LaserComm device manages dispersion

Many big enterprise users that are starting to consider high-speed optical network services are those with the farthest-flung locations.

But distance creates a chronic problem in optical networks as light pulses tend to spread out and bump into each other. That's why LaserComm, a 3-year-old maker of optical modules, is offering service providers a fix to the problem

LaserComm's Hi-Mode Dispersion Management Device (DMD) manages chromatic dispersion, which is a broadening or spreading of light pulses as they are propagated through fiber. Dispersion can cause some pulses to overlap, resulting in transmission errors caused by an inaccurate read of the pulses by the receiver.

Chromatic dispersion becomes more of an issue as light travels across longer distances and at higher bit rates. Indeed, the trend in optical networking is to increase the speed from 10G bit/sec to 40G bit/sec, increase the capacity of a single fiber to 160 channels, and extend distances from 400 kilometers to 2,000 kilometers before electrical regeneration is required.

DMD takes into account that dispersion differs for every wavelength in a fiber, on the conventional band and long band. This results in a dispersion "slope."

Vendors of optical gear, such as dense wave division multiplexers (DWDM), usually offer dispersion compensation modules (DCM) with their products to minimize the impact of dispersion. These modules only partially correct the dispersion slope, LaserComm claims.

By only partially correcting the dispersion slope, typical DCMs require network operators to deploy more regenerators, multiplexers and demultiplexers because the optical span is limited.

Hi-Mode DMD fully corrects the slope, and full slope correction increases fiber span distances, obviating the need for additional signal regeneration and wavelength multiplexing gear, the company claims.

Hi-Mode DMD will compete with DCMs from Corning and Lucent. The product is targeted at vendors of DWDM systems and network service providers.

Hi-Mode DMD is in field trails with carriers and systems integrators. It will be available later this quarter. LaserComm has not yet released pricing.

This story, "LaserComm device manages dispersion" was originally published by Network World.

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