Intel Corp. is claiming another advance in creating optical communications components from silicon, an effort designed to reduce the cost and increase the speed of transmitting computer data.
The company said it combined silicon -- the low-cost foundation for most computer chips -- with the element germanium to make a device called an avalanche photo detector that achieved record performance. Intel said the development marks the first time that a silicon-based optical component exceeded the performance of an equivalent device made from more costly conventional materials, such as indium phosphide.
But the importance of Intel's announcement was challenged by researchers at Luxtera, a closely held company that is already producing silicon-based optical components.
Optical communications involves encoding information on streams of light particles, generated by lasers. The technology brings big benefits in speed over standard electrical connections, and uses thin glass fibers rather than bulky cables. But optical connections are now mainly used for high-volume long-distance communications -- or connecting servers in massive supercomputers -- because key components often cost tens to hundreds of dollars each.
Researchers are hoping to drive those costs down to pennies by using materials found in conventional chips, a field known as silicon photonics. Intel, in particular, has been churning out a series of research papers describing prototype optical components made from silicon.
Its latest development, which was jointly funded by the U.S. Defense Advanced Research Projects Agency, is described in a paper in the journal Nature Photonics. Intel engineers collaborated with counterparts at Numonyx BV, a company comprised of former operations of Intel and STMicroelectronics NV. Experts at the University of Virginia and the University of California at Santa Barbara provided consulting and testing, Intel said.
Photo detectors are used to sense and amplify light pulses generated by lasers. The new prototype detector achieved a "gain-bandwidth product" of 340 gigahertz, which is the highest result recorded to date on that key metric of detector performance, said Mario Paniccia, who directs Intel's photonics-technology lab and holds the title of fellow.
Improvements in detector performance could be exploited in different ways, including boosting the speed data is sent, increasing the distance a signal goes or reducing the energy needed to send a signal a constant length, Mr. Paniccia said. "And we believe we can continue to improve the performance," he said.
Intel initially expects silicon-based optical components to send data between servers in a computer room and between chips in a system, though it later hopes to have optical connections inside its microprocessor chips, too. Mr. Paniccia said silicon-based detectors also could find uses outside communications, in applications such as optical sensors, cryptography and medicine. He didn't give a precise timetable for turning the new components into products, but indicated it would take several years to perfect the technology.
Meanwhile, Luxtera is "ramping up" production of its silicon-based optical components, said Greg Young, chief executive of the Carlsbad, Calif., company. He said the performance described in Intel's paper is "tremendous." But Mr. Young contends that Luxtera researchers actually were the first to top the performance of indium-phosphide photo detectors in research results published more than a year ago.
Mr. Young also asserted that Intel's technology is incompatible with conventional semiconductor-production processes, so it couldn't be used in a so-called wave-guide detector to work alongside other components on one piece of silicon.
Mr. Paniccia said Intel is developing a wave-guide version that could be integrated on a chip.
And many applications, including inexpensive fiber-optic links to homes, don't require wave guides, said John Bowers, a silicon photonics expert and professor of electrical and computer engineering at University of California-Santa Barbara. "It's a huge paradigm shift," he said of Intel's results.
Source : http://online.wsj.com/