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Going Long On Light

Light Reading
News Analysis
Light Reading
6/9/2000

This week, Alcatel SA http://www.alcatel.com announced a “world record” for carrying DWDM traffic over very long distances. It cited two successful trials - one carrying 80 channels of 10 Gbit/s traffic over 3,000 kilometers, and the other carrying 32 channels of 40 Gbit/s over 250 kilometers.

Big deal? Yes and no.

It is a big deal, because it addresses a real need for ultra-long distance optical transmission. Internet traffic volumes are exploding and many Internet connections run from coast to coast in the US -- far longer than the average connection distances in telephone networks. As a result, carriers are looking for ways of carrying light signals over thousands rather than hundreds of kilometers, to reduce the need for expensive electrical regeneration equipment.

On the other hand, Alcatel's achievement isn't such a big deal because trials like this are often conducted in ideal conditions. Real life distances might be a lot less. And plenty of other vendors and startups are developing technologies that could topple Alcatel’s record before too long.

Here’s a quick summary of the state of play:

Corvis Corp. http://www.corvis.com plans to combine two technologies to deliver all-optical networks that could eventually carry multiple 100 Gbit/s channels, according to Scott Clavenna, principal analyst at Pioneer Consulting http://www.pioneerconsulting.com. It will use Raman amplifiers to boost signals at intervals. This is done by pumping a different wavelength light into specially doped fiber carrying the signals. It will also use Soliton technology acquired through its purchase of Algety Telecom SA, a French startup (see Algety Telecom SA), to shape the light signals so they travel further and retain their strength. This promises to boost Corvis's IPO prospects (see Doctor Huber's Revenge).

Marconi PLC http://www.marconi.com recently set up a business unit called Marconi-Solstis to develop Soliton-based transport systems. The business unit comprises key staff from Aston University’s photonics lab in the UK. “We should have a system ready for field trials within a year,” says Professor Nick Doran, the unit’s CTO. In the past, Doran's team at Aston University has run 10 Gbit/s over 16,500 kilometers of un-repeatered standard fiber, and 40 Gbit/s over 1,000 kilometers.

Qtera Corp. http://www.qtera.com, acquired by Nortel Networks http://www.nortelnetworks.com, is adapting undersea cable technology for terrestrial use. Earlier this year , it claimed a record 4,000-km for 10 Gbit/s transmission (see http://www.qtera.com/sets/set_nortel_ultra_3-7-00.htm).

Pirelli Optical Systems, acquired by Cisco Systems Inc http://www.cisco.com is developing ultra-long distance 10 Gbit/s transport technology, according to Pioneer’s Clavenna. However, Cisco will offer it packaged with its routers as a complete solution, not as a standalone product, he adds. Cisco won’t go head to head with Ciena Corp http://www.ciena.com and Sycamore Networks Inc. http://www.sycamorenet.com, both of whom have their own long distance transport technologies, according to Clavenna.

Optimight Communications Inc http://www.optimight.com, a startup founded by the legendary entrepreneur Wu-Fu Chen, is planning a different approach to long distance optics. It’s using code division multiplexing to enable it to use a broader range of frequencies for carrying each wavelength, without suffering interference between adjoining channels. At the same time, it’s using higher power lasers. This approach is particularly appropriate when transporting light through all-optical switches in mesh networks, according to Clarel Thevenot, Optimight’s director of marketing. Optimight is still in stealth mode, and won’t say what sort of performance it will deliver. It expects to start lab trials at the end of the year.

Xtera Communications, Inc http://www.xtera.com, another startup in stealth mode, says it plans to offer high bandwidths as well as long distances. "Usually, you only get one or the other," says Paul Harrison, Xtera's VP of marketing. The big bandwidths will be delivered using Raman technology "but not in the way it's used today." Xtera will use "something totally different" to achieve ultra long reach, Harison adds.

Photonex Corp. http://www.photonex.com, another startup in stealth mode, is also developing ultra-long-distance optical transport systems.

By Peter Heywood, International Editor, Light Reading, http://www.lightreading.com

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