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8 September 2011
JDSU has integrated a tunable laser into an SFP+, the smallest pluggable optical transceiver form factor. The tunable SFP+ will span the C-Band and support 50GHz channel spacings. JDSU is demonstrating the tunable SFP+ to customers and expects the module to enter production in the next year.
The advent of a tunable SFP+ will enable more 10 Gbps interfaces to be crammed onto a line card for use in such platforms as IP routers, carrier Ethernet switch routers and Optical Transport Network (OTN) switches.
Packet-based and OTN platforms already use DWDM fixed-wavelength formats of SFP+ for backhaul or metro ring applications. “XFPs have been used on routers and OTN boxes - anything that has 10 Gig - and those have been migrated to SFP+ for compactness,” says Brandon Collins, CTO for communications and commercial optical products at JDSU. The expectation is that the next round of telecom equipment will use SFP+, and the tunable version, more widely.
JDSU says the optical performance of its tunable SFP+ will match that of its tunable XFP, which was launched in 2009. “We produced the XFP in a number of flavours, whether it is metro or long haul,” says Collins. “The initial versions of the SFP+ will likely be the metro reaches, 80km and things like that.”
In turn, the optical performance of a tunable XFP is only marginally less than that of a tunable 10Gbps in a 300-pin small form factor multi-source agreement (MSA) package. The 300-pin MSA has a better optical signal-to-noise ratio, meaning the signal can pass through more optical amplifier stages, but the XFP can achieve long-haul distances depending on how the optical link is designed. “You can push 1,000km,” says Collins.
The XFP specification has a maximum power consumption of 3.5W while for the SFP+ it is 1.5W.  JDSU admits that it may require another generation of design before it achieves 1.5W. “We are working with our customers to see what level they can tolerate,” says Collins. “We have to hit a lot less than 3.5W but it is not clear that we have to hit the MSA spec either.”  According to Collins, JDSU’s first design is already closer to 1.5W than 3.5W.
By Roy Rubenstein