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" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></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://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQwNjg2NzY1NTk3LU1vdXNlci1zcG9uc29yLTEtYS5qcGciLCJlZGl0cyI6eyJyZXNpemUiOnsid2lkdGgiOjk1MCwiZml0IjoiY292ZXIifX19" style="width: 766px;" class="fr-fic fr-dib"><hr><h3 id="isPasted">EPISODE NOTES</h3>(3:14) - Compact 3D Laser Nanoprinters<a href="https://www.wevolver.com/article/finding-inspiration-in-starfish-larva" target="_blank">&nbsp;</a>🖨🔦(16:17) - 3D Printing &amp; ML To Create Cochlear Implants👂🖨<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" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe>&nbsp;<h3 id="isPasted">EPISODE NOTES</h3>(1:09) - Scientists Set New Record With Bifacial Solar Cells:&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) - Smart Laser Cutter System Detects Different Materials:&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

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