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12 September 2011
ADVA Optical Networking has launched a 100Gbps transmission card designed for metro applications. The firm claims it is an industry first: a direct-detection-based 100Gbps design using four 28Gbps channels. The metro card will be used to connect enterprise data centers and to transport 100 Gigabit Ethernet traffic between core routers.
The card is designed for the FSP 3000 optical transport platform and delivers two-and-a-half times greater spectral efficiency compared to standard 10Gbps DWDM systems. In turn, the 100Gbps metro card has half the cost of a 100Gbps coherent design while requiring half the power and space, the company claims.
ADVA is using a CFP optical module to implement the 100Gbps metro design. The CFP's four 28Gbps signals are modulated using an optical duobinary scheme, which is more resilient to dispersion than standard on-off keying. By choosing duobinary, cheaper 10Gbps optics can be used.
The CFP-based card uses 200GHz of spectrum for each 100 Gbps light path. As noted, this is 2.5 times more spectrally efficient than 10x10Gbps design based on 50GHz channel spacings. However, while the design is cheaper, denser and less power hungry than 100 Gbps coherent, it has only one quarter of the spectral efficiency of coherent.
Jörg-Peter Elbers, vice president, advanced technology at ADVA Optical Networking, says duobinary can deliver closer channel spacing, promising a doubling in spectral density in future designs, by using 100Gbps in a 100GHz channel. The 100Gbps metro card supports 500km links using dispersion-compensated fibre.
Non-coherent designs for the metro are starting to appear despite 100Gbps optical transport being in its infancy. Besides ADVA Optical Networking's design, a component vendor is promoting a 100Gbps direct-detection scheme for metro DWDM. The 10x10 MSA group has also announced a DWDM range extension that will support four and eight 100Gbps channels. Metro direct-detection designs also face competition from system vendors developing coherent designs tailored to the metro.
Elbers says samples of the card are available now with volume production beginning at the end of 2011.
By Roy Rubenstein