Computers powered by frickin’ laser beams just came a step closer. Light-based, or photonic, computers would theoretically be much faster and smaller than the electronic computers we use today, but researchers have had a hard time putting theory into action. Now, a new study has shown that two laser beams can be harnassed to turn a single molecule into a transistor. However, the specialized conditions necessary for the trick to work mean that computer stores won’t have photonic sections anytime soon.
Conventional computers are based on transistors, which allow one electrode to control the current moving through the device and are combined to form logic gates and processors. The new component achieves the same thing, but for laser beams, not electric currents. A green laser beam is used to control the power of an orange laser beam passing through the device [New Scientist]. In the study, published in Nature, the green beam could make the orange beam either weak or strong, which is analagous to an electronic transistor turning a current on or off.
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In several labs around the world, sound waves are doing things they’ve never done before. Teams working in England and the Ukraine have made a sonic laser, or “saser,” which operates in the terahertz range, with sound waves oscillating more than a trillion times per second. Meanwhile, in an Israeli lab, researchers say they’ve created the first ever sonic black hole that traps sound waves and won’t let them escape.
The saser uses packets of sonic vibrations called “phonons” much like a regular laser uses photons. Specifically, the acoustic laser device consists of a sonic beam traveling through a “superlattice” constructed of 50 sheets of material each only atoms thick that are alternately made of gallium arsenide and aluminium arsenide, two materials found in semiconductor [CNET]. The phonons bounce back and forth inside the lattice, which causes more phonons to be released and amplifies the overall signal. The result is the formation of an intense series of synchronised phonons inside the stack, which leaves the device as a narrow saser beam of high-frequency ultrasound [New Scientist].
At the moment the terahertz saser, described in a paper published in the journal Physical Review B, is mainly a neat trick, but it may find practical applications down the line, says lead researcher Tony Kent. “Fifty years ago many eminent scientists said that light amplification by the stimulated emission of radiation [lasers] was no more than a scientific curiosity,” says Kent, but lasers are now used for everything from digital storage and cancer treatment to weaponry [New Scientist]. Kent says the new saser technology could lead to breakthroughs in imaging for tiny, nanoscale objects.
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The battle of the light bulb may not be quite over. While traditional incandescents will soon be phased out in the United States and abroad, researchers are plugging away to create more efficient versions that comply with looming new standards — while also providing an alternative for consumers who find compact fluorescents objectionable [The New York Times, blog]. In one new study, researchers have demonstrated how an incandescent bulb can be modified to give out much more light without requiring more power.
Lead researcher Chunlei Guo and his colleagues were experimenting with the effect of ultrafast laser pulses on metals when they noticed that pulses lasting only a few femtoseconds–quadrillionths of a second–could fundamentally change the molecular arrangement of metals without melting them [ScienceNOW Daily News]. The laser blasts caused the metal to turn black, which boosted its ability to absorb light. Because the law of thermal radiation state that materials that can absorb a great deal of energy will also emit large amounts of energy, the researchers decided to see if their laser treatment would boost the light output of the metal filament in an ordinary light bulb.
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Luminaries gathered today at a lab in Livermore, California to toast the opening of the National Ignition Facility, a massive physics experiment aiming to recreate the reaction that takes place in the hearts of stars: nuclear fusion. “Bringing Star Power to Earth” reads a giant banner that was recently unfurled across a building the size of a football stadium [The New York Times]. Scientists are now ready to begin firing the world’s most powerful laser, comprised of 192 separate beams, at a target the size of a match head. Yet for all the celebration and hoopla, doubters note that there’s no guarantee that the fusion researchers will achieve their goal.
The project’s director, Ed Moses, said that getting to the cusp of ignition (defined as the successful achievement of fusion) had taken some 7,000 workers and 3,000 contractors a dozen years, their labors creating a precision colossus of millions of parts and 60,000 points of control, 30 times as many as on the space shuttle. “It’s the cathedral story,” Dr. Moses said…. “We put together the best physicists, the best engineers, the best of industry and academia” [The New York Times]. The project has also cost at least $3.5 billion. NIF’s researchers will spend the next year gradually increasing the energy of the laser beams, and say serious ignition experiments will begin next year.
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Optics researchers have invented a camera that uses infrared lasers to bounce light off an object, and say the result should leave shutterbugs with a serious case of technology envy. Their device can take 6.1 million pictures in a single second, at a shutter speed of 440 trillionths of a second. Light itself moves just a fraction of a centimeter in that time…. “It’s the world’s fastest camera” [Wired], says study coauthor Keisuke Goda.
Conventional digital cameras use charge-coupled devices (CCDs) to take a picture. The devices contain semiconducting chips that … produce electrons in response to light. The electrons are read off the chip and their signals are then electronically amplified and encoded as a digital image [Nature News]. But that process has its limits. Top-notch conventional cameras top out at about 30 frames per second, while the fanciest scientific instruments can take about one million frames per second. For Goda and his colleagues, that just wasn’t fast enough.
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Researchers in California are preparing to fire 192 lasers at a minuscule pellet of fuel to create their first nuclear fusion reaction, the same reaction that takes place in the center of the sun. Within two to three years, the researchers at the National Ignition Facility (NIF) expect to be creating fusion reactions that release more energy than it takes to produce them. If they’re successful, it will be the first time this has been done in a controlled way–in a lab rather than a nuclear bomb, that is–and could eventually lead to fusion power plants [Technology Review].
Earlier this month, technicians test fired all 192 lasers at once, concentrating their beams on a single focal point in the middle of the chamber. For the test, the chamber was empty. But when real experiments begin within the next few months, the target will be a tiny gold capsule the size of an extra-strength Advil. The goal is to mash the contents of the capsule, a BB-size pellet of hydrogen frozen to nearly absolute zero, until the hydrogen atoms fuse into helium and release a gush of energy [Forbes Magazine].
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In a preview of possible high-tech battles to come, Boeing has announced the successful test of a laser weapon designed to shoot down unmanned aerial vehicles (UAVs). Robotic spy and combat planes are a hot field of military research because their use doesn’t endanger pilots, and because they can be smaller and harder to detect than conventional planes. But Boeing vice-president Gary Fitzmire argues that the military should be investing not just in UAVs, but also in devices that can destroy them. “Small UAVs armed with explosives or equipped with surveillance sensors are a growing threat on the battlefield,” he insists. “Laser Avenger, unlike a conventional weapon, can fire its laser beam without creating missile exhaust or gun flashes that would reveal its position. As a result, Laser Avenger can neutralize these UAV threats while keeping our troops safe” [The Register].
The weapon was tested at the White Sands Missile Range in New Mexico, where the Laser Avenger tracked three UAVs flying “against a complex background of mountains and desert”, shooting down one of the UAVs [Gizmodo]. The device got its sci-fi tinged name because it’s a modified version of the Army’s existing Avenger air defense system, which had two missile launchers mounted on a Humvee. To build the Laser Avenger, Boeing swapped its ray gun and a target tracker for one of those missile launchers.
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In several years police officers may have laser or microwave guns to point at miscreants, according to the Justice Department’s research and development agency. These nonlethal weapons build on knowledge gained from the Pentagon’s controversial Active Denial System (ADS) – first demonstrated in public last year, which uses a 2-metre-[wide] beam of short microwaves to heat up the outer layer of a person’s skin and cause pain. Like the ADS, the new portable devices will also heat the skin, but will have beams only a few centimetres across. They are designed to elicit what the Pentagon calls a “repel response” – a strong urge to escape from the beam [New Scientist]. But the idea of giving cops a tool capable of instantly inflicting pain from across a town square is raising protests from human rights advocates.
The Justice Department is working on two separate weapons. One, the Personnel Halting and Stimulation Response, or PHaSR, uses an infra-red laser to heat a patch of skin about 4 inches in diameter, and pairs that heat with another bright laser that dazzles the eyes. The PHaSR looks like a bulky rifle, and law enforcement officials say that a cheap, portable version could be very useful to police and prison guards. Sid Heal, formerly a Commander in the Los Angeles Sheriff’s Department (and before that a Marine) , has long been an advocate of non-lethal weapons and thinks the new devices might have potential. “Needless to say, the “market” is so vacant with alternatives that ANYTHING is going to be appealing at this point” [Wired News], says Heal.
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Military contractors have successfully fired a high-energy laser attached to a modified commercial aircraft, in a ground test that is a step towards testing the airborne laser system in flight. Boeing and Northrop Grumman are working on the system, which is intended to shoot down ballistic missiles.
The laser is in the back half of a Boeing 747-400F jumbo jet. Subsequent tests will increase duration and power before the beam is sent through a fire control system to a turret mounted in the nose of the aircraft [AP]. A long series of ground tests and flight tests will build up to an attempt to intercept and destroy a ballistic missile in flight; that test is scheduled for August 2009. The Defense Department has already spent $4 billion on the airborne laser system, and the final price tag is expected to reach $5 billion.
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