As the number of DWDM channels in optical networks multiplies, so do the number of fixed-wavelength lasers that are required to light them. This is a big problem for carriers, because it costs a lot of money to stock and manage inventory and spares for their systems. In fact, this problem prompted the development of widely tunable lasers (see Tune In!).

Early-stage startup KiloLambda Technologies Inc. has a new take on the problem. It is developing a laser subsystem that will deliver "hundreds or even thousands" of wavelengths simultaneously, according to its VP of marketing, Tzachi Ben-Gal. One of KiloLambda's subsystems could replace all the fixed-wavelength lasers in a DWDM system, he claims.

Too good to be true? Too early to say. Right now, KiloLambda's ideas are just that -- ideas. "We have 90 percent of the work done on the multiwavelength source, and expect to have prototypes in six months," says Ben-Gal.

It's worth pointing out that KiloLambda numbers only nine people, including the founders. The technology was invented by a father-and-son team, Moshe and Ram Oron, who started the company in February 2001.

But, despite its size, the company's founders appears to have influence -- Moshe Oron is the Israeli representative to the European Laser Network (Eulasnet), a collaborative effort among universities, R&D labs, and industry in Europe. He was previously the Israeli representative on the "Star Wars" project, President Reagan's misbegotten Strategic Defense Initiative of the 1980s.

Moshe, who holds the position of chief scientist, is also a part-time professor at the Technion-Israel Institute of Technology. His son, Ram, who recently gained a PhD from the Weizmann Institute of Science, is KiloLambda's CTO.

KiloLambda received an undisclosed amount of seed funding from Skypoint Capital Corp. and The Yozma Group. The startup says it has enough money to last two to three years and has no plans to grow until it makes its first sale.

Clearly, the company has its work cut out. Even if the product works as advertised, it still has to convince systems vendors and carriers of its usefulness.

KiloLambda has identified one application where its technology could give it the edge -- for increasing system capacity by using lots of channels crammed tightly together in frequency.

Right now, most carriers are considering OC768 (40 Gbit/s) systems as a way of increasing capacity while also cutting costs on their network. Although components for OC768 are more expensive than those for lower speeds, fewer components are required, so there should be an overall cost saving.

Other vendors have proposed using more channels rather than high-data rates to increase network capacity (see Essex Claims 4000-Channel DWDM and Essex Demos 40-Gig Alternative). But they always hit up against two problems. First, it's difficult to see how to reduce costs in high channel-count systems. When multiplying the number of channels, most of the components, and their associated costs, also have to be multiplied.

The second problem is that when channels are squashed together tightly, they start to interfere with each other. In order to get thousands of channels down a fiber, the data rate of each channel would have to be reduced to prevent crosstalk.

KiloLambda may have hit upon a way of solving, or at least mitigating, both difficulties. It's focusing on the lasers -- which makes sense, because lasers are one of the most expensive parts of an optical system. The startup is proposing a subsystem with just three basic building blocks. One of these is a laser; the company is keeping details of the other two under wraps.

As a result of volume advantages, its laser source might prove to be more cost effective to manufacture than today's fixed-wavelength lasers. In addition, only one laser source is needed per subsystem, and the two mystery building blocks might work out a lot cheaper to make than lasers -- although, of course, it's too early to tell if this will actually turn out to be the case.

KiloLambda claims that another key feature of its subsystem is that all the channels are extremely stable with respect to one another. "You only need to stabilize one channel, and the whole source is stabilized," says Ben-Gal. That's important, he explains, because it allows system bandwidth to be used more efficiently -- there's no need to leave dead space or "guard bands" between channels.

In the initial phase of development, KiloLambda plans to use channel spacings of 10 GHz to carry 10-Gbit/s signals -- for 100 percent bandwidth utilization. The International Telecommunication Union (ITU) standard for 100GHz channel spacing looks pretty inefficient by comparison. Every wavelength is allowed to move independently by 20 percent with respect to its center value, which effectively means that 40 percent of bandwidth is wasted.

— Pauline Rigby, Senior Editor, Light Reading
http://www.lightreading.com