Infinera introduces flexible grid 500G super-channel ROADM

Infinera has unveiled a flexible grid, reconfigurable optical add/drop multiplexer (ROADM) to complement its DTN-X optical networking platform.

An example showing the impact of a 500G super-channel ROADM node. Source: Infinera

"The FlexROADM will open up the Tier-1 operators in a way Infinera has not been able to do before," says Dana Cooperson, vice president, network infrastructure at market research firm, Ovum. "The DTN-X was necessary but not sufficient; the ROADM is the last piece."

The FlexROADM is claimed to deliver two industry firsts: it can add and drop flexible-grid-based 500 Gig super-channels, and uses the Internet Engineering Task Force’s (IETF) spectrum switched optical networks (SSON).

"SSON is the next generation of WSON [Wavelength Switched Optical Network control plane], except it manages spectrum," says Ron Kline, principal analyst, network infrastructure also at Ovum.

The DTN-X platform combines Infinera's 500 Gig photonic integrated circuits and OTN (Optical Transport Network) switching. With the FlexROADM, Infinera has added switching at the optical layer in 500 Gig increments. Infinera can now offer enhanced multi-layer network optimisation with the combination of electrical and optical switching.

"Optical bypass before was manual using patch cords, now operators can reconfigure with the FlexROADM," says Kline. "It also provides new optical restoration capabilities that Infinera did not have."

The FlexROADM supports up to nine degrees, and is available in colourless, colourless and directionless, and full colourless, directionless and contentionless (CDC) versions.

"The debate about contentionless continues," says Kline. "It is safe to assume that for the majority of applications flexible grid, colourless and directionless will be the high runner." Contentionless will be used by the big carriers, he says, but in certain locations only.

Infinera says the line system announced will support up to 24 Terabit-per-second (Tbps) when it ships in September. The maximum long-haul capacity using its current PM-QPSK super-channels is 9.5Tbps per fibre pair.

"In the future when we enable metro-reach super-channels using PM-16-QAM, they will support 24 Terabit-per-second per fibre pair using the line system we are announcing," says Geoff Bennett, director, solutions and technology at Infinera.

Bennett says the data rate and the spectral efficiency for a given sub-carrier can be varied depending on the reach required. The spacing between sub-carriers that make up a super-channel also can be varied depending on reach. Many different transmission possibilities exist, says Bennett, but to explain the concept, he cites two examples.

The 24Tbps capacity with PM-16-QAM modulation uses pulse shaping at the transmitter to achieve 'Nyquist DWDM' channel spacing, the spacing between channels that approximates the baud rate, says Bennett.

"At this time we are not disclosing the details of the channel spacing, or the number of sub-carriers used by our future line modules," says Bennett. "But the total super-channel spectral width is the equivalent of 200GHz if you are transmitting a one Terabit super-channel, for example." This equates to a spectral efficiency of 5b/s/Hz, and using 16-QAM, the reach achieved will be 600-700km.

"The system we have just launched is designed to operate in long-haul networks and uses PM-QPSK," says Bennett. "For an ultra long-haul reach requirement of 4,500km, the super-channel comprises ten sub-carriers; a total of 500 Gbps over a spectral width of 250 GHz." These line cards are available now, he says.

Infinera continues to make steady market progress, according to Ovum. The company is in the top 10 system vendors globally, while in backbone and 100 Gigabit, Infinera is fourth.