Terabit Networks Become Reality
R. Winn Hardin
A flexible, high-power, erbium-doped fiber amplifier technology, optimized planar waveguides and externally modulated lasers form the heart of a new optical network from Lucent Technologies that is capable of transmitting 3.2 Tb/s.
At the core of Lucent's WaveStar network are amplifiers that add just enough power to maintain the signal intensity without creating interference, said Lucent's director of strategy for optical networking, Kathy Szelag. The technology capitalizes on proprietary design and algorithm improvements.
Terabit networks capable of carrying the world's Internet traffic across eight optical fibers are now a commercial reality.
The smart device matches amplification with channel characteristics -- pumping less power to 2.5-Gb/s channels than it would to 10-Gb/s channels. By watching the power budget, the amplifier can pump up to 80 channels, enabling ultradense multiplexed transmission across distances up to 120 km.
When combined with externally modulated lasers and planar waveguides with 50 MHz (approximately 1 Å) of optical spacing, the system can deliver up to 40 channels at 10 Gb/s, up to 80 channels at 2.5 Gb/s or any combination of the two. "Some companies may already have 2.5-Gb/s systems and they're not ready to write them off yet," Szelag explained. "[Also] there is some standard fiber out there that will not support 10 Gb/s."
By combining eight fibers into a single network, Lucent claims to be able to deliver 3.2 Tb/s within the ITU standard wavelength division multiplexing range of 1525 and 1570 nm. To put that amount of data in perspective, Lucent's optical networking business chief operational officer, Harry Bosco, said it's the same as transmitting 90,000 volumes of an encyclopedia in one second, or the equivalent of the world's Internet traffic.
In addition to its bandwidth flexibility, the WaveStar system can bridge SONET and synchronous digital hierarchy protocol systems.
This advantage offers adaptability to service providers, according to AT&T's executive vice president of network and computing services, Frank Ianna.
"We are continually pursuing new technologies that will allow us to add capacity quickly and cost-effectively. Lucent's solution gives us tremendous flexibility in adding new capacity, further improving our unit cost efficiencies," he said.
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