Created a record source of terahertz radiation
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Greg Stewart/SLAC
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Scientists from Austria, Greece and Russia have managed to develop a source of terahertz radiation, which broke several records. It is extremely effective, and its spectrum is very wide and allows you to generate waves of terahertz range. Article researchers published in the journal Nature Communications.
Terahertz radiation is used for security checks at airports, for medical examinations and for quality control of various materials in industry. However, radiation in the terahertz range is extremely difficult to create.
“Terahertz radiation has unique properties, says one of the researchers, an employee of the Institute of Photonics, technical University of Vienna Claudia Gollner. It can easily penetrate many materials, but unlike x-rays, is harmless, as they do not have ionizing properties.”
However, from a technical point of view, terahertz radiation is located in a very remote region of frequencies — in a kind of “neutral” strip between the two well-known areas. Radiation with higher frequencies can be generated by conventional solid state lasers. Low-frequency radiation, on the other hand, can create an antenna. The biggest problems lie exactly between them in the terahertz range.
But researchers from the Vienna technical University and physics Institute imeni P. N. Lebedev Institute together with colleagues from Greece have managed to create a high-intensity terahertz source. The basis they took the infrared laser. Its peculiarity is that the laser beam in this system is passed through the nonlinear medium. Part of his after the passage of the changes, increasing its frequency twice. Then these two kinds of emission are superimposed on each other. This creates a wave whose electric field has a very specific asymmetry. Wave knocks electrons from the molecules, turning the air into plasma, and its asymmetry allows to specify the required radiation.
The new method is extremely effective. During his approximately 2.3% of supplied energy is converted into terahertz electromagnetic radiation that is orders of magnitude greater than can be achieved in other ways. This leads to the emergence of terahertz waves with high energies up to 200 µj. Another important advantage of the new method is that by using it you can create a very wide range of terahertz radiation. It allows you to emit different wavelengths simultaneously in the whole terahertz range.