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Sunday, August 7, 2011

Engineers Solve Longstanding Problem in Photonic Chip Technology: Findings Help Pave Way for Next Generation of Computer Chips

Stretching for thousands of miles beneath oceans, optical fibers now connect every continent except for Antarctica. With less data loss and higher bandwidth, optical-fiber technology allows information to zip around the world, bringing pictures, video, and other data from every corner of the globe to your computer in a split second. But although optical fibers are increasingly replacing copper wires, carrying information via photons instead of electrons, today's computer technology still relies on electronic chips.
Now, researchers led by engineers at the California Institute of Technology (Caltech) are paving the way for the next generation of computer-chip technology: photonic chips. With integrated circuits that use light instead of electricity, photonic chips will allow for faster computers and less data loss when connected to the global fiber-optic network.
 "We want to take everything on an electronic chip and reproduce it on a photonic chip," says Liang Feng, a postdoctoral scholar in electrical engineering and the lead author on a paper to be published in the August 5 issue of the journal Science. Feng is part of Caltech's nanofabrication group, led by Axel Scherer, Bernard A. Neches Professor of Electrical Engineering, Applied Physics, and Physics, and co-director of the Kavli Nanoscience Institute at Caltech.
In that paper, the researchers describe a new technique to isolate light signals on a silicon chip, solving a longstanding problem in engineering photonic chips.
An isolated light signal can only travel in one direction. If light weren't isolated, signals sent and received between different components on a photonic circuit could interfere with one another, causing the chip to become unstable. In an electrical circuit, a device called a diode isolates electrical signals by allowing current to travel in one direction but not the other. The goal, then, is to create the photonic analog of a diode, a device called an optical isolator. "This is something scientists have been pursuing for 20 years," Feng says.
Normally, a light beam has exactly the same properties when it moves forward as when it's reflected backward. "If you can see me, then I can see you," he says. In order to isolate light, its properties need to somehow change when going in the opposite direction. An optical isolator can then block light that has these changed properties, which allows light signals to travel only in one direction between devices on a chip.
"We want to build something where you can see me, but I can't see you," Feng explains. "That means there's no signal from your side to me. The device on my side is isolated; it won't be affected by my surroundings, so the functionality of my device will be stable."
To isolate light, Feng and his colleagues designed a new type of optical waveguide, a 0.8-micron-wide silicon device that channels light. The waveguide allows light to go in one direction but changes the mode of the light when it travels in the opposite direction.
A light wave's mode corresponds to the pattern of the electromagnetic field lines that make up the wave. In the researchers' new waveguide, the light travels in a symmetric mode in one direction, but changes to an asymmetric mode in the other. Because different light modes can't interact with one another, the two beams of light thus pass through each other.
Previously, there were two main ways to achieve this kind of optical isolation. The first way -- developed almost a century ago -- is to use a magnetic field. The magnetic field changes the polarization of light -- the orientation of the light's electric-field lines -- when it travels in the opposite direction, so that the light going one way can't interfere with the light going the other way. "The problem is, you can't put a large magnetic field next to a computer," Feng says. "It's not healthy."
The second conventional method requires so-called nonlinear optical materials, which change light's frequency rather than its polarization. This technique was developed about 50 years ago, but is problematic because silicon, the material that's the basis for the integrated circuit, is a linear material. If computers were to use optical isolators made out of nonlinear materials, silicon would have to be replaced, which would require revamping all of computer technology. But with their new silicon waveguides, the researchers have become the first to isolate light with a linear material.
Although this work is just a proof-of-principle experiment, the researchers are already building an optical isolator that can be integrated onto a silicon chip. An optical isolator is essential for building the integrated, nanoscale photonic devices and components that will enable future integrated information systems on a chip. Current, state-of-the-art photonic chips operate at 10 gigabits per second (Gbps) -- hundreds of times the data-transfer rates of today's personal computers -- with the next generation expected to soon hit 40 Gbps. But without built-in optical isolators, those chips are much simpler than their electronic counterparts and are not yet ready for the market. Optical isolators like those based on the researchers' designs will therefore be crucial for commercially viable photonic chips.
Source : Daily science web

Wednesday, May 25, 2011

Novel Artificial Material Could Facilitate Wireless Power

Electrical engineers at Duke University have determined that unique artificial materials should theoretically make it possible to improve the power transfer to small devices, such as laptops or cell phones, or ultimately to larger ones, such as cars or elevators, without wires.
This advance is made possible by the recent ability to fabricate exotic composite materials known as meta materials, which are not so much a single substance, but an entire human-made structure that can be engineered to exhibit properties not readily found in nature. In fact, the metamaterial used in earlier Duke studies, and which would likely be used in future wireless power transmission systems, resembles a miniature set of tan Venetian blinds.
Theoretically, this metamaterial can improve the efficiency of "recharging" devices without wires. As power passes from the transmitting device to the receiving device, most if not all of it scatters and dissipates unless the two devices are extremely close together. However, the metamaterial postulated by the Duke researchers, which would be situated between the energy source and the "recipient" device, greatly refocuses the energy transmitted and permits the energy to traverse the open space between with minimal loss of power.
"We currently have the ability to transmit small amounts of power over short distances, such as in radio frequency identification (RFID) devices," said Yaroslav Urzhumov, assistant research professor in electrical and computer engineering at Duke's Pratt School of Engineering. "However, larger amounts of energy, such as that seen in lasers or microwaves, would burn up anything in its path.
"Based on our calculations, it should be possible to use these novel metamaterials to increase the amount of power transmitted without the negative effects," Urzhumov said.
The results of the Duke research were published online in the journal Physical Review B. Urzhumov works in the laboratory of David R. Smith, William Bevan Professor of electrical and computer engineering at Pratt School of Engineering. Smith's team was the first demonstrate that similar metamaterials could act as a cloaking device in 2006.
Just as the metamaterial in the cloaking device appeared to make a volume of space "disappear," in the latest work, the metamaterial would make it seem as if there was no space between the transmitter and the recipient, Urzhumov said. Therefore, he said, the loss of power should be minimal.
Urzhumov's research is an offshoot of "superlens" research conducted in Smith's laboratory. Traditional lenses get their focusing power by controlling rays as they pass through the two outside surfaces of the lens. On the other hand, the superlens, which is in fact a metamaterial, directs waves within the bulk of the lens between the outside surfaces, giving researchers a much greater control over whatever passes through it.
The metamaterial used in wireless power transmission would likely be made of hundreds to thousands -- depending on the application -- of individual thin conducting loops arranged into an array. Each piece is made from the same copper-on-fiberglass substrate used in printed circuit boards, with excess copper etched away. These pieces can then be arranged in an almost infinite variety of configurations.
"The system would need to be tailored to the specific recipient device, in essence the source and target would need to be 'tuned' to each other," Urzhumov said. "This new understanding of how matematerials can be fabricated and arranged should help make the design of wireless power transmission systems more focused."
The analysis performed at Duke was inspired by recent studies at Mitsubishi Electric Research Labs (MERL), an industrial partner of the Duke Center for Metamaterials and Integrated Plasmonics. MERL is currently investigating metamaterials for wireless power transfer. The Duke researchers said that with these new insights into the effects of metamaterials, developing actual devices can be more targeted and efficient.
The Duke University research was supported by a Multidisciplinary University Research Initiative (MURI) grant through the Air Force Office of Scientific Research and the U.S. Army Research Office.
Source: Daily science website

Wednesday, May 11, 2011

Fundamental Question on How Life Started Solved: Supercomputer Calculates Carbon Nucleus

For carbon, the basis of life, to be able to form in the stars, a certain state of the carbon nucleus plays an essential role. In cooperation with US colleagues, physicists from the University of Bonn and Ruhr-Universität Bochum have been able to calculate this legendary carbon nucleus, solving a problem that has kept science guessing for more than 50 years.
 The researchers published their results in the coming issue of the scientific journal Physical Review Letters.
"Attempts to calculate the Hoyle state have been unsuccessful since 1954," said Professor Dr. Ulf-G. Meißner (Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn). "But now, we have done it!" The Hoyle state is an energy-rich form of the carbon nucleus. It is the mountain pass over which all roads from one valley to the next lead: From the three nuclei of helium gas to the much larger carbon nucleus. This fusion reaction takes place in the hot interior of heavy stars. If the Hoyle state did not exist, only very little carbon or other higher elements such as oxygen, nitrogen and iron could have formed. Without this type of carbon nucleus, life probably also would not have been possible.
The search for the "slave transmitter"
The Hoyle state had been verified by experiments as early as 1954, but calculating it always failed. For this form of carbon consists of only three, very loosely linked helium nuclei -- more of a cloudy diffuse carbon nucleus. And it does not occur individually, only together with other forms of carbon. "This is as if you wanted to analyze a radio signal whose main transmitter and several slave transmitters are interfering with each other," explained Prof. Dr. Evgeny Epelbaum (Institute of Theoretical Physics II at Ruhr-Universität Bochum). The main transmitter is the stable carbon nucleus from which humans -- among others -- are made. "But we are interested in one of the unstable, energy-rich carbon nuclei; so we have to separate the weaker radio transmitter somehow from the dominant signal by means of a noise filter."
What made this possible was a new, improved calculating approach the researchers used that allowed calculating the forces between several nuclear particles more precisely than ever. And in JUGENE, the supercomputer at Forschungszentrum Jülich, a suitable tool was found. It took JUGENE almost a week of calculating. The results matched the experimental data so well that the researchers can be certain that they have indeed calculated the Hoyle state.
More about how the Universe came into existence
"Now we can analyze this exciting and essential form of the carbon nucleus in every detail," explained Prof. Meißner. "We will determine how big it is, and what its structure is. And it also means that we can now take a very close look at the entire chain of how elements are formed."
In future, this may even allow answering philosophical questions using science. For decades, the Hoyle state was a prime example for the theory that natural constants must have precisely their experimentally determined values, and not any different ones, since otherwise we would not be here to observe the Universe (the anthropic principle). "For the Hoyle state this means that it must have exactly the amount of energy it has, or else, we would not exist," said Prof. Meißner. "Now we can calculate whether -- in a changed world with other parameters -- the Hoyle state would indeed have a different energy when comparing the mass of three helium nuclei." If this is so, this would confirm the anthropic principle.

Sunday, April 24, 2011

The iTracking "Scandal"

Wondering why your iPhone and 3G-enabled iPad are storing your general location in an easily accessible database on your PC? It's simple. Apple uses this information to build a cell tower and Wi-Fi access point location database, and the company admitted as much last year. At least that's my theory. Let's take a look.
The iTracking "Scandal"
On Wednesday, two researchers released an open source application called iPhone Tracker that pulls data from a hidden location history database contained in your iOS device's backup files saved on your PC. The app then plots this location information on a map allowing you to see your phone's travels over the past year. Your iOS devices have been building this location database since iOS 4 was released in June of last year, the researchers say.
The data appears to be based on cell tower triangulation and not GPS. This means the location information is not pinpoint accurate, but only shows your general location. The researchers also discovered in the database a list of Wi-Fi access points that your device has been in range of during the past year.
The researchers don't believe this data is leaving your custody, but I disagree. My best guess is that it is leaving your device as anonymized and encrypted information that Apple then uses to build its cell tower and Wi-Fi access point database.

New iPhone 5 Mockup Is Ultra Sexy

Stay calm, it's only a mockup. But Apple's iPhone 5 will be either a thing of beauty or the ugliest phone in existence -- depending on your tastes -- should any element of a new but credible Photoshopped suggestion make it into the end product.
The image was created by former Engadget chief Joshua Topolsky based on a sketched design from one of his sources as well as credible rumors he's heard. Topolsky admits the sketch might be little more than one of many prototype designs, but what the hey--it's fun to speculate!
Rumors have already suggested a virtually bezel-free screen, for example, courtesy of glass bonding breakthroughs at Apple HQ. Topolsky claims this allows for a slightly larger screen area of 3.7 inches -- 0.2 inches larger than the iPhone 4, but still retaining the ultra high-resolution Retina Display of over 300 pixels per inch.
It's even suggested that, somehow, the microphone and speaker might be behind the glass, although this isn't shown in the mockup. Apple has made much of how it carves MacBooks out of solid aluminum using lasers, including making microscopic holes for microphones and for power lights to shine through. It's possible the same techniques might have evolved so they can be used on glass, allowing sound to pass through.
In profile, Topolsky's iPhone 5 has a teardrop shape, rather like the MacBook Air, tapering towards the bottom, although Topolsky says this might not be as extreme as his mockup suggests, due to his lack of Photoshop skills.
One big change is the home button, which is expanded to become a "gesture area." How this works isn't clear, and in Topolsky's mockup the home button area is wide but not tall, indicating only side-to-side swipe gestures are possible. It's possible this is a labor-saving trick so users can simply swipe to activate the phone, rather than hit the home button first, and then swipe across the screen.
Although not featured in the mockup, the sketch Topolsky saw also showed induction-based power, which is to say, wire-free battery charging. This is already possible using third-party products so it isn't a leap of imagination, and there's been long-term rumors of Apple being interested in such technologies
The sketch also showed what Topolsky calls a "swipe area," which he suggests could be a near field communication (NFC) area. It's been rumored that NFC will be coming to the iPhone 5, although it would be strange of Apple to draw attention to a small area of the phone for NFC purposes. NFC payments are designed around the idea of simply tapping any part of a device against a receiver.
Creating rumors and even mockups is a crime with no consequences. Nobody's going to chide Topolsky when the iPhone 5 arrives and his mockups turn out to be bunkum. In fact, many Apple-watchers suggest that the iPhone 5 won't look much different from the iPhone 4. However, there's little doubt that Topolsky's sexy imagery pours petrol onto the flames of the iPhone 5 hype machine.

Thursday, March 17, 2011

Coca-Cola Camera

Coca-Cola Camera ($60) 

Although the Real Thing may rot your teeth and make you fat, this fructose-free fake can wreck your career. A video camera tucked inside a Coke can, it records your not-for-prime-time moments in 352-by-288-pixel resolution at 25 frames per second. And with 4GB of memory, a rechargeable battery, and up to 15 hours of continuous recording time, this aluminum-clad snoop is nothing to burp at.

Covert Cameras Designed to Spy on You

Sneaky Cams

What do calculators, cola cans, vacuum cleaners, houseplants, and neckties all have in common? Each might hide a miniature video camera that’s watching and recording your every move. These sneaky spy cameras are inexpensive and easy to buy online, too. We’ve compiled a gallery of covert cameras commercially available for spies, wannabe gumshoes, and (probably) creeps.

Covert Plant Camera 

Beware the potted fern--it may be a government plant. Nothing brightens up an office or a home more than a spot of greenery, but this undercover weed has darker intentions. Equipped with a wired or wireless, color or black-and-white spy cam, the Covert Plant Camera is well hidden and watches your every move. It doesn't capture audio, however, so feel free to speak openly in its presence.