How scaling optical networks is soon to change

Carrier division multiplexing and spatial division multiplexing (CSDM) are both needed, argues Lumentum’s Brian Smith.

The era of coherent-based optical transmission as is implemented today is coming to an end, argues Lumentum in a White Paper. 

Brian Smith

The author of the paper, Brian Smith, product and technology strategy, CTO Office at Lumentum, says two factors account for the looming change.

One is Shannon’s limit that defines how much information can be sent across a communications channel, in this case an optical fibre.

The second, less discussed regarding coherent-based optical transport, is how Moore’s law is slowing down.

”Both are happening coincidentally,” says Smith. “We believe what that means is that we, as an industry, are going to have to change how we scale capacity.”

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Nokia jumps a class with its PSE-6s coherent modem

• The 130 gigabaud (GBd) PSE-6s coherent modem is Nokia's first in-house design for high-end optical transport systems 
• The PSE-6s can send an 800 gigabit Ethernet (800GbE) payload over 2,000km and 1.2 terabits of data over 100km.
• Two PSE-6s DSPs can send three 800GbE signals over two 1.2-terabit wavelengths

Nokia has unveiled its latest coherent modem, the super coherent Photonic Service Engine 6s (PSE-6s) that will power its optical transport platforms in the coming years.

The PSE-6s comes three years after Nokia announced its current generation of coherent digital signal processors (DSPs): the PSE-Vs DSP for the long-haul and the compact PSE-Vc for the coherent pluggable market.

Nokia is only detailing the PSE-6s; its next-generation coherent modem for pluggables will be a future announcement.

Nokia will demonstrate the PSE-6s at the upcoming OFC show in March while field trials involving systems using the PSE-6s will start in the year's second half. 

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Infinera’s ICE6 crosses the 100-gigabaud threshold

Coherent discourse 3

• The ICE6 Turbo can send two 800-gigabit wavelengths over network spans of 1,100-1,200km using a 100.4 gigabaud (GBd) symbol rate.
• The enhanced reach can reduce the optical transport equipment needed in a network by 25 to 30 per cent.

Infinera has enhanced the optical performance of its ICE6 coherent engine, increasing by up to 30 per cent the reach of its highest-capacity wavelength transmissions.

Ron JohnsonThe ICE6 Turbo coherent optical engine can send 800-gigabit optical wavelengths over 1,100-1,200km compared to the ICE6’s reach of 700-800km.

ICE6 Turbo uses the same coherent digital signal processor (DSP) and optics as the ICE6 but operates at a higher symbol rate of 100.4GBd.

“This is the first time 800 gigabits can hit long-haul distances,” says Ron Johnson, general manager of Infinera’s optical systems & network solutions group.

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COBO: specification work nearing completion

The Consortium for On-board Optics (COBO) is on target to complete its specifications work by the year end. The work will then enter a final approval stage that will take up to a further three months.

On-board optics, also known as mid-board or embedded optics, have been available for years but vendors have so far had to use custom products. The goal of COBO, first announced in March 2015 and backed by such companies as Microsoft, Cisco Systems, Finisar and Intel, is to develop a technology roadmap and common specifications for on-board optics to ensure interoperability.

Brad Booth (pictured), the chair of COBO and principal architect for Microsoft’s Azure Global Networking Services, says that bringing optics inside systems raises a different set of issues compared to pluggable optical modules used on the front panel of equipment. “If you have a requirement for 32 ports on a faceplate, you know mechanically what you can build,” says Booth.

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OIF starts work on a terabit-plus CFP8-ACO module

The Optical Internetworking Forum (OIF) has started a new analogue coherent optics (ACO) specification based on the CFP8 pluggable module.

The CFP8 is the latest is a series of optical modules specified by the CFP Multi-Source Agreement and will support the emerging 400 Gigabit Ethernet standard.

Karl GassAn ACO module used for optical transport integrates the optics and driver electronics while the accompanying coherent DSP-ASIC residing on the line card.

Systems vendors can thus use their own DSP-ASIC, or a merchant one if they don’t have an in-house design, while choosing the coherent optics from various module makers. The optics and the DSP-ASIC communicate via a high-speed electrical connector on the line card.

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