The past is future

Service delivery has remained a constant requirement and ROADMs offer an option.

Nov 1st, 2003

If you had fallen into a deep sleep eight years ago—just before the U.S. Telecommunications Act of 1996 took effect—and woke up at the September 2003 National Fiber Optic Engineers Conference, you could be forgiven if you thought you had only dozed off. True, a revolution in optical communications technology and bandwidth capacity had taken place, and hundreds of new companies had come and gone. But these events might not be evident at first glance. Instead you might notice that the scale of the venue had changed from a modest downtown Boston convention space to the vast Orange County Convention Center in Orlando, FL. Yet the actual numbers of exhibitors and attendees at both shows were not so different, nor were the critical issues of the day.

The plenary talks in that long-ago Boston conference sound familiar, if slightly modified by developments in technology and jargon: Access Network Evolution—Cable vs. Telco; Video-on-Demand: Technologies and Services; Digital Video Trunking for Regional Networks; and Broadband Services: HFC or ADSL. However, the need to deliver these revenue-generating services was not as acute in 1995, when competition was just on the horizon, as now when there is a flood of wireline and wireless options.

Attendees at NFOEC 1995 also heard service-related talks about digital crossconnects to support SONET, fiber in the loop, and CATV initiatives. They learned about new technologies such as optical crossconnects, 10-Gbit/s transmission over standard fiber, and a multiwavelength reconfigurable all-optical network testbed.

Attendees at NFOEC 2003 heard similar talks about metro/access networking systems and systems management. In particular, attendees were drawn to developments in reconfigurable optical add/drop modules (ROADM), which carriers such as Verizon are beginning to deploy. These switching/blocking all-optical subsystems have been targeted at long-haul networks, but many companies are developing smaller (four- or eight-channel) ROADMs to provide service opportunities in metro applications.

The most common core technologies for ROADMs are MEMS and liquid crystals. For example, Active Optical Networks (Fremont, CA) exhibited its MEMS-based ROADM, while Arroyo Optics (Santa Monica, CA) described its liquid-crystal-based ROADM in private meetings. Corning (Corning, NY) had dominated the liquid-crystal switching market but dropped out earlier this year. Avanex (Fremont, CA), which bought most of Corning's optical component division, showed its own liquid-crystal waveblocker technology. Clarendon Photonics (Newton, MA) took a different tack with its waveguide-based ROADM. And in a traditional but reliable approach, Meriton Networks (Ottawa, Ontario) said that optical-electrical-optical conversion remains the best approach to ensuring add/drop performance monitoring and network management.

Off the exhibit floor in the technical sessions, researchers from Continuum Photonics (Billerica, MA) described the piezoelectric actuation of their MEMS-based beam-steering switch. Researchers from Movaz (Atlanta, GA) focused on all-digital drives for their MEMS-based switch. And a polymer planar lightwave circuit was the alternative approach described by researchers from DuPont Photonics Technologies (Wilmington, MA). Most ROADMs include a variable optical attenuation function.

A market survey by our sister organization, KMI Research, supports the hope that ROADMs will actually be deployed in substantial numbers. Metro and access carriers reported that the average number of optical add/drop modules in a network was 200 in 2003; by 2005, that number will more than double. In long-haul networks, the average number is currently 18 per network; by 2005 the number grows to 188. KMI believes that ROADMs will play an increasing role in new builds and retrofits, with more than 20% of the participants in their study saying that ROADMs would constitute 40% of their 2003 deployments of optical add/drop modules. By 2005, 31% of the participants expect to deploy more than 40% of their modules as reconfigurable.

Most people at NFOEC 2003 knew that attendance was an act of faith that market conditions will improve. As the past eight years have shown, no one can accurately forecast the future, but the essential need for services and related equipment is predictable.

Conard Holton is chief editor of WDM Solutions. He can be reached at cholton@pennwell.com.

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