There's two ways of developing metro DWDM gear - scaling down long-haul gear, or scaling up its short-haul equivalent.

Vendors have tried the first option -- and it didn't work. Prices were too high. Now, startup Novalux Inc. http://www.novalux.com is helping vendors try the second option. It's scaling up laser technology that's already been used in LAN environments, with a view to tackling the key issue for metro nets - cutting costs.

Here's the details: Novalux is making pump lasers - ones that ram short-wavelength light into the outer casing of fiber amplifiers to boost the strength of the light pulses traveling through the core. And it's doing this by adapting so-called vertical cavity surface emitting lasers (VCSELs) typically used in LAN environments.

Using VCSEL technology slashes costs, according to Novalux. That's because the light from the lasers comes out of the top of the substrate that it's made from, which means that each laser chip can be tested to see whether it works while it's still part of a wafer. If it doesn't work, it can be discarded without proceeding further.

This isn't the case for other types of laser, where the light is discharged out of the edge of the substrate. In that case, the chip has to be cut out of the wafer and enclosed in packaging before it can be tested. If there are a lot of duds, costs mount, because packaging often accounts for two-thirds of the cost of the laser, according to Novalux.

The big problem with VCSELs is that they're normally low power, which is why they're used in LANs and not telecom networks. Novalux claims to have solved this problem by using electrical pumping and increasing the area that emits light within the laser. It says it can double output in this way.

The proof will come at the end of the year, when Novalux aims to ship its first lasers. In the long term, it also plans to develop a tunable VCSEL laser, but that could take a couple more years.

by Marguerite Reardon, senior editor, Light Reading

http://www.lightreading.com