By KATHLEEN RICHARDS
The promise of tunable lasers in metropolitan-network applications has been touted by many companies-laser manufacturers and system startups-in the past year. These metro DWDM systems integrate tunable lasers to support intelligent bandwidth-on-demand applications, a departure from the technology's initial use as a cost-effective way to replace or spare the fixed lasers required for individual wavelengths. Finally, metro DWDM systems that integrate tunability are beginning to reach the market.
The first metro system to integrate tunable lasers was unveiled by Atoga Systems (Fremont, CA) at SuperNet, a communications conference held in Santa Clara, CA, in mid-January. Atoga's entry is the first product for the startup company, which was founded in December 1999 and has nearly 100 employees.
Atoga's Optical Application Router 5 (OAR 5), is an intelligent WDM edge device that routes voice and data traffic to either the metro core or the optical backbone, depending on where DWDM lies in the network. As such, it uses widely tunable lasers (up to 40 channels with 100-GHz channel spacing) for dynamic wavelength selection to enable bandwidth on demand for customers, as needed. The tunable lasers allow metro service providers to create multiple topologies in a physical ring. The OAR 5, in beta testing with service providers since January, is scheduled to be available this month.
The tunable-laser technology used in the Atoga system is acquired through a partnership with Agility Communications (Santa Barbara, CA). Last November, Agility announced a 4-mW widely tunable laser, the Agility 3040, which can tune to more than 100 ITU channels with 50-GHz channel spacing. The laser uses an indium phosphide chip manufactured at a wafer fab in the company's headquarters. Packaging takes place at the company's fully automated manufacturing facility in Allentown, PA.
"Tunability has two fundamental benefits," says Atoga CEO Cuneyt Ozveren. "It allows you to scale the network incrementally. To go from OC-48 to OC-192 with SONET, you have to rip out everything. Tunability allows you to add lasers to your network and increase the network capacity without the truck roll; you only need to add lasers where you need extra capacity and retune to match the traffic distribution."
"The second benefit is true dynamic provisioning. An analogy is when bridges get congested, they can [add or subtract] lanes; by retuning the lasers in the network based on what the traffic distribution is, you can allocate your traffic very dynamically."
The tunable-laser technology-among other features of the product like WDM and the capability to support per-application, per-customer service-level agreements-sets it apart from the current offerings of other companies in the metro-access device category. This differentiation may be just what the company needs in the crowded market, with companies such as Lucent Technologies, Nortel Networks, Appian Communications, and Mayan Networks competing for metro customers. Some of the issues with tunable lasers focus on cost-important in the metro market-and manufacturability.
"The OAR 5 is the first system to integrate tunable lasers, a long talked-about technology with a newness and expense that have, so far, kept the components out of metro systems," notes a market report by industry analyst G. Hansen of Current Analysis (Sterling, VA).
"The inclusion of tunable lasers in the OAR 5 gives customers a degree of provisioning flexibility that they have not had in previous offerings on the market," the report continues. "With the ability to scale optical networks on demand, customers will likely find more revenue opportunities...With carriers not finding the necessary profit return from selling bandwidth alone, the application stance of the OAR 5 is good positioning entering the market. With per-flow policing, bandwidth metering, four-level CoS [class- of- service] application-based pro visioning, and the benefits of tunable lasers, the OAR 5 has a very well-rounded application story coming to the market...Due to the inclusion of tunable lasers in the OAR system, the price points of the Atoga offering are likely to be higher than competing solutions. These competing solutions do not offer the same value proposition to carriers, however."
In his competitive analysis, Hansen states in his report, "All competitors in this space need to respond to the inclusion of tunable lasers in the OAR 5. Competitors will have to either set a product road map as to when they plan to include similar functionality in their own systems or refute the benefits of tunable-laser technology as simply being too expensive to be cost-effective or just not needed in the metro environment."
The OAR 5 condenses the functionality of several systems from the SONET, Internet Protocol, and WDM layers into a single box and enables top-down provisioning, counters Atoga's Ozveren. "In a commodity business, carriers were dishing out huge capital investments to build their networks, and the market could not sustain this. This shifted the industry focus to getting more revenue from existing customers by focusing on applications and services. Tunability helps tremendously, because it increases the number of applications that you can enable in the network."
Other companies expected to offer metro DWDM systems, which integrate widely tunable laser technology, include Network Photonics, Mahi Networks, and Zaffire. Like Atoga, these three companies have also partnered with Agility Communications.
These DWDM systems are designed to reside in the core of the metro network, an area frequently described as a traffic bottleneck. Arlon Martin, vice president of marketing at Agility, describes this portion of the network as distances of up to 100 km that connect back into the cross-continental links.
The service providers most likely to adopt these systems are the more "innovative" carriers such as MCI WorldCom, Qwest Communications, Sprint, and Williams Communications, according to Martin. "It's not the RBOCs [regional Bell operating companies]; life is not changing that quickly for them. What we are going to see during the year 2001 is a lot of field trials of widely tunable lasers. We expect to see deployment in networks carrying live traffic between the fourth quarter of 2001 and the beginning of 2002."
Meanwhile, the cost debate continues as the technology moves closer to becoming a market reality. "One of the concepts that has been a challenge for us is that the price of tunable lasers has to equal the price of fixed lasers," says Martin. "The price delta could be 20% to 30%, others say the premium is more like 100%. Our strategy is to be kind of between those two points. Basically, there are lots of applications where the tunable laser substantially-even at 2x-reduces the cost of systems and makes them far simpler. With things like routers, optical switches, and optical add/drop multiplexers, the tunable lasers actually remove lasers and other components from these systems; tunable lasers collapse the architectures and make them simpler than they are today. The laser price is about 10% or so of the total system cost, but even if the laser price is higher, the end user is looking at features that offer far more capability to the customer."