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2009 Physics Nobel Winners See the Big Picture
6 October 2009 (All day)
Within seconds of the announcement of this year's Nobel Prize in physics, photos and videos of the winners were zipping across the globe via the Internet. And it was the prize-winning discoveries that made this instantaneous dissemination possible. Half of the award goes to Charles Kao, an electrical engineer whose theoretical work lighted the way to practical optical fibers for high-speed telecommunications. The other half honors physicists Willard Boyle and George Smith for their invention of the first electronic chip that could capture an image.
Simply put, Kao figured out how to get light to travel far enough down a glass fiber to pass signals over great distances. Light tends to course down a microns-thick fiber instead of leaking out of the side, because it only strikes the surface of the fiber at a very small glancing angle and is reflected back into the glass. The glass itself can absorb light, however, and until Kao's work in 1966, such absorption would soak up 99% of all the light passing through a 20-meter optical fiber.
Kao, who was born in Shanghai, China, and earned his Ph.D. in the United Kingdom, fingered iron impurities as the essential cause of the light loss. Light can also bounce down a fiber in several different patterns or modes, and Kao, who was then working at the Standard Telecommunication Laboratories in Harlow, UK, correctly predicted that a very thin fiber that allowed the light to propagate in only one mode would be best for producing practical communications networks.
The 75-year old Kao "was the right choice because he was the one who brought it to the attention of the community that it was possible to reduce the losses," says Govind Agrawal, an optical physicist at the University of Rochester in New York state. Still, Agrawal adds, "when I heard the news my first thought was about the other people who could also have gotten it." In particular, he says, Donald Keck and colleagues at Corning Inc. in Corning, New York, were the first to produce the fibers Kao described theoretically.
Boyle, 85, and Smith, 79, invented the charge-coupled device (CCD), which was the first electronic chip capable of capturing an image. It remains a key technology for medical imaging, astronomical telescopes, and digital cameras. Boyle and Smith "have enabled pretty much all of the modern imaging systems," says George T. C. Chiu, an engineer specializing in imaging at Purdue University in West Lafayette, Indiana. "The CCD has changed everything about how we gather information and images."
The CCD contains a silicon chip that is divided into cells or "pixels." When light hits a pixel, it excites an electric charge in the silicon, which then induces a charge in a tiny electrode on the chip's surface. The charge then quickly passes from electrode to electrode down a whole row of pixels--that's the "charge coupling"--and is read out at the edge of the chip.
Boyle, who was born in Canada and lives in Halifax, says he and Smith thought up the device in a couple hours in 1969. "It was an October morning and he came up to my office for some brain-storming. And pretty soon we had some sketches on the black board and there it was." Says Smith: "We complemented each other. We just seemed to click." The two were working at Bell Labs in Murray Hill, New Jersey, when they made their advance. Although no longer the power that it once was, that famed institution can now claim a total of seven Nobel Prize-winning discoveries, a fact that Boyle says he finds more amazing than his own invention.