Infinera, meanwhile, is making its subsea push via its DTN solution based on the company's 100-Gbps photonic integrated circuit (PIC) technology, which integrates several hundred components and supporting 10 x 10G channels (with 25-MHz channel spacing) in a single optical chip on a submarine line module (SLM) that can reach distances of 6,500 km.
"These 100-Gbps submarine line modules map any client service - 2.5G, 10G, 40G and in future 100G - over 100Gbps of PIC-based WDM capacity," explains Serge Melle, Infinera's VP of technical marketing. "The PICs carry information over ten wavelengths operating at 10 Gbps each, but users can use the bandwidth as if it was one combined pool of 100G, using as little or as much of that as they need for a given service."
On the downside - at least for now - that means Infinera's 40G solution is still essentially a 4x10G solution, notes Ovum analyst Ron Kline.
"Infinera's approach requires the use of four wavelengths, compared to other vendors that use a single wavelength to provide 20G or 40G services," he said in a research note. "This puts Infinera at a disadvantage over some of its rivals because four wavelengths must be used for one 40G circuit. This disadvantage will last until its own 40G PIC technology (expected to be released in 2H09) is made generally available and adapted for this application."
That said, Kline adds that Infinera does offer other potential benefits. "Replacing existing SLTE terminals with DTN also gives subsea cable operators the rapid provisioning features that are available with Infinera's terrestrial systems. Operators that deploy both terrestrial and SLTE products from Infinera stand to benefit from much reduced optical-electrical-optical signal conversion costs at landing stations."
Cable diversity
The catch - and you knew there would be one - is that upgrading subsea cable capacity is not quite as simple as plugging in a 40G SLTE card, according to the old-school submarine cable suppliers that built the systems currently in the water.
For example, says Olivier Gatutheron, R&D technical director for Alcatel-Lucent's submarine network business, some subsea fiber systems are simply not designed to support waves faster than 10G.