In it for the short haul

W. Conard Holton

Associate Publisher/Editor in Chief

cholton@pennwell.com

If the words "metro" or "metro/access" seem ubiquitous in this issue, they are. The same sense was evident at the recent National Fiber Optic Engineers Conference in Denver, the European Conference on Optical Communications in Munich, and numerous other conferences over the past year. While the extent to which metropolitan WDM systems will be deployed is still an open question, component and system manufacturers are certainly rushing products to market.

At first glance, metro networks should offer a rewarding field for wavelength-division multiplexing technology. Metro WDM provides a way of breaking down the huge flow of information delivered by long-haul dense WDM networks into manageable slices for consumption by institutions and enterprises. These end-users want just the right amount of bandwidth exactly when they need it-the so-called bandwidth- and wavelength-on-demand services.

As described by Neil Dunay at KMI, the first deployments of metro DWDM systems are just under way, with point-to-point interoffice transport the initial application, followed by ring configurations with optical switches for restoration and protection. Yet the technical challenges to this service provisioning are formidable. There are enough real differences between the requirements of long-haul and metro that some new or modified technologies are needed.

Coarse WDM is an alternative to DWDM in metro networks. According to James Campbell at Tsunami Optics, the descriptor "coarse" is a misnomer in that the technology is not rough but rather offers cost advantages because it is unamplified and uses uncooled lasers.

The high price tag is the biggest limitation that metro carriers face in deploying WDM networks. As a result, component companies are rolling out products that can add more value by integrating several functions or offering new capabilities. Brian Lawrence and Michael Shimazu at Molecular OptoElectronics discuss the potential advantages of adding erbium-doped waveguide amplifiers to metro networks. Charles Duvall at Bandwidth9 shows how tunable vertical-cavity surface-emitting lasers can add flexibility to metro network design.

This issue also contains articles on other tools for both metro and long-haul WDM system designers, including circulators, which can reduce system complexity and provide add/drop functions (see p. 47), and polarization controllers, which address impairments that threaten system performance (see p. 63). CAD software, as readers know from our coverage every issue, is proving to be the essential tool for designing and integrating all these components while understanding their system effects (see p. 41).

More to come in 2001

After a short sabbatical, I`m happy to be back at WDM Solutions, which has continued to grow at a very fast clip. Many thanks to Steve Anderson for a great job on the last two issues. All of us at PennWell are looking forward to 2001, when this magazine will be published 10 times (excluding July and December).

WDM Solutions has kept its commitment to designers, engineers, and engineering managers. We aim to have articles that are technical and readable, with a focus on WDM components and subsystems. Yet as the magazine grows we will be adding new features, such as this month`s Perspectives column on coarse WDM. Look for more additions next year. And if you have an idea for an article you`d like to contribute, drop me line.

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