Warning: Tunable lasers are just the start

Tunability in multiple forms will finally make the difference for high-value networks.

May 1st, 2003

While riding the escalator, I quipped to John Clark, president of Iolon, that he and other tunable-laser makers were the happiest folks at an otherwise sober show. We were on our way to a session on tunable lasers at the Optical Fiber Communications conference (OFC; Atlanta, GA; March 23–28). "We're delusional," Clark said with a laugh. In fact, tunable lasers are moving into field deployment, primarily for sparing and remote provisioning. More important, service providers see tunable lasers as key tools for driving a return to profitability.

The service providers face a broken business model in which bandwidth demand continues to grow at 50% to 100% per year, but revenues remain flat at best and profitability looks difficult to achieve. In addition, business opportunity has shifted from long-haul networks to more competitive metro, access, and enterprise networks—arenas where the types of services offered are critical to success. As most companies now recognize, this business climate means that technology is less important than economics, so the value proposition of a product, along with the premium it commands, are closely scrutinized.

What they want

Stuart Elby, executive director of next-generation architecture at Verizon, says that wavelength tunability affords lower capital and operating expenditures, in addition to network flexibility needed to meet a steady flow of new orders, especially for 10-Gbit/s transmission. He estimates that a dynamic network, enabled by tunability, could provide savings of 35% in capital costs, although it may take several years to see the benefits.

Speaking at an OFC Market Watch session, Elby went down the standard list of applications for tunable lasers, including sparing, dynamic wavelength provisioning, and protection switches. But the one that stood out for me was reconfigurable optical add/drop multiplexers (ROADMs). These subsystems allow flexible provisioning from carrier nodes, with some wavelength bands passed through and some dropped or added. They can also be implemented incrementally and may displace the need for more expensive optical crossconnects.

The rub for the component makers is that Elby wants wideband tunable lasers for no more than a 10% to 15% premium over fixed-wavelength lasers and associated electronics. This is not the scenario that investors and startups had in mind for tunable lasers several years ago. An initial high premium was expected for tunable capabilities, and costs would drop as volume rose. However, service providers like Verizon are now in a position to squeeze suppliers on price. In addition, they're not willing to pay much of a premium for a technology that, while beneficial, requires substantial investment in related electronics and system controls. So it turns out that for tunable lasers to succeed, more than just the laser has to be tunable.

For their part, tunable-laser companies have been making every effort to accommodate their customers, and create a stable design and manufacturing infrastructure. Prices for wideband and narrowband tunable lasers have become more competitive with fixed-wavelength lasers; multisource agreements (MSAs) have been signed by numerous companies for both transceivers and transponders; and the OIF is coming to agreement on numerous specifications.

Lasers are not enough

These developments, however, are not yet enough to spark widespread deployment in dynamic networks. The links still developing include the ROADMs that Verizon seeks, along with related components such as dynamic gain equalizers, variable optical attenuators, and tunable dispersion compensators. And wideband tunable filters, the last piece, are just coming into their own as commercial products. Some tunable laser makers have even realized that they could produce a tunable filter to complement their lasers and provide a more complete solution for service providers.

It would be nice to think that all the innovation and investment that have gone into creating tunable lasers—and tunable-laser companies—will translate into value for customers and financial rewards. But instead of proving to be a disruptive technology, tunable lasers now look like the harbinger of a progressively growing fabric of tunable components and subsystems that will provide the value for which customers will pay a premium.

Conard Holton is editor in chief of WDM Solutions, and executive editor of Laser Focus World; e-mail: cholton@pennwell.com.

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