Overlapping blue lasers recording holograms in a GE micro-holographic disc. GE researchers have demonstrated a threshold micro-holographic storage material that can enable the storage of over 500 gigabytes in a standard DVD-size disc, equal to the capacity of 20 single-layer Blu-ray discs, 100 DVDs or the hard drive for a large desktop computer. (Photo: Business Wire)

GE Global Research, the technology development arm of the General Electric announced today a major breakthrough in the development of next generation optical storage technology.

GE researchers have successfully demonstrated a threshold micro-holographic storage material that can support 500 gigabytes of storage capacity in a standard DVD-size disc. This is equal to the capacity of 20 single-layer Blu-ray discs, 100 DVDs or the hard drive for a large desktop computer.

GE’s micro-holographic discs will be able to be read and recorded on systems very similar to a typical Blu-ray or DVD player. Holographic storage is different from today’s optical storage formats like DVDs and Blu-ray discs. DVDs and Blu-ray discs store information only on the surface of the disc; holographic storage technology uses the entire volume of the disc material.

Holograms, or three-dimensional patterns that represent bits of information, are written into the disc and can then be read out. Although GE’s holographic storage technology represents a breakthrough in capacity, the hardware and formats are so similar to current optical storage technology that the micro-holographic players will enable consumers to play back their CDs, DVDs and BDs.

The GE team successfully recorded micro-holographic marks approaching one percent reflectivity with a diameter of approximately one micron. When using standard DVD or Blu-ray disc optics, the scaled down marks will have sufficient reflectivity to enable over 500 GB of total capacity in a CD-size disc.

“GE’s breakthrough is a huge step toward bringing our next generation holographic storage technology to the everyday consumer,” said Brian Lawrence, who leads GE’s Holographic Storage program. “Because GE’s micro-holographic discs could essentially be read and played using similar optics to those found in standard Blu-ray players, our technology will pave the way for cost-effective, robust and reliable holographic drives that could be in every home. The day when you can store your entire high definition movie collection on one disc and support high resolution formats like 3-D television is closer than you think.”

GE has been working on holographic storage technology for over six years. The demonstration of materials that can support 500 gigabytes of capacity represents a major milestone in making micro-holographic discs that ultimately can store more than one terabyte, or 1,000 gigabytes of data. In addition to pushing the limits of storage capacity, GE researchers also have been very focused on making the technology easily adaptable to existing optical storage formats and manufacturing techniques.

“GE’s holographic storage program has turned the corner, and with this milestone we can now intensify our efforts in commercialization opportunities,” said Bill Kernick, who leads GE’s Technology Ventures team. “We’ll continue to engage with a variety of strategic partners to create the best route from product development to introduction into the marketplace.”

GE initially will be focusing on the commercial archival industry followed by the consumer market for its micro-holographic storage technology.

CORVALLIS, Ore. – Engineers at Oregon State University have discovered a way to use an ancient life form to create one of the newest technologies for solar energy, in systems that may be surprisingly simple to build compared to existing silicon-based solar cells.

The secret: diatoms.

These tiny, single-celled marine life forms have existed for at least 100 million years and are the basis for much of the life in the oceans, but they also have rigid shells that can be used to create order in a natural way at the extraordinarily small level of nanotechnology.

By using biology instead of conventional semiconductor manufacturing approaches, researchers at OSU and Portland State University have created a new way to make “dye-sensitized” solar cells, in which photons bounce around like they were in a pinball machine, striking these dyes and producing electricity. This technology may be slightly more expensive than some existing approaches to make dye-sensitized solar cells, but can potentially triple the electrical output.

“Most existing solar cell technology is based on silicon and is nearing the limits of what we may be able to accomplish with that,” said Greg Rorrer, an OSU professor of chemical engineering. “There’s an enormous opportunity to develop different types of solar energy technology, and it’s likely that several forms will ultimately all find uses, depending on the situation.”

Dye-sensitized technology, for instance, uses environmentally benign materials and works well in lower light conditions. And the new findings offer advances in manufacturing simplicity and efficiency.

“Dye-sensitized solar cells already exist,” Rorrer said. “What’s different in our approach are the steps we take to make these devices, and the potential improvements they offer.”

The new system is based on living diatoms, which are extremely small, single-celled algae, which already have shells with the nanostructure that is needed. They are allowed to settle on a transparent conductive glass surface, and then the living organic material is removed, leaving behind the tiny skeletons of the diatoms to form a template.

A biological agent is then used to precipitate soluble titanium into very tiny “nanoparticles” of titanium dioxide, creating a thin film that acts as the semiconductor for the dye-sensitized solar cell device. Steps that had been difficult to accomplish with conventional methods have been made easy through the use of these natural biological systems, using simple and inexpensive materials.

“Conventional thin-film, photo-synthesizing dyes also take photons from sunlight and transfer it to titanium dioxide, creating electricity,” Rorrer said. “But in this system the photons bounce around more inside the pores of the diatom shell, making it more efficient.”

The physics of this process, Rorrer said, are not fully understood – but it clearly works. More so than materials in a simple flat layer, the tiny holes in diatom shells appear to increase the interaction between photons and the dye to promote the conversion of light to electricity, and improve energy production in the process.

The insertion of nanoscale tinanium oxide layers into the diatom shell has been reported in ACS Nano, a publication of the American Chemical Society, and the Journal of Materials Research, a publication of the Materials Research Society. The integration of this material into a dye-sensitized solar cell device was also recently described at the fourth annual Greener Nanoscience Conference.

Source: Oregon State University

Religious technology may seem like an oxymoron, but as more people obtain mobile phones, iPhones and other devices to help them manage their lives, it’s only natural that many of them will be using their gadgets to help them enrich their spiritual life as well. Researchers at the Georgia Institute of Technology have developed a mobile application known as Sun Dial, which alerts Muslim users when it’s time to perform the five daily prayers known as salat. The device is currently being discussed this week at the human-computer interaction conference, CHI, in Boston.

“We have to understand religion because it’s such a central part of peoples lives,” explained Susan Wyche, doctoral candidate in the College of Computing and GVU Center at Georgia Tech.

Sun Dial is a mobile application that uses images to alert users to the five daily prayers of Islam.

Credit: Susan Wyche

Designing technological devices for religious use may be very different from designing devices for traditional uses in office settings.

“Efficiency and productivity tend to be driving forces when designing technology for offices, but these are not as central when designing applications for the home or religious settings. Why would you design a device that makes someone pray faster?,” said Wyche.

Wyche, along with her research team, chose to focus on Islam for this study, partially because of the religion’s popularity worldwide and partially because Muslims have historically used technology such as compasses and telescopes to help them determine the direction to face during prayer.

Working with seven focus groups, they determined that the greatest interest from the participants lay in prompting them when it was time to pray — not by using text, which some commercial applications use, but through imagery combined with audible alerts.

Sun Dial tells users that the time to pray is approaching by using an image of the sun lining up with a green circle. When the sun lines up with the circle, it’s time to pray.

“Unlike similar systems, ours relies on graphics rather than text and graphs to communicate prayer times. Users drove this choice by telling us that tracking the sun was the most religiously valued method to determine prayer times.”

Wyche and colleagues tested their application with Muslims from Georgia Tech and the greater Atlanta area for two weeks with favorable reaction. They’re currently working on implementing a few design changes such as a digital clock and a vibration alert. Eventually, they plan on making the application available for download.

“Sun Dial provided more than functionality or a prompt to the prayer times; it also contributed to users’ religious experience by reminding them they were part of a larger community. More broadly, carefully considering imagery is important when developing mobile phone applications, particularly ones that support personal and emotional activities, which may be sacred or secular.”

Source: Georgia Institute of Technology

Graphene may solve communications speed limit

CAMBRIDGE, Mass.–New research findings at MIT could lead to microchips that operate at much higher speeds than is possible with today’s standard silicon chips, leading to cell phones and other communications systems that can transmit data much faster.

The key to the superfast chips is the use of a material called graphene, a form of pure carbon that was first identified in 2004. Researchers at other institutions have already used the one-atom-thick layer of carbon atoms to make prototype transistors and other simple devices, but the latest MIT results could open up a range of new applications.

The MIT researchers built an experimental graphene chip known as a frequency multiplier, meaning it is capable of taking an incoming electrical signal of a certain frequency — for example, the clock speed that determines how fast a computer chip can carry out its computations — and producing an output signal that is a multiple of that frequency. In this case, the MIT graphene chip can double the frequency of an electromagnetic signal.

Frequency multipliers are widely used in radio communications and other applications. But existing systems require multiple components, produce “noisy” signals that require filtering and consume large power, whereas the new graphene system has just a single transistor and produces, in a highly efficient manner, a clean output that needs no filtering.

The findings are being reported in a paper in the May issue of Electron Device Letters and were also reported last week at the American Physical Society meeting by Tomás Palacios, assistant professor in MIT’s Department of Electrical Engineering and Computer Science and a core member of the Microsystems Technology Laboratories. The work was done by Palacios along with EECS Assistant Professor Jing Kong and two of their students, Han Wang and Daniel Nezich.

“In electronics, we’re always trying to increase the frequency,” Palacios says, in order to make “faster and faster computers” and cellphones that can send data at higher rates, for example. “It’s very difficult to generate high frequencies above 4 or 5 gigahertz,” he says, but the new graphene technology could lead to practical systems in the 500 to 1,000 gigahertz range.

“Researchers have been trying to find uses for this material since its discovery in 2004,” he says. “I believe this application will have tremendous implications in high-frequency communications and electronics.” By running several of the frequency-doubling chips in series, it should be possible to attain frequencies many times higher than are now feasible.

While the work is still at the laboratory stage, Palacios says, because it is mostly based on relatively standard chip processing technology he thinks developing it to a stage that could become a commercial product “may take a year of work, maximum two.” This project is currently being partially funded by the MIT Institute for Soldier Nanotechnology and by the Interconnect Focus Center program, and it has already attracted the interest of “many other offices in the federal government and major chip-making companies,” according to Palacios.

Graphene is related to the better-known buckyballs and carbon nanotubes, which also are made of one-atom-thick sheets of carbon. But in those materials, the carbon sheets are rolled up in the form of a tube or a ball. While physicists had long speculated that flat sheets of the material should be theoretically possible, some had doubted that it could ever remain stable in the real world.

“In physics today, graphene is, arguably, the most exciting topic,” Palacios says. It is the strongest material ever discovered, and also has a number of unsurpassed electrical properties, such as “mobility” — the ease with which electrons can start moving in the material, key to use in electronics — which is 100 times that of silicon, the standard material of computer chips.

One key factor in enabling widespread use of graphene will be perfecting methods for making the material in sufficient quantity. The material was first identified, and most of the early work was based on, using “sticky tape technology,” Palacios explains. That involves taking a block of graphite, pressing a piece of sticky tape against it, peeling it off and then applying the tape to a wafer of silicon or other material.

But Kong has been developing a method for growing entire wafers of graphene directly, which could make the material practical for electronics. Kong and Palacios’ groups are currently working to transfer the frequency multipliers to these new graphene wafers.

“Graphene will play a key role in future of electronics,” Palacios says. “We just need to identify the right devices to take full advantage of its outstanding properties. Frequency multipliers could be one of these devices.”

Source: Massachusetts Institute of Technology

Credit: Duke University

DURHAM, N.C. — Scientists have used a popular kids swimming pool game to guide their development of a system for controlling moving robots that can autonomously detect and capture other moving targets.

Engineers from Duke University and the University of New Mexico have used the simple pursuit-evasion game “Marco Polo” to solve a complex problem — namely, how to create a system that allows robots to not only “sense” a moving target, but intercept it.

Such systems have broad applications, ranging from security systems to track unwanted intruders like enemy ships or burglars, to systems that create radiation or environmental hazard maps, or even track endangered species.

Rafael Fierro is an associate professor of electrical engineering at the University of New Mexico.

Credit: University of New Mexico

The main challenge facing researchers is developing the artificial intelligence to control the robots and their sensors without direct human guidance.

The goal of the game “Marco Polo” is for the person who is “it” to tag another person, who then becomes the new pursuer. However, pursuers must keep their eyes closed. At any time, the pursuer can call out “Marco,” and everyone else must respond by saying “Polo.” In this way, the pursuer can gradually estimate where the targets are in the pool and where they might go.

“Games give us a good way of making these highly complex problems easier to visualize,” said Silvia Ferrari, assistant professor of mechanical engineering and materials science at Duke’s Pratt School of Engineering. Ferrari and colleague Rafael Fierro, associate professor of electrical engineering at the University of New Mexico, published the results from their latest experiments online in the Journal on Control and Optimization, a publication of the Society for Industrial and Applied Mathematics.

“Just as in ‘Marco Polo,’ we needed to create a way that permits mobile robots to detect other moving objects and make predictions about where the targets might go,” Ferrari said. “When done efficiently, the mobile sensor switches from pursuit mode to capture mode in the shortest amount of time.”

Ferrari’s laboratory had already developed a similar type of algorithm, known as cell decomposition, in which space is broken down into a series of distinct cells. Past experiments allowed a robot to move through space without colliding with stationary obstacles.

The latest experiments included not only robots equipped with camera sensors, but also stationary camera sensors, which allowed for “coverage” of all the cells within the space.

“The idea is that multiple sensors are deployed in the space to cooperatively detect moving targets within that space,” Fierro said. “As the sensor makes more detections, it is better able to predict the likely path of the intruder. The ultimate path taken by the robot sensor is one that maximizes the probability of detection and minimizes the distance needed to capture the target.”

While the security and military applications of this type of detection system are obvious, Fierro also points out that the new algorithms can be used in other ways to detect targets that aren’t necessarily intruders.

“Targets could be completely different things, like mines or explosives, or chemical or radiation leaks,” Fierro said. “The robots can use their sensors to keep track of the detected locations and build a ‘map’ to let people know where to go or not to go.”

The algorithms could also be used to help explain natural phenomena, such as the behaviors of members of a wolf pack as they chase and capture their prey.

The latest experiments were conducted at the University of New Mexico and involved intruders moving in straight lines at a constant speed.

“We are now developing algorithms that will more closely mimic the real world by giving intruders the ability to take evasive actions,” Ferrari said. “The other main issue is to ensure that all the different mobile sensors can communicate with each other at all times and coordinate their activities based on that communication.”

Source: Duke University

Major research conference to be held in San Diego, March 22-26

WASHINGTON, March 17—The world’s largest international conference on optical communications begins next week and continues from March 22-26 at the San Diego Convention Center in San Diego. The Optical Fiber Communication Conference and Exposition/National Fiber Optic Engineers Conference (OFC/NFOEC) is the premier meeting where experts from industry and academia intersect and share their results, experiences, and insights on the future of electronic and wireless communication and the optical technologies that will enable it.

Journalists are invited to attend the meeting, where more than 15,000 attendees are expected. This year’s lineup will have many engaging talks and panels, including:

* MARKET WATCH, a three-day series of presentations and panel discussions featuring esteemed guest speakers from the industrial, research, and investment communities on the applications and business of optical communications. See: http://www.ofcnfoec.org/conference_program/Market_Watch.aspx.

* PLENARY PRESENTATIONS: “The Changing Landscape in Optical Communications,” Philippe Morin, president, Metro Ethernet Networks; “Getting the Network the World Needs,” Lawrence Lessig, professor, Stanford Law School; “The Growth of Fiber Networks in India,” Shri Kuldeep Goyal, chairman and managing director, Bharat Sanchar Nigam Ltd. To access speaker bios and talk abstracts, see: http://www.ofcnfoec.org/conference_program/Plenary.aspx.

* SERVICE PROVIDER SUMMIT, a dynamic program with topics and speakers of interest to CTOs, network architects, network designers and technologists within the service provider and carrier sector. See: http://www.ofcnfoec.org/conference_program/Service_Provider_Summit.aspx

The OFC/NFOEC Web site is http://www.ofcnfoec.org. Also on the site is information on the trade show and exposition, where the latest in optical technology from more than 550 of the industry’s key companies will be on display.

SCIENTIFIC HIGHLIGHTS

The conference also features a comprehensive technical program with talks covering the latest research related to all aspects of optical communication. Some of the highlights at OFC/NFOEC 2009 include the following.

A simpler receiver to cut costs of tomorrow’s Internet

Upgrading broadband networks to handle the Internet traffic of the future is proving to be a big, expensive job. Engineers at NEC Laboratories America in Princeton, N.J. are hoping to cut costs by simplifying the hybrid optical/electronic receiver that sorts out the flood of data at the end of the optical fiber.

In recent years, telecommunications giants like Verizon and AT&T have begun to beef up their broadband networks from 10 gigabits per second (10G) to 40G, enough bandwidth to broadcast 1,000 Hollywood movies simultaneously. Achieving these high speeds requires data to be “multiplexed,” a process in which a single high-speed stream is split into several slower streams using a multi-level modulation format and polarization multiplexing technologies. The slower data streams are received and reassembled at the end of the line by an expensive device called a coherent receiver.

To cut costs, Dayou Qian and colleagues at NEC have eliminated expensive lasers and other components from the conventional coherent receiver. Their simpler “direct-detection receiver” relies instead on a narrow optical carrier signal that travels with the data along optical fibers, re-generates the electrical signal in the receiver and helps the digital signal processing algorithm to piece together the cut-up data.

The drawback to this approach is that this extra “carrier signal” consumes some of the transmission power, reducing the signal-to-noise ratio of the data in the line. Still, in data presented at OFC/NFOEC 2009 in San Diego, the researchers report using the device to reliably detect signals sent at 40G. They hope that this lower-cost technology will pave the way for cheaper, higher-speed upgrades to metropolitan areas and access/office networks.

Talk OTuO7, “22.4-Gb/s OFDM Transmission over 1000 km SSMF Using Polarization Multiplexing with Direct Detection” (Tuesday, March 24, 6:15 – 6:30 p.m.)

New standards released to guide evolution of Ethernet

For more than 30 years, computer networks running on Ethernet standards have allowed co-workers to send data back and forth in the office. But as the size of data grows exponentially, companies like Google and Facebook are realizing that the current 10G pipes will need to be much bigger in the future. At this year’s OFC/NFOEC, John D’Ambrosia, chair of the IEEE P802.3ba 40 Gb/s and 100 Gb/s Ethernet Task Force and Scientist for Force10 Networks, will be providing an update on the new physical layer specifications for tomorrow’s Ethernet.

The IEEE 802.3 Working Group formed the Higher Speed Study Group – a collection of server manager, network engineers, and companies that use Ethernet – in July 2006. One goal of the study group was to decide how fast the Ethernet of the future will need to be. Two speeds have been selected: 40G for computing applications and 100G for core networking applications, whose bandwidth requirements are growing even faster. This dual standard marks a break from the tradition of simply increasing Ethernet speed standards by a factor of 10.

In December of 2007 the IEEE P802.3ba 40Gb/s and 100Gb/s Ethernet Task Force was formed. In March 2009 the document was approved for Working Group ballot. After completion, the next scheduled steps in the effort will be the Sponsor Ballot in November of 2009 with approval of the standard in June 2010.

An overview of the architecture and physical layer standards will be presented at OFC/NFOEC. As for how long it will take new hardware meeting these specifications to find its way into offices, “that’s impossible to predict, but the market forces will work through the issues,” says D’Ambrosia.

Talk NTuA4, “The Continuing Evolution of Ethernet” (Tuesday, March 24, 3:20 – 4 p.m.)

New routers marry light and silicon to cut down on power and ramp up speed

Tomorrow’s ultra-fast broadband may be limited not by the speed at which data can be sent, but by the electrical power needed to route data to millions of users. A new technology that weds light and silicon hopes to keep up the massive connectivity of a faster Internet by cutting down on its power consumption.

To send a single stream of data to many computers, networks have to “multicast,” sending out multiple copies of a single input signal carried by an optical fiber. With electronic switching, this requires converting optical data into digital electronic data, making copies in the electronic domain, and converting electronic copies back into optical data. The amount of power that electronic multicasters require to do this is large and will increase exponentially as the speed of data transmission goes up, an energy bottleneck for the industry.

To solve this problem, a team of researchers at Columbia University and Cornell University has built a purely optical device that cuts out the energy-hungry electronic middleman. They use a pulsing laser to clone the light coming in from an optical fiber into eight identical waves going out, a process called “four-wave mixing.” This all happens in silicon – one of the most efficient materials for this process – directly embedded on a computer chip. So though the multicasting itself doesn’t require electronics, other electronic components, like switches, could be installed on the chip to modify the signal as it passes through.

The device can handle speeds of more than 160G and draws several orders of magnitude less power than current electronic devices. “We’re looking ahead to next-generation networks that will run at terabits per second,” says Keren Bergman of Columbia University. “You just can’t do that kind of multicasting in electronics.”

Talk OTuI3, “First Demonstration of On-Chip Wavelength Multicasting” (Tuesday, March 24, 6 – 6:15 p.m.)

Cost-effective solutions for ever-increasing speeds

The broadband market has traditionally been like a sponge – as it becomes saturated, it expands. The advent of high-speed broadband and its associated streams of videos, music, and phone in the last few years has only increased demand for even greater bandwidth and ever-higher speeds. The need for speed shows no signs of diminishing, says Jeffrey H. Sinsky, a scientist at Bell Labs, the research arm of Alcatel-Lucent. As a result, the need for new cost-effective technologies that can handle the higher speeds has become profound.

Some of the fastest transfer rates ever achieved in the laboratory top out above 100 billion bits per second (100G) – enough speed to copy a reasonably large personal computer hard drive in less than a second. Moving a signal over an optical fiber at speeds above 100G is challenging but achievable. The problem comes when the optical signals need to be converted into electric signals. Moving electrical signals at anything above 40G creates what are known as distributed circuit effects that can confound transmission and lead to a loss of data. One way to deal with this problem is to break optical signals into several lower rate, more easily handled parallel optical data streams, but this may require adding many extra components, which complicates packaging and inflates costs.

With the right know-how and with emerging technology, dealing with ever-increasing speeds can be done cost-effectively, says Sinsky, who is an expert in integrating optical components with electronic ones into small packages. In his talk, he will outline his designs for small integrated hybrid systems that can convert high-rate optical data streams into several lower-rate electrical streams that are easier to handle – and cost-effective even at state-of-the-art 100G speeds.

The demand for commercial Ethernet at these speeds is inevitable, says Sinsky. With new and even more bandwidth-hungry applications such as 3DTV and telepresence just on the horizon, it is clear that what is considered adequate network capacity today will fall far short of tomorrow’s demand. In anticipation, researchers are already beginning to explore so called “terabit” Ethernet that will perform at speeds of 1,000G.

Talk OThN6, “Integration and Packaging of Devices for 100-Gb/s Transmission” (Thursday, March 26, 2:30 – 3:00 p.m.)

Reliable multiplexing at 640G

Sliced light is how we communicate now. Millions of phone calls and cable television shows per second are dispatched through fibers in the form of digital zeros and ones formed by chopping laser pulses into bits. This slicing and dicing is generally done with an “electro-optic modulator,” a device for allowing an electric signal to switch a laser beam on and off at high speeds (the equivalent of putting a hand in front of a flashlight). Reliably reading that fast data stream is another matter. A new reliable speed-reading record – 640 billion bits per second – has now been established by a collaboration of scientists from Denmark and Australia.

Conventional readers of optical data depend on photo-detectors, electronic devices that can operate up to approximately 40G. This in itself represents a great feat of rapid reading, but it’s not good enough for the higher-rate data streams being designed now. The data receiving rate has to keep up. Sometimes several signals – each with its own stream of coded data – will be sent down an optical fiber at the same time to speed up data transmission. This process is called multiplexing. Ten parallel streams of 10 billion bits per second, abbreviated as 10G, would add up to an effective stream of 100G. At the receiving end the parallel signals have to be read out in a complementary process called de-multiplexing. Reliable and fast multiplexing and de-multiplexing represent a major bottleneck in linking up the electronic and photonic worlds.

The new de-multiplexing device demonstrated at the Technical University of Denmark, by contrast, can handle the high data rate, and do so in a stable manner. Furthermore, instead of fibers 50 meters long, the Danish researchers accomplish their untangling of the data stream with a waveguide only 5 cm long, an innovation developed by Danish scientist Leif K. Oxenlowe and his colleagues at the Technical University and at the Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS) in Australia.

Talk OThF3, “640 Gbit/s Optical Signal Processing” (Thursday, March 26, 8:30 – 9 a.m.)

Red-light metamaterials

Metamaterials make it possible to manipulate light on the nanoscale. They are nanostructured materials made of tiny metallic rings, rods, or strips arranged in such a way as to produce a negative index of refraction, or a situation unique to metamaterials when light is deflected away from an imaginary line passing perpendicularly between air and the material. This property in turn is expected to lead to novel optical devices, such as flat-panel lenses and hyperlenses. These lenses can be used to image objects with a spatial resolution smaller than the wavelength of the illuminating light source, thus circumventing the normal “diffraction limit,” which says that a lens cannot produce an image with a spatial resolution better than approximately half the wavelength of the light used to make the image.

Alexander Kildishev will report on optical metamaterial progress at Purdue, including the shortest wavelength light (710 nm) yet achieved for a negative index metamaterial, and the improved design of a cylindrical-shaped hyperlens. One goal in this work is to produce cloaking, rendering an object inside a metamaterial enclosure invisible to outside viewers. But Kildshev says achieving invisibility in the visible portion of the electromagnetic spectrum will be difficult. Shorter range applications of metamaterials, he says, will likely be seen in microscopy, biosensing, and in the harvesting of solar energy. (More information is available at http://cobweb.ecn.purdue.edu/~shalaev/MURI/overview.shtml.)

Talk OThK1, “Progress in Metamaterials for Optical Devices” (Thursday, March 26, 1 – 1:30 p.m.)

Optofluidic assembly of microlasers

One of the problems of marrying electronics and photonics is that they are embodied in very different elements. Many photonic components – such as modulators, detectors, switches, and waveguides – can be fashioned from silicon, but the light source itself, the microlaser, is often assembled from elements residing in columns III and V of the periodic table, and these elements don’t sit well on top of silicon. Ming-Chun Tien and Professor Ming Wu of the University of California, Berkeley will report on progress in their lab, where their team has been able to make III-V microlasers (6 microns in diameter and only 200 nm thick) using a wet chemical etch process. Once the microdisk lasers are formed, the lasers’ substrate (the indium phosphide [InP] platform on which the indium gallium arsenide phosphide [InGaAsP] lasers were built) is etched away. Then the lasers are floated in a mini-lake of ethanol (which accounts for the word “fluidics” in the name) and moved into position by a patterned array of light from a computer-controlled projector, which they refer to as optoelectronic tweezers (OET). The lasers are held in place over optical waveguides defined in silicon by an applied voltage until the attachment process is complete. Tien says that the microlasers, costing less than 1 cent each, can be positioned on the chip with better-than-quarter-micron accuracy.

Talk OMR7, “Optofluidic Assembly of InGaAsP Microdisk Lasers on Si Photonic Circuits with Submicron Alignment Accuracy” (Monday, March 23, 5:45 – 6:00 p.m.)

First true optical packet switching

Supercomputers have the capacity to process immense amounts of data in parallel. Traditionally computers relied on electrons moving in wires to be switched by electronic switches (relays in the early days, then vacuum tubes, then transistors). To support much higher data-flow rates computers now resort to encoding data into the form of light waves, and many high-caliber systems are necessarily opto-electronic hybrids. But how to switch and maneuver all that data? Optical switches are faster and consume less power than electronic switches. However, optical systems don’t do as good a job as their electronic counterparts when it comes to having a fast-access memory. Furthermore, optical switching is more expensive and harder to control.

Two corporations, IBM-Zurich and Corning, have collaborated on a new opto-electronic system, called OSMOSIS (Optical Shared Memory Supercomputer Interconnect System) for processing packets of optical data in and among supercomputers. This hybrid approach uses electronic circuitry for data buffering and control operations and optical circuitry for switching and transmitting data.

The result, to be announced at OFC/NFOEC, is the first true high-capacity optical packet switching system. With a cost close to other electronic products, the OSMOSIS system can move data through 64 ports at a rate of 40G for each port, for an overall data rate of 2.5 terabits per second. Other characteristics of the OSMOSIS architecture include a latency period (the time it takes between the sending and processing of the data packet) of less than 250 nsec and an optical switching time of 13 nsec.

Talk OTuF3, “The Osmosis Optical Packet Switch for Supercomputers” (Tuesday, March 24, 2:45 – 3:15 p.m.)

Source: Optical Society of America

Troy, N.Y. – Researchers at Rensselaer Polytechnic Institute have developed a new technique for growing slimmer copper nanorods, a key step for advancing integrated 3-D chip technology.

These thinner copper nanorods fuse together, or anneal, at about 300 degrees Celsius. This relatively low annealing temperature could make the nanorods ideal for use in heat-sensitive nanoelectronics, particularly for “gluing” together the stacked components of 3-D computer chips.

“When fabricating and assembling 3-D chips, and when bonding the silicon wafers together, you want as low a temperature as possible,” said Pei-I Wang, research associate at Rensselaer’s Center for Integrated Electronics. “Slimmer nanorods, by virtue of their smaller diameters, require less heat to anneal. These lower temperatures won’t damage or degrade the delicate semiconductors. The end result is a less expensive, more reliable device.”

Experimental 3-D computer chips are comprised of several layers of stacked components. Wang said these layers can be coated with thin nanorods, and then heated up to 300 degrees Celsius. Around that temperature, the thin nanorods anneal, turn into a continuous thin film, and fuse the layers together. This study was the first demonstration of slimmer nanorods enabling wafer bonding, according to Wang.

Fundamental research concerning the slimmer nanorods was led by Toh-Ming Lu, the R.P. Baker Distinguished Professor of Physics at Rensselaer. Results of the study were recently published in the journal Nanotechnology.

Research into wafer bonding and incorporating the slimmer nanorods into 3-D integrated computer chips was led by James Jian-Qiang Lu, associate professor in the Department of Electrical, Computer, and Systems Engineering (ECSE) and the Center for Integrated Electronics (CIE) at Rensselaer. Results of the study were recently published in the journal Electrochemical and Solid-State Letters.

The slimmer copper nanorods were formed by periodically interrupting the growth process. The vapor-deposition process was occasionally halted, and the fledgling nanorods were exposed to oxygen. This resulted in a forest of nanorods with diameters between 10 nanometers and 50 nanometers – far smaller than the typical 100-nanometer diameter copper nanorods grown conventionally without interruption.

Vast forests, or arrays, of copper nanorods are produced by vapor deposition at an oblique angle. In a conventional setting, with an uninterrupted stream of copper atoms deposited in a vacuum onto a substrate, the deposition angle naturally results in taller, thicker nanorods.

Periodically interrupting the deposition, and exposing the copper nanorods to ambient air, however, leads to oxygen being absorbed into the surface of the nanorods. During subsequent depositions, this oxidized copper helps to prevent the vaporized copper atoms from migrating away from the very tips of the nanorods. This ensures the nanorods grow taller, without necessarily growing in diameter. The more growth interruptions, the thinner the resulting nanorods, Wang said.

Wang and the research group have filed for a patent for this new technology. The patent is currently pending.

Source: Rensselaer Polytechnic Institute

Autosub, a robot submarine built and developed by the UK’s National Oceanography Centre, Southampton, has successfully completed a high-risk campaign of six missions travelling under an Antarctic glacier.

Autosub has been exploring Pine Island Glacier, a floating extension of the West Antarctic ice sheet, using sonar scanners to map the seabed and the underside of the ice as it juts into the sea. Scientists hope to learn why the glacier has been thinning and accelerating over recent decades. Pine Island Glacier is in the Amundsen Sea, part of the South Pacific bordering West Antarctica. Changes in its flow have been observed since the early 1970s, and together with neighbouring glaciers it is currently contributing about 0.25 mm a year to global sea level rise.

Steve McPhail led the Autosub team during the ten-day survey. He said:

“Autosub is a completely autonomous robot: there are no connecting wires with the ship and no pilot. Autosub has to avoid collisions with the jagged ice overhead and the unknown seabed below, and return to a pre–defined rendezvous point, where we crane it back onboard the ship.

“Adding to the problems are the sub zero water temperatures and the crushing pressures at 1000 m depth. All systems on the vehicle must work perfectly while under the ice or it would be lost. There is no hope of rescue 60 km in, with 500 metres of ice overhead.”

An international team of scientists led by Dr Adrian Jenkins of British Antarctic Survey and Stan Jacobs of the Lamont-Doherty Earth Observatory, Columbia University, New York on the American ship, the RVIB Nathaniel B Palmer, has been using the robot sub to investigate the underside of the ice and measure changes in salinity and temperature of the surrounding water.

After a test mission in unusually ice-free seas in front of the face of the glacier, they started with three 60km forays under the floating glacier and extended the length of missions to 110km round-trip. In all, a distance over 500km beneath the ice was studied.

Using its sonar, the Autosub picks its way through the water, while creating a three-dimensional map that the scientists will use to determine where and how the warmth of the ocean waters drives melting of the glacier base.

“There is still much work to be done on the processing of the data”, said Adrian Jenkins, “but the picture we should get of the ocean beneath the glacier will be unprecedented in its extent and detail. It should help us answer critical questions about the role played by the ocean in driving the ongoing thinning of the glacier.”

The lead US researcher on the project, Stan Jacobs, is studying the Pine Island Glacier with International Polar Year (IPY) funding from the National Science Foundation (NSF). One of the IPY research goals is to better understand the dynamics of the world’s massive ice sheets, including the massive West Antarctic Ice Sheet. If this were to melt completely global sea levels would rise significantly. The most recent report of the Intergovernmental Panel on Climate Change (IPCC) noted that because so little is understood about ice-sheet behaviour it is difficult to predict how ice sheets will contribute to sea level rise in a warming world. The behaviour of ice sheets the IPCC report said is one of the major uncertainties in predicting exactly how the warming of the global will affect human populations.

Complementing the Autosub exploration, other work during the 53-day NB Palmer cruise included setting out 15 moored instrument arrays to record the variability in ocean properties and circulation over the next two years, extensive profiling of ‘warm’ and melt-laden seawater, sampling the perennial sea ice and swath-mapping deep, glacially-scoured troughs on the sea floor.

Autosub is an AUV – Automated Underwater Vehicle, designed, developed and built at the National Oceanography Centre, Southampton with funding from the Natural Environment Research Council. Autosub has a maximum range of 400km and is powered by 5,000 ordinary D-cell batteries. The batteries are packed in bundles in pressure-tested housings. Either end of the seven-metre sub there are free-flooding areas where the payload of instruments are installed. It carries a multibeam sonar system that builds up a 3D map of the ice above and the seabed below.. It also carries precision instruments for measuring the salinity, temperature, and oxygen concentrations in the sea water within the ice cavity, which are vital to understanding the flow of water within the ice cavity and the rate of melting. Autosub is 7m long and weighs 3.5 tonnes. Travelling at 6km hour it is capable of diving up to 1600 m deep, and can operate for 72 hours (400 km) between battery changes.

Source: National Oceanography Centre, Southampton (UK)

The invisible light of a UV lamp “illuminates” the window panes and generates fluorescent radiation in the coating. This radiation is detected by sensors in the edges of the window.

Credit: Fraunhofer IAP

It is 6 p.m. and the museum is closing down for the night. The building’s alarm system is switched on and the security guard does his rounds. A novel motion sensor developed by the Fraunhofer Institutes for Applied Polymer Research IAP in Potsdam-Golm and for Computer Architecture and Software Technology FIRST in Berlin could provide even more security in future, enabling window panes and glass doors to detect movements thanks to a special coating. If anything changes in front of the pane, or someone sneaks up to it, an alarm signal is sent to the security guard.

“The glass is coated with a fluorescent material,” explains IAP group manager Dr. Burkhard Elling. “The coating contains nanoparticles that convert light into fluorescent radiation.” The principle is as follows: The invisible light of a UV lamp “illuminates” the window panes and generates fluorescent radiation in the coating. This radiation is channeled to the edges of the window, where it is detected by sensors. Simple applications require only one sensor. Similarly to a light barrier, if someone steps into the light of the lamp less light reaches the coating and less fluorescent radiation is produced. If several sensors are installed on all four sides of the window frame, conclusions can be drawn from the data as to how fast and in what direction an object is moving. Its size, too, can be estimated by the sensors. Is it a small creature such as a bird or is it a person? The threshold for the alarm can be set, so that moving objects the size of birds for instance do not trigger an alarm.

Likewise, the sensors do not react to light from passing cars, as the researchers at FIRST have developed a software application that can interpret different light signals. This enables the system to easily distinguish between the frequency of the UV lamp and the slowly changing light from a passing headlight. The system has further advantages: it does not infringe on anybody’s personal rights, as it only detects the change in radiation, and not who triggered it. It is also cost-efficient, because the coating can be sprayed onto the windows by airbrush or glued on as a film. A demonstrator system already exists, and the researchers now plan to optimize the dyes and their concentration in the coating.

Source: Fraunhofer-Gesellschaft

LIVERMORE, Calif. – By reversing a process that converts electrical signals into sounds heard out of a cell phone, researchers may have a new tool to enhance the way computer chips, LEDs and transistors are built.

Lawrence Livermore National Laboratory scientists have for the first time converted the highest frequency sounds into light by reversing a process that converts electrical signals to sound.

Commonly used piezo-electric speakers, such as those found in a cell phone, operate at low frequencies that human ears can hear.

But by reversing that process, lead researchers Michael Armstrong, Evan Reed and Mike Howard, LLNL colleagues, and collaborators from Los Alamos National Laboratory and Nitronex Corp., used a very high frequency sound wave – about 100 million times higher frequency than what humans can hear – to generate light.

“This process allows us to very accurately ’see’ the highest frequency sound waves by translating them into light,” Armstrong said.

The research appears in the March 15 edition of the journal Nature Physics.

During the last decade, pioneering experiments using sub-picosecond lasers have demonstrated the generation and detection of acoustic and shock waves in materials with terahertz (THz) frequencies. These very same experiments led to a new technique for probing the structure of semiconductor devices.

However, the recent research takes those initial experiments a step further by reversing the process, converting high-frequency sound waves into electricity. The researchers predicted that high frequency acoustic waves can be detected by seeing radiation emitted when the acoustic wave passes an interface between piezoelectric materials.

“This is a fundamentally new phenomenon and it can be used to probe structural properties of nanoscopic materials,” Armstrong said. “This method has the potential to characterize semiconductor devices more accurately than other nondestructive methods.”

Very high-frequency sound waves have wavelengths approaching the atomic-length scale. Detection of these waves is challenging, but they are useful for probing materials on very small length scales.

But that’s not the only application, according to Reed.

“This technique provides a new pathway to generation of THz radiation for security, medical and other purposes,” he said. “In this application, we would utilize acoustic-based technologies to generate THz.” Security applications include explosives detection and medical use may include detection of skin cancer.

And the Livermore method doesn’t require any external source to detect the acoustic waves.

“Usually scientists use an external laser beam that bounces off the acoustic wave – much like radar speed detectors – to observe high frequency sound. An advantage of our technique is that it doesn’t require an external laser beam – the acoustic wave itself emits light that we detect,” Armstrong said.

Source: DOE/Lawrence Livermore National Laboratory