Long-anticipated all-optical switches begin to reach customers

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In 1940, Bud Abbott and Lou Costello introduced audiences to their funny, albeit somewhat ridiculous, "Who's on First?" routine. In September, Lucent Technologies (Murray Hill, NJ) and Corvis Corp. (Columbia, MD) put a new spin on the old question. Both companies claim to have been the first to deliver the long-anticipated, much-hyped all-optical switch-Lucent to Global Crossing Ltd. (Hamilton, Bermuda) and Corvis to Broadwing Inc. (Austin, TX). More important than who was first, however, is the fact that Lucent and Corvis are even in a position to have this debate at all.

Many of the switches deployed in today's networks are optical, but they are not all-optical. Optical switches must first convert optical signals to electrical signals for processing, then reconvert those electrical signals back to optical signals. This OEO conversion is costly and slows down transmission, creating a bottleneck. With true all-optical switches, the signal remains in the optical domain throughout transmission, which reduces power consumption and operational costs.

The all-optical switch is considered by many to be the key to the all-optical network of the future. "If you look at the various devices that you may introduce into your network that would start to drive the right design considerations for an all-optical network, the optical switch is one of the keys," explains Mike Coghill, network operations manager at Global Crossing. "And from that point out, then you start looking at all the other devices and how they have to interoperate with that switching device."Th 1713lwe104

An engineer works on Corvis's CorWave all-optical switch, which is already in deployment in the Broad wing network.

Lucent began shipping its all-optical switch, the LambdaRouter, to Global Crossing July 31, and after successful lab testing, the companies began live network trials Sept. 22. Global Crossing has installed three Lucent switches on its transatlantic route: in London and New York City, and one at its cable-landing site in Brook haven, NY. In this initial phase, Global Crossing is using the Lambda Router to provide protection switching and some fast provisioning of optical private-line services.

The service provider makes it clear, however, that it has not made a commitment to Lucent. Explains Coghill, "We're testing the LambdaRouter and we're doing the things that are necessary to get it service-ready. Long-term, we will have services that use optical switches; it could be Lucent's optical switches, it could be someone else. The issue of interoperability between optical switches of different manufacturers is something we haven't really fully explored yet."

Broadwing, meanwhile, has already deployed the Corvis all-optical switch in six core sites on its network where three or more fiber routes enter and exit: Atlanta; Cleveland; Salt Lake City; Fort Worth, TX; Joplin, MO; and a site called Marketplace, just outside Las Vegas. Lucent may have shipped its all-optical switch first, but Corvis is the first to ship its switch for commercial deployment.

"Corvis is further along in selling the whole notion of an all-optical network than any other company," says Lawrence Gasman, president of Communications Industry Researchers (Herndon, VA). "They have the all-optical switch, they have long-haul all-optical transmission, they have a vision of an all-optical network that's going to go end-to-end, and they have more of that than anybody else that I can think of."Th 1713lwe105

Lucent's LambdaRouter transmits optical signals through the network using tiny mirrors, seen here through the eye of a needle.

Given the intense competition in this space, both camps are understandably reluctant to divulge the specifics of their hardware. Developed by Bell Labs, Lucent's WaveStar LambdaRouter is a 256x256-port switch based on MicroStar micro-electromechanical systems (MEMS) technology. A beam of light comes into the switch fabric, where it impinges on a very small mirror made out of silicon substrate. From that mirror, the light is guided through the system to another mirror, which reflects the light onto a fiber path moving out of the system (see Lightwave, May 2000, page 1). "This is one of those things where you don't mind saying that it's all done with mirrors-hopefully no smoke, but lots of mirrors," jokes Coghill.

The Corvis CorWave is an all-optical switch that sits at the junction sites where multiple fibers intersect-at the nodes of the mesh network. It can be configured to suit various architectures, including mesh or ring topologies, and is fully integrated with Corvis's entire line of all-optical products, including the optical-network gateway, optical amplifier, optical add/drop multiplexer, and Cor Manager network-management system. Broadwing currently employs all of these products in its network.

"We've been working closely with Corvis over the last year, year-and-a-half, as they have been developing this type of technology," says Dale Richard son, director of transmission systems engineering at Broadwing, "and we've been with them every step of the way. We've ensured that the deliverables they've been able to deliver met Broad wing specifications. So far, they have passed with flying colors."

What is most important then is not which company was first to ship an all-optical switch, but that all-optical switching is far enough along in its development to be deployed in the network for live traffic. When asked if we are witnessing the dawn of the era of all-optical switching, however, Gasman maintains that we have moved past dawn. "If dawn was six o'clock in the morning, we're at seven-thirty," he says.

If the past 12 months are any indication, we should be at mid-morning very soon. In March, Nortel Networks (Brampton, Ontario) acquired next-generation, large-scale photonic-switch manufacturer Xros (Sunnyvale, CA) for $3.25 billion and has since been working on its own all-optical switch, part of the Qteraline. In July, Siemens announced its investment in all-optical switch manufacturer OMM Inc. (San Diego), whose switch modules have been integrated into Siemens's optical crossconnect, the TransXpress Optical Services Node.

Also in July, Alcatel introduced its Cross Light photonic crossconnect using OMM modules, while Calient unveiled its DiamondWave 256 intelligent photonic switch at NFOEC in August. On Oct. 10, Calient acquired Kionix Inc. (Ithaca, NY), a company that holds nearly 80 patents in MEMS technology. A week later, Tellium Inc. (Oceanport, NJ) acquired Astarte Fiber Networks (Boulder, CO), manufacturer of photonic-matrix switching systems used in all-optical switches (see related story on page xx). Tellium also announced that Corning Inc. (Corning, NY) has licensed three Astarte patents pertaining to MEMS technology, ostensibly for use in the development of its own all-optical switches.

"By the beginning of next year, there will be Lucent, Nortel, Corvis, Calient, Siemens, Alcatel, and Tellium-all of whom have all-optical switches, and all of them will be shipping in that period," says Gasman. Coghill agrees: "Everyone who has anything optical in their name is doing pretty good. I think there's obviously consensus that photonic switching, optical switching, optical cores, optical networking is where it's happening."

Now that we've solved the question of who was first, the only thing left to ask is: Who's next?

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