be used as the basis of new imaging techniques that could shed more light on the intricacy of the human body, the MIT group explains. The experts were led by Qing Hu, who is a professor of electrical engineering at the Research Laboratory of Electronics. Details of the work appear in the current issue of the respected scientific journal Nature Photonics.
“Since the very beginning of terahertz development in the 1970s, people have been trying to make [high-power] sources that are compact and tunable, and so far, this is really the first example of such a source. Qing deserves a lot of credit for all the work he put in and the groundbreaking ideas he pioneered and pushed through despite lots of setbacks and competition from other groups. He really, in the end, came through with a fantastic breakthrough,” scientist Peter Siegel says. He is the leader of the Submillimeter Wave Advanced Technology group, which is based at the NASA Jet Propulsion Laboratory, in Pasadena, California.
Hu adds that his new lasers could be used by researchers working with visible light, in their attempt to image very, very small objects. On account of a physical limitation known as the diffraction limit, light cannot be used to look at objects that are less than half its wavelength in size. But the MIT team got past that limitation, by employing the help of a virtual particle called a plasmon, which allows for light to be used in circumstances otherwise out of reach. At this point, the lasers only work when cooled with liquid nitrogen.
But a variant that works at room temperature is theoretically possible, scientists add, and it could be used to fight terrorism both in the US and internationally. This could be achieved as new gas and chemical detectors relying on cascade lasers become operational. Such devices would be able to detect more chemicals and dangerous substances faster, because they function on variable wavelengths.