Innovative terahertz laser promises revolution in medicine and safety

From infrared to infrared, laser technology has already captured much of the electromagnetic spectrum – but not all. Now, a laser that emits terahertz radiation promises to fill a significant gap and be used in medical imaging technologies and illegal cargo detectors at customs and airports. of the frequency of light, which reaches trillions of cycles per second. It can penetrate opaque materials such as the human body or the walls of a suspicious truck, or even identify specific substances by their spectral signature. “To this day, terahertz technology remains largely untapped due to a lack of radiation sources in this part of the spectrum.” The first chip-based terahertz laser (solid state laser) was invented in 2002, but was practically difficult to use because it only operated at temperatures below -73 degrees Celsius. The new study laser operates at -23 degrees Celsius, which can be achieved even with portable refrigeration devices. Quantum wells As with all solid state lasers, the new chip is based on semiconductor alloys containing “quantum wells”. When an electron falls into such a well, it emits radiation at a specific wavelength that depends on the chip semiconductors. that no semiconductor alloy emits photons in the terahertz spectrum. The solution is to use multiple layers of semiconductors, which force electrons to switch from one layer to the next. The first terahertz lasers contained hundreds of such layers, but they had to be cooled to very low temperatures, otherwise electrons would “leak” from the first layer to the last without passing through the intermediates. In the new laser, the thickness of the individual layers has increased. “We used a higher barrier to prevent leakage, and that proved to be the key to our achievement,” explains Hu. He even hopes that the refinement of the technique will eventually allow the development of terahertz lasers operating at room temperature. a terahertz detector based on the Hu team chip – all that is needed is a portable cooling device and a detector. Another application could be the detection of explosives, drugs and other substances – as Hu points out, substances such as heroin, methamphetamine and TNT give characteristic spectral signatures in the spectrum In other words, detectors of this type can not only detect hidden items, but also to determine what material it is. Follow it on Google News and be the first to know all the news See all the latest News from Greece and the World, at

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