Posts belonging to Category plasmonics

Optical Computer

Researchers at the University of Sydney (Australia) have dramatically slowed digital information carried as light waves by transferring the data into sound waves in an integrated circuit, or microchipTransferring information from the optical to acoustic domain and back again inside a chip is critical for the development of photonic integrated circuits: microchips that use light instead of electrons to manage data.

These chips are being developed for use in telecommunications, optical fibre networks and cloud computing data centers where traditional electronic devices are susceptible to electromagnetic interference, produce too much heat or use too much energy.

The information in our chip in acoustic form travels at a velocity five orders of magnitude slower than in the optical domain,” said Dr Birgit Stiller, research fellow at the University of Sydney and supervisor of the project.

It is like the difference between thunder and lightning,” she said.

This delay allows for the data to be briefly stored and managed inside the chip for processing, retrieval and further transmission as light wavesLight is an excellent carrier of information and is useful for taking data over long distances between continents through fibre-optic cables.

But this speed advantage can become a nuisance when information is being processed in computers and telecommunication systems.


Big Data And Skyrmions

Today’s world, rapidly changing because of “big data”, is encapsulated in trillions of tiny magnetic objects magnetic bits – each of which stores one bit of data in magnetic disk drives.   A group of scientists from the Max Planck Institutes in Halle and Dresden have discovered a new kind of magnetic nano-object in a novel material that could serve as a magnetic bit with cloaking properties to make a magnetic disk drive with no moving parts – a Racetrack Memory – a reality in the near future.

Most digital data is stored in the cloud as magnetic bits within massive numbers of magnetic disk drives.  Over the past several decades these magnetic bits have shrunk by many orders of magnitude, reaching limits where the boundaries of these magnetic regions can have special properties.  In some special materials these boundaries – “magnetic domain walls” – can be described as being topological. What this means is that these walls can be thought of as having a special magical cloak – what is referred to by scientists as “topological protection”.   An important consequence is that such magnetic walls are more stable to perturbations than similar magnetic bits without topological protection that are formed in conventional magnetic materials.  Thus, these “topological magnetic objects could be especially useful for storing1”s and “0”s, the basic elements of digital data.   One such object is a “magnetic skyrmion” which is a tiny magnetic region, perhaps tens to hundreds of atoms wide, separated from a surrounding magnetic region by a chiral domain wall.  Until recently only one type of skyrmion has been found in which it is surrounded by a chiral domain wall that takes the same form in all directions.   But there have been predictions of several other types of skyrmions that were not yet observed.

Now in a paper published in Nature, scientists from Prof. Stuart Parkin’s NISE department at the Max Planck Institute for Microstructure Physics in Halle, Germany, have found a second class of skyrmions, what are called “anti-skyrmions”, in materials synthesized in Prof. Claudia Felser.   The scientists from Halle and Dresden have found these tiny magnetic objects in a special class of versatile magnetic compounds called Heusler compounds.   Of these Heusler compounds, a tiny subset have just the right crystal symmetry to allow for the possibility of forming anti-skyrmions but not skyrmions.

The special cloaking properties of skyrmions makes them of great interest for a radically new form of solid-state memorythe Racetrack Memory. In Racetrack Memory digital data is encoded within magnetic domain walls that are packed closely within nanoscopic magnetic wires.  One of the unique features of Racetrack Memory, which is distinct from all other memories, is that the walls are moved around the nanowires themselves using recent discoveries in spin-orbitronics domain walls.  Very short pulses of current move all the backwards and forwards along the nano-wires. The walls – the magnetic bits – can be read and written by devices incorporated directly into the nanowires themselves, thereby eliminating any mechanical parts.


How To Detect, Kill Circulating Tumor Cells

A nanolaser known as the spaser can serve as a super-bright, water-soluble, biocompatible probe capable of finding metastasized cancer cells in the blood stream and then killing these cells, according to a new research study. The spaser can be used as an optical probe and when released into the body (possibly through an injection or drinking a solution), it can find and go after circulating tumor cells (CTCs), stick to them and destroy these cells by breaking them apart to prevent cancer metastases. The spaser absorbs laser light, heats up, causes shock waves in the cell and destroys the cell membrane.

The spaser, which stands for surface plasmon amplification by stimulated emission of radiation, is a nanoparticle, about 20 nanometers in size or hundreds times smaller than human cells. It has folic acid attached to its surface, which allows selective molecular targeting of cancer cells. The folate receptor is commonly overexpressed on the surface of most human cancer cells and is weakly expressed in normal cells. The discovery was made by researchers at Georgia State University, the University of Arkansas for Medical Sciences, the University of Arkansas at Little Rock and the Siberian Branch of the Russian Academy of Science.

There is no other method to reliably detect and destroy CTCs,” said Dr. Mark Stockman, director of the Center for Nano-Optics and professor of physics at Georgia State. “This is the first. This biocompatible spaser can go after these cells and destroy them without killing or damaging healthy cells. Any other chemistry would damage and likely kill healthy cells. Our findings could play a pivotal role in providing a better, life-saving treatment option for cancer patients.”

Metastatic cancer occurs when cancer spreads to distant parts of the body, often to the bone, liver, lungs and brain, through a process called metastasis. Many types of cancers refer to this as stage IV cancer. Once cancer spreads, it can be difficult to control, and most metastatic cancer can’t be cured with current treatments, according to the National Institute of Health’s National Cancer Institute. One of the most dangerous ways metastasizing occurs is through the CTCs, which this study aims to detect and destroy using spasers. The spasers used in this study measure just 22 nanometers, setting the record for the smallest nanolasers.

The findings are published in the journal Nature Communications.


SuperPowerful Tiny Device Converts Light Into Electricity

In today’s increasingly powerful electronics, tiny materials are a must as manufacturers seek to increase performance without adding bulk. Smaller also is better for optoelectronic devices — like camera sensors or solar cells —which collect light and convert it to electrical energy. Think, for example, about reducing the size and weight of a series of solar panels, producing a higher-quality photo in low lighting conditions, or even transmitting data more quickly.

However, two major challenges have stood in the way: First, shrinking the size of conventionally used “amorphousthin-film materials also reduces their quality. And second, when ultrathin materials become too thin, they are almost transparent — and actually lose some ability to gather or absorb light.

Now, in a nanoscale photodetector that combines both a unique fabrication method and light-trapping structures, a team of engineers from the University at Buffalo (UB) and the University of Wisconsin-Madison (UW-Madison) has overcome both of those obstacles. The researchers — electrical engineers Qiaoqiang Gan at UB, and Zhenqiang (Jack) Ma and Zongfu Yu at UW-Madison — described their device, a single-crystalline germanium nanomembrane photodetector on a nanocavity substrate, in the July 7, 2017, issue of the journal Science Advances.

This image shows the different layers of the nanoscale photodetector, including germanium (red) in between layers of gold or aluminum (yellow) and aluminum oxide (purple). The bottom layer is a silver substrate

We’ve created an exceptionally small and extraordinarily powerful device that converts light into energy,” says Gan, associate professor of electrical engineering in UB’s School of Engineering and Applied Sciences, and one of the paper’s lead authors. “The potential applications are exciting because it could be used to produce everything from more efficient solar panels to more powerful optical fibers.”

The idea, basically, is you want to use a very thin material to realize the same function of devices in which you need to use a very thick material,” says Ma, the Lynn H. Matthias Professor and Vilas Distinguished Achievement Professor in electrical and computer engineering at UW-Madison, also a lead author. Nanocavities are made up of an orderly series of tiny, interconnected molecules that essentially reflect, or circulate, light.

The new device is an advancement of Gan’s work developing nanocavities that increase the amount of light that thin semiconducting materials like germanium can absorb. It consists of nanocavities sandwiched between a top layer of ultrathin single-crystal germanium and a bottom, reflecting layer of silver.


How To Strengthen 3-D Printed Parts

From aerospace and defense to digital dentistry and medical devices, 3-D printed parts are used in a variety of industries. Currently, 3-D printed parts are very fragile and traditionally used in the prototyping phase of materials or as a toy for display. A doctoral student in the Department of Materials Science and Engineering at Texas A&M University has pioneered a countermeasure to transform the landscape of 3-D printing today.

Brandon Sweeney and his advisor Dr. Micah Green, associate professor in the Department of Chemical Engineering, discovered a way to make 3-D printed parts stronger and immediately useful in real-world applications. Sweeney and Green applied the traditional welding concepts to bond the submillimeter layers in a 3-D printed part together, while in a microwave.

I was able to see the amazing potential of the technology, such as the way it sped up our manufacturing times and enabled our CAD designs to come to life in a matter of hours,” Sweeney said. “Unfortunately, we always knew those parts were not really strong enough to survive in a real-world application.

3-D printed objects are comprised of many thin layers of materials, plastics in this case, deposited on top of each other to form a desired shape. These layers are prone to fracturing, causing issues with the durability and reliability of the part when used in a real-world application, for example a custom printed medical device. “I knew that nearly the entire industry was facing this problem,” Sweeney said. “Currently, prototype parts can be 3-D printed to see if something will fit in a certain design, but they cannot actually be used for a purpose beyond that.”

When Sweeney started his doctorate, he was working with Green in the Department of Chemical Engineering at Texas Tech University. Green had been collaborating with Dr. Mohammad Saed, assistant professor in the electrical and computer engineering department at Texas Tech, on a project to detect carbon nanotubes using microwaves. The trio crafted an idea to use carbon nanotubes in 3-D printed parts, coupled with microwave energy to weld the layers of parts together.

The basic idea is that a 3-D part cannot simply be stuck into an oven to weld it together because it is plastic and will melt,” Sweeney said. “We realized that we needed to borrow from the concepts that are traditionally used for welding parts together where you’d use a point source of heat, like a torch or a TIG welder to join the interface of the parts together. You’re not melting the entire part, just putting the heat where you need it.” The technology is patent-pending and licensed with a local company, Essentium Materials.

The team recently published a paper “Welding of 3-D Printed Carbon Nanotube-Polymer Composites by Locally Induced Microwave Heating,” in Science Advances.


Use The Phone And See 3D Content Without 3D Glasses

RED, the company known for making some truly outstanding high-end cinema cameras, is set to release a smartphone in Q1 of 2018 called the HYDROGEN ONE. RED says that it is a standalone, unlocked and fully-featured smartphone “operating on Android OS that just happens to add a few additional features that shatter the mold of conventional thinking.” Yes, you read that right. This phone will blow your mind, or something – and it will even make phone calls.

In a press release riddled with buzzwords broken up by linking verbs, RED praises their yet-to-be smartphone with some serious adjectives. If we were just shown this press release outside of living on RED‘s actual server, we would swear it was satire. Here are a smattering of phrases found in the release.

Incredible retina-riveting display
Holographic multi-view content
RED Hydrogen 4-View content
Assault your senses
Proprietary H3O algorithm
Multi-dimentional audio

  • There are two models of the phone, which run at different prices. The Aluminum model will cost $1,195, but anyone worth their salt is going to go for the $1,595 Titanium version. Gotta shed that extra weight, you know?

Those are snippets from just the first three sections, of which there are nine. I get hyping a product, but this reads like a catalog seen in the background of a science-fiction comedy, meant to sound ridiculous – especially in the context of a ficticious universe.

Except that this is real life.

After spending a few minutes removing all the glitter words from this release, it looks like it will be a phone using a display similar to what you get with the Nintendo 3DS, or what The Verge points out as perhaps better than the flopped Amazon Fire Phone. Essentially, you should be able to use the phone and see 3D content without 3D glasses. Nintendo has already proven that can work, however it can really tire out your eyes. As an owner of three different Nintendo 3DS consoles, I can say that I rarely use the 3D feature because of how it makes my eyes hurt. It’s an odd sensation. It is probalby why Nintendo has released a new handheld that has the same power as the 3DS, but dropping the 3D feature altogether.

Anyway, back to the HYDROGEN ONE, RED says that it will work in tandem with their cameras as a user interface and monitor. It will also display what RED is calling “holographic content,” which isn’t well-described by RED in this release. We can assume it is some sort of mixed-dimensional view that makes certain parts of a video or image stand out over the others.


3-D Printed Graphene Foam

Nanotechnologists from Rice University and China’s Tianjin University have used 3-D laser printing to fabricate centimeter-sized objects of atomically thin graphene. The research could yield industrially useful quantities of bulk graphene and is described online in a new study in the American Chemical Society journal ACS Nano.

Laser sintering was used to 3-D print objects made of graphene foam, a 3-D version of atomically thin graphene. At left is a photo of a fingertip-sized cube of graphene foam; at right is a close-up of the material as seen with a scanning electron microscope

This study is a first of its kind,” said Rice chemist James Tour, co-corresponding author of the paper. “We have shown how to make 3-D graphene foams from nongraphene starting materials, and the method lends itself to being scaled to graphene foams for additive manufacturing applications with pore-size control.”

Graphene, one of the most intensely studied nanomaterials of the decade, is a two-dimensional sheet of pure carbon that is both ultrastrong and conductive. Scientists hope to use graphene for everything from nanoelectronics and aircraft de-icers to batteries and bone implants. But most industrial applications would require bulk quantities of graphene in a three-dimensional form, and scientists have struggled to find simple ways of creating bulk 3-D graphene.

For example, researchers in Tour’s lab began using lasers, powdered sugar and nickel to make 3-D graphene foam in late 2016. Earlier this year they showed that they could reinforce the foam with carbon nanotubes, which produced a material they dubbed “rebar graphene” that could retain its shape while supporting 3,000 times its own weight. But making rebar graphene was no simple task. It required a pre-fabricated 3-D mold, a 1,000-degree Celsius chemical vapor deposition (CVD) process and nearly three hours of heating and cooling.  “This simple and efficient method does away with the need for both cold-press molds and high-temperature CVD treatment,” said co-lead author Junwei Sha, a former student in Tour’s lab who is now a postdoctoral researcher at Tianjin. “We should also be able to use this process to produce specific types of graphene foam like 3-D printed rebar graphene as well as both nitrogen- and sulfur-doped graphene foam by changing the precursor powders.” Sha and colleagues conducted an exhaustive study to find the optimal amount of time and laser power to maximize graphene production. The foam created by the process is a low-density, 3-D form of graphene with large pores that account for more than 99 percent of its volume.

The 3-D graphene foams prepared by our method show promise for applications that require rapid prototyping and manufacturing of 3-D carbon materials, including energy storage, damping and sound absorption,” said co-lead author Yilun Li, a graduate student at Rice.


Semiconductors As Thin As An Atom

A two-dimensional material developed by physicist Prof. Dr. Axel Enders (Bayreuth University  in Germany) together with international partners could revolutionize electronicsSemiconductors that are as thin as an atom are no longer the stuff of .  Thanks to its semiconductor properties, this material could be much better suited for high tech applications than graphene, the discovery of which in 2004 was celebrated worldwide as a . This new material contains carbon, boron, and nitrogen, and its chemical name is “Hexagonal Boron-Carbon-Nitrogen (h-BCN)”. The new development was published in the journal ACS Nano.

2D material Bayreuth University

Our findings could be the starting point for a new generation of electronic transistors, circuits, and sensors that are much smaller and more bendable than the electronic elements used to date. They are likely to enable a considerable decrease in power consumption,” Prof. Enders predicts, citing the CMOS technology that currently dominates the electronics industry. This technology has clear limits with regard to further miniaturization. “h-BCN is much better suited than graphene when it comes to pushing these limits,” according to Enders.

Graphene is a two-dimensional lattice made up entirely of carbon atoms. It is thus just as thin as a single atom. Once scientists began investigating these structures more closely, their remarkable properties were greeted with enthusiasm across the world. Graphene is 100 to 300 times stronger than steel and is, at the same time, an excellent conductor of heat and electricity.


New Material Ten Times Stronger Than Steel, Designed From Graphene

A team of researchers at MIT has designed one of the strongest lightweight materials known, by compressing and fusing flakes of graphene, a two-dimensional form of carbon. The new material, a sponge-like configuration with a density of just 5 percent, can have a strength 10 times that of steel. In its two-dimensional form, graphene is thought to be the strongest of all known materials. But researchers until now have had a hard time translating that two-dimensional strength into useful three-dimensional materials.

The new findings show that the crucial aspect of the new 3-D forms has more to do with their unusual geometrical configuration than with the material itself, which suggests that similar strong, lightweight materials could be made from a variety of materials by creating similar geometric features.

graphene material

The team was able to compress small flakes of graphene using a combination of heat and pressure. This process produced a strong, stable structure whose form resembles that of some corals and microscopic creatures called diatoms. These shapes, which have an enormous surface area in proportion to their volume, proved to be remarkably strong. “Once we created these 3-D structures, we wanted to see what’s the limit — what’s the strongest possible material we can produce,” says Zhao Qin, research scientist at MIT. To do that, they created a variety of 3-D models and then subjected them to various tests. In computational simulations, which mimic the loading conditions in the tensile and compression tests performed in a tensile loading machine, “one of our samples has 5 percent the density of steel, but 10 times the strength,” Qin says.
The findings have been reported in the journal Science Advances.


How To Erase Chips Remotely

A military drone flying on a reconnaissance mission is captured behind enemy lines, setting into motion a team of engineers who need to remotely delete sensitive information carried on the drone’s chips. Because the chips are optical and not electronic, the engineers can now simply flash a beam of UV light onto the chip to instantly erase all content. Disaster averted.

This James Bond-esque chip is closer to reality because of a new development in a nanomaterial developed by Yuebing Zheng, a professor of mechanical engineering and materials science and engineering in the Cockrell School of Engineering. His team described its findings in the journal Nano Letters.


The molecules in this material are very sensitive to light, so we can use a UV light or specific light wavelengths to erase or create optical components,” Zheng said. “Potentially, we could incorporate this LED into the chip and erase its contents wirelessly. We could even time it to disappear after a certain period of time.”

To test their innovation, the researchers used a green laser to develop a waveguide — a structure or tunnel that guides light waves from one point to another — on their nanomaterial. They then erased the waveguide with a UV light, and re-wrote it on the same material using the green laser. The researchers believe they are the first to rewrite a waveguide, which is a crucial photonic component and a building block for integrated circuits, using an all-optical technique.


Swiches For Electricity: Atomic-Scale Manufacturing

Robert Wolkow is no stranger to mastering the ultra-small and the ultra-fast. A pioneer in atomic-scale science with a Guinness World Record to boot (for a needle with a single atom at the point), Wolkow’s team, together with collaborators at the Max Planck Institute in Hamburg, have just released findings that detail how to create atomic switches for electricity, many times smaller than what is currently used. With applications for practical systems like silicon semi-conductor electronics, it means smaller, more efficient, more energy-conserving nanocomputers, as just one example of the technology revolution that is unfolding right before our very eyes (if you can squint that hard).


It’s something you don’t even hear about yet, but atom-scale manufacturing is going to be world-changing. This is just the beginning of what will be at least a century of developments in atom-scale manufacturing, and it will be transformational“.  “This is the first time anyone’s seen a switching of a single-atom channel,” explains Wolkow, a physics professor at the University of Alberta and the Principal Research Officer at Canada’s National Institute for Nanotechnology. “You’ve heard of a transistor—a switch for electricity—well, our switches are almost a hundred times smaller than the smallest on the market today.

Today’s tiniest transistors operate at the 14 nanometer level, which still represents thousands of atoms. Wolkow’s and his team at the University of Alberta, NINT, and his spinoff QSi, have worked the technology down to just a few atoms. Since computers are simply a composition of many on/off switches, the findings point the way not only to ultra-efficient general purpose computing but also to a new path to quantum computing.


Light Makes OscillatorTo Oscillate Indefinitely

Researchers have designed a device that uses light to manipulate its mechanical properties. The device, which was fabricated using a plasmomechanical metamaterial, operates through a unique mechanism that couples its optical and mechanical resonances, enabling it to oscillate indefinitely using energy absorbed from light.

metamaterialThis work demonstrates a metamaterial-based approach to develop an optically-driven mechanical oscillator. The device can potentially be used as a new frequency reference to accurately keep time in GPS, computers, wristwatches and other devices, researchers said. Other potential applications that could be derived from this metamaterial-based platform include high precision sensors and quantum transducers..

Researchers engineered the metamaterial-based device by integrating tiny light absorbing nanoantennas onto nanomechanical oscillators. The study was led by Ertugrul Cubukcu, a professor of nanoengineering and electrical engineering at the University of California San Diego. The work, which Cubukcu started as a faculty member at the University of Pennsylvania and is continuing at the Jacobs School of Engineering at UC San Diego, demonstrates how efficient light-matter interactions can be utilized for applications in novel nanoscale devices.

Metamaterials are artificial materials that are engineered to exhibit exotic properties not found in nature. For example, metamaterials can be designed to manipulate light, sound and heat waves in ways that can’t typically be done with conventional materials.

Metamaterials are generally considered “lossy” because their metal components absorb light very efficiently. “The lossy trait of metamaterials is considered a nuisance in photonics applications and telecommunications systems, where you have to transmit a lot of power. We’re presenting a unique metamaterials approach by taking advantage of this lossy feature,” Cubukcu said. The researchers also point out that because the plasmomechanical metamaterial can efficiently absorb light, it can function under a broad optical resonance. That means this metamaterial can potentially respond to a light source like an LED and won’t need a strong laser to provide the energy.

Using plasmonic metamaterials, we were able to design and fabricate a device that can utilize light to amplify or dampen microscopic mechanical motion more powerfully than other devices that demonstrate these effects. Even a non-laser light source could still work on this device,” said Hai Zhu, a former graduate student in Cubukcu’s lab and first author of the study.

Optical metamaterials enable the chip-level integration of functionalities such as light-focusing, spectral selectivity and polarization control that are usually performed by conventional optical components such as lenses, optical filters and polarizers. Our particular metamaterial-based approach can extend these effects across the electromagnetic spectrum,” adds Fei Yi, a postdoctoral researcher who worked in Cubukcu’s lab.

The research was published in the journal Nature Photonics.