Researchers at RMIT University and the University of Adelaide have joined forces to create a stretchable nano-scale device to manipulate light.

The device manipulates light to such an extent that it can filter specific colours while still being transparent and could be used in the future to make smart contact lenses.

                                                             

 nanoscale glass structures that filter or manipulate light
credit: RMIT/The University of Adelaide

Using the technology, high-tech lenses could one day filter harmful optical radiation without interfering with vision – or in a more advanced version, transmit data and gather live vital information or even show information like a head-up display.

The light manipulation relies on creating tiny artificial crystals termed  “dielectric resonators”, which are a fraction of the wavelength of light – 100-200 nanometers, or over 500 times thinner than a human hair.

The research combined the University of Adelaide researchers’ expertise in interaction of light with artificial materials with the materials science and nanofabrication expertise at RMIT University.

Dr Withawat Withayachumnankul, from the University of Adelaide’s School of Electrical and Electronic Engineering, said: “Manipulation of light using these artificial crystals uses precise engineering.

“With advanced techniques to control the properties of surfaces, we can dynamically control their filter properties, which allow us to potentially create devices for high data-rate optical communication or smart contact lenses.

“The current challenge is that dielectric resonators only work for specific colours, but with our flexible surface we can adjust the operation range simply by stretching it.”

Associate Professor Madhu Bhaskaran, Co-Leader of the Functional Materials and Microsystems Research Group at RMIT, said the devices were made on a rubber-like material used for contact lenses.

“We embed precisely-controlled crystals of titanium oxide, a material that is usually found in sunscreen, in these soft and pliable materials,” she said.

“Both materials are proven to be bio-compatible, forming an ideal platform for wearable optical devices.

“By engineering the shape of these common materials, we can create a device that changes properties when stretched. This modifies the way the light interacts with and travels through the device, which holds promise of making smart contact lenses and stretchable colour changing surfaces.”

Lead author and RMIT researcher Dr. Philipp Gutruf said the major scientific hurdle overcome by the team was combining high temperature processed titanium dioxide with the rubber-like material, and achieving nanoscale features.

“With this technology, we now have the ability to develop light weight wearable optical components which also allow for the creation of futuristic devices such as smart contact lenses or flexible ultrathin smartphone cameras,” Gutruf said.

source ; RMIT news release link : click here

This post is copied from the materials in the RMIT website(news)

University of Toronto researchers successfully combine two different materials to create new hyper-efficient light-emitting crystal

                                                                     

Researchers in The Edward S. Rogers Sr. Department of Electrical & Computer Engineering used this insight to invent something totally new: they’ve combined two promising solar cell materials together for the first time, creating a new platform for LED technology.
                                                                     

A glowing quantum dot seamlessly integrated into a perovskite crystal matrix (Image: Ella Marushchenko).

The team designed a way to embed strongly luminescent nanoparticles called colloidal quantum dots (the chocolate chips) into perovskite (the oatmeal cookie). Perovskites are a family of materials that can be easily manufactured from solution, and that allow electrons to move swiftly through them with minimal loss or capture by defects.

The work is published today in the international journal Nature.

“It’s a pretty novel idea to blend together these two optoelectronic materials, both of which are gaining a lot of traction,” says Xiwen Gong (ECE), one of the study’s lead authors and a PhD candidate working with Professor Ted Sargent (ECE). “We wanted to take advantage of the benefits of both by combining them seamlessly in a solid-state matrix.”

                                                                        

(Image: Ella Marushchenko).

The result is a black crystal that relies on the perovskite matrix to ‘funnel’ electrons into the quantum dots, which are extremely efficient at converting electricity to light. Hyper-efficient LED technologies could enable applications from the visible-light LED bulbs in every home, to new displays, to gesture recognition using near-infrared wavelengths.

“When you try to jam two different crystals together, they often form separate phases without blending smoothly into each other,” says Dr. Riccardo Comin, a post-doctoral fellow in the Sargent Group. “We had to design a new strategy to convince these two components to forget about their differences and to rather intermix into forming a unique crystalline entity.”

The main challenge was making the orientation of the two crystal structures line up, called heteroexpitaxy. To achieve heteroepitaxy, Gong, Comin and their team engineered a way to connect the atomic ‘ends’ of the two crystalline structures so that they aligned smoothly, without defects forming at the seams. “We started by building a nano-scale scaffolding ‘shell’ around the quantum dots in solution, then grew the perovskite crystal around that shell so the two faces aligned,” explained coauthor Dr. Zhijun Ning, who contributed to the work while a post-doctoral fellow at UofT and is now a faculty member at ShanghaiTech.

The resulting heterogeneous material is the basis for a new family of highly energy-efficient near-infrared LEDs. Infrared LEDs can be harnessed for improved night-vision technology, to better biomedical imaging, to high-speed telecommunications.

Combining the two materials in this way also solves the problem of self-absorption, which occurs when a substance partly re-absorbs the same spectrum of energy that it emits, with a net efficiency loss. “These dots in perovskite don’t suffer reabsorption, because the emission of the dots doesn’t overlap with the absorption spectrum of the perovskite,” explains Comin.

Gong, Comin and the team deliberately designed their material to be compatible with solution-processing, so it could be readily integrated with the most inexpensive and commercially practical ways of manufacturing solar film and devices. Their next step is to build and test the hardware to capitalize on the concept they have proven with this work.

“We’re going to build the LED device and try to beat the record power efficiency reported in the literature,” says Gong.

This work was supported by the Ontario Research Fund Research Excellence Program, the Natural Sciences and Engineering Research Council of Canada (NSERC), and the King Abdullah University of Science & Technology (KAUST).

source: U of T engineering news   link : click here

New solar nanoparticle-based power material converts 90 percent of captured light into heat

Graduate student Bryan VanSaders measures how much simulated sunlight a novel material can absorb using a unique set of instruments that takes spectral measurements from visible to infrared. This testing is led by electrical engineering professor Zhaowei Liu.

Credit: David Baillot/UC San Diego Jacobs School of Engineering.

A multidisciplinary engineering team at the University of California, San Diego developed a new nanoparticle-based material for concentrating solar power plants designed to absorb and convert to heat more than 90 percent of the sunlight it captures. The new material can also withstand temperatures greater than 700 degrees Celsius and survive many years outdoors in spite of exposure to air and humidity. Their work, funded by the U.S. Department of Energy's SunShot program, was published recently in two separate articles in the journal Nano Energy.

By contrast, current solar absorber material functions at lower temperatures and needs to be overhauled almost every year for high temperature operations.
      "We wanted to create a material that absorbs sunlight that doesn't let any of it escape. We want the black hole of sunlight," said Sungho Jin, a professor in the department of Mechanical and Aerospace Engineering at UC San Diego Jacobs School of Engineering. Jin, along with professor Zhaowei Liu of the department of Electrical and Computer Engineering, and Mechanical Engineering professor Renkun Chen, developed the Silicon boride-coated nanoshell material. They are all experts in functional materials engineering.
The novel material features a "multiscale" surface created by using particles of many sizes ranging from 10 nanometers to 10 micrometers. The multiscale structures can trap and absorb light which contributes to the material's high efficiency when operated at higher temperatures.
              
Concentrating solar power (CSP) is an emerging alternative clean energy market that produces approximately 3.5 gigawatts worth of power at power plants around the globe—enough to power more than 2 million homes, with additional construction in progress to provide as much as 20 gigawatts of power in coming years. One of the technology's attractions is that it can be used to retrofit existing power plants that use coal or fossil fuels because it uses the same process to generate electricity from steam.
Traditional power plants burn coal or fossil fuels to create heat that evaporates water into steam. The steam turns a giant turbine that generates electricity from spinning magnets and conductor wire coils. CSP power plants create the steam needed to turn the turbine by using sunlight to heat molten salt. The molten salt can also be stored in thermal storage tanks overnight where it can continue to generate steam and electricity, 24 hours a day if desired, a significant advantage over photovoltaic systems that stop producing energy with the sunset.

The UC San Diego team's combined expertise was used to develop, optimize and characterize a new material for this type of system over the past three years. Researchers included a group of UC San Diego graduate students in materials science and engineering, Justin Taekyoung Kim, Bryan VanSaders, and Jaeyun Moon, who recently joined the faculty of the University of Nevada, Las Vegas. The synthesized nanoshell material is spray-painted in Chen's lab onto a metal substrate for thermal and mechanical testing. The material's ability to absorb sunlight is measured in Liu's optics laboratory using a unique set of instruments that takes spectral measurements from visible light to infrared.

Current CSP plants are shut down about once a year to chip off the degraded sunlight absorbing material and reapply a new coating, which means no power generation while a replacement coating is applied and cured. That is why DOE's SunShot program challenged and supported UC San Diego research teams to come up with a material with a substantially longer life cycle, in addition to the higher operating temperature for enhanced energy conversion efficiency. The UC San Diego research team is aiming for many years of usage life, a feat they believe they are close to achieving.
Modeled after President Kennedy's moon landing program that inspired widespread interest in science and space exploration, then-Energy Secretary Steven P. Chu launched the Sunshot Initiative in 2010 with the goal of making solar power cost competitive with other means of producing electricity by 2020.


source :   University of California - San Diego. , eurekalert.org

Nano-sized chip picks up scent of explosives molecules

The groundbreaking nanotechnology-inspired sensor, devised by Prof. Fernando Patolsky of Tel Aviv University's School of Chemistry and Center for Nanoscience and Nanotechnology, and developed by the Herzliya company Tracense, picks up the scent of explosives molecules better than a detection dog's nose. Research on the sensor was recently published in the journal Nature Communications.

Existing explosives sensors are expensive, bulky and require expert interpretation of the findings. In contrast, the new sensor is mobile, inexpensive, and identifies in real time -- and with great accuracy -- explosives in the air at concentrations as low as a few molecules per 1,000 trillion.

                                                                 

nanosensor

A nano-nose to compete with a dog's

"Using a single tiny chip that consists of hundreds of supersensitive sensors, we can detect ultra low traces of extremely volatile explosives in air samples, and clearly fingerprint and differentiate them from other non-hazardous materials," said Prof. Patolsky, a top researcher in the field of nanotechnology. "In real time, it detects small molecular species in air down to concentrations of parts-per-quadrillion, which is four to five orders of magnitude more sensitive than any existing technological method, and two to three orders of magnitude more sensitive than a dog's nose.

"This chip can also detect improvised explosives, such as TATP (triacetone triperoxide), used in suicide bombing attacks in Israel and abroad," Prof. Patolsky added.

The clusters of nano-sized transistors used in the prototype are extremely sensitive to chemicals, which cause changes in the electrical conductance of the sensors upon surface contact. When just a single molecule of an explosive comes into contact with the sensors, it binds with them, triggering a rapid and accurate mathematical analysis of the material.

"Animals are influenced by mood, weather, state of health and working hours, the oversaturation of olfactory system, and much more," said Prof. Patolsky. "They also cannot tell us what they smell. Automatic sensing systems are superior candidates to dogs, working at least as well or better than nature. This is not an easy task, but was achieved through the development of novel technologies such as our sensor."

A technology for a safer world

The trace detector, still in prototype, identifies several different types of explosives several meters from the source in real time. It has been tested on the explosives TNT, RDX, and HMX, used in commercial blasting and military applications, as well as peroxide-based explosives like TATP and HMTD. The latter are commonly used in homemade bombs and are very difficult to detect using existing technology.

"Our breakthrough has the potential to change the way hazardous materials are detected, and of course should provide populations with more security," said Prof. Patolsky. "The faster, more sensitive detection of tiny amounts of explosives in the air will provide for a better and safer world."

Tracense has invested over $10M in research and development of the device since 2007, and expects to go to market next year. Prof.Patolsky and his team of researchers are currently performing multiple and extensive field tests of prototype devices of the sensor.

Source: science daily, www.aftau.org/nano

"Nanocamera" takes pictures at distances smaller than light's own wavelength

Researchers at the University of Illinois at Urbana-Champaign have demonstrated that an array of novel gold, pillar-bowtie nanoantennas (pBNAs) can be used like traditional photographic film to record light for distances that are much smaller than the wavelength of light (for example, distances less than ~600 nm for red light). A standard optical microscope acts as a “nanocamera” whereas the pBNAs are the analogous film.
         “Unlike conventional photographic film, the effect (writing and curing) is seen in real time,” explained Kimani Toussaint, an associate professor of mechanical science and engineering, who led the research. “We have demonstrated that this multifunctional plasmonic film can be used to create optofluidic channels without walls. Because simple diode lasers and low-input power densities are sufficient to record near-field optical information in the pBNAs, this increases the potential for optical data storage applications using off-the-shelf, low-cost, read-write laser systems."

“Particle manipulation is the proof-of-principle application,” stated Brian Roxworthy, first author of the group’s paper, "Multifunctional Plasmonic Film for Recording Near-Field Optical Intensity," published in the journal, Nano Letters. “Specifically, the trajectory of trapped particles in solution is controlled by the pattern written into the pBNAs. This is equivalent to creating channels on the surface for particle guiding except that these channels do not have physical walls (in contrast to those optofluidics systems where physical channels are fabricated in materials such as PDMS).”

To prove their findings, the team demonstrated various written patterns—including the University’s “Block I” logo and brief animation of a stick figure walking—that were either holographically transferred to the pBNAs or laser-written using steering mirrors (see video).

Image of the Illinois “I” logo recorded by the plasmonic film; each bar in the letter is approximately 6 micrometers.

“We wanted to show the analogy between what we have made and traditional photographic film,” Toussaint added. “There’s a certain cool factor with this. However, we know that we’re just scratching the surface since the use of plasmonic film for data storage at very small scales is just one application. Our pBNAs allow us to do so much more, which we’re currently exploring.”

The researchers noted that the fundamental bit size is currently set by the spacing of the antennas at 425-nm. However, the pixel density of the film can be straightforwardly reduced by fabricating smaller array spacing and a smaller antenna size, as well as using a more tightly focusing lens for recording.

“For a standard Blu-ray/DVD disc size, that amounts to a total of 28.6 gigabites per disk,” Roxworthy added. “With modifications to array spacing and antenna features, it’s feasible that this value can be scaled to greater than 75 gigabites per disk. Not to mention, it can be used for other exciting photonic applications, such as lab-on-chip nanotweezers or sensing.”

“In our new technique, we use controlled heating via laser illumination of the nanoantennas to change the plasmonic response instantaneously, which shows an innovative but easy way to fabricate spatially changing plasmonic structures and thus opens a new avenue in the field of nanotech-based biomedical technologies and nano optics,”  said Abdul Bhuiya, a co-author and member of the research team.

source : University of Illinois College of Engineering.

silicon oxide technology for high-density, next-generation computer memory Read more: Breakthrough silicon oxide technology for high-density, next-generation computer memory

Oxide-based two-terminal resistive random access memory (RRAM) is considered one of the most promising candidates for next-generation nonvolatile memory. Rice university introduce here a new RRAM memory structure employing a nanoporous (NP) silicon oxide (SiO_x) material which enables unipolar switching through its internal vertical nanogap. Through the control of the stochastic filament formation at low voltage, the NP SiO_x memory exhibited an extremely low electroforming voltage (1.6 V) and outstanding performance metrics. These include multibit storage ability (up to 9-bits), a high ON–OFF ratio (up to 10⁷ A), a long high-temperature lifetime (≥10⁴ s at 100 °C), excellent cycling endurance (≥10⁵), sub-50 ns switching speeds, and low power consumption (6 × 10^–5 W/bit). Also provided is the room temperature processability for versatile fabrication without any compliance current being needed during electroforming or switching operations. Taken together, these metrics in NP SiO_x RRAM provide a route toward easily accessed nonvolatile memory applications.

      

                                     

“This memory is superior to all other two-terminal unipolar resistive memories by almost every metric,” Tour said. “And because our devices use silicon oxide — the most studied material on Earth — the underlying physics are both well-understood and easy to implement in existing fabrication facilities.” Tour is Rice’s T.T. and W.F. Chao Chair in Chemistry and professor of mechanical engineering and nanoengineering and of computer science.

Tour and colleagues began work on their breakthrough RRAM technology more than five years ago. The basic concept behind resistive memory devices is the insertion of a dielectric material — one that won’t normally conduct electricity — between two wires. When a sufficiently high voltage is applied across the wires, a narrow conduction path can be formed through the dielectric material.

The presence or absence of these conduction pathways can be used to represent the binary 1s and 0s of digital data. Research with a number of dielectric materials over the past decade has shown that such conduction pathways can be formed, broken and reformed thousands of times, which means RRAM can be used as the basis of rewritable random-access memory.

RRAM is under development worldwide and expected to supplant flash memory technology in the marketplace within a few years because it is faster than flash and can pack far more information into less space. For example, manufacturers have announced plans for RRAM prototype chips that will be capable of storing about one terabyte of data on a device the size of a postage stamp — more than 50 times the data density of current flash memory technology.

The key ingredient of Rice’s RRAM is its dielectric component, silicon oxide. Silicon is the most abundant element on Earth and the basic ingredient in conventional microchips. Microelectronics fabrication technologies based on silicon are widespread and easily understood, but until the 2010 discovery of conductive filament pathways in silicon oxide in Tour’s lab, the material wasn’t considered an option for RRAM.

Since then, Tour’s team has raced to further develop its RRAM and even used it for exotic new devices like transparent flexible memory chips. At the same time, the researchers also conducted countless tests to compare the performance of silicon oxide memories with competing dielectric RRAM technologies. “Our technology is the only one that satisfies every market requirement, both from a production and a performance standpoint, for nonvolatile memory,” Tour said. “It can be manufactured at room temperature, has an extremely low forming voltage, high on-off ratio, low power consumption, nine-bit capacity per cell, exceptional switching speeds and excellent cycling endurance.” In the latest study, a team headed by lead author and Rice postdoctoral researcher Gunuk Wang showed that using a porous version of silicon oxide could dramatically improve Rice’s RRAM in several ways. First, the porous material reduced the forming voltage — the power needed to form conduction pathways — to less than two volts, a 13-fold improvement over the team’s previous best and a number that stacks up against competing RRAM technologies. In addition, the porous silicon oxide also allowed Tour’s team to eliminate the need for a “device edge structure.” “That means we can take a sheet of porous silicon oxide and just drop down electrodes without having to fabricate edges,” Tour said. “When we made our initial announcement about silicon oxide in 2010, one of the first questions I got from industry was whether we could do this without fabricating edges. At the time we could not, but the change to porous silicon oxide finally allows us to do that.”   Wang said, “We also demonstrated that the porous silicon oxide material increased the endurance cycles more than 100 times as compared with previous nonporous silicon oxide memories. Finally, the porous silicon oxide material has a capacity of up to nine bits per cell that is highest number among oxide-based memories, and the multiple capacity is unaffected by high temperatures.” Tour said the latest developments with porous silicon oxide — reduced forming voltage, elimination of need for edge fabrication, excellent endurance cycling and multi-bit capacity — are extremely appealing to memory companies.

source nanowerk,rice university nanoletters

Mystery solved how printed diode works

Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile phones and printed e-tags. Here, we report an all-printed diode operating up to 1.6 GHz. The device, based on two stacked layers of Si and NbSi2 particles, is manufactured on a flexible substrate at low temperature and in ambient atmosphere. The high charge carrier mobility of the Si microparticles allows device operation to occur in the charge injection-limited regime. The asymmetry of the oxide layers in the resulting device stack leads to rectification of tunneling current. Printed diodes were combined with antennas and electrochromic displays to form an all-printed e-tag. The harvested signal from a Global System for Mobile Communications mobile phone was used to update the display. Our findings demonstrate a new communication pathway for printed electronics within IoT applications.
                                   

                             
   With an article published in the Proceedings of the National Academy of Sciences ("All-printed diode operating at 1.6 GHz"), a thirteen-year-long mystery that has involved a long series of researchers at both Linköping University and Acreo Swedish ICT has finally been solved.The article presents a diode in printed electronics that works in the GHz band, which opens up a new opportunity to send signals from a mobile phone to, for example, printed electronic labels. Energy from the radio signal is collected and used to switch the label's display. The diode being printed means that it is both cheap and simple to manufacture."This means that we can supply power to printed electronics within the 'internet of things' with the help of conventional mobile phones. This gives us new opportunities for communications," says Negar Sani, PhD student at the Laboratory for Organic Electronics at Linköping University.Researchers have long known that the diode works, but not how and why.

                In 2001, Petronella Norberg at Acreo Swedish ICT, laid a disc of silicon in a mortar, ground it down and produced a silicon paste that she then used as ink in a printing press. She produced a functional printed diode – the electronic key component that, among other things, converts alternating current to direct current. But the diode only worked up to 1 MHz, and no immediate field of use could be found.At Acreo Swedish ICT, a research team funded by the British company De La Rue, worked for several years on developing both the diode and new printing pastes. With a paste containing the transition metal niobium, in the form of niobium silicide, NbSi2, printed over the silicon paste, they got the whole thing to work at GHz as well."The results meant a world record for printed diodes, and we were also able to manufacture a demonstrator for De La Rue where the signal from a mobile phone was used to activate a printed display. We had demonstrated that it was possible to link paper to the Internet," says Göran Gustafsson, department head at Acreo Swedish ICT.But still nobody knew how the diode worked.Ms Sani has now taken the last decisive step toward solving the puzzle, naturally with the help of Professors Magnus Berggren and Xavier Crispin as well as Senior Lecturer and Project Manager Isak Engquist, and a number of people at Acreo Swedish ICT. The results of Ms Sani's work showed that it must have to do with tunnel effects, a phenomenon in quantum physics that makes it so that particles can get past obstacles. In this case, nano-thin films (1–2 nm) are formed around the micrometer-sized grains of silicon, where the current between anodes (aluminium) and cathodes (silver and carbon) pass through, but only in one direction.

               Thirteen years of work got an explanation – one that the editorial board of PNAS finally approved after more than five months of hard review by experts from various fields."This is the longest project I've worked on. What research sponsor wants to wait 13 years for publication? Without industry – De La Rue, in this case – we'd never have come this far. Now printed electronics are starting to get the same performance as traditional electronics, and this is another example of the fruitful combination of our research, developments at Acreo and needs from the industry," says Magnus Berggren, professor of Organic Electronics at Linköping University.

source: pnas.org, nanowerk,Linköping University.

Imaging and steering an optical wireless nanoantenna link

A team of scientists from the University of Stuttgart, the Max-Planck-Institute of Solid State Research in Stuttgart, the University of Pennsylvania and by Carl Zeiss AG Corporate Research has imaged wireless transmission of optical power between two optical nanoantennas. The researchers developed a novel method based on photoluminescence to sensitively probe optical fields around nanostructures and applied their technique to image the transmission of optical signals.The results appear in the latest issue of the journal Nature Communications ("Imaging and steering an optical wireless nanoantenna link"). The method developed by team is a very powerful tool in understanding the propagation of light between optical nanostructures.

                                             

                                    Optical nanoantennas tailor the transmission and reception of optical signals. Owing to their capacity to control the direction and angular distribution of optical radiation over a broad spectral range, nanoantennas are promising components for optical communication in nanocircuits. Here we measure wireless optical power transfer between plasmonic nanoantennas in the far-field and demonstrate changeable signal routing to different nanoscopic receivers via beamsteering. We image the radiation pattern of single-optical nanoantennas using a photoluminescence technique, which allows mapping of the unperturbed intensity distribution around plasmonic structures. We quantify the distance dependence of the power transmission between transmitter and receiver by deterministically positioning nanoscopic fluorescent receivers around the transmitting nanoantenna. By adjusting the wavefront of the optical field incident on the transmitter, we achieve directional control of the transmitted radiation over a broad range of 29°. This enables wireless power transfer from one transmitter to different receivers

                                                 

                           When you use your cell phone to place a call or to send a text message, your phone connects to a nearby transceiver station via an antenna link. Information is transmitted efficiently and wirelessly using this invisible cable connecting your hand-held device to the wire network. It has been a dream to take the concept of antenna links from the radio frequency regime to the optical domain. Combining the enormous bandwidth of optical communication with the flexibility and low loss of antenna links renders this a very exciting concept to transmit optical signals. An optical nanoantenna link would allow extremely high bandwidth signal transmission between nanoscale devices. This could be used for example to speed up communications between integrated circuits. Optical nanoantenna links could even be reconfigured by steering the transmitted beam in the same way as is done in radar technology.The team led by Prof. Harald Giessen of the 4 th Physics Institute at the University of Stuttgart fabricated optical nanoantenna structures using electron beam lithography in collaboration with the Max-Planck-Institute for Solid State Research. These nanometer scale metal structures control optical fields in the same way as conventional radio frequency antennas direct the transmission and reception of radio waves. The scientists then positioned photoluminescent molecules around the nanostructures with nanometer scale accuracy. This allowed them to image the distribution of optical energy around the nanoantennas. The team applied their technique to observe for the first time the transmission of optical energy between two linked optical nanoantennas. They further quantified the power transmission efficiency of the link and observed that the signal transmission has low loss, turning optical nanoantenna links into a very promising approach for transmission of optical signals.Having demonstrated the transmission of optical power between two optical nanoantennas, the researchers implemented a device capable of angular beam steering. This idea was inspired and supported by Dr. Michael Totzeck from Carl Zeiss AG in Oberkochen. An array of transmitting antennas was used, having slightly different phases of the signals transmitted from the individual antennas. This results in the radiated optical beam propagating in different directions depending on the phase of the transmitters due to interference. The research team achieved this by shaping the wave front of the field incident on the transmitting array. By controlling the wave front the transmitted radiation could be steered over a large angular range of 29 degrees

Source: University of Stuttgart