Materiale si echipamente cu proprietati in mascarea in domeniul vizibil ,IR , al undelor radar sau care pot avea proprietati in mimetism – Pagina 2

Lampă indicatoare(Pointing light)

echipa UCSB încearcă să difuzeze sau să direcționeze undele optice (cu frecvență în infraroșu) într-o anumită direcție, cu un grad ridicat de control la o frecvență extrem de ridicată. În mod tradițional, antenele au funcționat în domeniul gigahertz sau megahertz; Grupul lui Schuller lucrează la scară de zeci de terahertzi sau 1 triliu de cicluri pe secundă în gama de frecvențe optice.Sensibilizarea mediului în mod mai rapid și mai eficient ar fi un beneficiu în domenii precum teledetecția, vehiculele autonome și afișajele holografice.

Posted: Mar 01, 2018
Pointing light (Nanowerk News) Without the vast, nearly infinite web of crisscrossing electromagnetic waves that travel invisibly through the air, the modern world would cease to exist. Transmitting digital data and sensing and returning information about the environment at the speed of light, these waves are important in many emerging applications, including autonomous vehicles, Lidar and holographic displays, where the ability to direct and steer light beams over time is crucial to mapping surroundings or to immersion in an augmented reality.
UC Santa Barbara engineer Jon Schuller aims to manipulate specialized semiconductor materials and devices to control light without using mechanically moving parts — an achievement that could have wide-ranging applications. He is pursuing ways to use sub-wavelength interactions involving any element smaller than the wavelength of light (about one micron) to not only steer light, but also to enable faster, more efficient sensing. He also hopes to shrink the size of the system and improve its performance — all at a lower cost.

Sensing the environment more quickly and efficiently would be a benefit in such areas as remote sensing, autonomous vehicles and holographic displays. (Image: Peter Allen)
In a paper in the journal Nature Communications („Ultrawide thermal free-carrier tuning of dielectric antennas coupled to epsilon-near-zero substrates”), Schuller, an assistant professor, and his UCSB collaborators — Chris Palmstrøm, a professor of electrical and computer engineering and of materials, and graduate students Mihir Pendharkar and Prasad P. Iyer — describe a technique for applying heat to the semiconductor indium antimonide (InSb) to form an ideal material for controlling the phase of light necessary to achieve tunability.
“Sub-wavelength elements are essentially active mirrors, reflecting light with a controllable phase, and are able to generate and modulate the light when it interacts with matter,” said Schuller, a faculty member in UCSB’s Department of Electrical and Computer Engineering. “Our focus is on steering the beam. When multiple objects emit light, the different phases cause them to add up constructively in certain directions and destructively in others.”
One way to encode digital data is to turn a laser on and off rapidly, which can be achieved by splitting the laser into two waves, shifting the phase of one 180 degrees and recombining them. As the parallel beams travel through space, the waves align as mirror images of each other. The peaks of one wave line up with the troughs of the other, canceling out the signal. By switching the phase between 0 degrees (on) and 180 degrees (off) millions of times per second, information is encoded into the ones and zeroes of a digital data sequence.
To cause such phase shifts at the micron scale of light is much more difficult than doing so at the millimeter or centimeter scale. “At that scale, the phase-shifting device is so small that the light travels very little distance and therefore has very little time to interact with the material,” Schuller explained. “We need to find a much larger and more extreme light-matter interaction that can occur over such a small distance and time.”
For example, a material’s refractive index can be changed from 10-3 to 10-4 — one-tenth of a percent to one-hundredth of a percent — a significant increment in scientific terms. However, this research investigates effects that are one to 10,000 times bigger. The refractive index tells a lot about how light behaves in a material, such as its speed, its effective wavelength and the angle at which light rays bend as they enter or exit the material.
One type of modulation involves changing the number of mobile electrons in the material to alter its optical properties, which in turn affects the phases. It is possible to change electron density simply by changing the temperature of InSb without having to run a current through it.
Ultimately, the UCSB team is trying to broadcast or direct optical (infrared-frequency) waves in a particular direction with a high degree of control at an extremely high frequency. Traditionally, antennas have operated in the domain of gigahertz or megahertz; Schuller’s group is working at the scale of tens of terahertz, or 1 trillion cycles per second in the optical frequency range.
For now, the researchers are using their new thermal free-carrier method — employing heat to tune the number of electrons — to solve the challenges of optical tuning. Eventually, their goal is to activate InSb electrically, which — while faster and offering more benefits — poses another complex challenge. That makes the thermal approach even more valuable, permitting the researchers to experiment with the material without having to create an electrical system to activate it.
“Our temperature technique is a clever way to look at the basic physics of this problem — the basic optical materials science questions — and get all the complexities of the ultimate application that will use electricity,” said Schuller.

Source: UC Santa Barbara

Pielea pieptului poate fi soluția pentru camuflarea materialului(Squid skin could be the solution to camouflage material)

Organele de cromatopor, care apar ca sute de pistrui multi-colorate pe suprafața corpului cefalopodului, contribuie la schimbări rapide ale culorii pielii.Cercetatorii au descoperit ca aceste granule au calitati optice remarcabile si le-au folosit pentru a face filme subtiri si fibre care ar putea fi incorporate in textile, afise flexibile si dispozitive viitoare de schimbare a culorii.construiasca aceste dispozitive care sa se potriveasca cu culoarea, schimbarea culorii si camuflajul la fel ca cefalopodii, dar multi dintre ei nu vin aproape de viteza sau gama dinamica de culoare pe care animalele le pot expune .

Posted: Feb 27, 2018
Squid skin could be the solution to camouflage material (Nanowerk News) Cephalopods – which include octopuses, squid, and cuttlefish – are masters of disguise. They can camouflage to precisely match their surroundings in a matter of seconds, and no scientist has quite been able to replicate the spectacle. But new research by Leila Deravi, assistant professor of chemistry and chemical biology at Northeastern, brings us a step closer.
The chromatophore organs, which appear as hundreds of multi-colored freckles on the surface of a cephalopod’s body, contribute to fast changes in skin color. In a paper published in Advanced Optical Materials („Natural Light-Scattering Nanoparticles Enable Visible through Short-Wave Infrared Color Modulation”), Deravi’s group describes its work in isolating the pigment granules within these organs to better understand their role in color change.
The researchers discovered these granules have remarkable optical qualities and used them to make thin films and fibers that could be incorporated into textiles, flexible displays, and future color-changing devices. Deravi’s lab collaborated with the U.S. Army Natick Soldier Research, Development, and Engineering Center for the study.

Northeastern researcher Leila Deravi displays spools of thread that were created using squid pigment. (Image: Adam Glanzman/Northeastern University)
Chromatophores come in shades of red, yellow, brown, and orange. They are similar to the freckles on human skin that appear over time. But in cephalopods, these freckles open and close within a fraction of a second to give rise to a continuously reconfiguring skin color. Underneath the chromatophores is a layer of iridophores that act as a mirror. Together, these organs reflect all colors of visible light.
By removing individual pigment particles from the squid, Deravi was able to explore the breadth of their capabilities as static materials. One particle is only 500 nanometers in size, which is 150 times smaller than the diameter of a human hair. Deravi’s team layered and reorganized the particles and found they could produce an expansive color pallet.
„We’re showing these pigments are a powerful tool that can produce ultra-thin films that are really rich in colors,” Deravi said.
Her team also discovered the pigments can scatter both visible and infrared light. This enhances brightness and light absorption and affects how a final color is perceived. And when Deravi engineered a system that included a mirror – mimicking the layout of organs that squids have naturally–she was able to further enhance the perceived color through scattering light through and off the granules. This process could potentially be replicated on functional materials like solar cells to increase the absorption of sunlight, Deravi said.
„From a scientific and technical engineering perspective, understanding how light scattering affects color is very important, and this is an exciting new development in the field of optics in biology,” said Richard Osgood, a collaborator from the U.S. Army Natick Soldier Research, Development, and Engineering Center. „This is an unusual harnessing of optics and physics knowledge in scattering to understand biological systems.”
The researchers made spools of fibers from the squids’ pigment particles and are now exploring uses for the material. The fibers are so visually interesting that it’s not difficult to imagine weaving them into fabric for clothing or other art forms. But perhaps the most exciting possible application is wearable, flexible screens and textiles that are capable of adaptive coloration. Osgood said the research could allow the Army to create new capabilities for soldiers.
„For more than a decade, scientists and engineers have been trying to replicate this process and build these devices that can color match, color change, and camouflage just like the cephalopods, but many of them come nowhere near the speed or dynamic range of color that the animals can display,” Deravi said. „Cephalopods have evolved to incorporate these specific pigment granules for a reason, and we’re starting to piece together what that reason is.”

Source: By Allie Nicodemo, Northeastern University

Memorile MEMS obțin metatlenses(MEMS chips get metatlenses)

Lentilă plată bazată pe metasurface integrată pe un scaner MEMS: Micrografie electronică de scanare (stânga) și imagine microscopie optică (dreapta) a unui dispozitiv lentilă-MEMS. Integrarea dispozitivelor MEMS cu metalenze va ajuta la crearea unei noi paradigme pentru manipularea luminii prin combinarea puterii acestor tehnologii: control dinamic de mare viteză cu manipulare spațială precisă a frontelor de undă. Mai mult decât atât, această integrare a obiectivelor cu lentile plate bazate pe metasurface cu scanerele MEMS poate fi extinsă la părțile vizibile și la alte părți ale spectrului electromagnetic, implicând potențialul de aplicare pe câmpuri mai largi, cum ar fi sistemele microscopice bazate pe MEMS, imagistică holografică și de proiecție, scanere LIDAR (detectarea și măsurarea luminii) și imprimare laser. „

Posted: Feb 21, 2018
MEMS chips get metatlenses (Nanowerk News) Lens technologies have advanced across all scales, from digital cameras and high bandwidth in fiber optics to the LIGO lab instruments. Now, a new lens technology that could be produced using standard computer-chip technology is emerging and could replace the bulky layers and complex geometries of traditional curved lenses.
Flat lenses, unlike their traditional counterparts, are relatively lightweight, based on optical nanomaterials known as metasurfaces. When the subwavelength nanostructures of a metasurface form certain repeated patterns, they mimic the complex curvatures that refract light, but with less bulk and an improved ability to focus light with reduced distortion. However, most of these nanostructured devices are static, which limits their functionality.
Federico Capasso, an applied physicist at Harvard University who pioneered metalens technology, and Daniel Lopez, group leader of nanofabrication and devices at Argonne National Laboratory and an early developer of microelectromechanical systems (MEMS), brainstormed about adding motion capabilities like fast scanning and beam steering to metalenses for new applications.

Metasurface-based flat lens integrated onto a MEMS scanner: Scanning electron micrograph (left) and optical microscope image (right) of a lens-on-MEMS device. Integration of MEMS devices with metalenses will help to create a new paradigm to manipulate light by combining the strength of these technologies: high-speed dynamic control with precise spatial manipulation of wave-fronts. (Image: Center for Nanoscale Materials, Argonne National Lab)
Capasso and Lopez developed a device that integrates mid-infrared spectrum metalenses onto MEMS. The researchers report their findings this week in APL Photonics („Dynamic metasurface lens based on MEMS technology”).
MEMS is a circuit-based technology that incorporates microelectronics, like those found in computer chips, and includes mechanical microstructures like actuators and gears. Ubiquitous in everything from cellphones to airbags, biosensing devices, appliances and optics, MEMS are fabricated using the same techniques used for integrated circuits on typical computer chips.
“Dense integration of thousands of individually controlled lens-on-MEMS devices onto a single silicon chip would allow an unprecedented degree of control and manipulation of the optical field,” Lopez Said.
The researchers formed the metasurface lens using standard photolithography techniques on a silicon-on-insulator wafer with a 2-micron-thick top device layer, a 200-nanometer buried-oxide layer, and a 600-micron-thick handle layer. Then, they placed the flat lens onto a MEMS scanner, essentially a micromirror that deflects light for high-speed optical path length modulation. They aligned the lens with the MEMS’ central platform and fixed them together by depositing small platinum patches.
“Our MEMS-integrated metasurface lens prototype can be electrically controlled to vary the angular rotation of a flat lens and can scan the focal spot by several degrees,” Lopez said. “Furthermore, this proof-of-concept integration of metasurface-based flat lenses with MEMS scanners can be extended to the visible and other parts of the electromagnetic spectrum, implying the potential for application across wider fields, such as MEMS-based microscope systems, holographic and projection imaging, LIDAR (light detection and ranging) scanners and laser printing.”
When electrostatically actuated, the MEMS platform controls the angle of the lens along two orthogonal axes, allowing the scanning of the flat lens focal spot by about 9 degrees in each direction. The researchers estimate that the focusing efficiency is about 85 percent.
“Such metalenses can be mass produced with the same computer-chip fabrication technology and in the future, will replace conventional lenses in a wide range of applications,” Capasso said.

Source: American Institute of Physics

Printare, camuflaj colorat cu polimeri(Printable, colorful camouflage with polymers)

că au dezvoltat polimeri care pot imita mai bine abilitățile naturii de a schimba culoarea decât polimerii existenți. Se spune că materialele ar putea permite decorarea inteligentă, textilele de camuflaj și măsurile de combatere a contrafacerii îmbunătățite.

Posted: Feb 07, 2018
Printable, colorful camouflage with polymers (Nanowerk News) In nature, colors can serve as a form of communication, but they can also hide animals and plants, camouflaging them from sight. Researchers now report in ACS Applied Materials & Interfaces („Full Color Camouflage in a Printable Photonic Blue-Colored Polymer”) that they have developed polymers that can better mimic nature’s color-changing abilities than existing polymers. They say the materials could enable smart decorations, camouflage textiles and improved anti-counterfeiting measures.

Newly developed polymer can better mimic nature’s color-changing abilities. (Image: American Chemical Society)
Most of the colors that people are familiar with, such as hues on a piece of paper, are made with pigments. But another type, called structural color, exists, in which the color is produced by periodically arranged microscopic structures that interfere with visible light.
For example, peacock tail feathers are actually brown, but microscopic structures present in the feathers make them look blue and green to the naked eye. Scientists have used cholesteric liquid-crystalline (CLC) polymers to mimic the structural coloration found in nature because they can easily be made into responsive materials. But so far, researchers have only produced them in a limited range of colors. So Albertus P. H. J. Schenning and Monali Moirangthem wanted to make CLC polymers with the full visible spectrum of colors.
The team used inkjet printing technology and a calcium nitrate solution to print an image on a CLC polymer they developed. Printing successive layers changed the degree of swelling of the CLC polymer, changing the color. One layer resulted in an orange color, a second layer changed it to green, and a third layer made it blue.
As an example, the researchers used the method to draw a blue flower with green leaves on a reddish-orange background. After the ink dried, the image was no longer visible–the entire surface appeared blue. However, sprinkling water or breathing on it caused the full color image to re-appear.

Source: American Chemical Society

Cercetătorii dezvoltă un nou design de suprafață inspirat de pielea de șarpe(

Rezultatele lor sugerează o platformă versatilă atât pentru manipularea fluidelor, cât și pentru cele ușoare, atât la nivel micro, cât și la nivel macroscopic. Aplicațiile potențiale pot fi găsite în microfluidica digitală, dispozitive biomedicale, jaluzele virtuale, suprafețe de camuflaj și rețele de micromirror. cercetătorii săi au fost capabili să proiecteze, să caracterizeze și să analizeze o gamă largă de funcții, cum ar fi umectarea reglabilă, manipularea picăturilor, transmisia optică tunabilă și colorarea structurală, prin încorporarea unei game largi de scale – siliciu gol, și cântare fotonice de cristal – în configurații atât în plan, cât și în afara planului.

Posted: Feb 02, 2018
Researchers develop new surface design inspired by snake skin (Nanowerk News) Assistant Professor Seok Kim and graduate students Zining Yang and Jun Kyu Park have developed a design construct inspired in part by the surface of butterflies and snakes, where flexible skins are fully covered by rigid, discrete scales.
Their work was recently featured on the cover of Small („Magnetically Responsive Elastomer-Silicon Hybrid Surfaces for Fluid and Light Manipulation”).

Seok Kim Lab develops new surface design inspired by snake skin. (Image: University of Illinois Department of Mechanical Science and Engineering)
Their new surface design features rigid scales assembled into soft, ferromagnetic micropillars on a flexible substrate in a predesigned manner by transfer printing-based deterministic assembly. The nanostructured silicon scales on the magnetically responsive elastomer micropillar array enables fluid and light manipulation. The functional properties of the surface are dictated by the scales’ patterns, while the micropillar array is magnetically actuated with large-range, instantaneous, and reversible deformation.
Kim and his researchers were able to design, characterize, and analyze a wide range of functions, such as tunable wetting, droplet manipulation, tunable optical transmission, and structural coloration, by incorporating a wide range of scales–bare silicon, black silicon, and photonic crystal scales–in both in-plane and out-of-plane configurations.
Magnetically response materials like soft elastomers loaded with magnetic particles, are desirable for their real-time manipulation of fluid, light, solid particles, and living cells – thanks to their instantaneous structural tenability under a magnetic field. However, due to the fabrication process, most existing surfaces of this kind are limited in their functional ability.
Compared with common responsive surface with simple design (the magnetic micropillar array), the surface developed in our work not only has enhanced performance in directional liquid spreading and optical transmission tuning, but also enables novel functions such as droplet manipulation and dynamic structural coloration,” said Yang, PhD candidate and first author of the study.
Their results suggest a versatile platform for both fluid and light manipulations at both the micro and macroscale. Potential applications can be found in digital microfluidics, biomedical devices, virtual blinds, camouflage surfaces, and micromirror arrays. Further work could also result in more biomimetic functionalities such as robotic locomotion, swimming, self-cleaning, and solid object manipulation. Their design could also be integrated with active devices such as solar cells, light emitting diodes, and lasers as scales to form novel flexible optoelectronics.
Kim is a leading scientist in advanced transfer printing and transfer printing-based microassembly.

Source: University of Illinois College of Engineering

Țesături transparente vizibile și opace pentru infraroșu pentru gestionarea termică personală care poate fi purtată(Infrared-Transparent Visible-Opaque Fabrics for wearable Personal Thermal Management)

Țesături transparente vizibile și opace pentru infraroșu care poate fi purtată pentru gestionarea termică personală .Țesături transparente vizibile și opace cu infraroșu care asigură o răcire pasivă prin transmiterea radiațiilor termice emise de corpul uman direct în mediul înconjurător.Tehnicile personale de răcire controlează la nivel local temperatura unei persoane.

Infrared1 Infrared2 ACS

Vertx Downrange,Jachetă cu soft Shell(Vertex Downrange Soft Shell Jacket)

Jacket tactic cu VaporCore Umiditate-Wicking și Infraroșu-reflectând Fabric Tech pentru ascuns Carry și Combaterea Urban

Vertex

4 Cerințe de proiectare electronică ale soldatului integrat în sistem(4 Electronic Design Requirements Of the System-Integrated Soldier)

Detectarea și localizarea semnalelor ascunse și a interferențelor în operațiile militare;progresele înregistrate în domeniul optic pentru câmpul de luptă al secolului XXI;Dezvoltarea de antene purtabile pentru aplicații militare

0 (9)

Metalenzele grafene ultra-late și plate au mai multe proprietăți(Ultrathin and flat graphene metalenses gain more properties)

Metasuprafețele sunt materiale noi 2D care pot controla în mod eficient componentele electrice și magnetice ale luminii (și alte unde electromagnetice) și le îndoiesc în direcții personalizate. Controlul direcției fasciculului poate aduce fenomene interesante; cea mai incredibilă fiind „efectul invizibilității mantalei”, unde undele de lumină ocolește un obiect care recreează imaginea dincolo de obiect, deoarece apa care curge într-un râu ar ocoli o piatră.Metalenzele au fost proiectate pentru un tip de undă electromagnetică, care se încadrează între radiația infraroșie și radiația cu microunde, numită radiație terahertz. Acest tip de radiații poate trece prin anumite materiale (cum ar fi țesăturile și materialele plastice), dar la o adâncime mai mică decât radiațiile cu microunde, din acest motiv este folosit pentru supravegherea și screening-ul de securitate.

Posted: Nov 27, 2017
Ultrathin and flat graphene metalenses gain more properties (Nanowerk News) On the quest for miniaturization, scientists at the Center for Integrated Nanostructure Physics, within the Institute for Basic Science (IBS, South Korea), in collaboration with researchers from the University of Birmingham and the Korea Advanced Institute of Science and Technology (KAIST), develop credit card-thick, flat lenses with tunable features. These optical devices, made of graphene and a punctured gold surface, could become optical components for advanced applications, such as amplitude tunable lenses, lasers (i.e. vortex phase plates), and dynamic holography.

Comparison between conventional lenses and metalenses for terahertz (THz) radiation. Metalenses are ultrathin (around 25 micrometers in thickness) and also very flat compared with conventional ones.
Metasurfaces are new 2D materials that can effectively control the electric and magnetic components of light (and other electromagnetic waves) and bend them to bespoken directions. Controlling the beam’s direction can bring out interesting phenomena; the most incredible being the “invisibility cloak effect”, where light waves bypass an object recreating the image beyond the object, as flowing water in a river would bypass a stone.
Published in Advanced Optical Materials („Amplitude Modulation of Anomalous Refractive Terahertz Waves with Gated-Graphene Metasurfaces”), the study presents the properties of a metasurface which works as a convex lens. Specifically, it is made of a gold sheet pierced with micrometer-sized U-shaped holes and covered with graphene. As the shape of common convex lenses allows light to be concentrated on a spot (or focus), think about a magnifying glass which can concentrate a light beam and even start a fire, so the particular pattern of the tiny apertures of the metalenses works by focusing the incoming beam.

Metalenses’ features. a) The metalenses are made with an atom-thick graphene sheet and a gold thin surface with tiny U-shaped holes. b) The device can convert the circular polarization of the erahertz wave from left to right. Moreover, by rotating the holes’ pattern, the beam (or wave) can be bent it to the desired angle.
In addition, these microholes can also change light polarization. While natural light is generally unpolarized before being reflected, the team used circularly polarized waves, that is a light beam where the direction of the electric field is corkscrew spiraling. This metalens can convert the left-circular polarization wave (going counterclockwise if seen straight in front) to right-circular polarization (clockwise). The researchers managed to obtain a conversion rate of 35%. Converting circular polarization could be useful in a number of fields, for example biosensing and telecommunications.
In order to control even more properties, the scientists took advantage of graphene’s unique electronic features and used them to tune the output beam’s intensity or amplitude. Here graphene plays the role of the exposure of a camera. In the case of the camera, a mechanical control allows a certain shutter’s opening time and size to determine the amount of light entering the instrument. These metalenses instead, regulate the exposure via an electric tension applied to the graphene sheet, without the need for bulky components. When voltage is applied to the graphene layer, the output beam becomes weaker. “Using metalenses, you can make microscopes, cameras, and tools used in very sensitive optical measurements, much more compact,” clarifies Teun-Teun Kim, the first author of the study.

The function of the U-shaped pattern and graphene is to concentrate the beam’s direction and modulate signal intensity. Different U-shaped hole pattern on the metasurface create a striped (a) and a focalized (b) beam output. In b) the beam is concentrated to a small area (red spot), in the same way as a magnifying glass focuses light on a specific point. Moreover, by applying a gated voltage (2.2 V) on graphene, the output beam intensity becomes weaker. Graphene function could be compared to the exposure of a camera.
The metalenses were designed for a type of electromagnetic wave, which falls in-between infrared radiation and microwave radiation, called terahertz radiation. This type of radiation can pass through some materials (like fabrics and plastics), but at a shorter depth than microwave radiation, for this reason it is employed for surveillance and security screening.
“While conventional optical lenses have a thickness of several centimeters to several millimeters, this metalens is just a few tens of micrometers thick. The intensity of the focused light can be effectively controlled and it could find useful applications in ultra-small optical instruments,” highlights the scientists.Teun-Teun Kim, the first author of the study.

Source: Institute for Basic Science

Cercetătorii camuflează un cip optic care îl face invizibil(Researchers camouflage an optical chip rendering it invisible)

cercetatorii au realizat un progres in manipularea luminii pentru a face un obiect, cum ar fi un cip optic, invizibil.schema de invizibilitate. (© Nature)
Un cip de operare poate fi o extensie a tehnologiilor de bază cum ar fi vopseaua întunecată absorbantă radar utilizată pe avioane stealth, camuflajul local optic, răcirea suprafeței pentru a minimiza emisiile electromagnetice în infraroșu sau împrăștierea undei electromagnetice.

Posted: Nov 13, 2017
Researchers camouflage an optical chip rendering it invisible (Nanowerk News) Ben-Gurion University of the Negev (BGU) researchers have achieved a breakthrough in manipulating light to render an object, such as an optical chip, invisible.
According to the recent study published in Scientific Reports („Invisibility Cloaking Scheme by Evanescent Fields Distortion on Composite Plasmonic Waveguides with Si Nano-Spacer”), the researchers conceived a new method that deflects and scatters light away from a „cloaking” chip surface so it is not detected.

Illustration of the composite plasmonic waveguide structure and materials to study the invisibility cloaking scheme. (© Nature)
An operational cloaking chip can be an extension of the basic technologies such as radar-absorbing dark paint used on stealth aircraft, local optical camouflage, surface cooling to minimize electromagnetic infrared emissions, or electromagnetic wave scattering.
„These results open the door to new integrated photonic devices, harnessing electromagnetic fields of light at nanoscale for a variety of applications from on-chip optical devices to all-optical processing,” says Dr. Alina Karabchevsky, head of BGU’s Light-on-a-Chip Group and a member of the BGU Unit of Electro-Optical Engineering and the Ilse Katz Institute for Nanoscale Science and Technology. „We showed that it is possible to bend the light around an object located on the cloak on an optical chip. The light does not interact with the object, thus resulting in the object’s invisibility.”
The next step is for researchers to overcome the significant challenge of developing a prototype.

Source: Ben-Gurion University of the Negev

Materialul sintetic acționează ca un dispozitiv de mascare a insectelor(Synthetic material acts like an insect cloaking device)

Microsferele sintetice cu găuri la scară nanometrică pot absorbi lumina din toate direcțiile într-o gamă largă de frecvențe, făcându-i un candidat pentru acoperiri antireflective, Ca o acoperire antireflexivă, acest material ar putea avea aplicații în senzori și camere, unde captarea reflexiei nedorite a luminii ar putea crește raportul semnal-zgomot. Acest lucru ar putea fi deosebit de util în telescoape. Pentru aplicațiile cu celule solare, o acoperire cu brocozomi sintetici ar putea crește capturarea luminii la lungimi de undă multiple și din orice unghi datorită structurii 3D a mingii de fotbal a sferelor, ceea ce face necesar să se construiască dispozitive pentru urmărirea soarelui.

Posted: Nov 03, 2017
Synthetic material acts like an insect cloaking device (Nanowerk News) Synthetic microspheres with nanoscale holes can absorb light from all directions across a wide range of frequencies, making it a candidate for antireflective coatings, according to a team of Penn State engineers. The synthetic spheres also explain how the leaf hopper insect uses similar particles to hide from predators in its environment.
Scientists have long been aware that leaf hoppers extrude microparticles, called brochosomes, and wipe them on their wings. Because the particles are superhydrophobic, the leaf hopper’s wings stay dry in wet conditions. What was not understood before the current work is that the brochosomes also allow leaf hoppers and their eggs to blend in with their background at the wavelengths of light visible to their main predators, such as the ladybird beetle.

Synthetic brochosomes (false colored). (Image: Shikuan Yang, Birgitt Boschitsch/Penn State)
“We knew our synthetic particles might be interesting optically because of their structure,” said Tak-Sing Wong, assistant professor of mechanical engineering and the Wormely Family Early Career Professor in Engineering. “We didn’t know, until my former postdoc and lead author of the study Shikuan Yang brought it up in a group meeting, that the leaf hopper made these non-sticky coatings with a natural structure very similar to our synthetic ones. That led us to wonder how the leaf hopper used these particles in nature.”
Doing a search of the scientific literature turned up nothing about the leaf hopper brochosomes’ use as camouflage. But the pits’ sizes in the synthetic microspheres are very close to the wavelength of light, and can capture up to 99 percent of light ranging from ultraviolet through visible and into the near infrared. The particle surface acts like a metamaterial, the type of material used in cloaking devices.
“The problem is that in the field, these leaf hoppers produce very little of this product, and it is very hard to collect,” Wong said. “But we had already produced large quantities of these structures in the lab, enough to put inside a machine to look at their optical properties.”
In a paper published online in Nature Communications („Ultra-antireflective synthetic brochosomes”), the researchers simulated insect vision and found that the brochosomes are very likely camouflage coatings against leaf hopper predators. Camouflage is common in nature, but there are very few examples of natural antireflective coatings, moth eyes being a prominent exception. Moth eyes are covered in anti-reflective nanostructures that prevent light from reflecting off them at night when predators might see them.
The synthetic microspheres are produced via a rather complex five-step process using electrochemical deposition. However, the process can be scaled up and many different materials can be used to make the synthetic brochosomes, such as gold, silver, manganese oxide or even a conductive polymer.
“Different materials will have their own applications,” Wong said. “For example, manganese oxide is a very popular material used in supercapacitors and batteries. Because of its high surface area, this particle could make a good battery electrode and allow a higher rate of chemical reaction to take place.”
As an antireflective coating, this material could have applications in sensors and cameras, where capturing unwanted light reflection could increase the signal-to-noise ratio. This could be particularly useful in telescopes. For solar cell applications, a coating of synthetic brochosomes could increase light capture at multiple wavelengths and from every angle due to the 3D soccer ball-shape structure of the spheres, making it unnecessary to build devices to track the sun.
“This paper is more of a fundamental study,” Wong said. “In the future, we may try to extend the structure to longer wavelengths. If we made the structure a little larger, could it absorb longer electromagnetic waves such as mid-infrared and open up further applications in sensing and energy harvesting?” That remains to be studied.

Source: Penn State Materials Research Institute

Pointing light

Squid skin could be the solution to camouflage material

MEMS chips get metatlenses

Printable, colorful camouflage with polymers

Researchers develop new surface design inspired by snake skin

Ultrathin and flat graphene metalenses gain more properties

Researchers camouflage an optical chip rendering it invisible

Synthetic material acts like an insect cloaking device