UW-Madison engineers reveal record-setting flexible phototransistor

MADISON, Wis. -- Inspired by mammals' eyes, University of Wisconsin-Madison electrical engineers have created the fastest, most responsive flexible silicon phototransistor ever made.

The innovative phototransistor could improve the performance of myriad products -- ranging from digital cameras, night-vision goggles and smoke detectors to surveillance systems and satellites -- that rely on electronic light sensors. Integrated into a digital camera lens, for example, it could reduce bulkiness and boost both the acquisition speed and quality of video or still photos.

Developed by UW-Madison collaborators Zhenqiang "Jack" Ma, professor of electrical and computer engineering, and research scientist Jung-Hun Seo, the high-performance phototransistor far and away exceeds all previous flexible phototransistor parameters, including sensitivity and response time.

The researchers published details of their advance this week in the journal Advanced Optical Materials.

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Femtoseconds lasers help formation flying

The National Physical Laboratory (NPL) has helped to establish that femtosecond comb lasers can provide accurate measurement of absolute distance in formation flying space missions.

NPL, along with collaborators, produced technical reports for the European Space Agency (ESA). The conclusions demonstrated that the lasers were a suitable method for measurement in such missions.

Formation flying missions involve multiple spacecraft flying between tens and hundreds of metres apart, which autonomously control their position relative to each other. The benefit of such missions is they can gather data in a completely different way to a standard spacecraft – the formation can effectively act as one large sensor.

Measuring absolute distance between the formation spacecraft is critical to mission success. Femtosecond comb lasers are an accurate way of making such measurements. The lasers emit light with very short pulses – each lasting just a few femtoseconds (a femtosecond is one billionth of one millionth of a second). The short pulses allow time of flight measurements to be used to determine distance to a few microns.

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Engineers Ride ‘Rogue’ Laser Waves to Build Better Light Sources

New Technology Presented at World's Largest Optical Communication Conference Produces Better Sources of White Light

WASHINGTON, March 4—A freak wave at sea is a terrifying sight. Seven stories tall, wildly unpredictable, and incredibly destructive, such waves have been known to emerge from calm waters and swallow ships whole. But rogue waves of light -- rare and explosive flare-ups that are mathematically similar to their oceanic counterparts -- have recently been tamed by a group of researchers at the University of California, Los Angeles (UCLA).

UCLA's Daniel Solli, Claus Ropers, and Bahram Jalali are putting rogue light waves to work in order to produce brighter, more stable white light sources, a breakthrough in optics that may pave the way for better clocks, faster cameras, and more powerful radar and communications technologies. Their findings will be presented during the Optical Fiber Communication Conference and Exposition/National Fiber Optic Engineers Conference (OFC/NFOEC), taking place March 22-26 in San Diego.

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Tiny lasers get a notch up

<p>Tiny lasers get a notch up</p>

A new theoretical analysis could help design better microlasers

WASHINGTON, Jan. 22—Tiny disk-shaped lasers as small as a speck of dust could one day beam information through optical computers. Unfortunately, a perfect disk will spray light out, not as a beam, but in all directions. New theoretical results, reported in the Optical Society (OSA) journal Optics Letters, explain how adding a small notch to the disk edge provides a single outlet for laser light to stream out.

To increase the speed of computers and telecommunication networks, researchers are looking to replace electrical currents with beams of light that would originate from small semiconductor lasers. However, shrinking lasers down to a few micrometers in size is not easy. The typical laser builds up its concentrated light beam by bouncing light rays, or modes, back and forth inside a reflective cavity. This linear design is not practical for microlasers. Instead, scientists discovered in 1992 that they could get light amplification by having rays bounce around in a circle inside a small flat disk. These light rays are called "whispering gallery modes" because they are similar to sound waves that travel across a room by skimming along a curved wall or ceiling.

The problem is that a disk is rotationally invariant, so there is no preferred direction for the amplified light to escape. Many microlaser designs end up shooting light out in multiple directions within the plane of the disk. "The experimentalists have a holy grail of unidirectional emission in microlasers," says Martina Hentschel of the Max Planck Institute for the Physics of Complex Systems. In the past few years, some progress has been made with so-called spiral microlasers, which have a tiny notch that resembles the outer opening of a snail shell. Certain experiments have shown that light tends to propagate in a single direction from the notch. But other experiments have not been so lucky. In order to understand these contrasting results, Hentschel and her colleague Tae-Yoon Kwon have performed a systematic study of spiral microlasers using a state-of-the-art theoretical description.

Physicists typically treat the light rays trapped inside a cavity as if they were billiard balls bouncing off walls, Hentschel explains. Some light rays escape, but those rays that just barely graze the inside surface are fully reflected back into the cavity (this being the same effect that channels light beams along optical fibers). Unfortunately, this simple "billiard" model is not sufficient for explaining spiral microlasers, Hentschel says.

Hentschel and Kwon therefore chose a more sophisticated model based on the electromagnetic wave and laser equations. This framework allowed the researchers to control what part of the semiconductor material would be excited, or "pumped," to a light-emitting state. Numerical calculations showed that the two whispering gallery modes inside a spiral cavity—one traveling clockwise, the other counterclockwise—are coupled together, but only one of these modes is able to escape out through the spiral's notch. To maximize this unidirectional emission, the researchers found that the notch size should be roughly twice the wavelength of the light. Moreover, the pumping needs to be confined to the rim of the spiral, specifically the outer 10 percent. These parameters could aid in the design of better-collimated microlasers. "The optimal geometry and boundary pumping is very useful to know for an experimentalist," Hentschel says.

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Scientists demonstrate highly directional semiconductor lasers

CAMBRIDGE, Mass. – July 28, 2008 – Applied scientists at Harvard University in collaboration with researchers from Hamamatsu Photonics in Hamamatsu City, Japan, have demonstrated, for the first time, highly directional semiconductor lasers with a much smaller beam divergence than conventional ones. The innovation opens the door to a wide range of applications in photonics and communications. Harvard University has also filed a broad patent on the invention.

Spearheaded by graduate student Nanfang Yu and Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, all of Harvard's School of Engineering and Applied Sciences (SEAS), and by a team at Hamamatsu Photonics headed by Dr. Hirofumi Kan, General Manager of the Laser Group, the findings were published online in the July 28th issue of Nature Photonics and will appear in the September print issue.

"Our innovation is applicable to edge-emitting as well as surface-emitting semiconductor lasers operating at any wavelength—all the way from visible to telecom ones and beyond," said Capasso. "It is an important first step towards beam engineering of lasers with unprecedented flexibility, tailored for specific applications. In the future, we envision being able to achieve total control of the spatial emission pattern of semiconductor lasers such as a fully collimated beam, small divergence beams in multiple directions, and beams that can be steered over a wide angle."

While semiconductor lasers are widely used in everyday products such as communication devices, optical recording technologies, and laser printers, they suffer from poor directionality. Divergent beams from semiconductor lasers are focused or collimated with lenses that typically require meticulous optical alignment—and in some cases bulky optics.

To get around such conventional limitations, the researchers sculpted a metallic structure, dubbed a plasmonic collimator, consisting of an aperture and a periodic pattern of sub-wavelength grooves, directly on the facet of a quantum cascade laser emitting at a wavelength of ten microns, in the invisible part of the spectrum known as the mid-infrared where the atmosphere is transparent. In so doing, the team was able to dramatically reduce the divergence angle of the beam emerging from the laser from a factor of twenty-five down to just a few degrees in the vertical direction. The laser maintained a high output optical power and could be used for long range chemical sensing in the atmosphere, including homeland security and environmental monitoring, without requiring bulky collimating optics.

"Such an advance could also lead to a wide range of applications at the shorter wavelengths used for optical communications. A very narrow angular spread of the laser beam can greatly reduce the complexity and cost of optical systems by eliminating the need for the lenses to couple light into optical fibers and waveguides," said Dr. Kan.

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Advance brings low-cost, bright LED lighting closer to reality

Researchers at Purdue University have overcome a major obstacle in reducing the cost of "solid state lighting," a technology that could cut electricity consumption by 10 percent if widely adopted.

The technology, called light-emitting diodes, or LEDs, is about four times more efficient than conventional incandescent lights and more environmentally friendly than compact fluorescent bulbs. The LEDs also are expected to be far longer lasting than conventional lighting, lasting perhaps as long as 15 years before burning out.

 

"The LED technology has the potential of replacing all incandescent and compact fluorescent bulbs, which would have dramatic energy and environmental ramifications," said Timothy D. Sands, the Basil S. Turner Professor of Materials Engineering and Electrical and Computer Engineering.

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Light seems to defy its own speed limit

It's a speed record that is supposed to be impossible to break. Yet two physicists are now claiming they have propelled photons faster than the speed of light. This would be in direct violation of a key tenet of Einstein's special theory of relativity that states that nothing, under any circumstance, can exceed the speed of light.

Günter Nimtz and Alfons Stahlhofen of the University of Koblenz, Germany, have been exploring a phenomenon in quantum optics called photon tunnelling, which occurs when a particle slips across an apparently uncrossable barrier. The pair say they have now tunnelled photons "instantaneously" across a barrier of various sizes, from a few millimetres up to a metre. Their conclusion is that the photons traverse the barrier much faster than the speed of light.

Full story (available after August 18, 2007 from New Scientist)

Abstract

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Aluminum foil lamps outshine incandescent lights

CHAMPAIGN, Ill. -- Researchers at the University of Illinois are developing panels of microcavity plasma lamps that may soon brighten people’s lives. The thin, lightweight panels could be used for residential and commercial lighting, and for certain types of biomedical applications.

“Built of aluminum foil, sapphire and small amounts of gas, the panels are less than 1 millimeter thick, and can hang on a wall like picture frames,” said Gary Eden, a professor of electrical and computer engineering at the U. of I., and corresponding author of a paper describing the microcavity plasma lamps in the June issue of the Journal of Physics D: Applied Physics.

Like conventional fluorescent lights, microcavity plasma lamps are glow-discharges in which atoms of a gas are excited by electrons and radiate light. Unlike fluorescent lights, however, microcavity plasma lamps produce the plasma in microscopic pockets and require no ballast, reflector or heavy metal housing. The panels are lighter, brighter and more efficient than incandescent lights and are expected, with further engineering, to approach or surpass the efficiency of fluorescent lighting.

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Physicists control light at the nanoscale

Physicists in Europe have unveiled a new technique that can control the intensity distribution of laser pulses at dimensions that are much smaller than the wavelength of the laser light. The method combines pulse-shaping techniques with near-field optics and the researchers claim that it is a major step forward in the development of laser-based tools for the manipulation of matter on a very small length scales (Nature 446 301).

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Madison-based Alfalight receives $1.7 million contract

By AVRUM D. LANK

alank@journalsentinel.com
Posted: March 20, 2007

A small, fast-growing Madison company said Tuesday that it won a $1.7 million contract from the Army to help build high-power lasers.

Alfalight Inc. is to use the money to develop very high-power pump blocks, which are power sources for lasers.

The one-year contract is from the Army Research Laboratory in Adelphi, Md., for its scalable, high-efficiency solid-state laser program.

"We expect to develop both usable pump prototypes and provide valuable research results to the Army Research Laboratory upon completion," said Manoj Kanskar, vice president of research and development for Alfalight.

In addition to helping the Army develop lasers, the pump blocks could have uses in commercial material-handling equipment, Alfalight said.

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Rensselaer Researchers Create World’s First Ideal Anti-Reflection Coating

New class of nanomaterials could lead to more efficient solar cells, brighter LEDs

Troy, N.Y. — A team of researchers from Rensselaer Polytechnic Institute has created the world’s first material that reflects virtually no light. Reporting in the March issue of Nature Photonics, they describe an optical coating made from the material that enables vastly improved control over the basic properties of light. The research could open the door to much brighter LEDs, more efficient solar cells, and a new class of “smart” light sources that adjust to specific environments, among many other potential applications.

Most surfaces reflect some light — from a puddle of water all the way to a mirror. The new material has almost the same refractive index as air, making it an ideal building block for anti-reflection coatings. It sets a world record by decreasing the reflectivity compared to conventional anti-reflection coatings by an order of magnitude.

A fundamental property called the refractive index governs the amount of light a material reflects, as well as other optical properties such as diffraction, refraction, and the speed of light inside the material. “The refractive index is the most fundamental quantity in optics and photonics. It goes all the way back to Isaac Newton, who called it the ‘optical density,’” said E. Fred Schubert, the Wellfleet Senior Constellation Professor of the Future Chips Constellation at Rensselaer and senior author of the paper.

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New Technique Stores and Retrieves Entire Image from a Single Photon

Ultra-Dense Optical Storage — on One Photon

Researchers at the University of Rochester have made an optics breakthrough that allows them to encode an entire image's worth of data into a photon, slow the image down for storage, and then retrieve the image intact.

While the initial test image consists of only a few hundred pixels, a tremendous amount of information can be stored with the new technique.

The image, a "UR" for the University of Rochester, was made using a single pulse of light and the team can fit as many as a hundred of these pulses at once into a tiny, four-inch cell. Squeezing that much information into so small a space and retrieving it intact opens the door to optical buffering—storing information as light.

"It sort of sounds impossible, but instead of storing just ones and zeros, we're storing an entire image," says John Howell, assistant professor of physics and leader of the team that created the device, which is revealed in today's online issue of the journal Physical Review Letters. "It's analogous to the difference between snapping a picture with a single pixel and doing it with a camera—this is like a 6-megapixel camera."

"You can have a tremendous amount of information in a pulse of light, but normally if you try to buffer it, you can lose much of that information," says Ryan Camacho, Howell's graduate student and lead author on the article. "We're showing it's possible to pull out an enormous amount of information with an extremely high signal-to-noise ratio even with very low light levels."

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Light squeezes through nano coax

Physicists in the US have created the first nanoscale coaxial cables for the transmission of light. Operating much like the coaxial cables used to distribute television and radio signals, the cables can transmit light with wavelengths nearly four times their 200 nm diameter. The researchers claim that the ability to control light over sub-wavelength distances could lead to better optical microscopes, smaller computer chips and more efficient solar panels (Appl Phys Lett 90 021104)

Building a nano coax
Coaxial cables comprise an inner and outer conductor separated by an insulating dielectric layer and are used to transmit all manner of electromagnetic waves from radio to microwave. They are extremely useful because they can transmit waves with wavelengths much greater than their diameter, making cable television and other technologies possible.

Light is an electromagnetic wave so there is no reason why it cannot be transmitted in a similar manner via a coaxial cable -- but conventional wisdom had held that light could not travel through a cable of diameter less than its wavelength. Now, Boston College’s Jakub Rybczynski, Mike Naughton and colleagues realized that a coaxial could carry sub-wavelength light waves if it were miniaturized.

Their coaxial cable is based around a carbon nanotube, which forms the central conductor (see "Building a nano coax"). The nanotube is surrounded by a concentric ring of transparent aluminium oxide -- which acts as the dielectric layer -- and finally a concentric metal ring that acts as the outer conductor. The separation between the inner and outer conductors is about 100 nm.

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METAMATERIALS FOUND TO WORK FOR VISIBLE LIGHT

Ames Laboratory researchers announce findings in Science

AMES, Iowa – For the first time ever, researchers at the U.S. Department of Energy’s Ames Laboratory have developed a material with a negative refractive index for visible light. Ames Laboratory senior physicist Costas Soukoulis, working with colleagues in Karlsruhe, Germany, designed a silver-based, mesh-like material that marks the latest advance in the rapidly evolving field of metamaterials, materials that could lead to a wide range of new applications as varied as ultrahigh-resolution imaging systems and cloaking devices.

The discovery, detailed in the Jan. 5 issue of Science and the Jan. 1 issue of Optic Letters, and noted in the journal Nature, marks a significant step forward from existing metamaterials that operate in the microwave or far infrared – but still invisible –regions of the spectrum. Those materials, announced this past summer, were heralded as the first step in creating an invisibility cloak.

Metamaterials, also known as left-handed materials, are exotic, artificially created materials that provide optical properties not found in natural materials. Natural materials refract light, or electromagnetic radiation, to the right of the incident beam at different angles and speeds. However, metamaterials make it possible to refract light to the left, or at a negative angle. This backward-bending characteristic provides scientists the ability to control light similar to the way they use semiconductors to control electricity, which opens a wide range of potential applications.

“Left-handed materials may one day lead to the development of a type of flat superlens that operates in the visible spectrum,” said Soukoulis, who is also an Iowa State University Distinguished Professor of Liberal Arts and Sciences. “Such a lens would offer superior resolution over conventional technology, capturing details much smaller than one wavelength of light to vastly improve imaging for materials or biomedical applications,” such as giving researchers the power to see inside a human cell or diagnose disease in a baby still in the womb.

The challenge that Soukoulis and other scientists who work with metamaterials face is to fabricate them so that they refract light at ever smaller wavelengths. The “fishnet” design developed by Soukoulis’ group and produced by researchers Stefan Linden and Martin Wegener at the University of Karlsruhe was made by etching an array of holes into layers of silver and magnesium fluoride on a glass substrate. The holes are roughly 100 nanometers wide. For some perspective, a human hair is about 100,000 nanometers in diameter.

“We have fabricated for the first time a negative-index metamaterial with a refractive index of -0.6 at the red end of the visible spectrum (wavelength 780 nm),” said Soukoulis. “This is the smallest wavelength obtained so far.”

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Cheaper LEDs from breakthrough in zinc oxide (ZnO) nanowire research, Nano Letters study says

Engineers at UC San Diego have synthesized a long-sought semiconducting material that may pave the way for an inexpensive new kind of light emitting diode (LED) that could compete with today's widely used gallium nitride LEDs, according to a new paper in the journal Nano Letters.

To build an LED, you need both positively and negatively charged semiconducting materials; and the engineers synthesized zinc oxide (ZnO) nanoscale cylinders that transport positive charges or "holes" – so-called "p-type ZnO nanowires." They are endowed with a supply of positive charge carrying holes that, for years, have been the missing ingredients that prevented engineers from building LEDs from ZnO nanowires. In contrast, making "n-type" ZnO nanowires that carrier negative charges (electrons) has not been a problem. In an LED, when an electron meets a hole, it falls into a lower energy level and releases energy in the form of a photon of light.

Deli Wang, an electrical and computer engineering professor from UCSD's Jacobs School of Engineering, and colleagues at UCSD and Peking University, report synthesis of high quality p-type zinc oxide nanowires in a paper published online by the journal Nano Letters.

"Zinc oxide nanostructures are incredibly well studied because they are so easy to make. Now that we have p-type zinc oxide nanowires, the opportunities for LEDs and beyond are endless," said Wang.

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Growing Glowing Nanowires to Light Up the Nanoworld

Growing Glowing Nanowires to Light Up the Nanoworld

NIST "grows" semiconductor nanowires that emit ultraviolet light as part of a project to make prototype nano-lasers and other devices and the measurement tools needed to characterize them. Electron micrograph shows the gallium nitride wires growing on a silicon substrate (color added for contrast.)

The nano world is getting brighter. Nanowires made of semiconductor materials are being used to make prototype lasers and light-emitting diodes with emission apertures roughly 100 nm in diameter—about 50 times narrower than conventional counterparts. Nanolight sources may have many applications, including “lab on a chip” devices for identifying chemicals and biological agents, scanning-probe microscope tips for imaging objects smaller than is currently possible, or ultra-precise tools for laser surgery and electronics manufacturing.

Researchers at the National Institute of Standards and Technology (NIST) are growing nanowires made of gallium nitride alloys and making prototype devices and nanometrology tools. The wires are grown under high vacuum by depositing atoms layer by layer on a silicon crystal. NIST is one of few laboratories capable of growing such semiconductor nanowires without using metal catalysts, an approach believed to enhance luminescence and flexibility in crystal design. The wires are generally between 30 and 500 nanometers (nm) in diameter and up to 12 micrometers long. When excited with a laser or electric current, the wires emit an intense glow in the ultraviolet or visible parts of the spectrum, depending on the alloy composition.

A paper in the May 22 issue of Applied Physics Letters* reports that individual nanowires grown at NIST produce sufficiently intense light to enable reliable room-temperature measurements of their important characteristics. For example, the peak wavelength of light emitted with electric field parallel to the long axis of a nanowire is shifted with respect to the peak wavelength emitted with electric field perpendicular to the wire. Such differences in emission are used to characterize the nanowire materials and also may be exploited to make sensors and other devices.

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Light's Most Exotic Trick Yet: So Fast it Goes ... Backwards?

Light's Most Exotic Trick Yet: So Fast it Goes ... Backwards?

In the past few years, scientists have found ways to make light go both faster and slower than its usual speed limit, but now researchers at the University of Rochester have published a paper today in Science on how they've gone one step further: pushing light into reverse. As if to defy common sense, the backward-moving pulse of light travels faster than light.

Confused? You're not alone.

"I've had some of the world's experts scratching their heads over this one," says Robert Boyd, the M. Parker Givens Professor of Optics at the University of Rochester. "Theory predicted that we could send light backwards, but nobody knew if the theory would hold up or even if it could be observed in laboratory conditions."

Boyd recently showed how he can slow down a pulse of light to slower than an airplane, or speed it up faster than its breakneck pace, using exotic techniques and materials. But he's now taken what was once just a mathematical oddity—negative speed—and shown it working in the real world.

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NIST Photon Detectors Have Record Efficiency

NIST Photon Detectors Have Record Efficiency

The four yellow squares in the center of this micrograph are NIST single photon detectors. The top two detectors are 25 by 25 micrometers. The bottom two detectors are 50 by 50 micrometers. The detectors operate with a record 88 percent efficiency.

Sensors that detect and count single photons, the smallest quantities of light, with 88 percent efficiency have been demonstrated by physicists at the National Institute of Standard and Technology (NIST). This record efficiency is an important step toward making reliable single photon detectors for use in practical quantum cryptography systems, the most secure method known for ensuring the privacy of a communications channel.


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Scientists develop novel multi-color light-emitting diodes

Scientists develop novel multi-color light-emitting diodes
Contact: Todd Hanson, tahanson@lanl.gov, (505) 665-2085 (04-141)

LOS ALAMOS, N.M., May 17, 2005 -- A team of University of California scientists at Los Alamos National Laboratory have developed the first completely inorganic, multi-color light-emitting diodes (LEDs) based on colloidal quantum dots encapsulated in a gallium nitride (GaN) semiconductor. The work represents a new "hybrid" approach to the development of solid-state lighting. Solid-state lighting offers the advantages of reduced operating expenses, lower energy consumption and more reliable performance.

. . .

The secret to making the electrical connection to the quantum dots is the use of a technique developed at Los Alamos by Mark Hoffbauer and his team that utilizes a beam of energetic, neutral nitrogen atoms for growing GaN films. The technique, called ENABLE (for Energetic Neutral Atom Beam Lithography/Epitaxy), allows for the low-temperature encapsulation of nanocrystals in semiconducting GaN without adversely affecting their luminescence properties. By encapsulating one nanocrystal layer or two layers of nanocrystals of different sizes, the researchers have demonstrated that their LEDs can emit light of either a single color or two different colors. The two color-operation regime is an important step toward creating devices that produce white light.

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LASER SCIENTIST ILLUMINATES RESEARCH IN LIVING COLOR

LASER SCIENTIST ILLUMINATES RESEARCH IN LIVING COLOR

In art, color is information. Just look at a painting by an artist such as Monet: Each uniquely hued brushstroke brings to life a new blade of grass, a leaf, a flower petal, a slice of sky-each a component of the complete picture.

Scientists, too, use color to paint clearer pictures of the things-everything from combustion gases to cancer cells-they study. And as a result of a new laser system that rapidly delivers a pulsed rainbow of colors, those pictures will contain more information than ever before. Mechanical Engineering Assistant Professor Scott Sanders developed the system, which is highlighted in the cover story of the May issue of Optics and Photonics News.

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Optical computer made from frozen light

Optical computer made from frozen light
Tuesday 12 April 2005

Scientists at Harvard University have shown how ultra-cold atoms can be used to freeze and control light to form the “core” – or central processing unit – of an optical computer. Optical computers would transport information ten times faster than traditional electronic devices, smashing the intrinsic speed limit of silicon technology.

This new research could be a major breakthrough in the quest to create super-fast computers that use light instead of electrons to process information. Professor Lene Hau is one of the world’s foremost authorities on “slow light”. Her research group became famous for slowing down light, which normally travels at 186,000 miles per second, to less than the speed of a bicycle. Using the same apparatus, which contains a cloud of ultra-cold sodium atoms, they have even managed to freeze light altogether. Professor Hau says this could have applications in memory storage for a future generation of optical computers.

But Professor Hau’s most recent research addresses the issue of optical computers head-on. She has calculated that ultra-cold atoms known as Bose-Einstein condensates (BECs) can be used to perform “controlled coherent processing” with light. In ordinary matter, the amplitude and phase of a light pulse would be smeared out, and any information content would be destroyed. Hau’s work on slow light, however, has proved experimentally that these attributes can be preserved in a BEC. Such a device might one day become the CPU of an optical computer.

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Photonics Startup Pegs Q2'06 Production Date

Photonics Startup Pegs Q2'06 Production Date
By Mark Hachman

Startup Luxtera has announced its plans to enter the CMOS photonics market, anticipating the day when microprocessors will transmit information via light, not electrons.

The company claims that its optical modulator for transforming electrons into photons runs at 10-GHz, ten times the speed of an optical modulator Intel Corp. researchers began talking about last year. Beginning in mid-2006, Luxtera hopes to enter production of photonic devices using standard CMOS manufacturing processes.

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Unltrafast Biocavity Laser

Novel ultrafast laser detection of cancer cells also may improve understanding of stem cells
LOS ANGELES, Calif. — To investigate tumors, pathologists currently rely on labor-intensive microscopic examination, using century-old cell-staining methods that can take days to complete and may give false readings.

A lightning-fast laser technique, led by Sandia National Laboratories researcher Paul Gourley, has provided laboratory demonstrations of accurate, real-time, high-throughput identification of liver tumor cells at their earliest stages, and without invasive chemical reagents.

The technique generates a laser beam in single human cells pumped from a flask through tiny microchannels. The beam is altered by what it encounters. These changes, registered by an imaging spectrometer, instantly identify cancer-modified mitochondria in cells gone wrong. Mitochondria are known as the power pack of cells, energizing them like batteries do flashlight bulbs.

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Light may arise from relativity violations

Light may arise from relativity violations
FOR IMMEDIATE RELEASE

BLOOMINGTON, Ind. -- Light as we know it may be a direct result of small violations of relativity, according to new research scheduled for publication online Tuesday (March 22) in the journal Physical Review D.

In discussing the work, physics professor Alan Kostelecky of Indiana University described light as "a shimmering of ever-present vectors in empty space" and compared it to waves propagating across a field of grain. This description is markedly different from existing theories of light, in which scientists believe space is without direction and the properties of light are a result of an underlying symmetry of nature.

Instead the report, co-authored by Kostelecky with physics professor Robert Bluhm of Colby College, discusses the possibility that light arises from the breaking of a symmetry of relativity. "Nature's beauty is more subtle than perfect symmetry," Kostelecky said. "The underlying origin of light may be another example of this subtlety."

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In solution, tiny magnetic wires scatter light

In solution, tiny magnetic wires scatter light

SAN DIEGO - Maneuvering external magnets, scientists can command the direction in which light bounces off tiny, magnetic wires that sway like matchsticks in thick, slow-moving solutions.

Announcing her finding here today (March 13) at the 229th meeting of the American Chemical Society, University of Wisconsin-Madison materials chemist Anne Bentley described how suspended nickel wires - each 200 times thinner than a human hair - could one day serve as magneto-optical switches. The switches could aid in fields such as photonics, where light, rather than electricity, relays information.

"In a broader sense, it is also helpful to study how these wires behave in wet situations because if they are ever medically used, there is little inside our bodies that's dry," says Bentley, who suspended her wires in several types of fluids and found that the light-directing phenomenon was most consistent when she used "molasses-like" liquids such as glycerol.

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Laser pioneer scoops religion prize

Laser pioneer scoops religion prize
9 March 2005

Charles Townes, who co-invented the laser, has become the fourth physicist in six years to win the £795,000 Templeton prize for science and religion. The prize is given by the Wall Street financier Sir John Templeton for "progress toward research or discoveries about spiritual realities". Townes -- a practising Christian -- has written numerous articles and papers about science and religion over the past 40 years. Previous winners of the prize include Freeman Dyson, Paul Davies, John Polkinghorne and George Ellis,

Born in 1915 in South Carolina, Townes grew up in a Baptist household that prized intellectual pursuits and vigorous debate about the Bible. He raced through the education system and graduated with degrees in physics and modern languages at the age of 19, before receiving a PhD from Caltech in 1939. After a war-time stint at Bell Telephone Laboratories in New York, Townes joined Columbia University in 1948. It was here in 1951 -- while sitting on a park bench -- that he had a moment of revelation.

Townes, who was using microwaves to study the structure of molecules, conceived a way of amplifying electromagnetic waves by the stimulated radiation emission. Coming like a bolt from the blue, Townes has repeatedly cited the event as a crystallization of how topics that are normally associated with religion or science -- revelation, intuition, observation, faith and aesthetics -- can easily apply to both disciplines. Townes helped to build the first working "maser" in 1954 and in 1957 he and his brother-in-law Arthur Schawlow at Bell Labs built the first "laser", which operated at visible wavelengths.

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Life of Organic LED Extended Using Carbon-60

Organic light-emitting diodes (LEDs) are potentially attractive for applications because they are easy to process and can emit over the full visible spectrum. Light emission from organic materials relies on electrons and "holes" combining to form excited states called "excitons" that subsequently emit photons when they decay.

A typical LED contains a thin light-emitting layer sandwiched between layers that transport the holes and the electrons. One way of improving the performance of organic LEDs is to increase the mobility of the holes in the hole-transport layer by adding a dopant. This should lead to more holes combining with electrons in the device.

Jun Yeob Lee and Jang Hyuk Kwon at Samsung’s Corporate R&D Center in Yong-In City studied the effect of carbon-60 doping in phosphorescent devices that rely on an organic material called "TDAPB" as the hole-transport layer. Lee and Kwon varied the concentration of carbon-60 in the TDAPB from 0 to 3% while measuring the properties of the device with a spectrophotometer.

They found that the mobility of holes in devices doped with 3% carbon-60 was five times higher than that of pure TDAPB. The current density also increased by a factor of three, and there was a 30% increase in the luminance of the LED.

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China seeks LED solution to an energy-resource problem

China seeks LED solution to an energy-resource problem

Despite being a vast country, China's energy resources are relatively scarce. As a result, the government sees LED manufacturing as a key part of the country's future as its rapid economic expansion puts an increasing strain on power. Michael Hatcher reports.

With its fast-growing economy, China is using energy at an ever-increasing rate. The total electricity consumption in the world's most populous country is estimated at 2000 billion kWh this year, with 10-12% of that figure devoured by lighting applications.

With electricity use growing at 10% per year on average, it's not surprising that the Chinese government sees efficient semiconductor-based lighting as a key part of its - and, for that matter, the wider world's - economic future. In 5-10 years, China's lighting energy demand is expected to double.

Energy savings

Until about a month ago, Gordon Liu was the president of China-based Lumei Optoelectronics, the company that acquired the LED manufacturing technology previously owned by US-based substrate supplier AXT last year. Speaking at the recent CS-MAX conference in Monterey, CA, Liu estimated that, if widely implemented, LEDs could save China 400 billion kWh of energy over the next decade.

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New Journal of Physics has just published a focus issue on Ultrafast Optics

Friday 26 November 2004

New Journal of Physics has just published a focus issue on Ultrafast Optics, edited by Markus Pessa and Ian White. All contributions are listed below and are freely accessible via the links provided.

The establishment of ultrafast optics as an important research field followed the invention of the laser in the late 1950s. However although the generation of ultrashort optical pulses was observed not long after the laser was first invented, it is only in the last few years that ultracompact lasers have been devised which generate picosecond or sub-picosecond sources.

This focus issue reflects the rapid changes that have occurred within the field, incorporating a range of papers. These include reviews of the new generation of compact optical sources now able to generate short optical pulses, switching techniques and applications. Three main classes of mode-locked laser are studied - two particular papers concern solid state lasers (Brown et al) and fibre lasers equipped with efficient nonlinear SESAM reflectors for passive mode-locking of pulses (Okhotnikov et al). Semiconductor diode lasers are also reviewed.

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Ultrafast Laser Speeds Up Quest for Atomic Control

It's the scientific equivalent of having your cake and eating it too. A team of researchers from JILA, a joint institute of the Commerce Department's National Institute of Standards and Technology and the University of Colorado at Boulder, has developed an efficient, low-cost way to measure the energy levels of atoms in a gas with extremely high accuracy, and simultaneously detect and control transitions between the levels as fast as they occur. The technique is expected to have practical applications in many fields including astrophysics, quantum computing, chemical analysis, and chemical synthesis.

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New transistor laser could lead to faster signal processing

New transistor laser could lead to faster signal processing

James E. Kloeppel, Physical Sciences Editor
217-244-1073; kloeppel@uiuc.edu

11/15/04

CHAMPAIGN, Ill. — Researchers at the University of Illinois at Urbana-Champaign have demonstrated the laser operation of a heterojunction bipolar light-emitting transistor. The scientists describe the fabrication and operation of their transistor laser in the Nov. 15 issue of the journal Applied Physics Letters.

“By incorporating quantum wells into the active region of a light-emitting transistor, we have enhanced the electrical and optical properties, making possible stimulated emission and transistor laser operation,” said Nick Holonyak Jr., a John Bardeen Professor of Electrical and Computer Engineering and Physics at Illinois.

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Pattern matching finds CD forgers

11 November 2004

An Irish start-up unveils a machine vision system that traces optical discs back to the machine where they were pressed.

DiscMatch, a machine vision system that traces an optical disc back to the pressing machine in which it was created, could soon be causing counterfeiters some headaches. The system searches for marks inadvertently left on the disc from its manufacturing process and gives authorities vital evidence in their search for fraudulent activity.

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Optics Patent Highlights

Patent highlights
12 November 2004

The pick of this week's patent applications including a fiber-laser based EUV lithography source.

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Optical Nose

Designing an Ultrasensitive 'Optical Nose' for Chemicals

A laser-based method for identifying a single atom or molecule hidden among 10 trillion others soon may find its way from the laboratory to the real world.

Developed by physicists at the National Institute of Standards and Technology (NIST), the technique is believed to be more than 1,000 times more sensitive than conventional methods. Vescent Photonics of Denver, Colo., hopes to commercialize the method as an "optical nose" for atmospheric monitoring. The portable sensors would rapidly identify chemicals in a gas sample based on the frequencies of light they absorb. Other applications eventually may include detection of chemical weapons and land mines, patient breath analysis for medical diagnosis or monitoring, and industrial detection of leaks in subterranean pipes or storage tanks, the company says.

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Advanced Lighting Signs License with Super Vision

November 08, 2004 10:15 AM US Eastern Timezone

Advanced Lighting Signs License with Super Vision

ORLANDO, Fla.--(BUSINESS WIRE)--Nov. 8, 2004--Super Vision International, Inc. (NASDAQ:SUPVA) a world leading manufacturer of fiber optic and LED lighting announced today that Advanced Lighting Systems, Inc. (ASLI) of Sauk Centre, Minnesota has signed a license to Super Vision's "Variable Color Lighting System" 1990 patent developed in 1988 by Richard Belliveau of High End Systems. Super Vision purchased this patent from High End Systems to provide open access to the industry for intellectual property rights in the production and sale of color changing LED systems. Advanced Lighting specializes in the manufacture of fiber optic and LED lighting products for the architectural and entertainment industry.


Paul Streitz, President of ASLI: "Super Vision's making available the `687' patent to leading lighting manufacturers will help the LED industry move forward more freely with newer technology that will ultimately provide better products and services for our valuable end users. I am very enthused about ALSI's future in LED technology and appreciate the fair licensing agreement that Supervision has provided ALSI and our industry."

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Optics Patents

Patent highlights
5 November 2004

The pick of this week's applications including a tunable VCSEL and a way to measure the thickness of thin films.

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Ion-Beam Technology

Carving New Frontiers for Ion-Beam Technology
An Imprinter that Combines Electron and Ion Beams Opens the Way for Wider Applications
Contact: Paul Preuss, (510) 486-6249, paul_preuss@lbl.gov

BERKELEY, CA — An ion-beam system that simultaneously combines focused beams of electrons and positive ions promises to improve the versatility, efficiency, and economy of this important technology. The new system was developed by researchers at the Department of Energy's Lawrence Berkeley National Laboratory, who report its principles and applications in the November 8, 2004 issue of Applied Physics Letters.

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Optical Computing Steps Forward

All-optical switch demonstrated by Cornell researchers


ITHACA, NY | 29 October 2004 -- Cornell University researchers have demonstrated for the first time a device that allows one low-powered beam of light to switch another on and off on silicon, a key component for future "photonic" microchips in which light replaces electrons.

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Optical Stimulation of Neurons

Researchers Devise Optical Method To Safely, Effectively Stimulate Neurons
Nashville, Tenn. – Biomedical engineers and physicians at Vanderbilt University have brought the day when artificial limbs will be controlled directly by the brain considerably closer by discovering a method that uses laser light, rather than electricity, to stimulate and control nerve cells.

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Advances in Optics

Research round-up
28 October 2004

A look at some of the innovations in optics that have been reported in journals this month.

. . .

INTEGRATED OPTICS
In a move that could benefit chemical and biological sensing, researchers in the US have developed hollow optical waveguides that can guide liquids or gases.

. . .

LASER SURGERY
A research group from Poland's Military University of Technology, Warsaw, has produced a Q-switched Er:YAG laser set-up that delivers pulses as short as 91.2 ns with an energy of 137 mJ (at 3 Hz repetition rate).

. . .

PHOTONIC CRYSTAL FIBER
Scientists in the UK have developed an all-solid photonic crystal fiber (PCF) that acts as a high-performance bandgap filter.

. . .
LED
A team of researchers and engineers from the University of Strathclyde, UK, and HORIBA Jobin Yvon IBH has shown that a pulsed ultraviolet LED can act as a convenient source for exciting fluorescence from protein.

. . .

3D DISPLAY
A full-color auto stereoscopic three-dimensional display, which can be viewed without glasses, has been developed by researchers in South Korea.

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Silicon Laser

Scientists Demonstrate First Silicon Laser

Researchers at UCLA have demonstrated the first silicon laser, which could lead to more effective biochemical detection, secure communications and defense against heat-seeking missiles.

"This development shows that despite popular belief, a laser can indeed be made on a silicon chip," said Bahram Jalali, professor of electrical engineering at the UCLA Henry Samueli School of Engineering and Applied Science, who led the research team.

"The lack of a silicon laser has been a major roadblock in the progress of silicon optoelectronics and photonics," said Jagdeep Shah, program manager of the Defense Advanced Research Projects Agency Microsystems Technology Office, which funded the research. "The demonstration of a Raman laser in silicon has the potential to lead to new military applications in communications and sensing." Shah is a fellow of the American Physical Society and the Optical Society of America

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Transfer Information Between Matter And Light

Physicists Transfer Information Between Matter And Light; Advancing Quantum Communications
A team of physicists at the Georgia Institute of Technology has taken a significant step toward the development of quantum communications systems by successfully transferring quantum information from two different groups of atoms onto a single photon.

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LED array emits over 13 kilolumens

High-brightness LED lighting developer Lamina Ceramics says that it has made the brightest LED "light engine" ever.

LED-based lighting could be about to make a big impact in very-high-brightness applications, according to a US company that has developed a 13,300 lm source.

Lamina Ceramics, which is based in Westampton, NJ, claims that its 5-inch diameter light source is an order of magnitude brighter than anything previously demonstrated with LEDs.

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Protein makes phototransceiver debut

Scientists from the US and Hungary say they have blended the protein bacteriorhodopsin (bR) with electronics to make the world's first bio-phototransceiver. The device, which uses bR to detect incoming light, could find applications as an optical interconnect in artificial vision systems for robotics and high-speed tracking.


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A major step forward for optical sensing technology

Researchers guide light through liquids and gases on a chip, a major step forward for optical sensing technology

Researchers at the University of California, Santa Cruz, have reported the first demonstration of integrated optical waveguides with liquid cores, a technology that enables light propagation through small volumes of liquids on a chip. The new technology has a wide range of potential applications, including chemical and biological sensors with single-molecule sensitivity.

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