A new perforated metalens proves it is possible to use nano-optics to focus beams of extreme ultraviolet light (EUV) and could open new doors in microscopy, sensing, holography, and fundamental physics research. The advance is reported in&nbsp;Science.At the&nbsp;<a href="https://seas.harvard.edu/" target="_blank">Harvard John A. Paulson School of Engineering and Applied Sciences</a> (SEAS),&nbsp;<a href="https://seas.harvard.edu/person/federico-capasso" target="_blank">Federico Capasso&rsquo;s</a> lab unveiled in 2011 the groundbreaking concept of refracting metasurfaces, or sub-wavelength-spaced arrays of nanostructures, with a&nbsp;Science&nbsp;paper that has since been cited 7,000 times. In 2016, another&nbsp;Science&nbsp;paper reported the use of high-performance flat lenses made up of nanopillars and fabricated using lithography techniques, which unlocked a new strategy to focus light. That work was a major leap forward for conventional optical devices that had historically been fabricated by molding, making them thick and bulky.Since that initial metalens demonstration, researchers far and wide have been adopting the technique to create metalens designs that exert increasingly complex control over visible and infrared light &ndash; but harnessing such metasurfaces to control light in the EUV range has remained out of reach. EUV wavelengths are extremely small, around the 50-nanometer range, which is much smaller than visible wavelengths of light, which are 400 to 700 nanometers in size. At such a small wavelength, EUV is absorbed by all materials, preventing that light from being refracted and controlled by transmissive optics.The Capasso group&rsquo;s latest breakthrough &ndash; fabricating a metalens that uses nano-sized holes to vacuum-guide EUV -- introduces a game-changing workaround. &ldquo;This work will revolutionize optics in a spectral region (extreme UV) where, until now, there were no lenses or viable optics for high-performance or high-volume applications,&rdquo; says Capasso, co-corresponding author, who is the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS.&nbsp;The new work was in collaboration with Martin Schultze&rsquo;s lab at Graz University of Technology.The idea was originally conceived by Marcus Ossiander, a postdoctoral fellow in Capasso&rsquo;s group, whose background is in attosecond physics, or the study of how light and matter interact on the inconceivably-small timescale of quintillionths of a second. &ldquo;The only way you can create laser pulses on the attosecond scale is using these very short wavelengths of ultraviolet light,&rdquo; Ossiander says. &ldquo;I had this big dream, a bit of a moonshot, really, to create a metalens that could control EUV. And Federico will never stop you from pursuing a dream.&rdquo;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1681143867298-cover_xuv_metalens_v2.png" style="width: 300px;" class="fr-fic fr-dib">Typical metalenses rely on the fabrication of nanopillars that &ndash; sticking up like the skyscrapers of the Manhattan skyline &ndash; refract visible light and focus it in desired ways. But with EUV light being absorbed by all materials it reaches, Ossiander knew that strategy would not work. As he contemplated the way materials interact with light that oscillates incredibly fast, a creative new idea struck him.&ldquo;Why not flip the design&hellip; to make transmissive pillars&hellip; out of air?&rdquo; he says. By making holes in the surface of a material with a lower refractive index than air itself, he hypothesized that EUV could be guided and focused using the vacuum inside the holes. When computer simulations suggested it might actually work, he teamed up with nanofabrication expert Maryna Leonidivna Meretska, a postdoctoral researcher in Capasso&rsquo;s lab, to develop a prototype.&ldquo;Fabrication, in general, requires a lot of perseverance,&rdquo; Meretska says. &ldquo;It took many attempts to realize the working sample. We learned something new about the process with every attempt, and that kept me going.&rdquo;&ldquo;This work really pushed the limits of what&rsquo;s possible in nanotechnology today,&rdquo; Capasso says. &ldquo;We needed impeccable fabrication methods to make this metalens with features small enough to interact with EUV wavelengths, which means the features must be smaller than those wavelengths. It pushed us to shrink the metalens features by a factor of 10 compared to what&rsquo;s been done before &ndash; it was really a very large leap.&rdquo;Once the prototype was complete, Ossiander flew to the Institute of Experimental Physics at Graz University of Technology in Austria, one of few labs in the world that can create EUV. There, researchers led by attosecond physicist Martin Schultze (a co-corresponding author on the study) sent EUV radiation through the metalens prototype. After many experiments, the team saw what they had long dreamed of: a small spot, indicating the concentration of light, detected by a special camera.&ldquo;Every element [of this project] worked like in an orchestra,&rdquo; Meretska says. &ldquo;Both sample fabrication and measurement processes are incredibly challenging and knowing everything worked as designed was very satisfying.&rdquo;The breakthrough will have implications for attosecond physics, as the metalens can be used to better understand light and matter interactions on the nanoparticle scale. Capasso says the semiconducting industry will also benefit from EUV metalens technology because it will enable the fabrication of smaller and smaller transistors and processors. But, perhaps most exciting, Capasso says there are likely many future applications that haven&rsquo;t yet been thought of.&ldquo;We don&rsquo;t currently know all the fields that might benefit from EUV metalenses, because no one expected that this type of technology would be possible anytime soon,&rdquo; Ossiander says.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1681143890910-lens_rect_scale.png" style="width: 766px;" class="fr-fic fr-dib">Additional authors include Hana Kristin Hampel, Soon Wei Daniel Lim, Nico Knefz, Thomas Jauk.<a href="https://otd.harvard.edu/" target="_blank">Harvard&rsquo;s Office of Technology Development</a> has protected the intellectual property arising from this study and is exploring commercialization opportunities.Part of this work was performed at Harvard&rsquo;s Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the NSF under award no. ECCS-2025158. Computations were run on the FASRC Cannon cluster supported by the FAS Division of Science Research Computing Group at Harvard University. This research was supported by the Alexander von Humboldt Foundation (Feodor-Lynen Fellowship), the Austrian Science Fund (FWF, Start Grant Y1525), the European Union (grant agreement 01076933 EUVORAM), A*STAR Singapore through the National Science Scholarship Scheme, and the Air Force Office of Scientific Research (AFOSR) under award Number FA9550-21-1- 0312.

Nanofabrication technique, using holes to create vacuum guides, breaks a barrier in optics

First-of-its-kind metalens can focus extreme ultraviolet light

As technologies keep advancing at exponential rates and demand for new devices rises accordingly, miniaturizing systems into chips has become increasingly important. Microelectronics has changed the way we manipulate electricity, enabling sophisticated electronic products that are now an essential part of our daily lives. Similarly, integrated photonics has been revolutionizing the way we control light for applications such as data communications, imaging, sensing, and biomedical devices. By routing and shaping light using micro- and nanoscale components, integrated photonics shrinks full optical systems into the size of tiny chips.&nbsp;Despite its success, integrated photonics has been missing a key component to achieve complete miniaturization: high-performance chip-scale lasers. While some progress has been made on near-infrared lasers, the visible-light lasers that currently feed photonic chips are still benchtop and expensive. Since visible light is essential for a wide range of applications including quantum optics, displays, and bioimaging, there is a need for tunable and narrow-linewidth chip-scale lasers emitting light of different colors.&nbsp;<h2>Inventing high-performance lasers that fit on a fingertip</h2>Researchers at<a href="http://engineering.columbia.edu/" target="_blank">&nbsp;Columbia Engineering</a>&rsquo;s <a href="https://lipson.ee.columbia.edu/" target="_blank">Lipson Nanophotonics Group</a> have created visible lasers of very pure colors from near-ultraviolet to near-infrared that fit on a fingertip. The colors of the lasers can be precisely tuned and extremely fast &ndash; up to 267 petahertz per second, which is critical for applications such as quantum optics. The team is the first to demonstrate chip-scale narrow-linewidth and tunable lasers for colors of light below red -- green, cyan, blue, and violet. These inexpensive lasers also have the smallest footprint and shortest wavelength (404 nm) of any tunable and narrow-linewidth integrated laser emitting visible light. The <a href="https://www.nature.com/articles/s41566-022-01120-w" target="_blank">study</a>, which was first presented at the CLEO 2021 post-deadline session on May 14, 2021, was published online December 23, 2022, by&nbsp;Nature Photonics.&ldquo;What&rsquo;s exciting about this work is that we&rsquo;ve used the power of integrated photonics to break the existing paradigm that high-performance visible lasers need to be benchtop and cost tens of thousands of dollars,&rdquo; says the study&rsquo;s lead author Mateus Corato Zanarella, a PhD student who works with <a href="https://www.engineering.columbia.edu/faculty/michal-lipson" target="_blank">Michal Lipson</a>, Higgins Professor of <a href="https://www.ee.columbia.edu/" target="_blank">Electrical Engineering</a> and professor of <a href="https://www.apam.columbia.edu/" target="_blank">applied physics</a>. &ldquo;Until now, it&rsquo;s been impossible to shrink and mass-deploy technologies that require tunable and narrow-linewidth visible lasers. A notable example is quantum optics, which demands high-performance lasers of several colors in a single system. We expect that our findings will enable fully integrated visible light systems for existing and new technologies.&rdquo;&nbsp;<blockquote>What&rsquo;s exciting about this work is that we&rsquo;ve used the power of integrated photonics to break the existing paradigm that high-performance visible lasers need to be benchtop and cost tens of thousands of dollars.<footer>MATEUS CORATO ZANARELLA</footer><footer>LEAD AUTHOR OF THE STUDY AND PHD STUDENT IN THE LIPSON NANOPHOTONICS GROUP</footer></blockquote><section id="isPasted"><h2>Benefits of emitting wavelengths below red</h2>The importance of lasers emitting wavelengths shorter than red is clear when you consider some important applications. Displays, for example, require red, green, and blue light simultaneously to compose any color. In quantum optics, green, blue, and violet lasers are used for trapping and cooling atoms and ions. In underwater Lidar (Light Detection and Ranging), green or blue light is needed to avoid water absorption. However, at wavelengths shorter than red, the coupling and propagation losses of photonic integrated circuits increase significantly, which has prevented the realization of high-performance lasers at these colors.&nbsp;<h2>Solving coupling and propagation loss issues</h2>The researchers solved the coupling loss problem by choosing Fabry-Perot (FP) diodes as the light sources, which minimizes the impact of the losses on the performance of the chip-scale lasers. Unlike other strategies that use different types of sources, the team&rsquo;s approach enables the realization of lasers at record-short wavelengths (404 nm) while also providing scalability to high optical powers, FP laser diodes are inexpensive and compact solid-state lasers widely used in research and industry. However, they emit light of several wavelengths simultaneously and are not easily tunable, preventing them to be directly used for applications requiring pure and precise lasers. By combining them with the specially designed photonic chip, the researchers are able to modify the laser emission to be single-frequency, narrow-linewidth, and widely tunable.&nbsp;The team overcame the propagation loss issue by designing a platform that minimizes both the material absorption and surface scattering losses simultaneously for all the visible wavelengths. To guide the light, they used silicon nitride, a dielectric widely used in the semiconductor industry that is transparent for visible light of all colors. Even though there is minimal absorption, the light still experiences loss due to unavoidable roughness from the fabrication processes. The team solved this problem by designing a photonic circuit with a special type of ring resonator. The ring has a variable width along its circumference, allowing for single-mode operation characteristic of narrow waveguides, and low loss characteristic of wide waveguides. The resulting photonic circuit provides a wavelength-selective optical feedback to the FP diodes that forces the laser to emit at a single desired wavelength with very narrow linewidth.&ldquo;By combining these intricately designed pieces, we were able to build a robust and versatile platform that is scalable and works for all colors of light,&rdquo; said Corato Zanarella.&nbsp;<h2>Revolutionizing technologies</h2>&ldquo;As a laser manufacturer we recognize that integrated photonics will have a tremendous impact on our industry and will enable a new generation of applications that have so far been impossible,&rdquo; said Chris Haimberger, director of Laser Technology, TOPTICA Photonics, Inc. &ldquo;This work represents an important step forward in the pursuit of compact and tunable visible lasers that will power future developments in computing, medicine, and industry.&rdquo;The study&rsquo;s findings could revolutionize a broad range of applications, including:</section><section><a href="https://www.engineering.columbia.edu/news/high-performance-visible-light-lasers-fit-fingertip#" target="_blank"><ul><li> Quantum information</li></ul></a></section><section><a href="https://www.engineering.columbia.edu/news/high-performance-visible-light-lasers-fit-fingertip#" target="_blank"><ul><li>&nbsp;Atomic Clocks</li></ul></a></section><section><a href="https://www.engineering.columbia.edu/news/high-performance-visible-light-lasers-fit-fingertip#" target="_blank"><ul><li>&nbsp;Biosensing</li></ul></a></section><section><a href="https://www.engineering.columbia.edu/news/high-performance-visible-light-lasers-fit-fingertip#" target="_blank"><ul><li>&nbsp;Underwater Ranging</li></ul></a></section><section><a href="https://www.engineering.columbia.edu/news/high-performance-visible-light-lasers-fit-fingertip#" target="_blank"><ul><li style="font-weight: bold;">&nbsp;Li-Fi</li></ul></a></section><section><h2>Next steps</h2>The researchers, who have filed a provisional patent for their technology, are now exploring how to optically and electrically package the lasers to turn them into standalone units and use them as sources in chip-scale visible light engines, quantum experiments, and optical clocks.&ldquo;In order to move forward, we have to be able to miniaturize and scale these systems, enabling them to eventually be incorporated in mass-deployed technologies,&rdquo; said Lipson, a pioneer in silicon photonics whose research has strongly shaped the field from its inception decades ago, with foundational contributions in the active and passive devices that are part of any current photonic chip. She added, &ldquo;Integrated photonics is an exciting field that is truly revolutionizing our world, from optical telecommunications to quantum information to biosensing.&rdquo;</section>

Illustration of the integrated laser platform created by the Lipson Nanophotonics Group, where a single chip generates narrow linewidth and tunable visible light covering all colors. Credit: Myles Marshall/Columbia Engineering

In a significant advance for impactful technologies such as quantum optics and laser displays for AR/VR, Columbia Engineering’s Lipson Nanophotonics Group has invented the first tunable and narrow linewidth chip-scale lasers for visible wavelengths shorter than red.

High-performance Visible-light Lasers that Fit on a Fingertip

Printing objects from plastic precisely, quickly, and inexpensively is the goal of many 3D printing processes. However, speed and high resolution remain a technological challenge. A research team from the Karlsruhe Institute of Technology (KIT), Heidelberg University, and the Queensland University of Technology (QUT) has come a long way toward achieving this goal. It developed a laser printing process that can print micrometer-sized parts in the blink of an eye. The international team published the work in&nbsp;Nature Photonics. (DOI:&nbsp;<a href="https://www.nature.com/articles/s41566-022-01081-0" target="_blank">10.1038/s41566-022-01081-0</a>)Stereolithography 3D printing is currently one of the most popular additive manufacturing processes for plastics, both for private and industrial applications. In stereolithography, the layers of a 3D object are projected one by one into a container filled with resin. The resin is cured by UV light. However, previous stereolithography methods are slow and have too low a resolution. Light-sheet 3D printing, which is used by the KIT researchers, is a fast and high-resolution alternative.<h2>3D Printing with Two Colors in Two Stages</h2>In light-sheet 3D printing, blue light is projected into a container filled with a liquid resin. The blue light pre-activates the resin. In a second stage, a red laser beam provides the additional energy needed to cure the resin. However, 3D printing can only print quickly resins that quickly return from their pre-activated state to their original state. Only then can the next layer be printed. Consequently, the return time dictates the waiting time between two successive layers and thus the printing speed. &quot;For the resin we used, the return time was less than 100 microseconds, which allows for high printing speeds,&quot; says first author Vincent Hahn from KIT&#39;s Institute of Applied Physics (APH).<h2>Micrometer-sized Structures in Just the Blink of an Eye</h2>To take advantage of this new resin, the researchers built a special 3D printer. In this printer, blue laser diodes are used to project images into the liquid resin using a high-resolution display with a high frame rate. The red laser is formed into a thin &quot;light sheet&quot; beam and crosses the blue beam vertically in the resin. With this arrangement, the team was able to 3D print micrometer-sized parts in a few hundred milliseconds, i.e. in the blink of an eye. However, it should not stop there: &quot;With more sensitive resins, we could even use LEDs instead of lasers in our 3D printer,&quot; says Professor Martin Wegener of APH. &quot;Ultimately, we want to print 3D structures that are centimeters in size, while maintaining micrometer resolution and high printing speeds.&quot;The publication was produced within the framework of the joint &ldquo;3D Matter Made to Order&rdquo; Cluster of Excellence of the KIT and Heidelberg University. Junior Professor Dr Eva Blasco, a group leader at the Institute of Organic Chemistry and the Institute for Molecular Systems Engineering and Advanced Materials, was involved on the part of Heidelberg University.Original Publication: V. Hahn, P. Rietz, F. Hermann, P. M&uuml;ller, C. Barner-Kowollik, T. Schl&ouml;der, W. Wenzel, E. Blasco, and M. Wegener: Light-sheet three-dimensional microprinting via two-colour two-step absorption. Nature Photonics, 2022. DOI: 10.1038/s41566-022-01081-0 <a href="https://www.nature.com/articles/s41566-022-01081-0" target="_blank">https://www.nature.com/articles/s41566-022-01081-0</a><h2>Cluster of Excellence &quot;3D Matter Made to Order&rdquo;</h2>In the Cluster of Excellence &quot;3D Matter Made to Order,&quot; scientists from the Karlsruhe Institute of Technology (KIT) and Heidelberg University are conducting interdisciplinary research on innovative technologies and materials for digitally scalable additive manufacturing to improve the precision, speed, and performance of 3D printing. The goal of the work is to fully digitize 3D manufacturing and materials processing from the molecule to the microstructure. In addition to being funded as a Cluster of Excellence under the Excellence Strategy Competition of the German federal and state governments, &quot;3D Matter Made to Order&quot; is funded by the Carl Zeiss Foundation.Read more on the Cluster of Excellence<a href="https://www.3dmattermadetoorder.kit.edu/" target="_blank">&nbsp;&bdquo;3D Matter Made to Order&ldquo;</a><a href="https://www.materials.kit.edu/index.php" target="_blank">Details on the KIT Center Materials in Technical and Life Sciences</a>

In light sheet 3D printing, red and blue laser light is used to print objects precisely and quickly on a micrometer scale (Photo: Vincent Hahn, KIT)

Researchers from the Cluster of Excellence "3D Matter Made to Order" Print Microstructures by Crossing Red and Blue Laser Beams - Publication in Nature Photonics

Joining Forces: Fast-as-lightning 3D Microprinting with Two Lasers

The laser that will be the most powerful in the United States is preparing to send its first pulses into an experimental target at the University of Michigan.&nbsp;Funded by the National Science Foundation, it will be a destination for researchers studying extreme plasmas around the U.S. and internationally.Called ZEUS, the Zetawatt-Equivalent Ultrashort pulse laser System, it will explore the physics of the quantum universe as well as outer space, and it is expected to contribute to new technologies in medicine, electronics and national security.<iframe src="https://www.youtube.com/embed/xDDV0EjCXLM?&wmode=opaque&rel=0&enablejsapi=1&origin=https://www.wevolver.com" frameborder="0" allowfullscreen="" class="fr-draggable" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" style="width: 767px; height: 433px;"></iframe>&ldquo;ZEUS will be the highest peak power laser in the U.S. and among the most powerful laser systems in the world. We&rsquo;re looking forward to growing the research community and bringing in people with new ideas for experiments and applications,&rdquo; said <a href="https://ners.engin.umich.edu/people/krushelnick-karl/" rel="noreferrer noopener" target="_blank">Karl Krushelnick</a>, director of the Center for Ultrafast Optical Science, which houses ZEUS, and the Henry J. Gomberg Collegiate Professor of Engineering.The first target area to get up and running is the high-repetition target area, which runs experiments with more frequent but lower power laser pulses. Michigan alum <a href="https://www.physics.uci.edu/people/franklin-dollar" target="_blank">Franklin Dollar</a> (M.Eng Electrical Engineering &rsquo;10, PhD Applied Physics &rsquo;12), an associate professor of physics and astronomy at the University of California Irvine, is the first user, and his team is exploring a new kind of X-ray imaging.&nbsp;They will use ZEUS to send infrared laser pulses into a gas target of helium, turning it into plasma. That plasma accelerates electrons to high energies, and those electron beams then wiggle to produce very compact X-ray pulses.Dollar&rsquo;s team investigates how to make and use these new kinds of X-ray sources. Because soft tissues absorb X-rays at very similar rates, basic medical X-ray machines have to deliver high doses of radiation before they can distinguish between a tumor and healthy tissue, he said.But during his doctoral studies under Krushelnick, Dollar used ZEUS&rsquo;s predecessor to image a damselfly, showing the promise of laser-like X-ray pulses. Different soft tissues within the damselfly&rsquo;s carapace delayed X-rays to different degrees, creating interference patterns in the X-ray waves. Those patterns revealed the soft structures with very short X-ray pulses&mdash;a few millionths of a billionth of a second&mdash;and hence small X-ray doses.&ldquo;We could see every little organ as well as the tiny micro hairs on its leg,&rdquo; Dollar said. &ldquo;It&rsquo;s very exciting to think of how we could use these laser-like X-rays to do low-dose imaging, taking advantage of the fact that they&rsquo;re laser-like rather than having to rely on the absorption imaging of the past.&rdquo;In this first run, the ZEUS team is starting at a power of 30 terawatts (30 trillion watts), about 3% of the current most powerful lasers in the U.S. and 1% of ZEUS&rsquo;s eventual maximum power.&nbsp;&ldquo;During the experiment here, we&rsquo;ll put the first light through to the target chamber and develop towards that 300 terawatt level,&rdquo; said <a href="https://cuos.engin.umich.edu/researchgroups/hfs/profiles/john-nees/" rel="noreferrer noopener" target="_blank">John Nees</a>, a research scientist in electrical and computer engineering.&nbsp;Nees leads the building of the laser alongside <a href="https://cuos.engin.umich.edu/researchgroups/hfs/profiles/anatoly-maksimchuk/" rel="noreferrer noopener" target="_blank">Anatoly Maksimchuk</a>, a research scientist in electrical and computer engineering, who leads the development of the experimental areas.Dollar&rsquo;s team plans to return late in the fall for another run, aiming for the full power intended for the high repetition target area, 500 terawatts. The maximum power of 3 petawatts, or quadrillion watts, will go to different target areas to be completed later. The first test using the target area for ZEUS&rsquo;s signature experiment is anticipated in 2023.That experiment will use the laser to generate a beam of high-speed electrons and then run the electrons directly into the laser pulses. For the electrons, that simulates a zetawatt laser pulse&mdash;a million times more powerful than ZEUS&rsquo;s 3 petawatts. In addition to probing the foundations of our understanding of the quantum universe, ZEUS will enable researchers to study what&rsquo;s going on inside some of the most extreme objects in space.&ldquo;Magnetars, which are neutron stars with extremely strong magnetic fields around them, and objects like active galactic nuclei surrounded by very hot plasma&mdash;we can recreate the microphysics of hot plasma in extremely strong fields in the laboratory,&rdquo; said <a href="https://willingale.engin.umich.edu/" rel="noreferrer noopener" target="_blank">Louise Willingale,</a> associate director of ZEUS and an associate professor of electrical and computer engineering.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1663766147413-ZeusFL-content2.jpg" style="width: 766px;" class="fr-fic fr-dib">Research engineer Galina Kalinchenko (left) and link scientist Andrew Mckelvey. Photo: Marcin Szczepanski/Michigan Engineering&nbsp;ZEUS offers not only scientific and technological opportunities, but with the discipline-wide effort to grow the laser physics workforce, it creates career opportunities as well. Dollar brought his whole team to get the hands-on experience of a commissioning experiment at a world-class laser.&ldquo;At Michigan Engineering, we&rsquo;re fortunate to have some of the strongest academic and research capabilities in the world, and we&rsquo;re leveraging that strength to improve the lives of real people. ZEUS exemplifies our commitment to fundamental science&mdash;using engineering to understand matter at its most basic levels and then using that knowledge to build solutions to real-world problems,&rdquo; said <a href="https://www.engin.umich.edu/culture/leadership/dean-alec-d-gallimore/" target="_blank">Alec D. Gallimore</a>, the Robert J. Vlasic Dean of Engineering.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1663766172494-ZeusFL-content3.jpg" style="width: 766px;" class="fr-fic fr-dib">From left: Link scientist Andrew Mckelvey, research engineer Galina Kalinchenko, laser engineer Lauren Weinberg and research scientist John Nees. Photo: Marcin Szczepanski/Michigan Engineering&nbsp;The first experiment milestone feels especially hard-earned because of the way the pandemic disrupted construction early on, when the team was still reconfiguring the building to accommodate a much larger laser. Project manager&nbsp;<a href="https://zeus.engin.umich.edu/franko-bayer/" target="_blank">Franko Bayer</a> reconsidered the schedules, identifying work that could be done in parallel rather than in sequence, to keep as close as possible to the initial timelines.&ldquo;Our team at ZEUS is very excited that our hard work paid off, and despite all the post-pandemic equipment delivery delays, we are on schedule to our original timeline. &nbsp;This experiment is the beginning to gradually ramp up the power until full commissioning in the fall of 2023,&rdquo; Bayer said.Krushelnick is also a professor of nuclear engineering and radiological sciences and electrical and computer engineering. Gallimore is also the Richard F. and Eleanor A. Towner Professor of Engineering, an Arthur F. Thurnau Professor and a professor of aerospace engineering.

Laser engineer Lauren Weinberg, research scientist John Nees and research engineer Galina Kalinchenko working on the ZEUS laser. Photo: Marcin Szczepanski/Michigan Engineering

The ZEUS laser at the University of Michigan has begun its commissioning experiments

First light soon at the most powerful laser in the US

On-chip laser frequency combs &mdash; lasers that emit multiple frequencies or colors of light simultaneously separated like the tooth on a comb &mdash; are a promising technology for a range of applications including environmental monitoring, optical computing, astronomy, and metrology. However, on-chip frequency combs are still limited by one serious problem &mdash; they are not always efficient. There are several ways to mitigate the efficiency problem, but they all suffer from trade-offs. For example, combs can either have high efficiency or broad bandwidth but not both. The inability to design an on-chip laser frequency comb that is both efficient and broad has stymied researchers for years and hindered the widespread commercialization of these devices.Now, a team from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has developed an electro-optic frequency comb that is 100-times more efficient and has more than twice the bandwidth of previous state-of-the-art versions.&ldquo;Our device paves the way for practical optical frequency comb generators and opens the door for new applications, said&nbsp;<a href="https://www.seas.harvard.edu/directory/loncar" target="_blank">Marko Lončar,&nbsp;</a>the Tiantsai Lin Professor of Electrical Engineering at SEAS and senior author of the study.&nbsp;&ldquo;It also provides a platform to investigate new areas of optical physics.&rdquo;The research is published in&nbsp;<a href="https://www.nature.com/articles/s41566-022-01059-y.epdf?sharing_token=uPhgWeR0D2vxcIv-OMeB29RgN0jAjWel9jnR3ZoTv0PiGg0GmEmfD59hi91ED_DVhRWTQcdD4yhPmAKxTwZmcM0leN2KHawGB2NdcfjZx1vgPpBRCSVWBdx4maRTpHS1ZOBWNyOgmU7cDu7LISupGD_qInrHezLCcPDmymixq_0%3D" target="_blank">Nature Photonics</a>.&nbsp;This advancement builds upon previous research from Lončar and his team.In 2019, Lončar and his lab&nbsp;<a href="https://www.seas.harvard.edu/news/2019/03/chip-electronically-tunable-frequency-comb" target="_blank">demonstrated the first stable, on-chip frequency comb</a> that could be controlled with microwaves. This so-called electro-optical frequency comb, built on the lithium niobate platform pioneered by Lončar&rsquo;s lab, spanned the entire telecommunications bandwidth but was limited in its efficiency. &nbsp;In 2021, the team&nbsp;<a href="https://www.seas.harvard.edu/news/2021/11/shifting-colors-chip-photonics" target="_blank">developed a coupled resonators</a> device to control the flow of light, and used them to demonstrate&nbsp;&nbsp;on-chip frequency shifters &ndash; a device that can change the color of light with nearly 100% efficiency.&nbsp;The latest research applies the two concepts to address the challenge in resonator based electro-optic frequency combs &ndash; efficiency-bandwidth tradeoff.&ldquo;We demonstrated that by combining these two approaches &mdash; the coupled resonator with the electro-optical frequency comb &mdash; we could improve the efficiency a lot without sacrificing bandwidth. In fact, we actually improved bandwidth,&rdquo; said Yaowen Hu, a research assistant at SEAS and first author of the paper.&ldquo;We found that when you improve the performance of the comb source to this level, the device starts operating in an entirely new regime that combines the process of electro-optic frequency comb generation with the more traditional approach of a Kerr frequency comb,&rdquo; said Mengjie Yu, a former postdoctoral fellow at SEAS and co-first author of the paper.&nbsp;Yu is currently an Assistant Professor at the University of Southern California.&nbsp;This new comb can generate ultrafast femtosecond pulses at high power. Together with the high-efficiency and broadband, this device can be useful for applications in astronomy, optical computing, ranging and optical metrology.&nbsp;The research was co-authored by Brandon Buscaino, Neil Sinclair, Di Zhu, Rebecca Cheng, Amirhassan Shams-Ansari, Linbo Shao, Mian Zhang and Joseph M. Kahn.

A new on-chip frequency comb combines a coupled resonator with an electro-optical frequency comb to improve the efficiency of frequency combs and improve the bandwidth. (Credit: Yiqing Pei/Harvard SEAS)

Device opens the door to applications in optical communications, sensing, and the search for exoplanets

New on-chip frequency comb is 100x more efficient

<h2 dir="ltr" id="isPasted">What is Automated Fiber Placement (AFP)?&nbsp;</h2><a href="https://www.addcomposites.com/afpxs" target="_blank">Automated Fiber Placement (AFP)</a> is an additive manufacturing process that has three different inputs: fiber/polymer tape, heat, and pressure. The end-effector expertly handles the tape and deposits it onto a surface with the help of heat and pressure. The process allows the fabrication of highly customized parts as each ply can be placed at different angles to best carry the required loads. The use of robotics gives the operator active control over all of the process&#39;s critical variables, making the process highly controllable and repeatable. This process can result in additively manufactured composite parts that are two times stronger than steel at one-fifth of the weight.&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjU2MzMyNTI1NzYwLTE2NTYzMzI1MjU3NjAucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" width="624" id="isPasted" class="fr-fic fr-dii" style="width: 756px; height: 382.022px;">Figure 1. Automated Fiber Placement (AFP) System with IR Lamp&nbsp;<h2 dir="ltr">Process Fundamentals</h2>The AFP process is essentially a mechanical-chemical bonding reaction running at the velocity of the robot&#39;s motion. The chemical process is mostly heat-activated via heaters and pressed using a compaction roller to insure low porosity.&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjU2MzMzMzM0MzE5LTIucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 300px;" class="fr-fic fr-dib">Figure 2. Fundamentals of Automated Fiber Placement (AFP)&nbsp; <h2 dir="ltr">Automated Fiber Placement Manufacturing Process</h2>AFP systems consist of the following components:<ul><li dir="ltr">AFP tool mounted onto a robot</li><li dir="ltr">Automation control system</li><li dir="ltr">Planning and Simulation software</li></ul>&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjU2MzMyNTY5Mzc0LTE2NTYzMzI1NjkzNzQucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" width="624" id="isPasted" class="fr-fic fr-dii" style="width: 756px; height: 566.684px;">Figure 3. Single-tow Fiber Placement tool head mounted onto a KUKA Robot&nbsp;&nbsp;<h3 dir="ltr">AFP tool mounted onto a robot</h3>The <a href="https://www.addcomposites.com/afpxs" rel="noopener noreferrer" target="_blank">Automated Fiber Placement (AFP) tool head</a> handles either one tape or multiple narrow tapes and lays them down on a predefined mold surface in a specific manner. &nbsp;The material can either be mounted directly on the tool head or separate from the system entirely and then routed through various mechanisms to reach the head. Each material has its handling challenges, i.e. thermoset materials require additional cooled passage while thermoplastic tapes require a lot of heat at the endpoint of the tool.&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjU2MzMzMjgwNzk4LTMucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 766px;" class="fr-fic fr-dib">Figure 4. Automated Fiber Placement (AFP) Controller by Addcomposites team<h3 dir="ltr"> </h3><h3 dir="ltr">Automation Control System</h3>The automation control system ensures the communication between the robot and the tool, including its sensors and actuators. The AFP tool can be connected to multiple robot brands such as KUKA, ABB, Fanuc, etc., so it is very critical to ensure seamless communication with the robot. The automation system uses the fastest available protocols to communicate with the robot controller, ensuring instant signal sending/receiving.&nbsp;<h3 dir="ltr">Planning and Simulation</h3>Over recent years there have been great advances in the optimization of AFP layups with open access to 3D Composite Manufacturing Software - AddPath. As a consequence, it is now possible to design a part and simulate its manufacturing via AFP on personal or work computers, enabling digital composites additive manufacturing from home or office with the subscriptions. You can download the AddPath directly from <a href="https://www.addcomposites.com/post/addpath-installation-instruction" rel="noopener noreferrer" target="_blank">here</a> and start performing simulations now. <img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjU2MzMyNDc4MDU5LTE2NTYzMzI0NzgwNTkucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" width="624" id="isPasted" class="fr-fic fr-dii" style="width: 756px; height: 409.175px;">Figure 5. Simulation and Programming Software - AddPath User interaction data suggests the difficulty no longer lies with validating the concepts, but instead with figuring out how to maximize the potential of automation. Money fades whenever this equipment performs non-value-added tasks. Consequently, AFP owners want to eliminate unnecessary operations so the machines can focus on production. Through the use of advanced simulation tools, composites programmers can optimize their programs before they ever run, thus increasing up-time and freeing the system to manufacture valuable products. The key value such simulation software brings are:<ul><li dir="ltr">Simulation to eliminate costly &ldquo;dry runs&rdquo;</li><li dir="ltr">Compiled data to improve cycle-time estimates and help with process planning.</li><li dir="ltr">Detect robot singularities and range of motion issues, enabling virtual modification.</li><li dir="ltr">Identify and avoid inconsistent heating during layup.</li></ul><h3 dir="ltr">&nbsp;</h3><h2 dir="ltr">Pros and Cons of Automated Fiber Placement</h2>Compared to other composite fabrication methods there are a number of key advantages and disadvantages of using AFP. These include:<h3 dir="ltr">&nbsp;</h3><h3 dir="ltr">Pros</h3><ul><li dir="ltr">Automation benefits - lower labor cost and higher production rates</li><li dir="ltr">Repeatable production with high traceability</li><li dir="ltr">High quality and accuracy of placement</li><li dir="ltr">Low material wastage</li><li dir="ltr">Monthly rental of AFP (<a href="https://www.addcomposites.com/afpnext" target="_blank">read more</a>)</li><li dir="ltr">Reinforce 3D printed parts</li><li dir="ltr">3D print and finish the mold, then a layup and post-process the part all with the same robot cell</li><li dir="ltr">Layups with Thermoset, Thermoplastics, and Dry Fiber.</li><li dir="ltr">Create preforms and final part shapes</li></ul><h3 dir="ltr">&nbsp;</h3><h3 dir="ltr">Cons</h3><ul><li dir="ltr">Restrictions of part shape</li></ul><h2 dir="ltr">&nbsp;</h2><h2 dir="ltr">The Future of Automated Fiber Placement (AFP)</h2>The ongoing push for faster deposition rates, the development of new material combinations, and the increased pressure on cost reduction mean that AFP will continue to evolve in the coming years. It is expected that thermoplastics will continue to replace thermosets as the preferred polymer matrix. In addition to making better and cheaper AFP tools, they will also decrease in size, enabling a greater diversity of products to be made, and Addcomposites is at the forefront of these innovations.The video below is the collaboration with MBDA (France) and the Compositadour team (Bayonne, France) recently demonstrated the process for manufacturing rectangular tubes with the Single-tow Automated Fiber Placement (AFP-XS) and 3D Composites Manufacturing Software (AddPath). <iframe src="https://www.youtube.com/embed/FuORcX48LX4?&list=PLoE3rFEDI2sW8ExjfQYA0Ep-c94JaSkgC&index=3&wmode=opaque&rel=0&enablejsapi=1&origin=https://www.wevolver.com" frameborder="0" allowfullscreen="" class="fr-draggable" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" style="width: 626px; height: 433px;"></iframe><h2 dir="ltr"> </h2><h2 dir="ltr" id="isPasted">Addcomposites with Automated Fiber Placement (AFP) Ecosystem</h2>Addcomposites team has been working hard to bring the latest innovations to the <a href="https://www.addcomposites.com/afpxs" id="isPasted" target="_blank">Automated Fiber Placement (AFP)</a> ecosystem while achieving our mission of making composites manufacturing automation accessible. The major concern is that 65- 95% of thermoset composites manufacturing is still done by manual labor, let alone meeting the growing demand for automated thermoplastic composite manufacturing. With the growing demand for composites from various industries, the time for manufacturers to start planning for the future is now.We rely heavily on the input from our community, which has driven the constant evolution of&nbsp;<a href="https://www.addcomposites.com/afpxs" id="isPasted" target="_blank">Automated Fiber Placement (AFP)</a>. We&#39;re listening to our end-users, and continuously improving all aspects of the system. For any questions related to composites manufacturing, please contact us through <a href="mailto:info@addcomposites.com" target="_blank">info@addcomposites.com</a>.&nbsp;

Automated Fiber Placement (AFP) System with Humm3®

Automated Fiber Placement (AFP) is an additive manufacturing process that has three different inputs: fiber/polymer tape, heat, and pressure. This technology aims to replace manual workers in composites manufacturing with better productivity and less material waste. 

What is Automated Fiber Placement (AFP) in Composites Manufacturing?

A group of researchers from ITMO University, the Australian National University, and the Friedrich Schiller University Jena (Germany) has for the first time demonstrated effective generation of higher harmonics in silicon metasurfaces. This result was achieved due to resonant states with long lifietimes. The new discovery brings closer the creation of attosecond radiation sources based on semiconductor nanostructures. Ultrashort pulse lasers which earned their pioneers the Nobel Prize in Physics in 2018 make it possible to excite and explore very rapid processes in nature and matter. This opens new horizons for understanding ultrafast physics and faster information recording. &nbsp;&nbsp;High harmonics generation is a nonlinear optical process of photon interaction with nonlinear media that results in the generation of radiation with a frequency that is multiplied by a corresponding integer number (e.g., 5th harmonic generation = 5 times the frequency of the initial photon). For instance, during second-harmonic generation photons come together to form new photons with doubled energy and wave frequency but with a wavelength that is only half of the original one. The maximal known harmonic is over 100, meaning that in these cases radiation frequency is more than 100 times higher than excitation frequency. &nbsp;One of the actively researched areas these days is higher harmonic generation in noble gasses. Subjecting such gasses to interaction with ultrapowerful and ultrashort pulse lasers made it possible to achieve an effective nonlinear transformation of pumping light into higher harmonics. These harmonics demonstrate an important property – the duration of radiation in them can be reduced down to attoseconds, which is a quintillion times shorter than a second and by orders of magnitude shorter than the pumping laser pulse.&nbsp;Attosecond sources of radiation are used to detect ultraquick processes in various fields and materials. However, when such systems are based on rare gasses they require special conditions, namely, high vacuum and bulky gas tanks. That is why in this project the researchers tested the possibility of generating higher harmonics in solids, in particular, in resonant silicon nanostructures. These are metasurfaces that can support the so-called bound states in the continuum, meaning that they contain energy inside and do not emit it into their surroundings. These states can significantly increase nonlinear optical effects, including higher harmonic generation.&nbsp;Part of the project was conducted at the Nonlinear Physics Center of the Australian National University by a group of researchers including Yuri Kivshar, Kirill Koshelev, and Sergey Kruk, experts in the field of nonlinear resonant all-dielectric nanophotonics. It turned out that by changing the configuration of metasurfaces (disturbing their surface symmetry), one can produce fascinating effects:&nbsp;<blockquote>“We had a sample of optimized metasurfaces and we started by analyzing the process of harmonic generation (starting with the third and the fifth) in the laser system available in Australia. With the pulse of several picoseconds we couldn’t generate harmonics of a higher order than fifth, however we noticed that some metasurfaces could generate nonlinear radiation with an efficiency &nbsp;by a factor of 100 higher than others. This effect could be achieved because of the optimized geometry of a metasurface – meaning the size of metaatoms and the period of their location in the nanostructure,” explains George Zograf, lead author of the article and junior researcher at ITMO’s Faculty of Physics.&nbsp;</blockquote>Then, the researchers posited that higher-order harmonics could be generated with more powerful ultrashort pulse lasers with pulses of about 100 femtoseconds. This experiment was conducted on the optical setup with an ultrapowerful laser at the Friedrich Schiller University Jena in collaboration with the group headed by Prof. Christian Spielmann and Daniil Kartashov.&nbsp;It turned out that a more powerful laser makes it possible to use the same silicon metasurfaces to generate higher harmonics up to the 11th order while at the same time eliminating the previously observed twofold difference between resonant and nonresonant metasurfaces.&nbsp;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1646298751552-1243901.jpg" style="width: 766px;" class="fr-fic fr-dib">A 300*300 micrometers sample of the silicon metasurface. 3 sets of 8 metasurfaces were used in the experiment. Photo courtesy of the researchers&nbsp;As a result, the researchers have arrived at a counterintuitive conclusion: the more powerful the laser and the shorter the pulse interacting with a nanostructure, the smaller the effect of its resonance nature and high-quality states. This phenomenon is connected to the fact that when a metasurface is subjected to radiation from an ultrapowerful ultrashort pulse laser, electron-hole plasma is generated inside of it. This means that free electrons appear in the metasurface and their absorption increases the heat thus significantly damaging its resonating properties while at the same time allowing for higher-order harmonic generation.&nbsp;The main conclusion of this project is that while high-quality bound states in the continuum are crucial for linear effects, the material itself and not its structure is more important for ultrashort pulse and ultrapowerful systems. In order to allow for higher harmonic (and ultrashort pulse) generation, a material has to be highly crystalline and demonstrate a high damage threshold and low (or nonexistent) optical loss in the visible and infrared ranges of the spectrum.&nbsp;Prof. Sergey Makarov from ITMO’s Faculty of Physics explained that in the future, the researchers are planning to develop more compact designs for efficient higher harmonic generation by employing new materials (such as 2D ones or perovskites) and new approaches to nanoresonator design.&nbsp;<hr><a href="https://pubs.acs.org/doi/10.1021/acsphotonics.1c01511" target="_blank">Reference</a>: George Zograf, Kirill Koshelev, Anastasia Zalogina, Viacheslav Korolev, Richard Hollinger, Duk-Yong Choi, Michael Zuerch, Christian Spielmann, Barry Luther-Davies, Daniil Kartashov, Sergey Makarov, Sergey Kruk and Yuri Kivshar. High-Harmonic Generation from Resonant Dielectric Metasurfaces Empowered by Bound States in the Continuum. ACS Photonics, 2022.Translated by <a href="https://news.itmo.ru/en/profile/51/" rel="noopener noreferrer" target="_blank">Catherine Zavodova</a> and originally published by <a data-saferedirecturl="https://www.google.com/url?q=https://news.itmo.ru/en/&source=gmail&ust=1646297162957000&usg=AOvVaw25bJdK1_J8oF38DcmoXQbH" href="https://news.itmo.ru/en/" target="_blank">ITMO.NEWS</a>&nbsp;

Higher harmonic generation in a nonlinear silicon metasurface. Image courtesy of Ivan Pustovit, ITMO's Faculty of Physics

A group of researchers from ITMO University, the Australian National University, and the Friedrich Schiller University Jena (Germany) has for the first time demonstrated effective generation of higher harmonics in silicon metasurfaces.

Researchers Discover New Properties of Metasurfaces Thanks to Ultrashort Pulse Lasers

The perfect laser does not exist. There will always be a bit of phase noise because the laser light frequency moves back and forth a little. Phase noise prevents the laser from producing light waves with the perfect steadiness that is otherwise a characteristic feature of the laser.Most of the lasers we use on a daily basis do not need to be completely precise. For example, it is of no importance whether the frequency of the red laser light in the supermarket barcode scanners varies slightly when reading the barcodes. But for certain applications—for example in optical atomic clocks and optical measuring instruments—it is absolutely crucial that the laser is stable so that the light frequency does not vary.One way of getting closer to an ultra-precise laser is if you can determine the phase noise. This may enable you to find a way of compensating for it, so that the result becomes a purer and more accurate laser beam.This is precisely what Professor Darko Zibar from DTU Fotonik is working on. He heads a research group called Machine Learning in Photonic Systems, where the goal is to develop and utilize machine learning to improve optical systems. Most recently, researchers from the group have characterized the noise from a laser system from the Danish company NKT Photonics with unprecedented precision.“The question is how to measure that noise, and here we’ve developed the most accurate method available. We can measure much more precisely than others—our method has record-high sensitivity,” says Darko Zibar.He has developed an algorithm that can analyse and find laser light patterns using machine learning, where a model for the noise is constantly being improved. On this basis, the group of researchers hope to be able to develop a form of intelligent filter that continuously cleans the laser beam of noise.<h2>Quantum mechanics set the limit</h2>This is something that NKT Photonics can utilize in their optical measuring instruments, says Senior Researcher Poul Varming and his colleague Jens E. Pedersen, who have worked with the DTU researchers:“We work with fibre lasers that emit constant light, and where the noise level is particularly low. Our most important task is to limit the noise, and—in terms of measuring technology—we had difficulty measuring noise at very high frequencies,” says Poul Varming and continues:“But then we got in touch with Darko Zibar and his group, and we produced some lasers for them. The researchers were able to measure the noise up to very high frequencies, and the results actually contradict the established understanding of laser noise.”With the new, improved measuring method, the researchers could thus show that the theoretical basis for calculating the noise was not quite in place. With the more detailed knowledge of the noise, engineers can better identify the parts of the laser system from which the noise emanates, so that they know where to make improvements. The hope is that the machine learning system can also be used to attenuate the noise in real time.You cannot completely eliminate noise, because the laws of quantum mechanics set a very fundamental limit to how good a laser can be. Quantum noise is impossible to get rid of, but now it can at least be measured, says Darko Zibar:“We can measure in the frequencies in which quantum noise is dominant. In this way, we can determine the fundamental noise and find out how much it contributes to the total noise. Once we know the fundamental limit for how good the laser can be, we can then figure out how to suppress the rest of the noise.”“This is our next project—how we first identify and then suppress the noise, to obtain a laser that is only limited by quantum noise. This will enable us to produce some of the best lasers in the world.”<h2>Optical cable feels vibrations</h2>When the laser noise is known, it can be combated according to roughly the same principle used in noise-reducing headphones. Here, microphones pick up sound from the surroundings, and a signal is then sent in counter phase to the speakers, so that the noise and the new signal eliminate each other, and the result is silence.If the technique can be used to improve lasers by eliminating a large part of the noise so that the light frequency virtually does not vary, optical measuring instruments can have greater sensitivity and a longer range. At NKT Photonics, the technology can initially be used for distributed acoustic sensing, where a fibre optic cable is used as a sensor for measuring tiny vibrations. Distributed acoustic sensing can be used for various forms of monitoring. For example, an optical fibre can be laid along an oil or gas pipeline to ensure ultrafast detection of any ruptures. Or the technology can be used to monitor the fence around an airport or at a border—if a hole is cut in the fence, or someone tries to climb over it—the technology can not only signal what has happened, but also pinpoint where it has occurred.Such an optical monitoring system functions by a laser beam being sent into the optical fibre. During the process, a bit of the light is reflected back by tiny impurities in the fibre. However, if the fibre is affected along the way, the properties of the reflected light also change, which is measurable. Even very faint vibrations can be picked up and located with great accuracy.<h2>Monitoring of cables to the energy islands</h2>If the new technology from DTU provides more effective laser light noise attenuation, distributed acoustic sensing can be used over somewhat longer distances than today. Both the sensitivity and the range of distributed acoustic sensing can be increased with the more precise lasers, and this may—for example—be needed when electricity is to be transported from the coming energy islands in the North Sea to the mainland. Here, the power cables can be monitored using the technology, so that any ruptures can be detected and repaired quickly. Today, it is a challenge that the range of the current systems is limited to maximum 50 km, and the distance to the energy island will be somewhat longer.Poul Varming also mentions that a number of quantum technologies require extremely precise lasers. With noise-attenuated lasers, it becomes easier to develop ultra-precise optical atomic clocks and certain types of quantum computers, where lasers are used to cool individual atoms to close to absolute zero. The new generation of laser systems that may be the result of the researchers’ and engineers’ work thus offers great potential.

Ultra-precise lasers can be used for optical atomic clocks, quantum computers, power cable monitoring, and much more. But all lasers make noise, which researchers from DTU Fotonik want to minimize using machine learning.

Closer to the perfect laser

In this episode, we talk about how a breakthrough with compact laser nano-printers can make them more accessible for researchers and how leveraging 3D printing technology and machine learning will provide essential insight for developing next-gen cochlear implants. As always, you can find these and other interesting &amp; impactful engineering articles on Wevolver.com.&nbsp;<iframe height="200px" width="100%" frameborder="no" scrolling="no" seamless="" src="https://player.simplecast.com/d732a468-1bc4-4a26-9a9a-abb8dba7b2b7?dark=false" class="fr-draggable"></iframe> <hr>This podcast is sponsored by <a href="https://www2.mouser.com/" id="isPasted" rel="nofollow" target="_blank">Mouser Electronics</a>. &nbsp;&nbsp;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1640686765597-Mouser-sponsor-1-a.jpg" style="width: 766px;" class="fr-fic fr-dib"><hr><h3 id="isPasted">EPISODE NOTES</h3>(3:14) -&nbsp;<a href="https://www.wevolver.com/article/3d-laser-nanoprinters-become-compact" target="_blank">Compact 3D Laser Nanoprinters</a><a href="https://www.wevolver.com/article/finding-inspiration-in-starfish-larva" target="_blank">&nbsp;</a>🖨🔦(16:17) - <a href="https://www.wevolver.com/article/3d-printing-and-machine-learning-unite-in-new-research-to-improve-cochlear-implants-for-users" target="_blank">3D Printing &amp; ML To Create Cochlear Implants</a>👂🖨<hr>About the podcast:Every day, some of the most innovative universities, companies, and individual technology developers share their knowledge on Wevolver. To ensure we can also provide this knowledge for the growing group of podcast listeners, we started a collaboration with two young engineers, Daniel Scott Mitchell &amp; Farbod Moghaddam who discuss the most interesting content in this podcast series.&nbsp;To learn more about this show, please visit the <a href="https://www.wevolver.com/profile/the.next.byte" target="_blank">shows page</a>. By following the page, you will get automatic updates by email when a new show is published.Be sure to give us a follow and review on <a href="https://podcasts.apple.com/nl/podcast/the-next-byte/id1548255861?l=en" rel="nofollow" target="_blank">Apple</a> podcasts, <a href="https://open.spotify.com/show/6lPPsRtegnivsRUEsQ09R7?si=IPMiah7xT_apJtPjqvXMlA" rel="nofollow" target="_blank">Spotify</a>, and most of your favorite podcast platforms!Take a few seconds to leave us a review. It really helps!&nbsp;<a href="https://apple.co/2RIsbZ2" rel="nofollow" target="_blank">https://apple.co/2RIsbZ2</a>If you do it and send us proof, we’ll give you a shoutout on the show.

In this episode, we talk about how a breakthrough with compact laser nano-printers can make them more accessible for researchers and how leveraging 3D printing technology and machine learning will provide essential insight for developing next-gen cochlear implants.

Podcast: 3D Printed Cochlear Implants

Computer systems that are physically isolated from the outside world can also be exposed to attack. This is demonstrated by IT security experts at the Karlsruhe Institute of Technology (KIT) in the LaserShark project: With a directed laser, data can be transmitted to light-emitting diodes already installed in devices. In this way, attackers can secretly communicate with physically isolated systems over several meters. LaserShark shows that security-critical IT systems not only have to be well protected in terms of information and communication technology, but also optically.&nbsp;Hackers attack computers with lasers - this could be a scene in a James Bond film, but it is also possible in reality. At the beginning of December 2021, scientists from KIT, TU Braunschweig and TU Berlin presented their research project LaserShark, which investigates hidden communication via optical channels, at the 37th Annual Computer Security Applications Conference (ACSAC). Computers or networks in security-critical areas, such as those found in energy suppliers, in medical technology or in traffic control systems, are often physically isolated to prevent external access. With this so-called air gapping, the systems have neither wired nor wireless connections to the outside world. Previous approaches to this protection via electromagnetic, Breaking acoustic or optical channels only works over short spatial distances or at low data transmission rates; often they only allow data to be extracted.&nbsp;<h2>Hidden optical channel uses LEDs in standard office equipment&nbsp;</h2>The method demonstrated by the research group Intelligent System Security at the KASTEL - Institute for Information Security and Reliability of the KIT together with researchers from the TU Braunschweig and the TU Berlin, on the other hand, can initiate dangerous attacks: With a directed laser beam, outsiders can smuggle data into and out of systems protected by air gapping channel them out without the need for additional hardware on site. "This hidden optical communication uses light-emitting diodes as they are already built into devices, for example to display status messages on printers or telephones," explains junior professor Christian Wressnegger, head of the Intelligent System Security research group at KASTEL. "These LEDs are actually not intended for receiving light,&nbsp;<div class="fr-img-space-wrap"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1640338722943-2021_117_IT-Sicherheit_Computerangriffe+mit+Laserlicht_2_72dpi.jpg" style="width: 766px;" class="fr-fic fr-dib">Schematic representation of the hidden optical communication channel through which a physically isolated system can be attacked. (Image: KASTEL / KIT)&nbsp;</div><h2 id="isPasted">Data transfer works in both directions </h2>By directing laser light onto built-in LEDs and recording their reaction, they have for the first time set up a hidden optical communication channel that extends over distances of up to 25 meters, works bidirectionally - in both directions - and has high data transmission rates of 18.2 kilobits each Second inwards and 100 kilobits per second outwards.&nbsp;This possibility of attack affects commercially available office equipment such as those used in companies, universities and authorities.&nbsp;"Our LaserShark project shows how important it is to protect security-critical IT systems not only in terms of information and communication technology, but also optically," says Wressnegger.&nbsp;In order to advance research on the topic and to further develop protection against hidden optical communication, the researchers provide the program code used in their experiments, the raw data from their measurements and the scripts on the LaserShark project page:&nbsp;<a href="https://intellisec.de/research/lasershark" target="_blank">https://intellisec.de/research/lasershark</a> .<h2>Original publication</h2>Niclas Kühnapfel, Stefan Preußler, Maximilian Noppel, Thomas Schneider, Konrad Rieck, and Christian Wressnegger: LaserShark: Establishing Fast, Bidirectional Communication into Air-Gapped Systems. Proceedings of the 37th Annual Computer Security Applications Conference (ACSAC). 2021. DOI: 10.1145 / 3485832.348591&nbsp;

Data can also be transmitted by laser, so security-critical systems must be well protected optically. (Photo: Andrea Fabry, KIT)

LaserShark: KIT researchers investigate hidden communication via optical channels - data can be transmitted to light-emitting diodes already built into devices

IT security: computer attacks with laser light

Finding the biggest collisions in the universe takes time, patience, and super steady lasers.In May, NASA specialists working with industry partners delivered the first prototype laser for the European Space Agency-led Laser Interferometer Space Antenna, or LISA, mission. This unique laser instrument is designed to detect the telltale ripples in gravitational fields caused by the mergers of neutron stars, black holes, and supermassive black holes in space.Anthony Yu at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, leads the laser transmitter development for LISA.“We’re developing a highly stable and robust laser for the LISA observatory,” Yu said. “We've leveraged lessons learned from previous missions and the latest technologies in photonics packaging and reliability engineering. Now, to meet the challenging LISA requirements, NASA has developed a system that produces a laser transmitter by using a low-power laser enhanced by a fiber-optic amplifier."The team is building upon the laser technology used in NASA’s&nbsp;<a href="https://www.nasa.gov/mission_pages/Grace/index.html" target="_blank">Gravity Recovery and Climate Experiment, or GRACE</a>, mission. “We developed a more compact version as a master oscillator,” Yu said. “It has much smaller size, weight, and power consumption to allow for a fully redundant master oscillator for long-duration lifetime requirements.”The LISA laser prototype is a 2-watt laser operating in the near-infrared part of the spectrum. “Our laser is about 400 times more powerful than the typical laser pointer that puts out about 5 milliwatts or less,” Yu said. “The laser module size, not including the electronics, is about half the volume of a typical shoe box.”The Swiss Center for Electronics and Microtechnology (CSEM), headquartered in Neuchâtel, Switzerland,&nbsp;<a href="https://www.csem.ch/page.aspx?pid=164922" target="_blank">confirmed receipt of the lasers</a> and will begin testing them for stability.LISA will consist of three spacecraft following Earth in its orbit around the Sun and flying in a precision formation, with 1.5 million miles (2.5 million kilometers) separating each one. Each spacecraft will continuously point two lasers at its counterparts. The laser receiver must be sensitive to a few hundreds of picowatts of signal strength, as the laser beam will spread to about 12 miles (20 kilometers) by the time it reaches its target spacecraft. A time-code signal embedded in the beams allows LISA to measure the slightest interference in these transmissions.Ripples in the fabric of space-time as small as a picometer – 50 times smaller than a hydrogen atom – will produce a detectable change in the distances between the spacecraft. Measuring these changes will give scientists the general scale of what collided to produce these ripples and an idea of where in the sky to aim other observatories looking for secondary effects.These gravitational wave fluctuations are so small they would be obscured by external forces such as dust impacts and the radiation pressure of sunlight on the spacecraft. To mitigate this, the drag-free control concept – demonstrated on the&nbsp;<a href="https://www.nasa.gov/feature/goddard/2016/lisa-pathfinder-mission-paves-way-for-space-based-detection-of-gravitational-waves" target="_blank">LISA Pathfinder mission in 2015</a> – uses free-floating test masses sheltered inside each spacecraft as reference points for the measurement.LISA expands on work by the National Science Foundation’s Laser Interferometer Gravitational-Wave Observatory (LIGO), which&nbsp;<a href="https://www.ligo.caltech.edu/news/ligo20160211" target="_blank">captured its first recording of gravitational waves in 2015</a>. Since then, the pair of ground-based observatories in Hanford, Washington, and Livingston, Louisiana, have captured four dozen mergers.&nbsp;Thomas Hams, program scientist for LISA at NASA Headquarters in Washington, said the precision laser measurements will allow us to zoom in on the gravitational wave signatures of these mergers and enable other observatories to focus on the right part of the sky to capture these events in the electromagnetic spectrum.NASA’s&nbsp;<a href="https://www.nasa.gov/content/fermi-gamma-ray-space-telescope" target="_blank">Fermi Gamma-ray Space Telescope</a> picked up the&nbsp;<a href="https://www.nasa.gov/press-release/nasa-missions-catch-first-light-from-a-gravitational-wave-event" target="_blank">first such multimessenger observation</a> just seconds after LIGO detected a merger of two neutron stars through gravitational waves.“With LISA, the hope is you will be able to see these things develop before the merger actually happens,” Hams said. “There will be an indicator that something is coming.”Industry PartnershipTo achieve the required stability, the team brought Fibertek Inc. in Herndon, Virginia, and Avo Photonics Inc. in Horsham, Pennsylvania, to develop the laser, oscillator, and power amplifier, and an independent optical engineer in San Jose, California.Avo Photonics built the laser for the observatory.“Here you have the challenges of spaceborne ruggedness needs, on top of submicron-level optical alignment tolerance requirements. These really push your optical, thermal, and mechanical design chops,” Avo Photonics President Joseph L. Dallas said. “In addition, the narrow linewidth, low noise, and overall stability needed for this mission is unprecedented.”Photonics pioneer Tom Kane invented the monolithic laser oscillator technology that Goddard used to stabilize the frequency of the laser light. “Your average laser can be very messy,” Kane said. “They can wander all around their target frequency. You need a ‘quiet’ laser that’s exactly one wavelength and a perfect beam out to 15 decimal places of accuracy.”His oscillator technology uses feedback loops to keep the laser burning at such precision. “The wavelength ends up becoming the ruler for these incredible distances,” Kane said.The high-power, low-noise amplifier came from Fibertek.Fibertek also contributed to NASA’s&nbsp;<a href="https://www.nasa.gov/content/goddard/icesat-2" target="_blank">Ice Cloud and Land Elevation Satellite (ICESat) 2</a> and the&nbsp;<a href="https://www.nasa.gov/mission_pages/calipso/main/index.html" target="_blank">Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO),</a> which has been operating a laser pointed at Earth for 15 years.Including time for testing on the ground and potential mission extensions, LISA’s lasers must operate without skipping a hertz for up to 16 years, Goddard’s Yu said.“Once launched, they will need to be in 24/7 operation for five years for the initial mission, with a possible six to seven years of extended mission after that,” Yu explained. “We need them to be stable and quiet.”

The first prototype of a laser sits on a testbed at the Swiss Center for Electronics and Microtechnology (CSEM), headquartered in Neuchâtel, Switzerland. CSEM will test and characterize the laser, which will be used to conduct gravitational wave experiments in space for the LISA mission. Credits: European Space Agency/CSEM

Finding the biggest collisions in the universe takes time, patience, and super steady lasers.

NASA Provides Laser for LISA Mission

In this episode, we talk about how Australian National University researchers broke the world record for solar cell efficiency and a new AI-powered device coming out of MIT that can help you determine if the material you want to use for laser cutting is safe + what settings to use. As always, you can find these and other interesting &amp; impactful engineering articles on Wevolver.com.<iframe height="200px" width="100%" frameborder="no" scrolling="no" seamless="" src="https://player.simplecast.com/c804ffff-8729-468e-ba2e-c8ce075f61d4?dark=false" class="fr-draggable"></iframe>&nbsp;<h3 id="isPasted">EPISODE NOTES</h3>(1:09) -&nbsp;<a href="https://www.wevolver.com/article/scientists-set-new-record-with-bifacial-solar-cells" target="_blank">Scientists Set New Record With Bifacial Solar Cells</a>:&nbsp;Australian National University just broke a world record for solar efficiency by harvesting solar energy reflected from the ground behind a solar panel using their novel double sided approach.(7:27) -&nbsp;<a href="https://www.wevolver.com/article/smart-laser-cutter-system-detects-different-materials" target="_blank">Smart Laser Cutter System Detects Different Materials</a>:&nbsp;Have you ever wanted to use a laser cutter without needing to research the right settings for the material you want to cut? Well, MIT has developed an AI powered optical sensor that can determine whether your material is safe and if so, it’ll tell you the exact parameters to use!--About the podcast:Every day, some of the most innovative universities, companies, and individual technology developers share their knowledge on Wevolver. To ensure we can also provide this knowledge for the growing group of podcast listeners, we started a collaboration with two young engineers, Daniel Scott Mitchell &amp; Farbod Moghaddam who discuss the most interesting content in this podcast series.&nbsp;To learn more about this show, please visit the <a href="https://www.wevolver.com/profile/the.next.byte" target="_blank">shows page</a>. By following the page, you will get automatic updates by email when a new show is published.Be sure to give us a follow and review on <a href="https://podcasts.apple.com/nl/podcast/the-next-byte/id1548255861?l=en" rel="nofollow" target="_blank">Apple</a> podcasts, <a href="https://open.spotify.com/show/6lPPsRtegnivsRUEsQ09R7?si=IPMiah7xT_apJtPjqvXMlA" rel="nofollow" target="_blank">Spotify</a>, and most of your favorite podcast platforms!Take a few seconds to leave us a review. It really helps!&nbsp;<a href="https://apple.co/2RIsbZ2" target="_blank">https://apple.co/2RIsbZ2</a>if you do it and send us proof, we’ll give you a shoutout on the show.

Image: Eric Byler/The Autralian National University

In this episode, we talk about how Australian National University researchers broke the world record for solar cell efficiency and a new AI-powered device coming out of MIT that can help you determine if the material you want to use for laser cutting is safe + what settings to use.

Podcast: The Solar Panel That Broke The World Record

Understanding how light waves oscillate in time as they interact with materials is essential to understanding light-driven energy transfer in materials, such as solar cells or plants. Due to the fantastically high speeds at which light waves oscillate, however, scientists have yet to develop a compact device with enough time resolution to directly capture them.Now, a team led by MIT researchers has demonstrated chip-scale devices that can directly trace the weak electric field of light waves as they change in time. Their device, which incorporates a microchip that uses short laser pulses and nanoscale antennas, is easy to use, requiring no special environment for operation, minimal laser parameters, and conventional laboratory electronics.The team’s work,&nbsp;<a href="https://www.nature.com/articles/s41566-021-00792-0" target="_blank">published earlier this month</a> in&nbsp;Nature Photonics, may enable the development of new tools for optical measurements with applications in areas such as biology, medicine, food safety, gas sensing, and drug discovery.“The potential applications of this technology are many,” says co-author Phillip Donnie Keathley, group leader and Research Laboratory of Electronics (RLE) research scientist. “For instance, using these optical sampling devices, researchers will be able to better understand optical absorption pathways in plants and photovoltaics, or to better identify molecular signatures in complex biological systems.”Keathley’s co-authors are lead author Mina Bionta, a senior postdoc at RLE; Felix Ritzkowsky, a graduate student at the Deutsches Elektronen-Synchrotron (DESY) and the University of Hamburg who was an MIT visiting student; and Marco Turchetti, a graduate student in RLE. The team was led by Keathley working with professors Karl Berggren in the MIT Department of Electrical Engineering and Computer Science (EECS); Franz Kärtner of DESY and University of Hamburg in Germany; and William Putnam of the University of California at Davis. Other co-authors are Yujia Yang, a former MIT postdoc now at École Polytechnique Fédérale de Lausanne (EFPL), and Dario Cattozzo Mor, a former visiting student.<h2>The ultrafast meets the ultrasmall — time stands still at the head of a pin</h2>Researchers have long sought methods for measuring systems as they change in time. Tracking gigahertz waves, like those used for your phone or Wi-Fi router, requires a time resolution of less than 1 nanosecond (one-billionth of a second). To track visible light waves requires an even faster time resolution — less than 1 femtosecond (one-millionth of one-billionth of a second).The MIT and DESY research teams designed a microchip that uses short laser pulses to create extremely fast electronic flashes at the tips of nanoscale antennas. The nanoscale antennas are designed to enhance the field of the short laser pulse to the point that they are strong enough to rip electrons out of the antenna, creating an electronic flash that is quickly deposited into a collecting electrode. These electronic flashes are extremely brief, lasting only a few hundred attoseconds (a few one-hundred-billionths of one-billionth of 1 second).Using these fast flashes, the researchers were able to take snapshots of much weaker light waves oscillating as they passed by the chip.“This work shows, once more, how the merger of nanofabrication and ultrafast physics can lead to exciting insights and new ultrafast measurements tools,” says Professor Peter Hommelhoff, chair for laser physics at the University of Erlangen-Nuremberg, who was not connected with this work. “All this is based on the deep understanding of the underlying physics. Based on this research, we can now measure ultrafast field waveforms of very weak laser pulses.”The ability to directly measure light waves in time will benefit both science and industry, say the researchers. As light interacts with materials, its waves are altered in time, leaving signatures of the molecules inside. This optical field sampling technique promises to capture these signatures with greater fidelity and sensitivity than prior methods while using compact and integratable technology needed for real-world applications.

As a laser illuminates these nanometer-scale devices (blue wave), attosecond electron flashes are generated (red pulse) at the ends of nanotips and used to trace out weak light fields (red wave). Credits:Image: Marco Turchetti