Optical building block shipments top 10k

JDS Uniphase's announcement that it has shipped over 10,000 reconfigurable optical add/drop multiplexers (ROADMs) marks the increasing use of agile networking at the network's optical layer. But Europe is lagging when it comes to using such devices.

"European carriers are somewhat behind," Sinclair Vass, JDSU's director of EMEA for optical communications, told NGN. "There are some trials by European carriers but no hard deployments."

One reason why European carriers have yet to adopt ROADMs is that metro rings are generally too small to warrant them. Bandwidth requirements are growing but still not enough for carriers to embrace ROADMs. But Vass expect deployments to start in 2007.

ROADMs deliver several benefits to the network. They reduce the need by carriers to plan traffic patterns, and they reduce provisioning times. The newer ROADM systems also extend performance and support multiple protocols and services efficiently.

There are three main ROADM types: the traditional wavelength blocker which passes or drops light paths (and have degree 2 connectivity), the planar lightwave circuit (PLC) based ROADM that uses optical integration techniques to reduce cost, and which also has degree two connectivity, and the sophisticated wavelength-selective switch which offers a higher degree of connectivity and typically is used to connect metro rings.

The majority of the 10,000 ROADMs shipped by JDSU are wavelength-blocker-based designs, used for long-haul DWDM mainly. But by mid-2007, it will be superseded by the newer PLC and wavelength-selective switch ROADMs.

Meanwhile, certain North American operators are enquiring about miniature ROADMs. These will support fewer wavelengths - typically 4 and maybe 8 - for use at the network edge.

Why is there a need to add or drop wavelengths right at the network edge? It's a question of what the traffic looks like in the network and its predictability, says JDSU. Carriers may say they need such tiny ROADMs but the expectation is that they will be deployed from 2009 at the earliest.