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Corvis's Secret Sauce?

Light Reading
News Analysis
Light Reading
8/28/2000

DENVER - A possible clue to the technology being used by Corvis Corp. to develop its all-optical switch may have surfaced today, in a briefing from Iolon Inc., a startup that’s developing some breakthrough optical components.

The components in question are a 1-by-4 optical switch the size of an average silicon chip and a tunable laser that promises to deliver particularly high power (20 milliwatts) at the same time as being tunable over a wide (40 nanometer) range of frequencies.

From an engineering standpoint, that’s pretty powerful stuff, but what makes things really interesting are Iolon's backers. They include Vinod Khosla of Kleiner Perkins Caufield & Byers and Optical Capital Group, the venture capital company founded by David Huber, Corvis’s founder, president, and CEO.

Khosla’s backing pretty much indicates that Iolon is onto something, and the implication of Huber’s involvement is that it will be used in Corvis’s products. Iolon itself declines to comment on this speculation, although Cindana Turkatte, its vice president of marketing, acknowledges that it's an example of Kleiner Perkins's “keiretsu” at work.

"Keiretsu" is a reference to the networks of companies in Japan that work together for their common good. In this case, Kleiner Perkins was an early investor in Corvis, and now Khosla and Huber are investing in Iolon -- presumably with the goal of giving everybody an inside track.

Getting a hint of what Corvis might be using to build its optical switch is quite a coup. Huber has been very tight-lipped about it. Even telecom operators that are trialing Corvis’s equipment have had a hard time getting him to divulge details. It's known to be the only all-optical switch to be anywhere close to deployment, and it's also known to have a relatively low number of ports, but that's about it.

This sketchy description could fit a switch based on Iolon's developments. Iolon is using MEMS (micro-electro-mechnical systems), but it’s not following in the footsteps of startups like Calient Networks Inc. and Xros, the startup bought by Nortel Networks, who are developing giant arrays of tiny tilting mirrors for very large switches, ones with 1,000 or more ports. Iolon is developing a tiny 1-by-4 switch that would be installed on a circuit board in a more modestly sized switch, like Corvis’s.

Iolon is using MEMS as a way of automating the manufacture of its switch component as much as possible, with a view to selling it in very large volumes. In order to do this, it’s making a MEMS-based actuator -- a half-wheel-shaped device formed from interleaved combs, made from silicon using an etching process. When electric currents are applied to the interleaved combs, they open and close, rotating the tiny structure to and fro by up to six degrees in each direction. The mirrors are made separately and are slotted singly into the hub of each half-wheel.

The whole actuator and mirror assembly is tiny. It's about about one millimeter across, and is placed in front of a so-called GRIN lens in the packaged component. The four fibers carrying light into and out of the switch butt up to the other side of the GRIN lens. In operation, light pulses come out of one fiber, pass through the GRIN lens to keep them focussed and then hit the mirror, which deflects them back through the GRIN lens into another fiber.

The other clever bit about Iolon’s switch is the conrol system that automates movement of the tiny actuator based on feedback from the switch output. This eliminates laborious manual alignment processes, according to Tim Harris, Iolon’s vice president of operations. As a result, manufacturing is much easier and faster. The control system can also move the mirror very quickly. The switching speed is less than five milliseconds, says Jill Berger, Iolon's manager of optical design.

This whole system -- the MEMS actuator and the control mechanism -- started life as part of a project to develop next-generation disc drives, which have to locate information on discs very accurately and quickly. That explains why the third major investor in Iolon is Seagate Technology Inc., a major vendor of data storage equipment.

Evidence that Iolon's technology may not be in use in Corvis's current switch comes done to two issues. First, Iolon has only been shipping samples of its switch component since March of this year. That's hardly enough time for Corvis to integrate it into its switch, which is said to be in the early stages of trials. Second, Corvis maintains that the components its using in its switch are all NEBS compliant, a standard of engineering quality required by most telecom operators. Right now, no MEMS based devices have won NEBS approval, according to Corvis

Iolon’s tunable laser is based on the same fundamental technologies but is at an earlier stage of development.

-- Peter Heywood, international editor, Light Reading

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