How to Teach Old Fiber New Tricks

Don't underestimate the cable industry's role in next-generation network development.

CableLabs has started a new R&D project aimed at radically expanding bandwidth capacity in the access network. The kicker? The technology applies not just to cable infrastructure, but to any type of access architecture.

Called coherent optics, the new work coming out of CableLabs adapts techniques used in long-haul optical networks to the much shorter links deployed closer to broadband subscribers. For a cable operator, this means the fiber network segment between a cable headend and a cable node. However, the same technology could be implemented in a telecom access environment just as easily.

Coherent optics works by using multiple dimensions within an optical carrier to transmit information. What that boils down to is an ability to create more capacity in each wavelength, which can then be combined with other wavelengths in a fiber strand to deliver significantly greater bandwidth to an optical endpoint. (See New CableLabs Optical Tech Promises Big Bandwidth Boost.)

How much more bandwidth?

"In the lab we have reached 2 terabits per second -- 2,048 gigabits per second over eight wavelengths, [or] eight optical carriers," says CableLabs Distinguished Technologist Alberto Campos. "But these optical carriers are closely spaced. We don't occupy too much of the spectrum resources that you have in fiber, so potentially you could occupy significantly more of the fiber spectrum, and have significantly more capacity. Or you [could] also improve the efficiency on a per-optical-carrier basis and increase capacity like that. So there is a lot of room for improvement. This is just the beginning."

Just the beginning is right. CableLabs hasn't even formed a working group to advance the coherent optics project yet, but it expects to do so in late spring or early summer. The group will likely consist of traditional cable vendors, but also newer entities to the CableLabs family including optical transceiver companies. Following the group's efforts, CableLabs will eventually publish technical specifications to be shared with the industry as a whole.

— Mari Silbey, Senior Editor, Cable/Video, Light Reading