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Russian researchers have developed a new material that converts infrared light to ultrashort pulses of ultraviolet. For this purpose, the scientists exposed silicon film to a laser so that its relief adjusted under the light wavelength and made properties of the material resonant. The result was a cheap and easy-to-make metasurface as effective as existing ones. The new technology is applicable in compact UV generators for biophotonics and medicine, and also devices for ultradense data processing in optical communications. The study was published in Nanoscale.
Biological media can reflect, absorb, scatter and re-emit light waves. Each of these processes contains information about micro- and macrostructure of the media, as well as shape and motion of its components. In this regard, deep ultraviolet is a promising tool for biology and medicine. Its application includes laser diagnostics and control of fast processes in cells, laser therapy and surgery at the molecular level.
Researchers from ITMO University and Saint Petersburg Academic University have developed a new method for nanostructures fabricating, which is able to convert infrared light to deep ultraviolet. The structure is a film with a regular massive of nanolumps – metasurface. It is generated by radiating silicon film, whose thickness is 100 nanometers, with ultrashort or femtosecond laser pulses that form its relief. On the film surface, the laser smelts such nanolumps, which resonate only with its wavelength and thus allow more radiation to be turned into ultraviolet. In other words, the laser adjusts metasurface to itself. When the relief is formed, the scientists reduce the power so the film starts converting radiation without deformation.
The researchers have managed not only to convert infrared light into violet, but also to get deep ultraviolet. Such radiation is strongly localized, has very short wavelength and distributes as femtosecond pulses. "For the first time, we've created a metasurface that stably emits femtosecond pulses of high power in the ultraviolet range," notes Anton Tsypkin, assistant of ITMO's Department of Photonics and Optical Information Technology. "Such light can be applied in biology and medicine, as femtosecond pulses affect biological objects more precisely."
S. V. Makarov et al. Self-adjusted all-dielectric metasurfaces for deep ultraviolet femtosecond pulse generation, Nanoscale (2016). DOI: 10.1039/C6NR04860A
(Score: 0) by Anonymous Coward on Tuesday December 27 2016, @05:11AM
Typically one can only go from high energy (short wavelength, high frequency) to low energy (long wavelength, low frequency) photons. This is doing the opposite, which is really weird. How...?