Chips Under Glass

Moving toward all-optical nets

Using technology as old as World War II and as young as last weeks breakthrough, chipmakers are transforming optical networks with devices that slice, dice and relight optical fiber and all its traffic.

The companies are not short on astonishing claims: Gemfire has a device that it says can pump erbium atoms onto eight channels at a time, slicing regeneration costs in half. Vitesse Semiconductor says it has a single-chip optical device that cuts the need for regeneration by decoding incoming data loaded with errors and restoring it to what the sender had in mind. Zolo Technologies says it can separate 200 channels in a far simpler way than ever before.

While the optical switch wars make headlines, components engineers seem to be having more fun, designing chips the size of playing cards, postage stamps or wafers that will simplify life for service providers and their business and residential customers.

The chips — optical or semiconductor — go into the equipment that systems makers are selling to carriers. But someday soon, theyll be the systems themselves, replacing routers, cross-connects and switches.

"The components guys drive the tech engine that feeds the evolution of the network," says Ed Rodriguez, head of KPMGs Electronics Industry Group. "Were almost seeing systems-on-a-chip on the network side, just as Intel did in microprocessors. Its very realistic that theyll go down that same path with high-horsepower routers and switches."

Of course, its sometimes difficult to sort out what looks great on the wafer table from what can be produced in volume and work in a real, live, lit network. And its tough distinguishing between all-optical and semi-electronic solutions — or, for that matter, figuring out why the carrier or end user should care.

"Theres a lot of fiction out there," says Simon Keeton, optical manager at Vitesses forward-error-correction unit. "All-optical networking is a buzzword right now. But youd be hard-pressed to find anyone delivering true all-optical solutions, because of the physical limitations."

Some 30 percent to 60 percent of the costs of optical networks are in regenerating the signal about every 50 miles. The greater the distance signals can travel without needing regeneration, the faster carriers will adopt optical networks for all traffic.

Vitesses forward-error correction leans on technology developed by World War II code breakers to clean up signals. Its a stand-alone hardware device that sits close to the fiber, using parallel buses to slow the information down. The data is channeled into a single-bit stream running at the speed of the network, perhaps 10 gigabits per second, and handed off to a multiplexer. After the traffic is converted into electric signals and demultiplexed, it goes into Vitesses single-chip algorithm device for decoding and error correction.

All-optical devices are transparent and dont care about technologies or protocols. But, made with bubbles or mirrors, theyre hard to manufacture in volume, are prone to failure and are relatively dumb devices.

Optical technology so far cant process information, monitor performance or determine whether a stream of traffic needs top priority — such as a phone call — or is merely coach-class service — such as e-mail.

"You can do more intelligent switching in the electronic universe," Keeton says. "Were going to see people look more toward optical switches and at new ways of monitoring that signal. But were never going to get the same level of monitoring that you can get with an electronic switch."

Optical Switch is building optical switching components for systems that require just a handful of channels per fiber because thats where 95 percent of the demand is today, says Chief Executive Gary B. Nabhan. In three years, when $15 billion worth of optical components are expected to be sold, 80 percent of orders will still be for systems with 32 channels or fewer, he predicts.

"Theres a tendency in the investment world to think the transition to an all-optical network will occur overnight," Nabhan says. "I dont think so. I think it will be phased in over five or 10 years."

Optical Switch has invented and patented a tool that automates setup of a chip laboratorys optical table, where the components are manufactured, Nabhan says. "It used to take our Ph.D.s all day to set up a table and produce one or two wafers," he says. "Now that weve computerized and automated the process, we can process multiple wafers per minute."

And producing products quickly may become a key differentiator.

"In this industry theres an awful lot of hype, people saying, I can do this many channels, " says Zolo Chief Technology Officer Andrew Sappey. "The question you really need to ask is not what 20 Ph.D.s are doing in a lab, but what is it you can deliver in two weeks? "

Despite the current slowdown in the systems business, there remains a severe shortage of some of the components that make those systems work.

"The ability to manufacture and get these things out is a huge deciding point for systems vendors on whose components they are going to use," says Grier Hansen, an analyst at Current Analysis. "Theyre going to pick a component they can actually get."