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Science & Technology: FIBER OPTICS
FIBER OPTICS: THROUGH A GLASS QUICKLY
Advances are revolutionizing telecom
Everyone knows about the Silicon Revolution. But what about glass, the foundation of the coming optics epoch? Invisible to most people, a web of lightning-fast optical fibers already encases the modern world. Today, these hair-thin glass strands handle most long-distance phone traffic and some local traffic in cities--and they'll soon begin arriving at nearly everyone's front door. A single laser beam pulsing through these fibers can transmit thousands of simultaneous voice conversations, or millions of bits of digital data, every second.
That's a lot--but not nearly enough. Ever since Internet traffic began to boom and the television business decided to go digital, computer companies and online services have been warning that tremendous increases in our ability to deliver information--voice, video, and data--will be needed. Worldwide demand just for Internet capacity is projected to surge 4,600% by 2002.FANCY PRISMS. Fortunately, a stunning advance in fiber-optic technology is now pumping up the available capacity to levels that could revolutionize telecommunications. The technology is dubbed wavelength division multiplexing, or WDM. But you can think of it as a rainbow. With WDM, the light streaming through fibers consists of many colors--although all are in the invisible infrared spectrum. Each hue stretches from end to end of a glass strand and can carry its own stream of data. Thus, WDM makes it possible to greatly multiply the amount of data flowing through one fiber.
Despite the fibers' slender width, optical engineers are developing fancy prisms that can split infrared light into an ever-growing number of colors--just as silicon engineers keep increasing the number of transistors on chips. In 1995, WDM made its debut as a rainbow of just eight colors. Today, commercial WDM systems with 40 hues are available.
Last spring, researchers at Lucent Technologies Inc.'s Bell Laboratories stuffed 100 beams into a fiber--and jacked up the data rate of each laser to 10 gigabits (10 billion bits) per second, four times today's usual drumbeat. That means the total throughput from that single glass strand was an amazing 1 trillion bits per second. That's more than enough to accommodate all of North America's telecom needs. Bell Labs expects this technology will be on the market by 2000. With such enormous capacity, Hollywood could deliver movies to theaters in the blink of an eye. Product development could be greatly accelerated because engineers could instantly access huge three-dimensional models of components and manufacturing operations."MIND-BOGGLING." And 1 trillion bits (one terabit) per fiber is just for starters. Alastair Glass, head of photonics research at Bell Labs, envisions lasers pulsing at 40 gigabits a second--and optical fibers crammed with hundreds, even thousands, of WDM beams. Ultimately, each wispy fiber may transmit close to an incredible 200 terabits per second. That's enough to deliver the entire contents of the Library of Congress every single second. "It's mind-boggling," says Glass.
The numbers grow more extraordinary when you consider that fiber-optic cables used as so-called trunk lines to link cities and span oceans hold as many as 432 fibers. So even with today's commercial WDM technology--40 beams, each pumping at 2.5 gigabits per second--fiber cables can carry tens to hundreds of terabits per second. Next year, says Glass, 80 WDM beams could become common, each one beating at 10 gigabits, and 160 beams are on the horizon.
That's the magic of WDM. Once the fiber is in the ground, its capacity can be multiplied just by upgrading the electronics at both ends. The WDM electronics package isn't cheap, at roughly $30,000 per fiber at each end, but that's a pittance compared to the cost of digging up the ground to lay new cable.
When Denver-based Qwest Communications International Inc. began laying 96-strand optical cables along railway lines in 1996, each fiber was designed to carry eight WDM channels. But the technology is advancing so fast that most sections have already been upgraded to 16 channels, doubling the initial capacity. If customers demand still more, Qwest can quickly double capacity again by adding more WDM lasers. And if that's still not enough, Qwest may be able to quadruple capacity with faster lasers.
In a chase after Qwest, similar trunk networks are being built by IXC Communications, Level 3 Communications, and Williams Communications. By 2000, these four companies will have planted 50% more miles of fiber-optic cable than the 41,000 miles operated by AT&T. And other companies are laying still more new fiber--such as NorthEast OpticNetwork Inc., which is installing 600 miles along the East Coast corridor.
Now, the WDM race is spreading around the globe. In Europe, Britain's Cable & Wireless Communications began upgrading its existing fiber networks in 1997, using the 16-wavelength WDM systems that Ciena has been supplying to Sprint since 1996. Since August, 1997, China has been buying WDM systems from Lucent and more recently, Japan's NEC. And Alcatel and Fujitsu Ltd. are about to construct an 18,000-mile undersea WDM cable looping from Australia and New Zealand to the U.S., then back through Hawaii and Fiji to Australia.
In short, the world is getting wired as never before. For the suppliers of the exotic equipment that creates the infrared rainbows inside optical fibers, it's a bonanza. Sales of WDM gear are projected to more than quadruple, to $4 billion, by 2002, according to Insight Research Corp. in Parsippany, N.J. (chart, page 96). "It looks like another California gold rush," says Insight President Robert Rosenberg. All the telecom-tech heavyweights--such as Ericsson, Northern Telecom, and Pirelli Cable--are rushing to stake claims with their own WDM technology.
So much additional capacity will be coming onstream that some analysts wonder what the world will do with it all. Not even the enormous appetite of Internet traffic, which will surpass the volume of voice calls any day now, will eat it all. The looming glut heralds good tidings for every company that has a phone line, predicts Rosenberg of Insight Research. "Everybody's going to see a big drop in communications costs," he says. Indeed, Wall Street analysts are beginning to worry about a major shakeout in the telecom industry.BABE IN ARMS. That might be a short-term danger, but Harry Bosco, chief operating officer of Lucent's optical networking business, isn't concerned. The dynamics of ever cheaper bandwidth, he predicts, will spur innovations that will far outstrip what the spread of PCs has brought. "As cost comes down, it's going to constantly drive up demand by creating new opportunities," he says.
Bosco envisions a day when every manufacturer and department store has a separate high-speed WDM channel that's continuously open to each supplier. Bandwidth might become so cheap that every PC and home could also have its own open line to the Internet. So-called "metropolitan" WDM systems designed for short-haul links are now starting to show up in cities, he notes, and plug-in optical "cards" for local-area WDM networks are in the works at several telecom suppliers, including startups LightPath Technologies Inc. in Albuquerque and Eagle Optoelectronics Inc. in Boulder, Colo.
The WDM revolution is still such a babe in arms, and is advancing so swiftly, that most businesses haven't begun to grapple with the notion of an online world in which bandwidth is essentially unlimited and is practically free. Even Glass of Bell Laboratories has to scratch his head in amazement at the phenomenal progress. WDM technology is actually outrunning silicon's advances, he says. If it weren't for IBM's breakthrough silicon-germanium material, a hybrid semiconductor that produces far faster chips than ordinary silicon, the telecom computers that do traffic-cop duTy could become Keystone Kops. "Silicon isn't keeping up," says Glass, because light has unlimited bandwidth. "Paradigm shift" is a much overused term, he adds, but it certainly applies to what's happening on this side of WDM's magic rainbow.By Otis Port in New YorkReturn to top