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  • richardmitnick 12:25 pm on September 19, 2017 Permalink | Reply
    Tags: EPFL, , Tilt-less electron microscopy   

    From EPFL: “New microscopy method offers one-shot 3D imaging of nanostructures” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    07.09.17 [Where has this been hiding?]
    Nik Papageorgiou

    1
    Superposed, tilt-less electron microscopy stereo image (color-filtered) of carbon nanospheres decorated with nanoparticles. The same structures appear in red and blue and the nanoparticles are slightly shifted according to their 3D distribution in the carbon sphere. This image shows the applicability of the new tilt-less 3D imaging techniques to other structures. © Cécile Hébert/Emad Oveisi/EPFL

    EPFL scientists have developed a scanning transmission electron microscopy method that can quickly and efficiently generate 3D representations of curvilinear nanostructures.

    Physical and biological sciences increasingly require the ability to observe nano-sized objects. This can be accomplished with transmission electron microscopy (TEM), which is generally limited to 2D images. Using TEM to reconstruct 3D images instead usually requires tilting the sample through an arc to image hundreds of views of it and needs sophisticated image processing to reconstruct their 3D shape, creating a number of problems. Now, EPFL scientists have developed a scanning transmission electron microscopy (STEM) method that generates fast and reliable 3D images of curvilinear structures from a single sample orientation. The work is published in Scientific Reports.

    The labs of Cécile Hébert and Pascal Fua at EPFL have developed an electron microscopy method that can obtain 3D images of complex curvilinear structures without needing to tilt the sample. The technique, developed by EPFL researcher Emad Oveisi, relies on a variation of TEM called scanning TEM (STEM), where a focused beam of electrons scans across the sample.

    The novelty of the method is that it can acquire images in a single shot, which opens the way to study samples dynamically as they change over time. Furthermore, it can rapidly provide a “sense” of three dimensions, just like we would have with a 3D cinema.

    “Our own eyes can see 3D representations of an object by combining two different perspectives of it, but the brain still has to complement the visual information with its previous knowledge of the shape of certain objects,” says Hébert. “But in some cases with TEM we know something about what shape the sample’s structure must have. For example, it can be curvilinear, like DNA or the mysterious defects that we call ‘dislocations’, which govern the optoelectronic or mechanical properties of materials.”

    The classical approach

    TEM is a very powerful technique that can provide high-resolution views of objects just a few nanometers across — for example, a virus, or a crystal defect. However TEM only provides 2D images, which are not enough for identifying the 3D morphology of the sample, which often limits research. A way around this problem is to acquire consecutive images while rotating the specimen through a tilt arc. The images can then be reconstructed on a computer to gain a 3D representation of the sample.

    The problem with this approach is that it requires extreme precision on hundreds of images, which is hard to achieve. The 3D images generated in this way are also prone to artefacts, which are difficult to remove afterwards. Finally, taking multiple images with TEM requires shooting a beam of electrons though the sample each time, and the total dose can actually affect the sample’s structure during acquisition and produce a false or corrupted image.

    The new approach

    In the STEM method developed by the researchers, the sample stands still while the microscope sends two beams of electrons tilted against each other, and two detectors are simultaneously used to record the signal. As a result, the process is much faster than previous TEM 3D imaging technique and with almost no artefacts.

    The team also used a sophisticated image-processing algorithm, developed in collaboration with Fua’s CVlab, to reduce the number of images needed for 3D reconstruction to only two images taken at different electron beam angles. This increases the efficiency of data acquisition and 3D reconstruction by one to two orders of magnitude compared to conventional TEM 3D techniques. At the same time, it prevents structural changes on the sample due to high electron doses.

    Because of its speed and immunity to problems with standard TEM methods, this “tilt-less 3D electron imaging” method is of great advantage for studying radiation-sensitive, polycrystalline, or magnetic materials. And because the total electron dose is reduced to a single scan, the method is expected to open up new avenues for real-time 3D electron imaging of dynamic material and biological processes.

    Funding

    Swiss National Science Foundation

    Reference

    Emad Oveisi, Antoine Letouzey, Duncan T.L. Alexander, Quentin Jeangros, Robin Schäublin, Guillaume Lucas, Pascal Fua, Cécile Hébert. Tilt-less 3-D electron imaging and reconstruction of complex curvilinear structures.Scientific Reports, 06 September 2017. DOI: 10.1038/s41598-017-07537-6

    See the full article here .

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

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  • richardmitnick 1:51 pm on September 14, 2017 Permalink | Reply
    Tags: , , , , , EPFL,   

    From EPFL: “Unexpected facets of Antarctica emerge from the labs” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    14.09.17
    Sarah Perrin

    1
    the Akademik Treshnikov Russian icebreaker

    Six months after the Antarctic Circumnavigation Expedition ended, the teams that ran the 22 scientific projects are hard at work sorting through the many samples they collected. Some preliminary findings were announced during a conference in Crans Montana organized by the Swiss Polar Institute, who just appointed Konrad Steffen as new scientific director (see the interview below).

    Nearly 30,000 samples were taken during the Antarctic Circumnavigation Expedition (ACE). And now, barely six months after the voyage ended, the research teams tasked with analyzing the samples have already produced some initial figures and findings. These were presented in Crans Montana during a conference put together earlier this week by the Swiss Polar Institute (SPI), the EPFL-based entity that ran the expedition. The event, called “High altitudes meet high latitudes,” brought together world-renowned experts in polar and alpine research in an exercise aimed at highlighting the many similarities between these two fields of study.

    Over the course of three months – from December 2016 to March 2017 – 160 researchers from 23 different countries sailed around the Great White Continent on board a Russian icebreaker. They ran 22 research projects in an effort to learn more about the impact of climate change on these fragile and little-known regions. The valuable samples, taken from the Southern Ocean, the atmosphere and a handful of remote islands, are now back at the labs of the 73 scientific institutions involved in the expedition.

    1
    The route of the ACE expedition.

    Most of the teams that ran the 22 projects are still carrying out the preliminary task of sorting through and identifying the samples, which means the initial results are necessarily incomplete and provisional. It is only later that the samples will be analyzed. Some important observations can nevertheless be made at this stage.

    A solid database

    The sum total of the samples collected represents an impressive and valuable database. The SPI must now come up with ways to organize, group and present the data so that researchers can readily access and make use of it. What’s more, “the large number of potential collaborations and exchanges between projects is becoming clear,” says David Walton, the chief scientist on the expedition. “Some research projects have been found to have links with as much as nine others.” And some startling figures have already been released – here is a look at just a few of them.

    For the SubIce project, around 100 meters of ice cores were taken on five subantarctic islands and the Mertz Glacier, which sits on the edge of the Antarctic continent. The chemical composition of the cores will be analyzed in an attempt to trace climate change over recent decades. In some places, like Balleny, Peter 1st or Bouvet Islands, it was the first time an ice sample had ever been taken. “Of all the islands where we were able to take samples, that last one was the farthest from the continent,” says Liz Thomas, from British Antarctic Survey. “It’s also the island where the ice in the samples is the most granular. Our findings confirm significant seasonal variations at this location.”

    The air on the continent is so pure that even the hottest cup of tea does not produce any steam. “No particles, no clouds,” explains Julia Schmale, a researcher with the Paul-Scherrer-Institute who measured for aerosols – tiny chemical particles like grains of sand, dust, pollen, soot, sulfuric acid, and so on – throughout the expedition. These particles attach to water molecules and aggregate to form clouds. On Mertz Glacier, her measurements revealed aerosol levels below 100 particles per cm3, which is less than the level found in a cleanroom.

    Christel Hassler and her team, from the University of Geneva, studied bacteria and virus populations in the Southern Ocean. The team took some 170 samples from all around the continent. For the time being, their work consists in isolating and culturing the numerous cells found in the samples. “We will then analyze their DNA in order to identify them,” says Marion Fourquez, a marine biologist. “That will show us whether we have come across any new bacterial strains that have yet never been observed in this region.”

    2
    Bacteria collected on the sedimental floor beneath Mertz glacier, on the Antarctic continent, as part of Christel Hassler’s project (University of Geneva). ©M.Fourquez.

    One of the subsequent lines of research will be to determine their geographical distribution. The researchers will be able to tell if there’s a link between the presence of a given bacterium and that of other microorganisms by comparing their data with data from other projects, like Nicolas Cassar’s. Cassar, from Duke University in the United States, measured concentrations of phytoplankton, which sit at the very bottom of the region’s food chain. “This approach worked out well, and we have nearly continuous samples from along the entire route,” says Walton.

    More than 3,000 whales

    Brian Miller, from the Australian Antarctic Division, was interested in somewhat larger animals. For his project, he used a piece of sophisticated acoustic equipment to listen for and count the number of whales in the Southern Ocean. Walton notes: “In around 500 hours of recordings, the researchers counted for example over 3,000 individual blue whales, although we actually saw only three or so at the surface.” These cetaceans appear to be particularly plentiful in the depths of the Ross Sea.

    Peter Ryan, from the University of Cape Town in South Africa, observed and counted bird populations. He discovered that one of the largest colonies of king penguins, on Pig Island in the Crozet archipelago, had declined drastically – he estimates the numerical loss to be around 75%. “That’s around half a million animals,” says Walton. “We don’t know if they’ve died or migrated to other colonies, like the one in St. Andrews Bay, in South Georgia, which is actually in a growth phase.”

    More complete and detailed results will be published in the coming months.

    Detailed information on SPI and ACE can be found on http://spi-ace-expedition.ch

    __________________________________________________________________________

    “We urgently need to coordinate our efforts.”

    3
    Konrad Steffen, a glaciologist and the new scientific director of the Swiss Polar Institute (SPI), has been involved in polar research for the past 40 years. His work has focused primarily on the Arctic, particularly the changes taking place within Greenland’s ice sheet. He is also a professor at ETH Zurich and director of the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.

    Professor Steffen, why is the Swiss Polar Institute so necessary today?

    Research in this field tended to be conducted by small groups that organized their own expeditions and ran their own projects. In Switzerland, there had never been any kind of initiative aimed at coordinating all this work. The effects of climate change on polar and alpine regions are now so evident that we urgently need to coordinate our efforts and conduct cross-disciplinary research. This is what we did with the ACE project, where researchers from fields like oceanography, glaciology and biology came together in an attempt to improve our understanding of the climate-change process in a region.

    What for you is the top priority when it comes to the polar regions?

    At the SPI, one of our aims is to devise a strategic plan within the scientific community. More personally, I think that we urgently need to assess the mass balance of ice sheets across the globe. That’s what will have the greatest and swiftest impact in terms of rising sea levels and changes to our coastlines. Instead of studying individual glaciers in the Alps, we need to look at the bigger picture and observe in detail how the atmosphere interacts with large ice sheets, such as those in Greenland and the Antarctic. We need to connect the dots to see how the system as a whole is affected.

    What made the ACE such an innovative expedition?

    There have been many scientific expeditions to the Antarctic, but they usually only cover part of the continent. This was the first time that an expedition went all the way around the continent in one three-month period, studying all the oceans during the same season. That provides a fuller picture of the issues, such as microplastics – during the trip, we really saw that they were everywhere! The expedition also served up attractive career opportunities for budding young scientists and enabled several research groups to establish long-term partnerships.

    Are any other expeditions in the pipeline?

    Yes, the next one is planned for 2019. The aim is to sail around Greenland. We are in the process of looking for a vessel and determining what sort of research will be undertaken during the trip.

    __________________________________________________________________________

    See the full article here .

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 1:46 pm on September 6, 2017 Permalink | Reply
    Tags: A scintillating fiber tracker dubbed SciFi, , , EPFL, , , ,   

    From EPFL via phys.org: “Particle physicists on a quest for ‘new physics'” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    phys.org

    Contacts

    Sandy Evangelista Press
    sandy.evangelista@epfl.ch
    +41 79 502 81 06

    Aurelio Bay High Energy Physics Laboratory 1
    aurelio.bay@epfl.ch
    +41 21 693 04 74

    Olivier Schneider High Energy Physics Laboratory 2
    olivier.schneider@epfl.ch
    +41 21 693 05 07

    Tatsuya Nakada High Energy Physics Laboratory 3
    tatsuya.nakada@epfl.ch
    +41 21 693 04 75

    1
    After five years of work, EPFL’s physicists, together with some 800 international researchers involved in the CERN’s LHCb project, have just taken an important step by building a new detector — a scintillating fiber tracker dubbed SciFi — to harvest more data from the collider. Credit: CERN

    3
    Construction of the tracker, which incorporates 10,000 kilometers of scintillating fibers each with a diameter of 0.25mm, has already begun. When particles travel through them, the fibers will give off light signals that will be picked up by light-amplifying diodes. The scintillating fibers will be arranged in three panels measuring five by six meters, installed behind a magnet, where the particles exit the LHC accelerator collision point. The particles will pass through several of these fiber ‘mats’ and deposit part of their energy along the way, producing some photons of light that will then be turned into an electric signal.

    The Large Hadron Collider (LHC) at CERN, the European Organization for Nuclear Research, produces hundreds of millions of proton collisions per second. But researchers working on the Large Hadron Collider beauty (LHCb) experiment, which involves physicists from EPFL, can only record 2,000 of those collisions, using one of the detectors installed on the accelerator. So in the end, this technological marvel leaves the physicists wanting more. They are convinced that the vast volume of uncaptured data holds the answers to several unresolved questions.

    In elementary particle physics, the Standard Model – the theory that best describes phenomena in this field – has been well and truly tried and tested, yet the researchers know that the puzzle is not complete. That’s why they are studying phenomena that are not accounted for by the Standard Model. This quest for “new physics” seeks to explain the disappearance of antimatter after the Big Bang and the nature of the dark matter that, although it represents around 30% of the universe, can only be detected by astronomical measurements at this point.

    “To extract more information from the LHC data, we need new technologies for our LHCb detector,” says Aurelio Bay from EPFL’s Laboratory for High Energy Physics. EPFL has teamed up with several research institutes to develop the new equipment that will upgrade the experiment in 2020.

    Using scintillating fiber to detect particles

    Data on how the particles traverse the fibers will be enough to reconstruct their trajectory. The physicists will then use this information to restore their primitive physical state. “What we will essentially be doing is tracing these particles’ journey back to their starting point. This should give us some insight into what happened 14 billion years ago, before antimatter disappeared, leaving us with the matter we have today,” says Bay.

    Huge data flows

    SciFi is a key component for acquiring data at the highest speed, as it includes filters that are designed to preserve only useful data. In an ideal world, the physicists would collect and analyze all of the data without needing to use too many filters. But that would involve a massive amount of data.

    “We may already be at the limit, because we of course have to save the data somewhere. First we use magnetic storage and then we distribute the data on the LHC GRID, which includes machines in Italy, the Netherlands, Germany, Spain, at CERN, and in France and the UK. Many countries are taking part, and numerous studies on this data are being run simultaneously,” adds Bay. He points to his computer screen: red is used to denote programs that are not working well or those that have been trying for several days to be included among the priorities.

    Bay neatly puts this initiative into a physicist’s perspective: “If the LHC doesn’t have enough power to uncover new physics, it’s all over for my generation of physicists! We will have to come up with a new machine, for the next generation.”

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 10:44 am on September 4, 2017 Permalink | Reply
    Tags: , Carving diamonds for optical components, EPFL, Microscopically cutting diamonds into a particular shape and smoothing them at an atomic level   

    From EPFL: “Carving diamonds for optical components” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    04.09.17
    Laure-Anne Pessina

    1
    Thanks to a new technique developed at EPFL, optical diffraction gratings can now be made out of pure diamond, with their surfaces smoothed down to the very last atom. These new devices can be used to alter the wavelength of high-powered lasers or in cutting-edge spectrographs.

    A team of EPFL researchers has developed an unconventional way of microscopically cutting diamonds into a particular shape and smoothing them at an atomic level. This new technique, which will be presented at the International Conference on Diamond and Carbon Materials DCM2017 on 5 September, makes it possible to manufacture diffraction gratings out of pure diamond, which has unique properties that are ideal for both spectroscopy and the optical components used in high-powered lasers.

    Diffraction gratings are made up of parallel grooves that break up light into its spectral components, kind of like a prism. These gratings are usually made out of glass and silicon, materials that have already been used in spectrographs and to alter the color emitted by lasers.

    The team, led by Niels Quack, a SNSF-funded professor at the School of Engineering, has now found a way to make these gratings out of single crystal diamond as well, opening up the field to an array of new possibilities. Diamonds are unmatched in terms of their thermal conductivity, which is between five and ten times greater than that of any other material used for this purpose. Diamonds are also extremely hard and work well with UV rays, as well as infrared and visible beams. “Diamonds are chemically inert, which means that even the most aggressive chemical substances can’t attack them. But it also means that they are very difficult to machine,” explains Dr. Quack. “So this new way of carving diamonds could prove very useful.”

    Using oxygen to cut diamonds

    The technique developed by the researchers is groundbreaking because it allows them to etch well defined shapes into millimeter sized single-crystal diamond plates, with the grooves separated by just a few microns and with incredibly smooth surfaces. To develop their technique, the researchers used diamonds created synthetically through chemical vapor deposition.

    The diamonds are etched in several stages. First, a hard mask is deposited and structured on the surface of a diamond plate, which is then exposed to an oxygen plasma. The oxygen ions in the plasma are accelerated onto the surface of the diamond by an electric field. Where not covered by the hard mask, the oxygen ions remove carbon atoms from the diamond’s surface one by one. “By adjusting the intensity of the electric field, we can alter the shape we etch into the diamond,” explains Dr. Quack. “For the diffraction gratings, we carve out triangular grooves that are just a few microns apart from each other. We adjust the process parameters to selectively reveal a set of well-defined crystal planes, allowing us to create V-shaped grooves that are smoothed down almost to the atomic level. It is impossible to get this kind of precision when the diamonds are simply cut with a laser.”

    This new technology, which was developed using the facilities in the Center of MicroNanoTechnology (CMI), is the subject of a recent patent application. The same principle has already been used using silicon, but it had never before been demonstrated in diamond. In recognition of the importance of this contribution, doctoral student Marcell Kiss has been shortlisted as one of the six finalists of the Young Scholar Award DCM2017.

    EPFL Quack Group Q-LAB

    The researchers are collaborating on this development with LakeDiamond SA, a Swiss manufacturing company of high purity single crystal diamond substrates.

    The project is funded by the Swiss National Science Foundation (SNF) and by the Gebert Rüf Stiftung.

    See the full article here .

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 4:16 pm on June 23, 2017 Permalink | Reply
    Tags: Broadband light harvesting and energy storage, broadband optical camouflaging (“invisibility cloaking”), Casting aside reciprocity, EPFL, Medicine and the environment and telecommunications, More electromagnetic energy can be stored in wave-guiding systems than previously thought, On-chip spectroscopy, , Q factor at Western Electric, The trick was to create asymmetric resonant or wave-guiding systems using magnetic fields   

    From EPFL: “A 100-year-old physics problem has been solved at EPFL” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    1
    Generic image illustrating wave-interference and resonant energy transfer from
    one source to another distant source or object, pertaining to the fundamental concept of
    resonances. No image credit.

    23.06.17
    Laure-Anne Pessina

    EPFL researchers have found a way around what was considered a fundamental limitation of physics for over 100 years. They were able to conceive resonant systems that can store electromagnetic waves over a long period of time while maintaining a broad bandwidth. Their study, which has just been published in Science, opens up a number of doors, particularly in telecommunications.

    At EPFL, researchers challenge a fundamental law and discover that more electromagnetic energy can be stored in wave-guiding systems than previously thought. The discovery has implications in telecommunications. Working around the fundamental law, they conceived resonant and wave-guiding systems capable of storing energy over a prolonged period while keeping a broad bandwidth. Their trick was to create asymmetric resonant or wave-guiding systems using magnetic fields.

    The study, which has just been published in Science, was led by Kosmas Tsakmakidis, first at the University of Ottawa and then at EPFL’s Bionanophotonic Systems Laboratory run by Hatice Altug, where the researcher is now doing post-doctoral research.

    This breakthrough could have a major impact on many fields in engineering and physics. The number of potential applications is close to infinite, with telecommunications, optical detection systems and broadband energy harvesting representing just a few examples.

    Casting aside reciprocity

    Resonant and wave-guiding systems are present in the vast majority of optical and electronic systems. Their role is to temporarily store energy in the form of electromagnetic waves and then release them. For more than 100 hundred years, these systems were held back by a limitation that was considered to be fundamental: the length of time a wave could be stored was inversely proportional to its bandwidth. This relationship was interpreted to mean that it was impossible to store large amounts of data in resonant or wave-guiding systems over a long period of time because increasing the bandwidth meant decreasing the storage time and quality of storage.

    This law was first formulated by K. S. Johnson in 1914, at Western Electric Company (the forerunner of Bell Telephone Laboratories). He introduced the concept of the Q factor, according to which a resonator can either store energy for a long time or have a broad bandwidth, but not both at the same time. Increasing the storage time meant decreasing the bandwidth, and vice versa. A small bandwidth means a limited range of frequencies (or ‘colors’) and therefore a limited amount of data.

    Until now, this concept had never been challenged. Physicists and engineers had always built resonant systems – like those to produce lasers, make electronic circuits and conduct medical diagnoses – with this constraint in mind.

    But that limitation is now a thing of the past. The researchers came up with a hybrid resonant / wave-guiding system made of a magneto-optic material that, when a magnetic field is applied, is able to stop the wave and store it for a prolonged period, thereby accumulating large amounts of energy. Then when the magnetic field is switched off, the trapped pulse is released.

    With such asymmetric and non-reciprocal systems, it was possible to store a wave for a very long period of time while also maintaining a large bandwidth. The conventional time-bandwidth limit was even beaten by a factor of 1,000. The scientists further showed that, theoretically, there is no upper ceiling to this limit at all in these asymmetric (non-reciprocal) systems.

    “It was a moment of revelation when we discovered that these new structures did not feature any time-bandwidth restriction at all. These systems are unlike what we have all been accustomed to for decades, and possibly hundreds of years», says Tsakmakidis, the study’s lead author. “Their superior wave-storage capacity performance could really be an enabler for a range of exciting applications in diverse contemporary and more traditional fields of research.” Hatice Altug adds.

    Medicine, the environment and telecommunications

    One possible application is in the design of extremely quick and efficient all-optical buffers in telecommunication networks. The role of the buffers is to temporarily store data arriving in the form of light through optical fibers. By slowing the mass of data, it is easier to process. Up to now, the storage quality had been limited.+

    With this new technique, it should be possible to improve the process and store large bandwidths of data for prolonged times. Other potential applications include on-chip spectroscopy, broadband light harvesting and energy storage, and broadband optical camouflaging (“invisibility cloaking”). “The reported breakthrough is completely fundamental – we’re giving researchers a new tool. And the number of applications is limited only by one’s imagination,” sums up Tsakmakidis.

    —–

    Source: Breaking Lorentz reciprocity to overcome the time-bandwidth limit in physics and engineering

    Cover image capture: Generic image illustrating wave-interference and resonant energy transfer from
    one source to another distant source or object, pertaining to the fundamental concept of
    resonances.

    Study conducted by:

    Kosmas Tsakmakidis, lead author, former researcher at the University of Ottawa and currently an EPFL Fellow in EPFL’s Bionanophotonic Systems Laboratory
    Linfang Shen and collaborators, Institute of Space Science and Technology, Nanchang University, Nanchang, China and State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, China
    Prof. Robert Boyd and collaborators, University of Ottawa
    Prof. Hatice Altug, director of EPFL’s Bionanophotonic Systems Laboratory
    Prof. Alexandre Vakakis, University of Illinois at Urbana-Champaign

    See the full article here .

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 11:07 am on June 8, 2017 Permalink | Reply
    Tags: , Center for MicroNanotechnology (CMi) at EPFL, EPFL, EPFL’s Laboratory of Photonics and Quantum Measurements (LPQM), Institute of Microstructure Technology (IMT), KIT’s Institute of Photonics and Quantum Electronics (IPQ), LiGenTec SA, Optical frequency combs, , , , Wavelength division multiplexing (WDM)   

    From EPFL: “Ultra-fast optical data transfer using solitons on a photonic chip” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    08.06.17
    Nik Papageorgiou

    1
    Optical micro resonators made from silicon nitride on a chip using for soliton based communications. © V. Brasch (LPQM, EPFL)
    Researchers from EPFL and Karlsruhe Institute of Technology use a soliton frequency combs from optical microresonators to transmit data at speeds of more than 50 terabits per second.

    Optical solitons are special wave packages that propagate without changing their shape. They are ubiquitous in nature, and occur in Plasma Physics, water waves to biological systems. While solitons also exist in optical fiber, discovered at Bell labs in the 1980’ies, there technological use so far has been limited. While researchers studied their use for optical communication, eventually the approach was abandoned. Now, a collaboration of a research group at KIT’s Institute of Photonics and Quantum Electronics (IPQ) and Institute of Microstructure Technology (IMT) with EPFL’s Laboratory of Photonics and Quantum Measurements (LPQM) have shown that solitons may experience a comeback: Instead of using a train of soliton pulses in an optical fiber, they generated continuously circulating optical solitons in compact silicon nitride optical microresonators. These continuously circulating solitons lead to broadband optical frequency combs. Two such superimposed frequency combs enabled massive parallel data transmission on 179 wavelength channels at a data rate of more than 50 terabits per second – a record for frequency combs. The work is published in Nature [link is below].

    Optical frequency combs, for which John Hall and Theodor W. Hänsch were awarded the Nobel Prize in Physics in 2005, consist of a multitude of neighboring spectral lines, which are aligned on a regular equidistant grid. Traditionally, frequency combs serve as high-precision optical references for measurement of frequencies. The invention of so-called Kerr frequency combs, which are characterized by large optical bandwidths and by line spacings that are optimal for communications, make frequency combs equally well suited for data transmission. Each individual spectral line can be used for transmitting a data signal.

    In their experiment, the researchers from KIT and EPFL used optical silicon nitride micro-resonators on a photonic chip that can easily be integrated into compact communication systems. For the communications demonstration, two interleaved frequency combs were used to transmit data on 179 individual optical carriers, which completely cover the optical telecommunication C and L bands and allow a transmission of data rate of 55 terabits per second over a distance of 75 kilometers. “This is equivalent to more than five billion phone calls or more than two million HD TV channels. It is the highest data rate ever reached using a frequency comb source in chip format,” explains Christian Koos, professor at KIT’s IPQ and IMT and recipient of a Starting Independent Researcher Grant of the European Research Council (ERC) for his research on optical frequency combs.

    The components have the potential to reduce the energy consumption of the light source in communication systems drastically. The basis of the researchers’ work are solitons generated in low-loss optical silicon nitride micro-resonators. In these, an optical soliton state was generated for the first time by Kippenberg’s lab at EPFL in 2014. ”The soliton forms through nonlinear processes occurring due to the high intensity of the light field in the micro-resonator” explains Kippenberg. The microresonator is only pumped through a continuous-wave laser from which, by means of the soliton, hundreds of new equidistant laser lines are generated. The silicon nitride integrated photonic chips are grown and fabricated in the Center for MicroNanotechnology (CMi) at EPFL. Meanwhile, a startup from LPQM, LiGenTec SA, is also offering access to these photonic integrated circuits to interested academic and industrial research laboratories.

    The work shows that microresonator soliton frequency comb sources can considerably increase the performance of wavelength division multiplexing (WDM) techniques in optical communications. WDM allows to transmit ultra-high data rates by using a multitude of independent data channels on a single optical waveguide. To this end, the information is encoded on laser light of different wavelengths. For coherent communications, microresonator soliton frequency comb sources can be used not only at the transmitter, but also at the receiver side of WDM systems. The comb sources dramatically increase scalability of the respective systems and enable highly parallel coherent data transmission with light. According to Christian Koos, this is an important step towards highly efficient chip-scale transceivers for future petabit networks.

    This work was supported by the European Research Council (Starting Grant ‘EnTeraPIC’), the European Union (project BigPipes), the Alfried Krupp von Bohlen und Halbach Foundation, the Karlsruhe School of Optics & Photonics (KSOP), and the Helmholtz International Research School for Teratronics (HIRST), the Erasmus Mundus Doctorate Program Europhotonics, the Deutsche Forschungsgemeinschaft (DFG), the European Space Agency, the US Air Force (Office of Scientific Research), the Swiss National Science Foundation (SNF), and the Defense Advanced Research Program Agency (DARPA) via the program Quantum Assisted Sensing and Readout(QuASAR).

    Reference

    Pablo Marin-Palomo, Juned N. Kemal, Maxim Karpov, Arne Kordts, Joerg Pfeifle, Martin H. P. Pfeiffer, Philipp Trocha, Stefan Wolf, Victor Brasch, Miles H. Anderson, Ralf Rosenberger, Kovendhan Vijayan, Wolfgang Freude, Tobias J. Kippenberg, Christian Koos. Microresonator solitons for massively parallel coherent optical communications.Nature 08 June 2017.

    See the full article here .

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    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 8:31 am on May 20, 2017 Permalink | Reply
    Tags: , , , , , , EPFL   

    From EPFL: “Software developed at EPFL used to control a flotilla of satellites” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    1
    © 2017 EPFL

    19.05.17 – This past week, 28 CubeSats were released from the International Space Station (ISS). Eight of them are running EPFL software that was originally developed for SwissCube.

    Code name: QB50. This refers to the European research program begun in early 2016 with the aim of launching 50 miniature satellites – CubeSats – into orbit around the Earth. Their mission: to observe and measure the thermosphere, which is the layer of the atmosphere from 100 to 600 kilometers above the Earth’s surface. Research institutes and universities from 23 countries are involved in the project, and their attention was focused on the skies this past week: on Monday, the ISS began launching the CubeSats that they developed.

    2
    (Ejection d’un CubeSat. © NASA)

    Seven years ago, EPFL sent the SwissCube into space. That was the first Swiss satellite, and it was designed and built by students. EPFL may not have a satellite on board this time around, but it is involved in the control systems of eight of the 28 satellites that entered orbit this past week. “We developed satellite control software for SwissCube – called simply Satellite Control System (SCS) – that is extremely lean and sturdy,” says Muriel Richard, from EPFL’s Space Engineering Center (eSpace). “Using a secure and automated process, SCS encodes the instructions that need to be sent to the satellite, transmits them when the satellite is flying over a base station and receives information back from the satellite.”

    Eight organizations from seven different countries – Turkey, Taiwan, South Korea, Israel, Spain, Ukraine and China – chose EPFL’s open-source software, which they adapted to their own needs. “This is extremely positive and a real boost for our work,” says Richard, who noted that SCS is also able to control larger satellites.

    EPFL’s software has been chosen for other ongoing projects as well. It will run CleanSpace One, a satellite that is being designed to de-orbit SwissCube so that it does not end up as more space debris. It will also control the first two prototypes of a planned constellation of 60 nanosatellites; the prototype launch, scheduled for next year, is being run by EPFL startup ELSE. These projects are helping to put EPFL at the center of a growing ecosystem of specialized space-related expertise.

    See the full article here .

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  • richardmitnick 7:38 am on May 19, 2017 Permalink | Reply
    Tags: , , , Baryonic Oscillation Spectroscopic Survey [BOSS], , , EPFL,   

    From EPFL: “Astronomers make the largest map of the Universe yet” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    19.05.17
    Nik Papageorgiou

    1
    One of the SDSS telescopes at Apache Point Observatory in New Mexico (USA) ©SDSS

    Astronomers of the extended Baryonic Oscillation Spectroscopic Survey [BOSS], led by EPFL Professor Jean-Paul Kneib, used the Sloan telescope to create the first map of the Universe based entirely on quasars.

    BOSS Supercluster Baryon Oscillation Spectroscopic Survey (BOSS)

    Quasars are incredibly bright and distant points of light powered by supermassive black holes. As matter and energy fall into the black hole, they heat up to incredible temperatures and begin to glow with excessive brightness. By observing this cosmic glow, the scientists of the multi-institutional Sloan Digital Sky Survey (SDSS), which includes EPFL, have constructed the largest map of the distant Universe to-date. The work will be published in the Monthly Notices of the Royal Astronomical Society.

    Quasars are supermassive black holes at the centers of galaxies and they radiate huge amounts of electromagnetic energy. “Because quasars are so bright, we can see them all the way across the Universe,” says study co-leader Ashley Ross (Ohio State University). “That makes them the ideal objects to use to make the biggest map yet.”

    “These quasars are so far away that their light left them when the Universe was between 3 and 7 billion years old, long before the Earth even existed,” adds Gongbo Zhao from the National Astronomical Observatory of China, the study’s other co-leader.

    To construct the map, the scientists used the SDSS telescopes at New Mexico to measure accurate 3D positions for an unprecedented sample of over 147,000 quasars. This work took place during the first two years of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), one of the component research projects of SDSS led by Jean-Paul Kneib, Professor of Astrophysics at EPFL. The SDSS telescope observations gave the astronomers the quasars’ distances, which they then used to pinpoint the quasars’ positions in a 3D map.

    But the scientists didn’t stop there; they wanted to use to understand the expansion history of the Universe. For this they went a step further and used a clever technique that involves “baryon acoustic oscillations” (BAOs). These are the present-day imprint of sound waves that travelled through the early Universe, when it was much hotter and denser than it is now. But when the Universe was 380,000 years old, conditions changed suddenly and the sound waves became “frozen” in place, imprinted in the 3D structure of the Universe we see today.

    The process that produced these frozen BAOs is simple, which means that scientists can have a very good idea of what BAOs must have looked like in the early Universe. So when we look at the 3D structure of the Universe today, it contains these ancient BAOs, but massively stretched out by the expansion of the universe.

    The astronomers used the observed size of a BAO as “standard ruler” to measure distances in their 3D map, the way we can estimate the length of a football field by measuring the apparent angle of a meter rule on one side. “You have meters for small units of length, kilometres or miles for distances between cities, and we have the BAO scale for distances between galaxies and quasars in cosmology,” says Pauline Zarrouk, a PhD student at Irfu/CEA (University Paris-Saclay) who measured the projected BAO scale.

    Working backwards in time, the SDSS astronomers covered a range of time periods never observed before. The study measured the conditions when the Universe was just 3 to 7 billion years old, more than 2 billion years before the Earth formed.

    See the full article here .

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  • richardmitnick 10:05 am on April 27, 2017 Permalink | Reply
    Tags: A new EPFL incubator for education technology, , , EPFL, , Swiss EdTech Collider   

    From EPFL: “A new EPFL incubator for education technology” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    27.04.17
    Sarah Bourquenoud

    1
    © Alain Herzog / EPFL 2017

    EPFL’s new Swiss EdTech Collider will be home to around 30 startups involved in developing new education technologies. This coworking space, which is being inaugurated today, will give these companies the chance to enhance their visibility among both clients and investors and to generate synergies. The startups will also have the opportunity to become involved in the cutting-edge research conducted by EPFL professors who specialize in education technology.

    For several years now, EPFL has played a leading role in developing digital education, particularly through its massive open online courses (MOOCs), which more than 1.5 million users have signed up for since they were launched in 2012. Digital education platforms are an ever-growing market, and investments in this area will exceed USD 250 billion in 2020 (according to the EdTechXGlobal and IBIS Capital report, 2016). In Europe alone, EUR 227 million was invested in this sector in 2016, primarily in France and Germany.

    With its new Swiss EdTech Collider, EPFL has taken a decisive step towards developing an international hub for digital education based in Switzerland.

    Entrepreneurs active in educational technologies and EPFL professors conducting cutting-edge research will be able to come together in this nearly 300m2 coworking space. Thanks to its location in the EPFL Innovation Park, this unique ecosystem will also benefit from being close to the EPFL campus and to the current Center for Digital Education and several research laboratories.

    The challenges of an increasingly digital society

    The main aim of the Swiss EdTech Collider is to contribute to the development of the education technology sector in Switzerland. Using new methods and solutions, the incubator will strive to meet the challenges of an increasingly digital society, from nursery schooling to continuing education for adults and corporate training. The latest studies in machine learning and data science will also be used to enhance research in the area of education.

    The Swiss EdTech Collider is managed by a not-for-profit association and has four EPFL professors on staff: Pierre Dillenbourg, Denis Gillet, Francesco Mondada and Marcel Salathé. The association will work in partnership with the Digital Switzerland initiative. The incubator received funding from EPFL, the Jacobs Foundation, the Henri Moser Foundation and the EPFL Innovation Park Foundation.

    See the full article here .

    Please help promote STEM in your local schools.

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    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 11:29 am on April 25, 2017 Permalink | Reply
    Tags: , Crystalline solar cells, EPFL   

    From EPFL: “A simplified fabrication process for high efficiency solar cells” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    25.04.17
    Author:Mediacom / CSEM

    1
    © 2017 CSEM / David Marchon

    A team of EPFL and CSEM researchers in Neuchâtel has featured in Nature Energy with an astonishing new method for the creation of crystalline solar cells. These cells have electrical contacts at the back, which removes all shadowing at the front. Thanks to this new inexpensive approach, the fabrication process is greatly simplified, with efficiencies in the laboratory already surpassing 23%.

    In the quest for more efficient crystalline silicon solar cells with low manufacturing costs, one of the most promising approaches is to bring all electrical contacts to the back of the device. This removes all shadowing at the front, increasing the current and the efficiency. This approach generally requires several delicate processing steps. Well-defined narrow negative and positive contact lines need to be created, which will then collect the electrons (negative charges) and holes (positive charges). This usually requires several steps of photolithography masking, to create the alternate positive (+) and negative (-) areas.

    The teams at the EPFL Photovoltaics laboratory and at the CSEM PV-center succeeded in establishing an innovative process in which the positive and negative contacts align automatically. This is made possible by depositing the first “negative” contact by a plasma process through a mask. Subsequently, a second layer (positive) is deposited over the full surface. The growth of this layer is such that the negative contact, even when placed under the positive contact, remains negative.

    Using this simple process, 25 cm2 solar cells have already reached 23.2% efficiency, with a potential to reach close to 26% efficiency. The researchers are working with the Meyer Burger Company, leading equipment makers for solar cell production lines, to work out industrial solutions for this kind of solar cells, and at the same time valorizing the so-called silicon heterojunctions technology, which served as the basis for this work.

    The research was funded by the Meyer Burger Company, the Commission for Technology and Innovation (CTI) and the Swiss Federal Office of Energy (SFOE). The work will continue within the European project H2020 Nextbase.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
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