Posted: 01/2000

Lucent Unveils Breakthrough Optical
Cross-Connect
By Charolette Wolter

Optical networking took a major step forward as Lucent Technologies Inc. (www.lucent.com)
introduced a truly optical cross-connect, the Wave-Star LambdaRouter, that
switches wavelengths of light in a dense wave-division multiplexing (DWDM)
system. The cross-connect, which is less than 1 inch across, is a 256-by-256
matrix which uses microscopic mirrors that change shape with heat to reflect the
wavelengths in different directions.

Each mirror is less than a human hair in diameter, and the entire 256-by-256
matrix is less that an inch across, although input and output mechanisms will
make the finished product much larger.

There is no foreseeable limit on the amount of bandwidth that each mirror
could switch, says Kathy Szelag, vice president, marketing, Lucent Optical
Networking Group. "It has 256 ports and conservatively could switch 40
gigabits per second (gbps) per port," she says. "So, if someone did
terabit fiber, it could switch 256 terabits."

The matrix, however, has the flexibility to switch small or large data
streams, as long as they are contained in wavelengths or lambdas. It ostensibly
could switch groups of lambdas on one mirror, according to report by market
research firm Current Analysis Inc. (www.currentanalysis.com).
"There are no mechanical reasons why lambdas that have been grouped
together cannot be simultaneously switched without having to be broken down
individually. This would extend the capacity of the switching system, although
it would require a more intelligent front-end muxing/demuxing system."

Lucent estimates the product will deliver 50 percent to 75 percent savings
over intelligent optical systems using electrical cross-connects to switch
wavelengths at network hubs.

However, the system’s performance is potentially far superior to digital
cross-connects, because they must use the processing power of chip to do
switching, rather than just reflecting a wave off a mirror. This becomes
particularly acute as bandwidth ramps up, Szelag says. "If you do a digital
cross-connect, it will never be able to switch at the speed of optical. But this
year we reached speeds of 40 gigs [in SONET (synchronous optical network)
muxes]. The state-of-the-art today [in digital cross-connects] is 2.5 gigabits
per second, and I heard rumors that some might come out with OC-192s (10 gbps).
But for OC-768, for sure optical is the only way to do it."