A laser for penetrating waves

phys.org | 7/11/2019 | Staff
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The Landau-level laser is an exciting concept for an unusual radiation source. It could efficiently generate so-called terahertz waves, which can be used to penetrate materials, with possible applications in data transmission. So far, however, nearly all attempts to make such a laser have failed. An international team of researchers has now taken an important step in the right direction: In the journal Nature Photonics, they describe a material that generates terahertz waves by simply applying an electric current. Physicists from the German research center Helmholtz-Zentrum Dresden-Rossendorf (HZDR) played a significant role in this project.

Like light, terahertz waves are electromagnetic radiation in a frequency range between microwaves and infrared radiation. Their properties are of great technological and scientific interest, as they allow fundamental researchers to study the oscillations of crystal lattices or the propagation of spin waves.

Terahertz - Waves - Interest - Applications - Substances

"Terahertz waves are of interest for technical applications because they can penetrate numerous substances that are otherwise opaque, such as clothing, plastics and paper," HZDR researcher Stephan Winnerl explains. Terahertz scanners are already used today for airport security checks, detecting whether passengers are concealing dangerous objects under their clothing—without having to resort to harmful X-rays.

Because terahertz waves have a higher frequency than the radio waves we use today, they could also be harnessed for data transmission one day. Current WLAN technology, for instance, operates at frequencies of two to five gigahertz. Since terahertz frequencies are about 1000 times higher, they could transmit images, video and music much faster, albeit across shorter distances. However, the technology is not yet fully developed. "There has been a lot of progress in recent years," Winnerl reports. "But generating the waves is still a challenge—experts speak of a veritable terahertz gap." A particular issue is the lack of a terahertz laser that is compact, powerful, and tunable at the...
(Excerpt) Read more at: phys.org
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