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  • richardmitnick 3:35 pm on December 6, 2016 Permalink | Reply
    Tags: , Laser Technology,   

    From Technion via Futurism: “Scientists Have Created a Totally New Type of Laser With Light and Water Waves” 

    Technion bloc




    Dom Galeon

    In Brief

    Using a device smaller than the width of a human hair, scientists have produced laser radiation through the interaction of light and water waves, a first in the field of laser tech.
    This new type of laser could be used on tiny ‘lab-on-a-chip’ technologies, enabling researchers to more effectively study microscopic cells and test different drug therapies.

    Of Waves and Lightwaves

    There’s a new kid in town with respect to laser technology. Researchers at the Technion–Israel Institute of Technology have developed laser emissions through the interaction of light and water waves, combining two areas of study previously thought unrelated.

    Typically, lasers are produced by exciting electrons in atoms using energy from an outside source. This excitement causes the electrons to emit radiation as laser light. The Technion team, led by Tal Carmon, discovered that wave oscillations in a liquid device can produce laser radiation as well, according to the study published in Nature Photonics.

    This possibility had never been explored previously, Carmon told Phys.org, primarily due to enormous differences in frequencies between water waves on a liquid’s surface and light wave oscillations. The former have a low frequency of approximately 1,000 oscillations per second, while the latter have a higher frequency of around 1014 oscillations per second.

    The researchers built a device that used an optical fiber to deliver light into a small droplet of octane and water. It compensated for the otherwise low efficiency between light waves and water waves, allowing the two types to pass through each other approximately 1 million times within the droplet. The energy generated by this interaction leaves the droplet as the laser emission.

    Credits: The Technion-Israel Institute of Technology

    Greater Control

    This interaction between light and fluid happens on a scale smaller than the width of a human hair. Additionally, water is a million times softer than typical materials used in existing laser technology. Accordingly, the Technion researchers say the droplet deformation caused by this very small pressure from the the light is a million times greater than what’s seen in current optomechanical devices, so this laser tech would be easier to control.

    Because they would work on such a small scale and be easier to control, this new type of laser could open up a wealth of possibilities for tiny sensors that use a combination of light waves, water waves, and sound waves. They could be used on tiny ‘lab-on-a-chip’ technologies, enabling researchers to more effectively study microscopic cells and test different drug therapies that could lead to better healthcare down the road. Indeed, these tiny lasers could have big implications in the world of technology.

    See the full article here .

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  • richardmitnick 8:34 am on September 30, 2016 Permalink | Reply
    Tags: , Laser Technology, Matter and Antimatter, Physicists have figured out how to create matter and antimatter using light,   

    From Science Alert: “Physicists have figured out how to create matter and antimatter using light” 


    Science Alert

    Wikimedia Commons

    29 SEP 2016

    A team of researchers from the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS) has just announced that they managed to calculate how to create matter and antimatter using lasers.

    This means that, by focusing high-powered laser pulses, we might soon be able to create matter and antimatter using light.

    To break this down a bit, light is made of high-energy photons. When high-energy photons go through strong electric fields, they lose enough radiation that they become gamma rays and create electron-positron pairs, thus creating a new state of matter.

    “A strong electric field can, generally speaking, ‘boil the vacuum,’ which is full of ‘virtual particles,’ such as electron-positron pairs. The field can convert these types of particles from a virtual state, in which the particles aren’t directly observable, to a real one,” says Igor Kostyukov of IAP RAS, who references their calculations on the concept of quantum electrodynamics (QED).

    NASA Astrophysics

    A QED cascade is a series of processes that starts with electrons and positrons accelerating within a laser field. It will then be followed by the release of high-energy photons, electrons, and positrons.

    As high-energy photons decay, it will produce electron-positron pairs. Essentially, a QED cascade will lead to the production of electron positron high-energy photon plasmas – and while it perfectly illustrates the QED phenomenon, it is a theory that has yet to be observed under lab conditions.

    Based on this, researchers observed how intense laser pulses would interact with a foil via numerical simulations. Surprisingly, they discovered that there were more high-energy photons produced by the positrons versus electrons produced of the foil.

    And if you could produce a massive number of positrons via a corresponding experiment, you can conclude that most were generated via a QED cascade.

    As complicated as all that sounds, here’s the bottom line – this discovery can open new doors in terms of how we can efficiently and cost-effectively produce matter and antimatter, the latter of which can significantly change the way we power our spaceships.

    As has been previously noted, making this potential power source is not cheap:

    “The problem lies in the efficiency and cost of antimatter production and storage. Making 1 gram of antimatter would require approximately 25 million billion kilowatt-hours of energy and cost over a million billion dollars.”

    This work offers us a new way forward.

    Their study also offers major insight into the properties of different types of interactions that could eventually pave the way for practical applications, including the development of advanced ideas for the laser-plasma sources of high-energy photons and positrons that will exceed the brilliance of any available source we have today.

    “Next, we’re exploring the nonlinear stage when the self-generated electron-positron plasma strongly modifies the interaction,” the researchers add.

    “And we’ll also try to expand our results to more general configurations of the laser-matter interactions and other regimes of interactions – taking a wider range of parameters into consideration.”

    This article was originally published by Futurism.

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  • richardmitnick 3:04 pm on July 18, 2016 Permalink | Reply
    Tags: 3D printing could revolutionize laser design, Laser Technology,   

    From LLNL: “3D printing could revolutionize laser design” 

    Lawrence Livermore National Laboratory

    Jul. 18, 2016
    Jeremy Thomas

    Ibo Matthews inspects an in situ diagnostics test bench his team developed for studying laser-driven powder bed fusion additive manufacturing. High-speed thermal and optical mapping of the laser-powder interaction has enabled the team to reveal new physics associated with the process and helped guide high-performance computing simulations. Photo by Julie Russell.

    LLNL researchers are exploring the use of metal 3D printing to create strong, lightweight structures for advanced laser systems – an effort they say could alter the way lasers are designed in the future.

    In a Laboratory Directed Research and Development (LDRD) program, physicist Ibo Matthews and his team are experimenting with a new research-based metal 3D printer, one of only four of its kind in the world, using a customized software platform capable of unprecedented design control.

    The powder bed laser-melting printer, made by the Fraunhofer Institute for Laser Technology (ILT) and German startup Aconity 3D, was installed in December 2015. Lab engineers have added diagnostics and high-speed cameras to examine thermal emissions and to image the surface of parts as they’re being built. Matthews said the modifications will help the researchers determine how defects or deformations occur during the 3D printing process.

    “It’s very flexible; it allows us to change any of the parameters we want,” he said. “We’re developing confidence in what we’ve built. If any defects occur, it is our aim that the user can have a 3D map available at the end of the build that shows what and where it happened.”

    Matthews and his team are building on their experience in laser materials processing and interaction gained in support of both the National Ignition Facility (NIF) and directed energy projects to develop new approaches to metal 3D printing. Their work is part of an overall strategy to broaden the NIF & Photon Science (NIF&PS) laser applications portfolio and maintain core competencies in laser-matter interaction science. Moreover, NIF scientists are intrigued by the potential for the metal 3D printing platform to support lasers – not just at NIF, but in airborne systems that need to be extremely lightweight, such as those used for remote sensing and aerial scanning.

    “With precision, predictive control of 3D printing you can put the stiffness where you need it,” said Mike Carter, NIF&PS program director for Department of Defense Technologies. “You can create functionally graded structures for optical lasers and mounts that are impossible to make by conventional manufacturing methods.”

    NIF has utilized some metal parts printed at the Lab in structures for lasers. In order to use them in critical systems on a regular basis, however, researchers must be assured that each part is sound.

    To speed up the certification process, Lab engineers are attempting to shorten the development phase by taking a completely different approach – a “feed-forward” method based on computer modeling instead of trial and error. If successful, said Wayne King of LLNL’s Physical and Life Sciences Directorate, the research could fundamentally change the way metal components – including those used in optical systems – are designed and fabricated.

    “Unless you take a science-based approach to this, you won’t know why part A is different from part B,” King said. “We’re really pushing the state of the art. We’re at the beginning of seeing some applications of the technology already.”

    In the three-year LDRD project that began last year, Matthews and his team will be combining metal 3D printing with both high-fidelity optical diagnostics and high-performance computing to create more confidence in the parts they create.

    “What we’d like to do is drive this process based on simulation, and create a ‘digital fingerprint’ of certification based on optical monitoring to ensure the part is built right the first time,” Matthews said. “We’d like to be predictive, based on our physics models, to find out what we can expect with any given build and have monitoring data to show that predictions matched the outcome.”

    Matthews added that the Lab’s newest machine will go a long way toward discovering the capabilities and application of metal 3D printing for laser design.

    “It takes you from this black box to something you have control over,” he said. “It puts us two years ahead of where we would’ve been if we hadn’t bought it.”

    NIF&PS and the Lab’s Weapons and Complex Integration and Engineering directorates are jointly supporting the new printing platform.

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  • richardmitnick 10:13 am on June 28, 2016 Permalink | Reply
    Tags: , Laser Technology, , New mid-infrared laser system could detect atmospheric chemicals   

    From MIT: “New mid-infrared laser system could detect atmospheric chemicals” 

    MIT News
    MIT News
    MIT Widget

    June 28, 2016
    David L. Chandler | MIT News Office

    This diagram depicts the way a mid-infrared laser (red cylinder, left) can send a beam through the atmosphere that generates filaments of ionized air molecules (multicolored beam, center, shown with magnified view). These filaments, which can be kilometers long, help to keep the beam concentrated enough to generate mid-infrared light in air (blue cloud, right) that can reveal detailed chemical composition through spectral analysis (chart at right) of the light picked up by a mid-infrared detector (bottom). Diagram courtesy of the researchers.

    Researchers at MIT and elsewhere have found a new way of using mid-infrared lasers to turn regions of molecules in the open air into glowing filaments of electrically charged gas, or plasma. The new method could make it possible to carry out remote environmental monitoring to detect a wide range of chemicals with high sensitivity.

    The new system makes use of a mid-infrared ultra-fast pulsed laser system to generate the filaments, whose colors can reveal the chemical fingerprints of different molecules. The finding is being reported this week in the journal Optica, in a paper by principal investigator Kyung-Han Hong of MIT’s Research Laboratory of Electronics, and seven other researchers at MIT; in Binghamton, New York; and in Hamburg, Germany.

    Hong explains that such filaments, as generated by lasers in the near-infrared part of the electromagnetic spectrum, have been widely studied already because of their promise for uses such as laser-based rangefinding and remote sensing. The filament phenomenon, generated by high-power lasers, serves to counter the diffraction effects that usually take place when a laser beam passes through air. When the power level reaches a certain point and the filaments are generated, they provide a kind of self-guiding channel that keeps the laser beam tightly focused.

    But it is the mid-infrared (mid-IR) wavelengths, rather than the near-IR, that offer the greatest promise for detecting a wide variety of biochemical compounds and air pollutants. Researchers who have tried to generate mid-IR filaments in open air have had little success until now, however.

    Only one previous research team has ever succeeded in generating mid-IR laser filaments in air, but it did so at a much slower rate of about 20 pulses per second. The new work — which uses 1,000 pulses per second — is the first to be carried out at the high rates needed for practical detection tools, Hong says.

    “People want to use this kind of technology to detect chemicals in the far distance, several kilometers away,” Hong says, but they have had a hard time making such systems work. One key to this team’s success is the use of a high-power femtosecond laser with pulses just 30 femtoseconds, or millionths of a billionth of a second, long. The longer the wavelength, the more laser peak power is needed to generate the desired filaments, due to stronger diffraction, he says. But the team’s femtosecond laser, coupled with what is known as a parametric amplifier, provided the necessary power for the task. This new laser system has been developed together with Franz X. Kaertner in Hamburg and other group members for last several years. At these mid-IR wavelengths, Hong says, this device produces “one of the highest peak-power levels in the world,” producing 100 gigawatts (GW, or billion watts) of peak power.

    It takes at least 45 GW of power to generate the filaments at these mid-infrared wavelengths, he says, so this device easily meets that requirement, and the team proved that it did indeed work as expected. That now opens up the potential for detecting a very wide range of compounds in the air, from a distance.

    Using spectrally broadened mid-IR laser filaments, “we can detect virtually any kind of molecule you want to detect,” Hong says, including various biohazards and pollutants, by detecting the exact color of the filament. In the mid-IR range, the absorption spectrum of specific chemicals can be easily analyzed.

    So far, the experiments have been confined to shorter distances inside the lab, but the team expects that there’s no reason the same system wouldn’t work, with further development, at much larger scales. “This is just a proof-of-principle demonstration,” Hong says.

    This research “is one of the very first investigations of self-channeling of ultraintense mid-IR laser pulses in the air,” says Pavel Polynkin, an associate research professor of optical sciences at the University of Arizona, who was not involved in this work. “Whether there will be new and exciting applications, time will show.”

    “I think there is an agreement in the ultrafast laser community that the exploration of the mid-infrared spectral domain is going to be a new frontier in ultrafast laser science,” Polynkin adds. “The extension of intense atmospheric propagation regimes into the mid-IR spectral range certainly holds a lot of promise to overcome the limitations associated with the very well-explored near-IR spectral range, namely the very unstable propagation dynamics in the near-IR. The authors tapped into a new domain of intense nonlinear optics. Without a doubt there will be follow-up work.”

    The research team also included MIT postdoc Houkun Liang; doctoral student Peter Krogen PhD ’16; alumnus Chien-Jen Lai PhD ’14; adjunct professor and group leader Franz X. Kaertner at the University of Hamburg, Germany; and Assistant Professor Bonggu Shim and his doctoral students at Binghamton University in New York. This work was funded by U.S. Air Force Office of Scientific Research.

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  • richardmitnick 8:45 am on June 14, 2016 Permalink | Reply
    Tags: , Laser Technology, , Terahertz radiation and “phase locking”   

    From MIT: “New approach to microlasers” 

    MIT News

    MIT Widget
    MIT News

    June 13, 2016
    Larry Hardesty | MIT News Office

    Researchers at MIT and Sandia National Laboratories have designed a device that is an array of 37 microfabricated lasers on a single chip. Its power requirements are relatively low because the radiation emitted by all of the lasers is “phase locked,” meaning that the troughs and crests of its waves are perfectly aligned. Image courtesy of the researchers.

    Technique for “phase locking” arrays of tiny lasers could lead to terahertz security scanners.

    Terahertz radiation — the band of electromagnetic radiation between microwaves and visible light — has promising applications in security and medical diagnostics, but such devices will require the development of compact, low-power, high-quality terahertz lasers.

    In this week’s issue of Nature Photonics, researchers at MIT and Sandia National Laboratories describe a new way to build terahertz lasers that could significantly reduce their power consumption and size, while also enabling them to emit tighter beams, a crucial requirement for most practical applications.

    The work also represents a fundamentally new approach to laser design, which could have ramifications for visible-light lasers as well.

    The researchers’ device is an array of 37 microfabricated lasers on a single chip. Its power requirements are so low because the radiation emitted by all of the lasers is “phase locked,” meaning that the troughs and crests of its waves are perfectly aligned. The device represents a fundamentally new way to phase-lock arrays of lasers.

    In their paper, the researchers identified four previous phase-locking techniques, but all have drawbacks at the microscale. Some require positioning photonic components so closely together that they’d be difficult to manufacture. Others require additional off-chip photonic components that would have to be precisely positioned relative to the lasers. Hu and his colleagues’ arrays, by contrast, are monolithic, meaning they’re etched entirely from a single block of material.

    “This whole work is inspired by antenna engineering technology,” says Qing Hu, a distinguished professor of electrical engineering and computer science at MIT, whose group led the new work. “We’re working on lasers, and usually people compartmentalize that as photonics. And microwave engineering is really a different community, and they have a very different mindset. We really were inspired by microwave-engineer technology in a very thoughtful way and achieved something that is totally conceptually new.”

    Staying focused

    The researchers’ laser array is based on the same principle that underlies broadcast TV and radio. An electrical current passing through a radio antenna produces an electromagnetic field, and the electromagnetic field induces a corresponding current in nearby antennas. In Hu and his colleagues’ array, each laser generates an electromagnetic field that induces a current in the lasers around it, which synchronizes the phase of the radiation they emit.

    This approach exploits what had previously been seen as a drawback in small lasers. Chip-scale lasers have been an active area of research for decades, for potential applications in chip-to-chip communication inside computers and in environmental and biochemical sensing. But as the dimensions of a laser shrink, the radiation the laser emits becomes more diffuse. “This is nothing like a laser-beam pointer,” Hu explains. “It really radiates everywhere, like a tiny antenna.”

    If a chip-scale laser is intended to emit radiation in one direction, then any radiation it emits in lateral directions is wasted and increases its power consumption. But Hu and his colleagues’ design recaptures that laterally emitted radiation.

    In fact, the more emitters they add to their array, the more laterally emitted radiation is recaptured, lowering the power threshold at which the array will produce laser light. And because the laterally emitted radiation can travel long distances, similar benefits should accrue as the arrays grow even larger.

    “I’m a firm believer that all physical phenomena can be pros or cons,” Hu says. “You can’t just say unequivocally that such-and-such a behavior is universally a good or bad thing.”

    Tightening up

    In large part, the energy from the recaptured lateral radiation is re-emitted in the direction perpendicular to the array. So the beam emitted by the array is much tighter than that emitted by other experimental chip-scale lasers. And a tight beam is essential for most envisioned applications of terahertz radiation.

    In security applications, for instance, terahertz radiation would be directed at a chemical sample, which would absorb some frequencies more than others, producing a characteristic absorption fingerprint. The tighter the beam, the more radiation reaches both the sample and, subsequently, a detector, yielding a clearer signal.

    Hu is joined on the paper by first author Tsung-Yu Kao, who was an MIT graduate student in electrical engineering when the work was done and is now chief technology officer at LongWave Photonics, a company that markets terahertz lasers, and by John Reno of Sandia National Laboratories.

    “The use of phased arrays of antennas is widespread in the microwave and allows one to direct radiation in a very narrow beam, in a specific direction,” says Benjamin Williams, an associate professor of electrical engineering at the University of California at Los Angeles. “In the microwave, however, it is straightforward to drive each antenna with the same phase so that all the contributions to the field add up constructively in the far field. It is more complicated to do the same thing using an array of laser emitters, since you can’t easily control the phase of each element. Rather, you must coax each laser emitter to phase-lock with its neighbors through some mechanism. This work has shown a new method to phase-lock large arrays of lasers.”

    “The work is also important for addressing an ongoing challenge for terahertz QC [quantum cascade] lasers, namely, how can you generate a high-quality beam with good efficiency?” he adds. “This has traditionally been tough for terahertz QC lasers, since the individual laser cavities are smaller than the wavelength. It turns out that this fact means you can borrow many of the techniques from the microwave — like phased-array antennas. The work shows a high-quality beam with very high slope efficiency in a monolithic surface-emitting package.”

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  • richardmitnick 2:57 pm on June 8, 2016 Permalink | Reply
    Tags: , Laser Technology, patent new class of lasers, , Researchers invent   

    From phys.org: “Researchers invent, patent new class of lasers” 


    June 8, 2016
    No writer credit found

    Kristan Corwin, left, and Brian Washburn, both associate professors of physics at Kansas State University, have invented a new patented class of lasers. Credit: Kansas State University

    A new class of lasers developed by a team that included physics researchers at Kansas State University could help scientists measure distances to faraway targets, identify the presence of certain gases in the atmosphere and send images of the earth from space.

    These energy-efficient lasers also are portable, produce light at difficult-to-reach wavelengths and have the potential to scale to high-powered versions.

    The new lasers were invented by Brian Washburn and Kristan Corwin, both associate professors of physics at Kansas State University’s College of Arts & Sciences, along with Andrew Jones, a May 2012 doctoral graduate in physics, and Rajesh Kadel, a May 2014 doctoral graduate in physics. Other contributors include three University of New Mexico physics and astronomy researchers: Wolfgang Rudolf, a Regents professor and department chair, Vasudevan Nampoothiri, a research assistant professor, and Amarin Ratanavis, a doctoral student; and John Zavada, a Virginia-based optic and photonic physicist who brought them all together.

    The new lasers are fiber-based and use various molecular gases to produce light. They differ from traditional glass-tube lasers, which are large and bulky, and have mirrors to reflect the light. But the novel lasers use a hollow fiber with a honeycomb structure to hold gas and to guide light. This optical fiber is filled with a molecular gas, such as hydrogen cyanide or acetylene. Another laser excites the gas and causes a molecule of the excited gas to spontaneously emit light. Other molecules in the gas quickly follow suit, which results in laser light.

    “By putting the gas in a hollow core, we can have really high intensities of light without having to put such high amounts of power into the laser,” Corwin said. “If you had a glass tube of that size and put light in it, the light would escape through the sides. It’s actually the structure that makes it work.”

    The structure also allows for portability. In contrast to traditional lasers, which are fragile and cumbersome to move, the researchers’ more durable fiber laser is about the thickness of a single strand of hair and can wrap around itself for compact storage and transportation.

    “The smallness is nice,” Washburn said. “You can wrap up the coil like a string.”

    The invention process began when Zavada brought Washburn and Corwin, who already had expertise putting gas into hollow fibers, together with Rudolph and Nampoothiri, who were skilled in making optically pumped gas lasers.

    “We thought hard about how this would all work together, and after about a year and a half, we came up with this,” Corwin said.

    The inventors’ lasers use gas, which was the popular method before manufacturers moved to solid-state materials. For example, up until the mid-1990s, grocery store scanners were gas lasers, while present-day grocery scanners use solid-state lasers.

    “What we’ve done is use an old-school technology medium in a new-school package,” Washburn said.

    The researchers are continuing to study and improve the lasers using fibers from Fetah Benabid at Xlim in Limoges, France, with funding from the U.S. Air Force Office of Scientific Research and the U.S. Air Force Research Laboratory.

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  • richardmitnick 3:40 pm on June 6, 2016 Permalink | Reply
    Tags: , Laser Technology, Scientists Use a Frozen Gas to Boost Laser Light to New Extremes,   

    From SLAC: “Scientists Use a Frozen Gas to Boost Laser Light to New Extremes” 

    SLAC Lab

    June 6, 2016

    For the experiment, Stanford graduate student Georges Ndabashimiye had to figure out how to freeze argon gas into a thin layer inside a small vacuum chamber chilled to 20 kelvins – close to absolute zero. (SLAC National Accelerator Laboratory)

    SLAC/Stanford Study Opens a Path to Creating Attosecond Laser Pulses by Inducing ‘High Harmonic Generation’ in a Solid

    To observe something as small and fast as an electron rushing to form a chemical bond, you need a bright light with an incredibly small wavelength that comes in very fast pulses – just a few attoseconds, or billionths of a billionth of a second, long.

    Scientists figured out more than a decade ago how to make this specialized form of light through a process known as “high harmonic generation,” or HHG, which shifts laser light to much shorter wavelengths and shorter pulses by shining it through a cloud of gas.

    Now researchers at the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University and Louisiana State University have achieved an even more dramatic HHG shift by shining an infrared laser through argon gas that’s been frozen into a thin, fragile solid whose atoms barely cling to each other.

    The laser light that emerged from the frozen gas was in the extreme ultraviolet range, with wavelengths about 40 times shorter than the light that went in, they report today in the journal Nature.

    The results give researchers a potential new, solid-state tool for “attosecond science,” which explores processes like the motions of electrons in atoms and the natural vibrations of molecules.

    And in the longer term, they could lead to bright, ultrafast, short-wavelength lasers that are much more compact, and perhaps even electronic devices that operate millions of times faster than current technology, says David Reis, a co-author of the report and deputy director of the Stanford PULSE Institute, a joint institute of SLAC and Stanford.

    Making the First Key Comparisons

    “Now, for the first time, we are able to directly compare how high harmonic generation works in the solid and gaseous forms of a single element. We did this in both argon and krypton,” Reis said.

    “These comparisons should allow us to resolve a number of outstanding questions – for instance, what, exactly, is the effect of packing the atoms closer together? In our study it seemed to enhance the HHG process. We expect that these results, and follow-up studies that are already underway, will give us a much better understanding of the fundamental physics.”

    High harmonic generation is far from new. Discovered in the late 1980s, it offers a way to produce laser-like bursts of light at far higher frequencies and shorter wavelengths than a laser can generate directly. But only in the past decade has it been developed into a readily accessible tool for exploring the attosecond realm.

    Today scientists generally use argon gas as the medium for generating attosecond laser pulses with HHG. Laser light shining on the gas liberates electrons from all the argon atoms it hits. The electrons fly away, loop back and reconnect with their home atoms all at the same time. This reconnection generates attosecond bursts of light that combine to form an attosecond laser pulse.

    Tricky Work with Fragile Crystals

    In 2010, a PULSE team led by Reis and SLAC staff scientist Shambhu Ghimire reported the first observation of HHG in a crystal ­– zinc oxide, a semiconducting material that is probably most familiar as a white powder in sunscreens.

    But it was difficult to compare how HHG proceeds in this complex solid to what happens in a gas. So in 2011 they began a series of experiments to directly compare HHG in gaseous and solid argon.

    “This is a conceptually simple but technically very challenging experiment,” Ghimire says. “Argon crystals are extremely, extremely fragile, and the reason they’re fragile is that the interaction between the atoms is very weak. But this was just what we wanted – something that looked just like a gas, but at higher density.”

    The work of performing the experiment and analyzing the data fell to Georges Ndabashimiye, a graduate student at PULSE and the Stanford Department of Applied Physics, who had to figure out how to freeze argon gas into a thin layer inside a small vacuum chamber chilled to 20 kelvins – close to absolute zero.

    Ndabashimiye says he had to be patient with the challenging process. “I didn’t really know how it was going to turn out, but it kept working and I found I could do more and learn more. That was quite exciting,” he says.

    Looking Toward Potential Applications

    When used to perform HHG, the argon crystal reduced the wavelength of incoming laser light 40-fold, compared to 20-fold in argon gas hit with the same level of illumination. Consequently, it also produced a laser beam of much higher energy – 40 electronvolts, versus 25 electronvolts in argon gas.

    Packing the atoms closer together appears to produce higher harmonics than using single, widely spaced atoms, the researchers said, and working with these frozen gases should help them figure out why.

    There are also many commonalities between the behavior in gases and solids, which leads them to believe that techniques developed for working with gases can be applied to solids, too.

    “If a wide range of different types of solids can produce these attosecond pulses, we might be able to engineer the right solid with the right properties for things like inspecting semiconductor chips and masks, developing new types of microscopy and mapping out how electrons behave inside solids,” Reis said.

    Theorists at Louisiana State University also contributed to the research, which was funded by the DOE Office of Science and the National Science Foundation. The research team also used SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), a DOE Office of Science User Facility, to measure the quality of the frozen argon crystals.

    Citation: G. Ndabashimiye et al., Nature, 6 June 2016 (10.1038/nature17660).

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

  • richardmitnick 5:46 am on April 21, 2016 Permalink | Reply
    Tags: , Laser Technology, ,   

    From Stanford: “Peering deep into materials with ultrafast science” 

    Stanford University Name
    Stanford University

    March 31, 2016 [Just appeared in social media]
    Glenn Roberts Jr.

    New techniques developed at SLAC and Stanford allow scientists to observe changes at the nanoscale that occur in fractions of a second in response to light. This artist’s conception depicts the first step in the photovoltaic response that light produces in lead titanate.

    Laser light exposes the properties of materials used in batteries and electronics

    Creating the batteries or electronics of the future requires understanding materials that are just a few atoms thick and that change their fundamental physical properties in fractions of a second. Cutting-edge facilities at SLAC National Accelerator Laboratory and Stanford University have allowed researchers like Aaron Lindenberg to visualize properties of these nanoscale materials at ultrafast time scales.

    In one experiment, a team led by Lindenberg showed atoms shifting in trillionths of a second to produce a wrinkle in a 3-atom-thick sample of a material that might someday be used in flexible electronics. Another study observed semiconductor crystals — called “quantum dots” because they defy classical physics at the nanoscale — expand and shrink in response to ultrafast pulses of laser light.

    A three-atom-thick material wrinkles in response to a laser pulse. Understanding these dynamic ripples could provide crucial clues for the development of next-generation solar cells, electronics and catalysts.

    Revealing such intriguing properties at the nanoscale gives clues about the fundamental nature of materials and how they perform in applications we rely on for energy or information.

    “Even though some of these materials are completely embedded in everyday technologies, not a lot is understood about how they work,” says Lindenberg, who is an associate professor of materials science and engineering and of photon science. He is also a principal investigator for two SLAC/Stanford joint institutes — Stanford Institute for Materials and Energy Sciences and Stanford PULSE Institute.

    “Part of the reason some phenomena are not well understood is because they happen so fast – in billionths, trillionths or even quadrillionths of a second. For the first time, we have tools that allow us to see these things,” he says.

    Working at the intersection of materials science and engineering, Lindenberg and his team have a particular focus on finding promising materials for next-generation electronics, light-based data storage technologies and energy applications.

    “There are a broad range of new properties that emerge at the nanoscale,” Lindenberg says. “The tiniest samples, with just tens or hundreds of atoms, can have nearly flawless structures that make them ideal test tubes for very fundamental questions about what happens when a material transforms.”

    The team uses different types of laser light at SLAC and Stanford labs to learn how simple tweaks in the size, shape and design of materials can change their basic properties in unexpected ways, which could lead to new applications. Taking advantage of the powerful X-rays at SLAC facilities, including the Linac Coherent Light Source [LCLS] and the Stanford Synchrotron Radiation Lightsource [SSRL] , they explore ultrafast changes in nanoscale samples.



    “We are trying to understand how electrons or atoms move in materials, which in turn determines, for example, the efficiency of solar cells and other energy-related materials, and how materials switch between different forms,” he says. “Ultrafast techniques allow you to see these kinds of things in a completely new way.”

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 1:53 pm on January 26, 2016 Permalink | Reply
    Tags: , Laser Technology, , , ,   

    From PPPL: “PPPL team wins 80 million processor hours on nation’s fastest supercomputer” 


    January 26, 2016
    John Greenwald

    The U.S Department of Energy (DOE) has awarded a total of 80 million processor hours on the fastest supercomputer in the nation to an astrophysical project based at the DOE’s Princeton Plasma Physics Laboratory (PPPL). The grants will enable researchers led by Amitava Bhattacharjee, head of the Theory Department at PPPL, and physicist Will Fox to study the dynamics of magnetic fields in the high-energy density plasmas that lasers create. Such plasmas can closely approximate those that occur in some astrophysical objects.

    The awards consist of 35 million hours from the INCITE (Innovative and Novel Impact on Computational Theory and Experiment) program, and 45 million hours from the ALCC, (ASCR — Advanced Scientific Computing Research — Leadership Computing Challenge.) Both will be carried out on the Titan Cray XK7 supercomputer at Oak Ridge National Laboratory. This work is supported by the DOE Office of Science.

    ORNL Titan Supercomputer
    Titan Cray XK7 supercomputer

    The combined research will shed light on large-scale magnetic behavior in space and will help design three days of experiments in 2016 and 2017 on the world’s most powerful high-intensity lasers at the National Ignition Facility (NIF) at the DOE’s Lawrence Livermore National Laboratory.

    Livermore NIF Banner
    Livermore NIF

    “This will enable us to do experiments in a regime not yet accessible with any other laboratory plasma device,” Bhattacharjee said.

    The supercomputer modeling, which is already under way, will investigate puzzles including:

    Magnetic field formation. The research will study Weibel instabilities, the process by which non-magnetic plasmas merge in space to produce magnetic fields. Understanding this phenomena, which takes place throughout the universe but has proven difficult to observe, can provide insight into the creation of magnetic fields in stars and galaxies.

    Magnetic field growth. Another mystery is how small-scale fields can evolve into large ones. The team will model a process called the Biermann battery, which amplifies the small fields through an unknown mechanism, and will attempt to decipher it.

    Explosive magnetic reconnection. The simulations will study still another process called plasmoid instabilities that have been widely theorized. These instabilities are believed to play an important role in producing super high-energy plasma particles when magnetic field lines that have separated violently reconnect.

    The NIF experiments will test these models and build upon the team’s work at the Laboratory for Laser Energetics at the University of Rochester. Researchers there have used high-intensity lasers at the university’s OMEGA EP facility to produce high-energy density plasmas and their magnetic fields.

    At NIF, the lasers will have 100 times the power of the Rochester facility and will produce plasmas that more closely match those that occur in space. The PPPL experiments will therefore focus on how reconnection proceeds in such large regimes.

    Joining Bhattacharjee and Fox on the INCITE award will be astrophysicists Kai Germaschewksi of the University of New Hampshire and Yi-Min Huang of PPPL. The same team is conducting the ALCC research with the addition of Jonathan Ng of Princeton University. Researchers on the NIF experiments, for which Fox is principal investigator, will include Bhattacharjee and collaborators from PPPL, Princeton, the universities of Rochester, Michigan and Colorado-Boulder, and NIF and the Lawrence Livermore National Laboratory.

    See the full article here .

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    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

  • richardmitnick 8:24 pm on January 25, 2016 Permalink | Reply
    Tags: , HAPLS, Laser Technology,   

    From LLNL: “Petawatt laser system passes a key milestone” 

    Lawrence Livermore National Laboratory

    Jan. 22, 2016
    Breanna Bishop

    HAPLS  High-Repetition-Rate Advanced Petawatt Laser System LLNL
    This computer-aided design shows HAPLS’ two interconnected Livermore-developed laser systems. The diode-pumped, solid-state laser will deliver up to 200 joules of energy at a repetition rate of 10 Hz. At the pump laser output, a frequency converter doubles the laser frequency from infrared to green. The solid-state, short-pulse laser converts the energy from the pump laser to 30-joule, 30-femtosecond pulses for a peak power exceeding one petawatt. The laser system measures 4.6 meters wide and 17 meters long.

    The High-Repetition-Rate Advanced Petawatt Laser System (HAPLS) under construction at LLNL recently achieved a key average power milestone more than two months ahead of schedule, and is now moving into the next phase in its development.

    The HAPLS high-energy diode-pumped solid-state pump laser, firing at a repetition rate of 3.3 Hz (3.3 shots per second), achieved 70 joules of infrared (1,053-nanometer) energy and 39 joules of green (527-nm) energy. Completion of this average-power milestone marks another major step in the HAPLS commissioning plan: the beginning of the integration of the pump laser with the HAPLS high-energy short-pulse beamline.

    “Ramping the pump laser to this intermediary performance level was an important step for HAPLS,” said Constantin Haefner, program director for Advanced Photon Technologies. “For the first time we ran the pump laser at significant energy and average power levels, meeting and exceeding the required goals for this milestone. This accomplishment required a huge team effort and the team worked extremely hard to make this happen.

    “We are taking a risk-balanced approach in ramping HAPLS to its full performance. The data we collected confirmed our performance models and gave the green light to start integration with the short-pulse beamline before ramping to even higher power levels.”

    Representatives from the European Union’s Extreme Light Infrastructure Beamlines (ELI-Beamlines) facility in the Czech Republic, where HAPLS will be installed, attended the demonstration. “We are delighted to see the HAPLS pump laser work with a performance exceeding the project expectations for this phase, and achieve this important milestone on budget and ahead of schedule,” said ELI Beamlines Chief Laser Scientist Bedrich Rus. “The partnership with LLNL has been a tremendously successful story, and this demonstration shows the robustness of the underlying design and technology. The L3 (HAPLS) beamline will be an ELI Beamlines’ user facility workhorse.”

    HAPLS is designed to reach a peak power exceeding one petawatt at a repetition rate of 10 times per second to deliver intensities on target up to 1023 watts per square centimeter. Achieving this intensity would open up entirely new areas of laser–matter investigation, enable new applications of laser-driven X rays and particles, and for the first time allow researchers to study laser interactions with the sea of virtual particles that comprise a vacuum.

    Ramping of the laser to its full performance has been organized in several phases. The first phase, completed last October, brought the pump laser to an intermediate performance level in a “single shot” regime, as opposed to an average power regime in which the amplifiers are thermally loaded. “In the second phase,” Haefner said, “we brought it up to average power, and that was an intermediate performance level. And now we’re integrating the pump laser and the short-pulse system. Together with ELI Beamlines we will integrate the short-pulse performance diagnostics, and then we will ramp the short-pulse laser system, similar to what we did for the pump laser system, first to energy and then to average power.”

    “The reason for the phased approach,” said Systems Architect and Commissioning Manager Andy Bayramian, “is that we operate the laser at the intermediate performance level, learn how to operate it, identify operational challenges and input-data errors if they exist, and once we have gained operational experience, then we ramp it to its full performance.”

    The engineering of the HAPLS laser combines many disciplines to produce a high-quality design. Electrical, mechanical, optical, precision, controls, vacuum and infrastructure engineering teams have contributed to deliver the required components for a fully functional laser.

    HAPLS is designed to allow for future upgrades and scaling to even higher energies and repetition rates, which will ensure the longevity and scientific competitiveness of the ELI Beamlines facility.

    “HAPLS will allow its users for the first time to approach the commercial applications arena for laser-generated secondary sources,” Haefner said. “There’s no other laser which actually can produce sufficient average power of the high-intensity light required for commercial applications.”

    The system’s pulses will be used to generate extremely bright and short X-ray pulses for imaging cells and proteins at unprecedented spatial and temporal resolution. Another application is generating bunches of protons or ions for medical therapy and materials science research. Scientists also will study the interaction of intense laser light with matter to improve understanding of high energy density science.

    See the full article here .

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    LLNL Campus

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
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