Radiophysicists will double the quality of terahertz devices

Ksenia Akenteva

https://phys.org/wire-news/327646606/radiophysicists-will-double-the-quality-of-terahertz-devices.html

Radiophysicists from Tomsk and Novosibirsk are planning to double the resolution of the terahertz range. In particular, this will help to more thoroughly examine works of art—old books, manuscripts, and paintings—without touching them. The experiment will begin in mid-August. 

- Terahertz radiation is used for various purposes, including the study of works of art, because unlike optical illumination, it penetrates deeply, but unlike X-ray, does not shine through. It is possible for example to view text or drawings in old books layer by layer at different frequencies without touching them and therefore without damaging them, - said Valentin Suslyaev, manager of the project, associate professor at TSU, head of the Laboratory of Terahertz Research. - The same radiation is used to diagnose and treat skin diseases, for example, various types of skin cancer. 

In both cases, the terahertz beam must be as focused as possible, that is, its resolution must be high. The finer this beam, the greater the resolution it has, and therefore the more carefully it can identify the features of the object that needs to be studied. 
- There is a physical law that limits the resolution to half the wavelength, but it can be overcome using lenses. Our colleagues from Novosibirsk, Oleg Minins and Igor Minins, showed that it is possible to use simple manufactured lenses and simple geometric shapes—cuboids and ellipsoids. Making a cube is easier than a lens, and using it, you can double the resolution, - explained Valentin Suslyaev. 

Oleg and Igor Minins used mathematical modeling to prove the possibility of increasing the resolution of terahertz radiation using cuboids, and Tomsk radiophysicists will conduct an experimental study. TSU scientists have already developed an experimental design in free space and in an open resonator to prove the Minins' theoretical results. 
- One of the problems that we are solving is the influence of the tool on the object of study. We created a probe that when it is moved, makes it possible to determine the size of the area of focused terahertz radiation, but the probe affects the size of the focused radiation. Now in Minsk, our employees are developing solid-state detectors based on graphene to consider this area with less impact on the object, -added Valentin Suslyaev. 

A physical experiment will take place in mid-August. According to the forecasts of TSU radiophysicists, they will get the first results by the beginning of September.

More information:
Cheng-Yang Liu et al. Periodical focusing mode achieved through a chain of mesoscale dielectric particles with a refractive index near unity, Optics Communications (2018). DOI: 10.1016/j.optcom.2018.10.044

Provided by Tomsk State University