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News Article | April 24, 2017
Site: phys.org

Optical engineers from ITMO University in Saint Petersburg developed an express method for estimating the distribution of particles in optically transparent media based on correlation analysis of holograms. As a big part of the study, they created an algorithm capable of image processing in a few seconds. The new method can be applied to engineering devices for monitoring metal shavings in engine oil, studying a plankton in water, or tracking viruses in living cells. The work was published in Scientific Reports.


Flash Physics is our daily pick of the latest need-to-know developments from the global physics community selected by Physics World's team of editors and reporters It should be possible to create a matter-wave tractor beam that grabs hold of an object by firing particles at it – according to calculations by an international team of physicists. Tractor beams work by firing cone-like "Bessel beams" of light or sound at an object. Under the right conditions, the light or sound waves will bounce off the object in such a way that the object experiences a force in the opposite direction to that of the beam. If this force is greater than the outward pressure of the beam, the object will be pulled inwards. Now, Andrey Novitsky and colleagues at Belarusian State University, ITMO University in St Petersburg and the Technical University of Denmark have done calculations that show that beams of particles can also function as tractor beams. Quantum mechanics dictates that these particles also behave as waves and the team found that cone-like beams of matter waves should also be able to grab hold of objects. There is, however, an important difference regarding the nature of the interaction between the particles and the object. Novitsky and colleagues found that if the scattering is defined by the Coulomb interaction between charged particles, then it is not possible to create a matter-wave tractor beam. However, tractor beams are possible if the scattering is defined by a Yukawa potential, which is used to describe interactions between some subatomic particles. The calculations are described in Physical Review Letters. Household WiFi routers can be used to produce 3D holograms of rooms. The futuristic imaging process has been developed by Philipp Holl and Friedemann Reinhard of the Technical University of Munich in Germany. Using one fixed and one movable antenna, they measure the distortions in the router's microwave signal caused by it reflecting off and travelling through objects. The data are then fed through reconstruction algorithms enabling the researchers to produce 3D images of the environment surrounding the router at centimetre precision. The technique is simpler than optical holography, which relies upon elaborate laser equipment, and will have improved resolution when future WiFi technology has increased speed and bandwidth. The research has, however, raised concerns about privacy. "It is rather unlikely that this process will be used for the view into foreign bedrooms in the near future." Reinhard says to address these worries: "For that, you would need to go around the building with a large antenna, which would hardly go unnoticed." The method is also limited because microwaves come from so many devices and from multiple directions. Instead, Holl and Reinhard hope the technology, presented in Physical Review Letters, will be applied to recover victims buried under collapsed buildings or avalanches. Unlike conventional methods, it could provide spatial representation of the structures surrounding victims, allowing swifter and safer rescue. The UK Nuclear Industry Association (NIA) has called on the UK government to work closely with the nuclear industry to avoid a "cliff-edge" scenario after the country leaves the European Atomic Energy Community (Euratom). In its report – Exiting Euratom – the trade association for the UK's civil nuclear industry, which represents more than 260 companies, outlines six priority areas for negotiations with the European Commission as part of the "Brexit" negotiations. These include agreeing a new funding arrangement for the UK's involvement in Fusion 4 Energy, which is responsible for providing Europe's contribution to ITER fusion reactor in France, as well as setting out the process for the movement of nuclear material, goods, people and services post Brexit. The NIA also says that if a new Euratom deal is not agreed by the time the UK leaves the European Union in 2019 then the existing arrangement should continue until a new one is implemented.


News Article | September 14, 2016
Site: www.chromatographytechniques.com

Magnetic resonance imaging (MRI) is a common diagnostic tool used for imaging sensitive areas like the spine, the brain and various regions of the body afflicted by cancers. These procedures have become such staples in the healthcare field, in fact, that at last count, the Peter G. Peterson Foundation reported 107 MRIs per 1000 citizens are conducted annually in the U.S. Now, an international team of researchers may have just discovered how to make these important procedures safer and faster for both patients and hospitals around the globe. At the core of this new development are metasurface resonators created by a team of scientists hailing from Australia, Russia and the Netherlands. These metasurfaces—two-dimensional analogs of metamaterials—are artificial structures that contain many sub wavelength resonant elements. In an MRI scan, proof-of-principle experiments have shown that these metasurface resonators can spatially redistribute electromagnetic near fields and boost the signal-to-noise ratio in the specific region of the patient by more than twofold. How, though? The discovery is a product of research into negative refraction and the creation of left-handed metamaterials that respond to electromagnetic radiation differently, bending waves in the opposite direction. As the discussion surrounding the nonlinear properties of these left-handed metamaterials grows in the physics space, possibilities for the fabrication are also on the rise. “The idea was around but [there] was no demonstration to support it,” Professor Yuri Kivshar, the project leader and Head of the Nonlinear Physics Center at the Australian National University (ANU), told Laboratory Equipment. “We did the first experiment with a fish to better understand how the metamaterial technology can be used in principle, and then moved to scan a mouse.” Consider a typical MRI today. Due to a small signal-to-noise ratio, the acquisition of a signal that can support a reliable image quality can take a while. Patients can face clinical protocols lasting upward of 40 minutes, forced to remain motionless during the procedure. Hospitals, then, are limited by how many patients they can scan per day due to long procedure times and, in some cases, may still struggle with output resolution. Because the metasurface resonators at least double the signal-to-noise ratio, examinations can be completed faster without sacrificing resolution. It's better than that—resolution may actually be improved, allowing healthcare providers to potentially diagnose tumors or other diseases in earlier stages. Another advantage of the metamaterial technology is its resistance to tissue heating, a problem that has traditionally plagued this type of diagnostic test. In most cases, the heating is caused by the electric field, which is then absorbed in the body—similar to the way food is heated inside a microwave oven. “Our metamaterial is smart enough to suppress the heating from the electric field,” Alexey Slobozhanyuk, a Ph.D. student and the first author of the published paper, explained to Laboratory Equipment. “It allows for the redistribute spatially of the near field to keep the electric field far from the imaged area, while it also enhances the magnetic field [which gives the MRI signal] in the region of interest. If you place a patient in a specially designed metasurface, the examinations will be safe but with improved performance.” There are three ways in which the team—comprised of scientists from ITMO University, ANU, Ioffe Physical-Technical Institute, University Medical Center Utrecht and Institute of Experimental Medicine RAMS—say their approach could be used in future hospital applications. For instance, a metasurface resonator can be embedded in a patient table. In this application, a passive metasurface would be added to collimate the field and add image enhancement while still minimizing the signal drop-off from the coil to the patient. In another potential application, the metasurface could be inserted into the space between the patient and the coil, serving as a liner of sorts within the machine. This technique can create possibilities for more efficient matching between the coils and the patient. Lastly, metal resonators could be printed on or sewn into clothing to allow the metasurface to cover the patient from all sides, further increasing the resolution of the image output. So, just where is this research headed? Although Russian collaborators recently secured a grant to access experiments testing metasurface resonators in hospital-based MRI machines on humans, the project is still “a long way from installing into day-to-day hospital operation.” However, the science is patented, and researchers are in the process of developing a commercial prototype while in discussions with London-based medical company Mediwise, among others.


News Article | April 13, 2016
Site: phys.org

Information security is becoming more and more of a critical issue, not only for large companies, banks and defense enterprises, but even for small businesses and individual users. However, the data encryption algorithms we currently use for protecting our data are imperfect—in the long-term, their logic can be cracked. Regardless of how complex and intricate the algorithm is, getting round it is just the matter of time. Contrary to algorithm-based encryption, systems that protect information by making use of the fundamental laws of quantum physics can make data transmission completely immune to hacker attacks in the future. Information in a quantum channel is carried by single photons that change irreversibly once an eavesdropper attempts to intercept them. Therefore, the legitimate users will instantly know about any kind of intervention. Researchers from the Quantum Information Centre of the International Institute of Photonics and Optical Information Technology at ITMO University, along with colleagues from Heriot-Watt University in Edinburgh, have devised a new way to effectively generate and distribute quantum bits. This is the first system in Russia that can compete with the best existing analogues and makes it possible to share quantum signals via optical fiber across 250 kilometers in distance. "To transmit quantum signals, we use the so-called side frequencies," says Artur Gleim, head of the Quantum Information Centre at ITMO University, "This unique approach gives us a number of advantages, such as considerable simplification of the device architecture and large pass-through capacity of the quantum channel. In terms of bit rate and operating distance, our system is comparable to absolute champions in the field of quantum communications." The very possibility of stable transmission of quantum signals through fiber optical channels is instrumental to subsequent integration of quantum key distribution systems that will be used to secure the useful data. According to Robert Collins, research associate at the Institute of Photonics and Quantum Sciences at Heriot-Watt University and one of the authors of the study, the work may become a big pivot point for the whole field of quantum communication and cryptography: "Down the track, this new approach can enable smooth coexistence of numerous data streams with different wavelengths in one single optical cable. Moreover, these quantum streams can be fed into the already existing fiber optic lines along with conventional communications." In order to encode quantum bits in the system, laser radiation is directed into a special device called the electro-optical phase modulator. Inside the modulator, the central carrier wave emitted by the laser is split into several independent waves. After the signal is transmitted through the cable, the same splitting occurs on the receiver end. Depending on the relative phase shift of the waves generated by the sender and the receiver, the waves will either enhance or cancel each other. This pattern generated by overlapping wave phases is then converted into a combination of binary digits, which serves to compile a quantum key. Importantly, the scientists have achieved high stability of the relative phase shifts of the signal in the system. "All waves undergo random changes while passing through the fiber," explains Oleg Bannik, one of the authors of the study and researcher at Quantum Information Centre, "But these changes are always identical and get smoothed over during the additional run through the receiver's modulator. In the end, the receiver observes the same combination as the sender." Now the researchers are developing a full-fledged quantum cryptographic system that will generate and distribute quantum keys and transmit useful data simultaneously. Explore further: Verification testing of quantum cryptographic communication system that theoretically cannnot be tapped More information: A. V. Gleim et al. Secure polarization-independent subcarrier quantum key distribution in optical fiber channel using BB84 protocol with a strong reference, Optics Express (2016). DOI: 10.1364/OE.24.002619


News Article | April 14, 2016
Site: www.nanotech-now.com

Abstract: A group of scientists from ITMO University in Saint Petersburg, Russia has developed a novel approach to the construction of quantum communication systems for secure data exchange. The experimental device based on the results of the research is capable of transmitting single-photon quantum signals across distances of 250 kilometers or more, which is on par with other cutting edge analogues. The research paper was published in the Optics Express journal. Information security is becoming more and more of a critical issue not only for large companies, banks and defense enterprises, but even for small businesses and individual users. However, the data encryption algorithms we currently use for protecting our data are imperfect - in the long-term, their logic can be cracked. Regardless of how complex and intricate the algorithm is, getting round it is just the matter of time. Contrary to algorithm-based encryption, systems that protect information by making use of the fundamental laws of quantum physics, can make data transmission completely immune to hacker attacks in the future. Information in a quantum channel is carried by single photons that change irreversibly once an eavesdropper attempts to intercept them. Therefore, the legitimate users will instantly know about any kind of intervention. Researchers from the Quantum Information Centre of the International Institute of Photonics and Optical Information Technology at ITMO University along with colleagues from Heriot-Watt University in Edinburgh have devised a new way to effectively generate and distribute quantum bits. This is the first system in Russia, which can compete with the best existing analogues and makes it possible to share quantum signals via optical fiber across 250 kilometers in distance. "To transmit quantum signals, we use the so-called side frequencies," says Artur Gleim, head of the Quantum Information Centre at ITMO University, "This unique approach gives us a number of advantages, such as considerable simplification of the device architecture and large pass-through capacity of the quantum channel. In terms of bit rate and operating distance our system is comparable to absolute champions in the field of quantum communications." The very possibility of stable transmission of quantum signals through fiber optical channels is instrumental to subsequent integration of quantum key distribution systems that will be used to secure the useful data. According to Robert Collins, research associate at the Institute of Photonics and Quantum Sciences at Heriot-Watt University and one of the authors of the study, the work may become a big pivot point for the whole field of quantum communication and cryptography: "Down the track, this new approach can enable smooth coexistence of numerous data streams with different wavelengths in one single optical cable. On top of it, these quantum streams can be fed into the already existing fiber optic lines along with conventional communications." In order to encode quantum bits in the system, laser radiation is directed into a special device called the electro-optical phase modulator. Inside the modulator the central carrier wave emitted by the laser is split into several independent waves. After the signal is transmitted through the cable, the same splitting occurs on the receiver end. Depending on the relative phase shift of the waves generated by the sender and the receiver, the waves will either enhance or cancel each other. This pattern generated by overlapping wave phases is then converted into the combination of binary digits, 1 and 0, which serves to compile a quantum key. Importantly, the scientists have achieved high stability of the relative phase shifts of the signal in the system. "All waves undergo random changes while passing through the fiber," explains Oleg Bannik, one of the authors of the study and researcher at Quantum Information Centre, "But these changes are always identical and get smoothed over during the additional run through the receiver's modulator. In the end, the receiver observes the same combination as the sender." Now the researchers are on the mission to create a full-fledged quantum cryptographic system, which will generate and distribute quantum keys and transmit useful data simultaneously. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article | December 5, 2016
Site: phys.org

Scientists from Russia and the U.K. have developed an antenna that can aid in reducing sources of terahertz radiation down to the size of a fingertip. The antenna is a "sandwich" of semiconductor layers combined with quantum dots. The scientists demonstrated that such antennas provide a foundation for a new universal system capable of both transmitting and receiving terahertz radiation. Compact devices, operating at terahertz range, have applications in medicine and biology for tumor visualization and in the aerospace industry for high-speed communication systems. The study was published in Laser & Photonics Reviews. The terahertz range lies between infrared and microwave spectra. Terahertz radiation can penetrate living tissues, but unlike X-rays, is not ionizing and poses no health hazard. Therefore, medical practitioners could benefit immensely from compact terahertz scanners that can obtain pictures of tissues in living organisms. Researchers from Aston University and ITMO University used quantum dots to develop an antenna that can significantly reduce the size of terahertz sources. The work was supported by scientists from the University of Strathclyde and University of Sheffield, as well as TeraVil Ltd company and Center for Physical Sciences and Technology in Vilnius. "It was a technological challenge," says the study's academic supervisor Edik Rafailov, professor at Aston Institute of Photonic Technologies and leading research associate at ITMO University. "We demonstrated that quantum dots are a good alternative for conventional semiconductors. This new technology gives us an opportunity to generate terahertz at room temperature. And potentially make terahertz devices compact and cheap." Today, terahertz generation relies on sources that involve conversion of infrared laser beam into terahertz. The transformation is carried out with intricate systems of waveguides, semiconductor crystals or diodes. The search for alternative ways of generating and detecting terahertz waves is still underway, but such devices remain bulky, expensive and operate only at low temperatures. The new antennas make it possible not only to use terahertz sources at room temperature, but also to miniaturize them. "We are able to create very compact sources of terahertz radiation the size of a fingertip," comments leading author of the paper Andrei Gorodetsky, researcher at the Department of Photonics and Optical Information Technology of ITMO University and research associate at Aston Institute of Photonic Technologies. "With the new antennas, we managed to remove the limitation associated with the narrow light spectrum that is used by current converts. This gives us an opportunity to combine the antennas with compact infrared lasers. Additionally, the antennas are 20 times more resistant to damage than typical semiconductor devices. Both factors allow us to incorporate the antenna into the laser instead of setting it apart." The researchers suggest that their findings can be used in high-speed communication systems and also in compact terahertz scanners, which would give dynamic imaging of deep skin layers, embryo development, brain processes, and scanning of internal organs or tumors. Terahertz radiation is not harmful, as it does not scatter too much in biological tissues. As a result, terahertz systems are more informative, sensitive and fast compared to their substitutes from other parts of electromagnetic spectrum. Explore further: Wearable terahertz scanning device for inspection of medical equipment and the human body More information: Ross R. Leyman et al. Quantum dot materials for terahertz generation applications, Laser & Photonics Reviews (2016). DOI: 10.1002/lpor.201500176


News Article | September 5, 2016
Site: www.materialstoday.com

A new study has shown how silicon nanoparticles can be controlled to achieve effective non-linear light manipulation, a breakthrough that could help introduce new optical devices with many functionalities, such as transmitting, reflecting or scattering incident light in a particular direction, depending on its intensity. Devices based on the nanoparticles could also allow flexible data processing in optical communication systems and be integrated into microchips to bring ultrafast all-optical signal processing in optical communication lines and new optical computers. Devices that require electromagnetic waves for information transmission and processing require an antenna to receive or transmit signals in a specific direction. However, as incoming signals often need to be flexibly processed, it is key to have a reconfigurable antenna whose characteristics can be altered in a specific way during signal processing. Although quickly transmitting information through is already achievable, silicon-based electronics can’t process incoming data as fast as fiber optics; non-linear nanoantennas that operate at optical wavelengths could resolve this problem. To demonstrate non-linear switching, researchers from Moscow Institute of Physics and Technology in Dolgoprudny and ITMO University, St. Petersburg, whose work has appeared in ACS Photonics [Baranov et al., ACS Photonics (2016) DOI: 10.1021/acsphotonics.6b00358], examined a dielectric nanoantenna, an optically resonant spherical nanoparticle made from silicon. Although all spherical particles show resonances, their size determines its resonant wavelength. The first resonance, observed at the longest wavelength, is the magnetic dipole resonance. Incident light of a specific wavelength induces a circular electric current in the particle. As silicon has a high refractive index, particles with diameters approaching 100 nm will show magnetic dipole resonance at optical frequencies, thus achieving enhanced optical effects at the nanoscale. The team carried out photoexcitation of a silicon nanoparticle using a femtosecond laser pulse, with intense irradiation exciting electrons in the silicon nanoparticle into the conduction band, thereby changing the optical properties of the particle such that it enables unidirectional scattering of incident light. This allowed them to develop an analytical model explaining the ultrafast non-linear dynamics of the nanoantenna. As researcher Denis Baranov explains, “It sheds light on non-linear response of optical silicon nanoantennas and provides insight on behavior of more complicated structures.” Silicon nanoparticles could therefore become the basis for ultrafast optical nanodevices, and the team is looking to apply the model to simulate the non-linear behavior of more complicated structures involving resonant silicon nanoparticles, thereby allowing the manipulation of light in unusual ways, such as rotating a beam in a desired direction depending on its intensity.


News Article | April 29, 2016
Site: www.nanotech-now.com

Abstract: A group of scientists from ITMO University in Saint Petersburg has put forward a new approach to effective manipulation of light at the nanoscale based on hybrid metal-dielectric nanoantennas. The new technology promises to bring about a new platform for ultradense optical data recording and pave the way to high throughput fabrication of a wide range of optical nanodevices capable of localizing, enhancing and manipulating light at the nanoscale. The results of the study were published in Advanced Materials. Nanoantenna is a device that converts freely propagating light into localized light - compressed into several tens of nanometers. The localization enables scientists to effectively control light at the nanoscale. This is one of the reasons why nanoantennas may become the fundamental building blocks of future optical computers that rely on photons instead of electrons to process and transmit information. This inevitable replacement of the information carrier is related to the fact that photons surpass electrons by several orders of magnitude in terms of information capacity, require less energy, rule out circuit heating and ensure high velocity data exchange. Until recently, the production of planar arrays of hybrid nanoantennas for light manipulation was considered an extremely painstaking process. A solution to this problem was found by researchers from ITMO University in collaboration with colleagues from Saint Petersburg Academic University and Joint Institute for High Temperatures in Moscow. The research group has for the first time developed a technique for creating such arrays of hybrid nanoantennas and for high-accuracy adjustment of individual nanoantennas within the array. The achievement was made possible by subsequently combining two production stages: lithography and precise exposure of thenanoantenna to a femtosecond laser - ultrashort impulse laser. The practical application of hybrid nanoantennas lies, in particular, within the field of ultradense data recording. Modern optical drives can record information with density around 10 Gbit/inch2, which equals to the size of a single pixel of a few hundred nanometers. Although such dimensions are comparable to the size of the nanoantennas, the scientists propose to additionally control their color in the visible spectrum. This procedure leads to the addition of yet another 'dimension' for data recording, which immediately increases the entire data storage capacity of the system. Apart from ultradense data recording, the selective modification of hybrid nanoantennas can help create new designs of hybrid metasurfaces, waveguides and compact sensors for environmental monitoring. In the nearest future, the research group plans to focus on the development of such specific applications of their hybrid nanoantennas. The nanoantennas are made of two components: a truncated silicon cone with a thin golden disk located on top. The researchers demonstrated that, thanks to nanoscale laser reshaping, it is possible to precisely modify the shape of the golden particle without affecting the silicon cone. The change in the shape of the golden particle results in changing optical properties of the nanoantenna as a whole due to different degrees of resonance overlap between the silicon and golden nanoparticles. "Our method opens a possibility to gradually switch the optical properties of nanoantennas by means of selective laser melting of the golden particles. Depending on the intensity of the laser beam the golden particle will either remain disc-shaped, convert into a cup or become a globe. Such precise manipulation allows us to obtain a functional hybrid nanostructure with desired properties in the flicker of a second," comments Sergey Makarov, one of the authors of the paper and researcher at the Department of Nanophotonics and Metamaterials of ITMO University. Contrary to conventional heat-induced fabrication of nanoantennas, the new method raises the possibility of adjusting individual nanoantennas within the array and exerting precise control over overall optical properties of the hybrid nanostructures. "Our concept of asymmetric hybrid nanoantennas unifies two approaches that were previously thought to be mutually exclusive: plasmonics and all-dielectric nanophotonics. Our hybrid nanostructures inherited the advantages of both approaches - localization and enhancement of light at the nanoscale, low optical losses and the ability to control the scattering power pattern. In turn, the use of laser reshaping helps us precisely and quickly change the optical properties of such structures and perhaps even record information with extremely high density," concludes Dmitry Zuev, lead author of the study and researcher at the Department of Nanophotonics and Metamaterials of ITMO University. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Researchers from ITMO University, the Hebrew University of Jerusalem and Cyril and Methodius University in Skopje have fabricated a new magnetically controlled material composed of enzymes entrapped directly within magnetite particles. Combined with water, it forms a stable solution that can be used for safe intravenous injection for targeted treatment of cancer and thrombosis. Previously, the synthesis of similar materials involved additional components that impaired the magnetic response and enzymatic activity and created obstacles for intravenous injection into the human body. The results of the study were published in the Chemistry of Materials magazine.


News Article | November 16, 2016
Site: www.eurekalert.org

A team of physicists from ITMO University, MIPT, and The University of Texas at Austin have developed an unconventional nanoantenna that scatters light in a particular direction depending on the intensity of incident radiation. The research findings will help with the development of flexible optical information processing in telecommunication systems. Photons--the carriers of electromagnetic radiation--have neither mass nor electric charge. This means that light is relatively hard to control, unlike, for example, electrons: their flow in electronic circuits can be controlled by applying a constant electric field. However, such devices as nanoantennas enable a certain degree of control over the propagation of electromagnetic waves. One area that requires the "advanced" light manipulation is the development of optical computers. In these devices, the information is carried not by electrons, but by photons. Using light instead of charged particles has the potential to greatly improve the speed of transmitting and processing information. To make these computers a reality, we need specific nanoantennas with characteristics that can be manipulated in some way--by applying a constant electric or magnetic field, for instance, or by varying the intensity of incident light. In the paper published in Laser & Photonics Reviews, the researchers designed a novel nonlinear nanoantenna that can change the direction of light scattering depending on the intensity of the incident wave (Fig. 1). At the heart of the proposed nanoantenna are silicon nanoparticles, which generate electron plasma under harsh laser radiation. The authors previously demonstrated the possibilities of using these nanoparticles for the nonlinear and ultrafast control of light. The researchers then managed to manipulate portions of light radiation scattered forward and backward. Now, by changing the intensity of incident light, they have found a way to turn a scattered light beam in the desired direction. To rotate the radiation pattern of the nanoantenna, the authors used the mechanism of plasma excitation in silicon. The nanoantenna is a dimer--two silicon nanospheres of unequal diameters. Irradiated with a weak laser beam, this antenna scatters the light sideways due to its asymmetric shape (blue diagram in Fig. 2A). The diameters of the two nanoparticles are chosen so that one particle is resonant at the wavelength of the laser light. Irradiated with an intense laser pulse, electron plasma is generated in the resonant particle which causes changes in the optical properties of the particle. The other particle remains nonresonant, and the powerful laser field has little effect on it. Generally speaking, by accurately choosing the relative size of both particles in combination with the parameters of the incident beam (duration and intensity), it is possible to make the size of the particles virtually the same, which enables the antenna to bounce the light beam forward (red diagram in Fig. 2a). "Existing optical nanoantennas can control light in a fairly wide range. However, this ability is usually embedded in their geometry and the materials they are made of, so it is not possible to configure these characteristics at any time," says Denis Baranov, a postgraduate student at MIPT and the lead author of the paper. "The properties of our nanoantenna, however, can be dynamically modified. When we illuminate it with a weak laser impulse, we get one result, but with a strong impulse, the outcome is completely different." The scientists performed numerical modeling of the light scattering mechanism, Fig. 2b. The simulation showed that when the nanoantenna is illuminated with a weak laser beam, the light scatters sideways. However, if the nanoantenna is illuminated with an intense laser impulse, that leads to the generation of electron plasma within the device and the scattering pattern rotates by 20 degrees (red line). This provides an opportunity to deflect weak and strong incident impulses in different directions. Sergey Makarov, a senior researcher at the Department of Nanophotonics and Metamaterials at ITMO University concludes: "In this study, we focused on the development of a nanoscale optical chip measuring less than 200×200×500 nanometers. This is much less than the wavelength of a photon, which carries the information. The new device will allow us to change the direction of light propagation at a much better rate compared to electronic analogues. Our device will be able to distribute a signal into two optical channels within a very short space of time, which is extremely important for modern telecommunication systems." Today, information is transmitted via optical fibers at speeds of up to hundreds of Gbit/s. However, even modern electronic devices process these signals quite slowly: at speeds of only a few Gbit/s for a single element. The proposed nonlinear optical nanoantenna can solve this problem, as it operates at 250 Gbit/s. This paves the way for ultrafast processing of optical information. The nonlinear antenna developed by the researchers provides more opportunities to control light at nanoscale, which is what is required in order to successfully develop photonic computers and other similar devices.

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