Optical/IP Networks

Pushing the Limits on Optical Monitoring

Startup BTI Photonics Inc. is hoping to make a bit of a splash at the upcoming Supercomm 2002 show by telling the world how its subsystem can provide optical monitoring capabilities that it claims will go far beyond what's available today.

This also gives the company a second opportunity to explain what it is actually making; it was tough to figure that out from its previous press release, at the OFC show in March (see BTI Offers OLS).

To be fair, the OLS (optical link subsystem) is a complicated bit of kit. It does more than just optical monitoring -- it also integrates a slew of other functions, including optical amplification, dynamic gain equalization, dispersion compensation, and others that have yet to be disclosed.

The aim is to make life simpler for original equipment manufacturers (OEMs) of transport gear by integrating all of these functions into a single platform that can be addressed by their network management system. Traditionally, OEMs have done this integration for themselves. Using the OLS could shorten their time-to-market and cut costs, because they won't need to employ as many engineers.

"It's the first time traditionally discrete network elements have come together in a network-ready solution as a managed element, independent of the specific terminal equipment," the company boasts.

The development of BTI's subsystem is a rather convoluted tale. The company was founded in 1997 and started out developing Erbium Doped-Fiber Amplifiers (EDFAs), but by the time it was ready to sell them the components market had collapsed. "Nine months ago was a very difficult time to enter the market as an EDFA manufacturer," president and CEO Lance Laking notes wryly.

The one area in which BTI got traction was test and measurement. In addition to offering its amplifiers as standard gain-blocks, it offered a rack mount system and included a user interface so they could be used in testing houses.

As a result of this engagement, BTI got drawn into discussions with systems vendors, which were struggling to integrate amplification with other functions in their boxes, Laking says. Typically, they wanted to include dynamic gain equalization, to balance the power levels inside the amplifier, and optical monitoring, to calculate the degree of attenuation for each channel.

BTI decided to take the idea one step further. Rather than just correcting for attenuation, which is one instance of signal impairment in optical fibers, why not create a subsystem that corrects for all possible degradation issues, including Chromatic Dispersion and Polarization Mode Dispersion (PMD)?

Bringing all these functions together made perfect sense, Laking contends. Signal conditioning is typically very lossy, so it is sensible to combine it with amplification. Optical performance monitoring complements both functions, because it creates a feedback signal for controlling them.

Equally important, however, is the fact that the OLS incorporates remote network management. When combined with optical monitoring, this creates a powerful way to troubleshoot optical links, the company claims. This is what BTI will be talking up at Supercomm.

Currently, systems vendors have to source an expensive box from test equipment vendors in order to check the health of their optical links. This gear, which is placed at the ends of the link, can tell the vendor whether the link is working, but it cannot be used to test points along the link.

It would be much more cost effective, Laking contends, for carriers to use built-in test gear to locate faults and to monitor performance in real-time, so potential future faults can be avoided. BTI's gear will do this by offering remote reporting from multiple points along the link.

BTI's pitch isn't unique: Startup Lightchip Inc. also offers remote optical monitoring subsystems, which apparently scored quite a hit with Cisco Systems Inc. (Nasdaq: CSCO) (see Why Cisco Loves Lightchip). "It's the only company with software anything close to what we're offering today," Laking acknowledges.

The key difference is that BTI's gear does amplification and signal conditioning, whereas Lightchip's does wavelength multiplexing. "The two approaches are potentially complementary," says Laking, inadvertently revealing that the two companies have been discussing ways in which they might work together.

A second important distinction, says Laking, is that BTI has designed a modular system comprising a management module and what BTI calls "circuit packs": plug-and-play modules that can be EDFAs, tunable dispersion compensators, PMD compensators, optical channel monitors, or any other technology it cares to introduce. The customer can choose the combination of circuit packs that suit his application, and address them all using a single interface.

A single 2U-high unit has space for six circuit packs, the company says. By ganging units together, the subsystem can support up to 115 circuit packs.

To make this idea a reality, however, BTI needs to partner with other vendors to supply the technology it doesn't have in-house. BTI takes the core technology from its partners and packages it in the compact circuit-pack form.

So far, BTI has signed up LightConnect Inc. for dynamic gain equalization (see BTI, LightConnect Team on DGE). It's also closing in on partnerships with a vendor of optical channel monitoring gear and chromatic dispersion compensation, which it hopes to be able to announce at Supercomm.

"The opportunity to partner is huge," says Laking. "There are lots of companies with really cool technologies. We provide them with a route to market."

The snag? OLS won't be available for some time. BTI hopes to start the first customer trials before the end of June. But the subsystem won't become all-singing, all-dancing until more partners have signed up and had their technology redesigned into circuit packs, which then must be manufactured and qualified.

BTI is funded by BCE Capital, Kodiak Venture Partners, Lucent Venture Partners Inc., Primaxis Technology Ventures Inc., and Purple Angel, a group of former Nortel Networks Corp. (NYSE/Toronto: NT) executives (see BTI Photonics Funding Hits US$7.8M). Skeptics might say that it's making a big fuss now because it needs to raise a new round of funding before it can get the product into production.

— Pauline Rigby, Senior Editor, Light Reading
http://www.lightreading.com For more information on Supercomm 2002, please visit: Supercomm Special

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