Coherent Technology, Automatic Power Balancing Expand Optical Network Capabilities

By Paula Bernier

Optical networking continues to move forward as the supplier community comes out with new advancements in the areas of coherent optics, automatic power balancing for DWDM networks and other innovations that enable higher bit rates over increasingly longer distances.

For example, Fujitsu Network Communications recently unveiled the third generation 40gbps optical interfaces for its FLASHWAVE 7500 ROADM. These interfaces, which incorporate advanced coherent detection technology and DP-QPSK modulation, will allow for larger geographic networks with longer optical spans and eliminate the need for dispersion compensation modules.

The FLASHWAVE 7500 is an optical hubbing and transport solution deployed in telecom and cable networks to support core network consolidation, metro/regional capacity relief, and triple-play service delivery. It supports spans from simple two-degree ROADM ring networks to advanced 12-degree optical hubbing/mesh applications. And it allows for network sizes of up to 1200 km, up to 24 add/drop nodes per network, and a capacity of up to 1.6tbps.

"Fujitsu has been the leader in optical communications patents for four consecutive years thanks to our sizeable investment in core optical R&D," says Bill Erickson, senior vice president of planning and development at Fujitsu Network Communications. "We first introduced 40gbps interfaces in 2007 and with the introduction of these third-generation units, Fujitsu continues to back up our R&D investment with commercially available product innovations that significantly advance high-speed optical networking options."

Ron Kline, principal analyst of network infrastructure at Ovum, says the market for 40gbps transport gear surpassed $500 million in 2009, and expects the market to double in 2010 and exceed $3 billion by 2014.

"The latest Fujitsu 40G products respond to evolving and growing market needs for systems with higher tolerance to dispersion while at the same time shortening the 100gbps developmental cycle," he says.

In other recent 40gbps news, XO Communications has announced plans to deploy Nokia Siemens Networks' 40gbps dense wavelength division multiplexing solution. That involves the NSN hiT 7300 platform, which will enable XO Communications to respond in a timely fashion to changes in traffic demand.
The hiT 7300 is based on a common hardware platform, which saves staff training time and opex, and reduces the number of spare parts needed to be stocked. To accommodate the continued growth in data traffic on the XO network, the hiT 7300 platform provides network flexibility and capacity that can be extended to 80x40G to meet future requirements.

"Nokia Siemens Networks' 40G DWDM solution is optimized for the increased bandwidth and faster connectivity needs of today's networks," says Randy Nicklas, chief technology officer at XO Communications. "The hiT 7300platform provides a smooth evolution path to 100G, the next step in optical transport technology and the next step for the XO network."

Also on the DWDM front, Optelian has announced the availability of automatic power balancing. This enables automatic power measurement and adjustment on DWDM networks, eliminating the need for a technician to travel to every node in a network with optical spectrum analyzers, which creates significant cost savings. Whenever new channels are added to a DWDM system, the optical power levels of all other channels are affected, so this automatic power adjustment capability is an important innovation.

"The great advantage of Optelian's power balancing capability is its cost effectiveness and ease of implementation," said Dave Mills, vice president of sales at Optelian. "It pays for itself very quickly when there is growth or change on any multi-node DWDM network, especially when the network spans a large geographic area.

"The automatic power balancing is a feature of Optelian's RDM-2x1 wavelength selective switch together with the OCM-40 optical channel monitor. It can be used with any vendor's DWDM system, including Optelian's own LightGAIN system.

Also this spring, NeoPhotonics made available its Integrated Coherent Receiver for 100gbps and 40gbps transmission systems. This solution provides advanced demodulation to analyze the state-of-polarization and optical phase of a phase-modulated signal relative to an externally supplied optical reference. That enables recovery of the phase-polarization constellation of 100gbps DP-DQPSK format signals.

"We are pleased to add the ICR to our existing line of PIC products for high-speed transmission systems. We utilize our hybrid PIC technology to combine an integrated dual 90 Hybrid Coherent Mixer with four balanced photodiodes and the requisite linear amplifiers in a single compact package," says Tim Jenks, chairman and CEO of NeoPhotonics.

Elsewhere on the optics scene, Alcatel-Lucent's Bell Labs demonstrated at the recent Optical Fiber Conference in San Diego, Calif., innovations involving the application of higher-order modulation techniques, use of multi-stage algorithms and increased spectral efficiencies that enable the transmission of significantly higher bit rates over increasingly longer distances.

Also on the optical front, Metaswitch says it offers the industry's first portable protocol solution for signaling and routing in G.709 Optical Transport Networks.

"Metaswitch's OTN control plane technology is available today to our MPLS and IP routing customers as a straightforward, in-service software upgrade," says Jonathan Hardwick, director of product management for Metaswitch's Network Protocols Division. "This enables our customers to introduce an industry standard OTN control plane solution in the fastest time possible."

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