ITMO

Russia
Russia
SEARCH FILTERS
Time filter
Source Type

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 | May 17, 2017
Site: phys.org

Protein renaturation in eight stages. Molecules with native structure are in green, folded proteins - in red. Credit: ITMO University Scientists from ITMO University in Saint Petersburg and Hebrew University in Jerusalem have found a way to recover a protein structure after its chemical denaturation. The method is based on electrostatic interaction between folded, or denatured, proteins and alumina, which unwrap them. The authors highlight the versatility of the method, which works for both specific molecules and multiprotein systems. Theoretically, this can simplify and cheapen the production of drug proteins for Alzheimer's and Parkinson's. The study appeared in Scientific Reports. Proteins, especially including enzymes as accelerators of chemical reactions, are the basis of pharmaceutical and food industries. Meanwhile, 80 percent of these substances are lost during synthesis. Influenced by unfavorable factors like strong acids, alkalis or heating, proteins denature, losing their native shape and thus any chemical activity. As a result, researchers seek a universal method for recovering protein structure, which could make production more effective and less costly. Russian chemists in cooperation with foreign colleagues have proposed a solution to this issue with a technological process that returns protein molecules to their original form after denaturation. In the new research, the chemists unfolded molecules of three enzymes: carbonic anhydrase, phosphatase and peroxidase. Denatured by a strong alkaline, the proteins were mixed with nanoparticles of alumina in water. Due to electrostatic interaction, the enzymes attracted the nanoparticles and engaged them in forming a supramolecular complex with physical bonds. This shell of nanoparticles protected the protein molecules from aggregation, enabling the scientists to easily extract them from the aggressive media. Washed from denaturing substances, the enzymes restored their structure by themselves. "Constant exposure of denaturing agents and the tendency of curling macromolecules to aggregation are major obstacles for recovering proteins. When correcting these factors, we were able to regenerate our objects," says Katerina Volodina, second-year graduate student at ITMO University. Changing the pH, the scientists separated nanoparticles from proteins, showing that the substances involved in the experiment can be repeatedly used. The authors applied their method to a mixture of two enzymes: carbonic anhydrase and phosphatase (САВ and АсР), renaturating more than half of the molecules, which was an unprecedented result. "Renaturating of multiprotein mixtures is a unique process; it has never been done before. But my colleagues and I believe that further research in this area is in the interest of pharmaceutical companies right now. Theoretically, our method can simplify and cheapen the manufacture of drugs for Alzheimer's or Parkinson's therapy. Many of these medicines are made of proteins," notes Katerina Volodina. Besides its versatility and high performance, the technology proposed by ITMO University's chemists is also fast and low-cost. The scientists are going to evolve the approach mostly to renaturation of proteins in complex mixtures. More information: Katerina V. Volodina, David Avnir and Vladimir V. Vinogradov (2017), Alumina nanoparticle-assisted enzyme refolding: A versatile methodology for proteins renaturation, Scientific Reports, www.nature.com/articles/s41598-017-01436-6


News Article | May 25, 2017
Site: www.eurekalert.org

Scientists from the Netherlands and Russia designed and tested a new metasurface-based technology for enhancing the local sensitivity of MRI scanners on humans for the first time. The metasurface consists of thin resonant strips arranged periodically. Placed under a patient's head, it provided much higher signals from the local brain region. The results published in Scientific Reports, show that the use of metasurfaces can potentially reduce image acquisition time, thus improving comfort for patients, or acquire higher resolution images for better disease diagnosis. Magnetic resonance imaging (MRI) is a widely used medical technique for examination of internal organs, which can provide, for example, information on structural and functional damage in neurological, cardiovascular, in musculoskeletal conditions, as well as playing a major role in oncology. However, due to its intrinsically lower signal-to-noise ratio, an MRI scan takes much longer to acquire than a computed tomography or ultrasound scan. This means that a patient must lie motionless within a confined apparatus for up to an hour, resulting in significant patient discomfort, and relatively long lines in hospitals. Specialists from Leiden University Medical Center in the Netherlands and ITMO University in Russia for the first time have acquired human MR-images with enhanced local sensitivity provided by a thin metasurface - a periodic structure of conducting copper strips. The researchers attached these elements to a thin flexible substrate and integrate them with close-fitting receive coil arrays inside the MRI scanner. "We placed such a metasurface under the patient's head, after that the local sensitivity increased by 50%. This allowed us to obtain higher image and spectroscopic signals from the occipital cortex. Such devices could potentially reduce the duration of MRI studies and improve its comfort for subjects", says Rita Schmidt, the first author of the paper and researcher at the Department of Radiology of Leiden University Medical Center. The metasurface, placed between a patient and the receive coils, enhances the signal-to-noise ratio in the region of interest. "This ratio limits the MRI sensitivity and duration of the procedure", notes Alexey Slobozhanyuk, research fellow at the Department of Nanophotonics and Metamaterials of ITMO University. "Often the scans must be repeated many times and the signals added together. Using this metasurface reduces this requirement. Conventionally, if now an examination takes twenty minutes, it may only need ten in the future. If today hospitals serve ten patients a day, they will be able to serve twenty with our development." Alternatively, according to the scientists, the metasurface could be used to increase the image resolution. "The size of voxels, or 3D-pixels, is also limited by the signal-to-noise ratio. Instead of accelerating the procedure, we can adopt an alternative approach and acquire more detailed images", says Andrew Webb, the leader of the project, professor of Radiology at Leiden University Medical Center. Until now, no one has shown integration of metamaterials into close-fitting receive arrays because their dimensions were much too large. The novel ultra-thin design of the metasurface helped to solve this issue. "Our technology can be applied for producing metamaterial-inspired ultra-thin devices for many different types of MRI scans, but in each case, one should firstly carry out a series of computer simulations as we have done in this work. One needs to make sure that the metasurface is appropriately coupled", concludes Rita Schmidt. Rita Schmidt, Alexey Slobozhanyuk, Pavel Belov and Andrew Webb (2017), Flexible and compact hybrid metasurfaces for enhanced ultra high field in vivo magnetic resonance imaging, Scientific Reports, https:/ ITMO University (Saint Petersburg) is a national research university, the leading Russian university in the field of information and photonic technologies. The university is the alma mater of winners of numerous international programming competitions: ACM ICPC (the only six-time world champions), Google Code Jam, Facebook Hacker Cup, Yandex Algorithm, Russian Code Cup, Topcoder Open etc. Priority research areas: IT, photonic technologies, robotics, quantum communication, translational medicine, urban studies, art&science, and science communication. Starting from 2013, the university has been a member of Project 5-100, which unites top Russian universities to improve their status in the international research and education arena. In 2016 ITMO University became 56th among the world's top universities in Computer Science, according to the Times Higher Education ranking, and scored 3rd among Russian universities in the overall THE ranking.


News Article | May 26, 2017
Site: www.nanotech-now.com

Abstract: Scientists from the Netherlands and Russia designed and tested a new metasurface-based technology for enhancing the local sensitivity of MRI scanners on humans for the first time. The metasurface consists of thin resonant strips arranged periodically. Placed under a patient's head, it provided much higher signals from the local brain region. The results published in Scientific Reports, show that the use of metasurfaces can potentially reduce image acquisition time, thus improving comfort for patients, or acquire higher resolution images for better disease diagnosis. Magnetic resonance imaging (MRI) is a widely used medical technique for examination of internal organs, which can provide, for example, information on structural and functional damage in neurological, cardiovascular, in musculoskeletal conditions, as well as playing a major role in oncology. However, due to its intrinsically lower signal-to-noise ratio, an MRI scan takes much longer to acquire than a computed tomography or ultrasound scan. This means that a patient must lie motionless within a confined apparatus for up to an hour, resulting in significant patient discomfort, and relatively long lines in hospitals. Specialists from Leiden University Medical Center in the Netherlands and ITMO University in Russia for the first time have acquired human MR-images with enhanced local sensitivity provided by a thin metasurface - a periodic structure of conducting copper strips. The researchers attached these elements to a thin flexible substrate and integrate them with close-fitting receive coil arrays inside the MRI scanner. "We placed such a metasurface under the patient's head, after that the local sensitivity increased by 50%. This allowed us to obtain higher image and spectroscopic signals from the occipital cortex. Such devices could potentially reduce the duration of MRI studies and improve its comfort for subjects", says Rita Schmidt, the first author of the paper and researcher at the Department of Radiology of Leiden University Medical Center. The metasurface, placed between a patient and the receive coils, enhances the signal-to-noise ratio in the region of interest. "This ratio limits the MRI sensitivity and duration of the procedure", notes Alexey Slobozhanyuk, research fellow at the Department of Nanophotonics and Metamaterials of ITMO University. "Often the scans must be repeated many times and the signals added together. Using this metasurface reduces this requirement. Conventionally, if now an examination takes twenty minutes, it may only need ten in the future. If today hospitals serve ten patients a day, they will be able to serve twenty with our development." Alternatively, according to the scientists, the metasurface could be used to increase the image resolution. "The size of voxels, or 3D-pixels, is also limited by the signal-to-noise ratio. Instead of accelerating the procedure, we can adopt an alternative approach and acquire more detailed images", says Andrew Webb, the leader of the project, professor of Radiology at Leiden University Medical Center. Until now, no one has shown integration of metamaterials into close-fitting receive arrays because their dimensions were much too large. The novel ultra-thin design of the metasurface helped to solve this issue. "Our technology can be applied for producing metamaterial-inspired ultra-thin devices for many different types of MRI scans, but in each case, one should firstly carry out a series of computer simulations as we have done in this work. One needs to make sure that the metasurface is appropriately coupled", concludes Rita Schmidt. About ITMO University ITMO University (Saint Petersburg) is a national research university, the leading Russian university in the field of information and photonic technologies. The university is the alma mater of winners of numerous international programming competitions: ACM ICPC (the only six-time world champions), Google Code Jam, Facebook Hacker Cup, Yandex Algorithm, Russian Code Cup, Topcoder Open etc. Priority research areas: IT, photonic technologies, robotics, quantum communication, translational medicine, urban studies, art&science, and science communication. Starting from 2013, the university has been a member of Project 5-100, which unites top Russian universities to improve their status in the international research and education arena. In 2016 ITMO University became 56th among the world's top universities in Computer Science, according to the Times Higher Education ranking, and scored 3rd among Russian universities in the overall THE ranking. 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 | May 26, 2017
Site: phys.org

Scientists from the Netherlands and Russia have designed and tested a new metasurface-based technology for enhancing the local sensitivity of MRI scanners on humans for the first time. The metasurface consists of thin resonant strips arranged periodically. Placed under a patient's head, it provided much higher signals from the local brain region. The results published in Scientific Reports, show that the use of metasurfaces can potentially reduce image acquisition time, thus improving comfort for patients, or acquire higher resolution images for better disease diagnosis. Magnetic resonance imaging (MRI) is a widely used medical technique for examination of internal organs, as well as playing a major role in oncology. However, due to its intrinsically lower signal-to-noise ratio, an MRI scan takes much longer to acquire than a computed tomography or ultrasound scan. This means that a patient must lie motionless within a confined apparatus for up to an hour, resulting in significant patient discomfort, and relatively long lines in hospitals. Specialists from Leiden University Medical Center in the Netherlands and ITMO University in Russia have acquired human MRI with enhanced local sensitivity provided by a thin metasurface—a periodic structure of conducting copper strips. The researchers attached these elements to a thin flexible substrate and integrated them with close-fitting receive coil arrays inside the MRI scanner. "We placed such a metasurface under the patient's head, after that, the local sensitivity increased by 50 percent. This allowed us to obtain higher image and spectroscopic signals from the occipital cortex. Such devices could potentially reduce the duration of MRI studies and improve its comfort for subjects," says Rita Schmidt, the first author of the paper and researcher at the Department of Radiology of Leiden University Medical Center. The metasurface, placed between a patient and the receive coils, enhances the signal-to-noise ratio in the region of interest. "This ratio limits the MRI sensitivity and duration of the procedure," notes Alexey Slobozhanyuk, research fellow at the Department of Nanophotonics and Metamaterials of ITMO University. "Often, the scans must be repeated many times and the signals added together. Using this metasurface reduces this requirement. Conventionally, an examination that now takes 20 minutes may only need 10 in the future. A hospitals that serves 10 patients a day will be able to serve 20 with our development." Alternatively, according to the scientists, the metasurface could be used to increase the image resolution. "The size of voxels, or 3-D-pixels, is also limited by the signal-to-noise ratio. Instead of accelerating the procedure, we can adopt an alternative approach and acquire more detailed images," says Andrew Webb, the leader of the project, professor of radiology at Leiden University Medical Center. Until now, no one has integrated metamaterials into close-fitting receive arrays because their dimensions are much too large. The novel ultra-thin design of this metasurface helped to solve the issue. "Our technology can be applied for producing metamaterial-inspired, ultra-thin devices for many different types of MRI scans, but in each case, one should first carry out a series of computer simulations, as we have done in this work. One needs to make sure that the metasurface is appropriately coupled," concludes Rita Schmidt. More information: Rita Schmidt et al, Flexible and compact hybrid metasurfaces for enhanced ultra high field in vivo magnetic resonance imaging, Scientific Reports (2017). DOI: 10.1038/s41598-017-01932-9


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 | 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


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.

Loading ITMO collaborators
Loading ITMO collaborators