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Work of Russian scientists to give push to creation of new-generation electronics and optoelectronics

01.06.2017

The Scientific Reports magazine has published an article by an international team of scientists who for the first time measured giant electromagnetic fields arising in small dielectric particles in the scattering of electromagnetic waves.

The publication aroused great interest among physicists: over a month it was read by more than 500 scientists from different countries. The idea of ​​the experiment was proposed by Dr of Physics and Maths, professor of MEPhI and Lomonosov Moscow State University M. Tribelsky with the support of colleagues from Australia, headed by Yu. Kivshar (Australian National University).

Mikhail Tribelsky told about the amazing work and its prospects:

– Our article attracted attention because it reports the first direct experimental confirmation of a new important effect. It is known that light is electromagnetic oscillations of very high frequency. There is an X-ray radiation widely used in medicine. There is ultraviolet – thanks to it we are sunbathing. There is visible light perceived by the human eye. There is thermal infrared radiation – it can not be seen, but you can feel it, for example, bringing your hand closer to the hot iron. Finally, there are radio waves. And all this is electromagnetic oscillations, whose waves are of the same nature and differ from each other only by the frequency of oscillations. In a vacuum, they propagate with the same speed – the speed of light, and in the material their speed is different: the higher the refractive index of light, the lower the speed. It was believed that if an electromagnetic wave falls on a particle with a large refractive index, the size of which is small in comparison with the wavelength of the radiation, then the electromagnetic field does not penetrate almost inside such a particle. It turned out that this is not quite so. At certain frequencies of the incident radiation, the situation is exactly the opposite: the field does not simply penetrate the particle, but its giant concentration occurs. A particle, like a funnel, collects the incident radiation from space and concentrates itself. Before our work, physicists had only theoretical results (including my own) predicting this effect, and indirect experimental data, in which its existence could be judged by some secondary features. We, as I can judge, for the first time conducted direct measurements.

– What was your experiment?

– Its main difficulty, speaking of optical frequencies, was in the necessity to carry out measurements on a very small scale with an accuracy of spatial resolution of the order of several nanometers (one billionth of a meter) and at the same time contrive to move a sensor that perceives radiation at various points inside particles.

 – How did you manage to deal with all this?

 – Quite simply. First, we took advantage of the fact that all electromagnetic waves are of the same nature, and instead of experimenting at optical frequencies, we made it in the radio range. This allowed us to move from nanoscale to a "particle" of a centimeter size. Secondly, in order to be able to measure the field at different points inside the particle, we used a thin-walled, radiation-transparent container filled with a liquid with a large refractive index. The sensor measuring radiation was immersed in a liquid, and it was easy to move it there. A piece of plastic pipe, bought in the construction market was used as a container. An ordinary distilled water, which in the radio range has the properties we need served as a liquid with a large refractive index. However you shouldn’t overestimate the simplicity of the experiment. Our St. Petersburg colleagues had to work hard to make the necessary measurements and correctly interpret them. But they successfully coped with this task.

– What are the possibilities of practical application of the effect?

– There are tremendous opportunities, first of all, for creation of new highly nonlinear materials and devices. What is it? In linear materials the response is proportional to the incoming signal. All of us know the law of Hooke: the force is proportional to the deformation. This is the linear response. But Hooke's law is valid, as long as the deformations are small. With large deformations, it is broken, and fundamentally new effects arise. The same is true in electrodynamics. For sufficiently large fields, fundamentally new effects appear. For example, radiation of one frequency is incident on the substance, and the radiation of the other is emitted. Now special crystals of macroscopic size are used as such frequency converters. By using our effect, the same result can be obtained on nanoparticles.

Or, let's say, in biology. Suppose a biologist wants to destroy only a certain part of a living cell to see how this affects the cell as a whole. What do I need to do? There are no such miniature scalpels to perform this operation, but with the help of our effect it is possible to achieve it: it is enough to introduce a nanoparticle into the cell and irradiate the entire cell with the light of the desired frequency. Due to the high concentration of electromagnetic energy inside the particle, it is highly heated and can completely evaporate. There is a "nano-explosion" that destroys that part of the cell in which the nanoparticle was located, while the rest of the cell remains intact.

You will agree, it is not always convenient to charge a mobile phone through a power outlet. And now imagine that your mobile phone has a special antenna arranged according to the principle of our particle – it collects scattered radiation in space and concentrates energy inside itself. Then your mobile phone can be charged and not be connected to the outlet. Isn’t it much more convenient?

– Will this phenomenon discovered by you help to develop subminiature devices?

– Yes, certainly. It will give push to the creation of electronics and optoelectronics of a new generation, although not today, but rather tomorrow or even the day after tomorrow. It could be devices for recording and transmitting information, miniature computers and microscopes of very high resolution.

– How do you assess your work: is it a discovery or, let’s say, a new step in physics?

– It's not for me to judge: only time can show it. Who remembers how the appearance of the first personal computers in the late 70s of the last century was regarded? Probably, with caution, and today, in my opinion, the importance of this invention’s influence on man is comparable to the "domestication" of the fire by primitive people. The technical revolution continues. Mankind is moving to a qualitatively new state, and, I hope, our work – the phenomenon described by us – helps this transition a little. A surge of interest in the opening perspectives can happen very quickly. Moreover, there are technologies for the practical application of the phenomenon today. It is necessary to invent nothing fundamentally new. Only interest, desire and the corresponding concrete idea are needed. Note that today the processes of mastering technical innovations have accelerated tremendously. An example of this is nanoparticles: they started talking about them about 20 years ago, at the time they were received only in several laboratories around the world. And today nanotechnologies, and products created on their basis, are accessible to all who need them. Because there is a demand. I would like to hope that the phenomenon described by us will not be unclaimed.

On the photo: The installation on which measurements were taken

Read the full interview on http://www.poisknews.ru/theme/innovation/25557/ (in Russian).

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