DECEMBER 21, 2009 By Stephen Hardy -- You can add JDSU to the list of companies that believe dual polarization quadrature phase-shift keying (DP-QPSK) with coherent detection has a play at 40 Gbps as well as 100 Gbps. And unlike its current approach to 40G, the company plans to address this next generation with a homegrown offering.
In an interview conducted today with Lightwave, Alex Schoenfelder, vice president, product line management within JDSU’s Optical Communications group, said that three factors have inhibited growth in the 40G market:
- a lack of industry consensus on modulation formats and the continuing requirement for external compensation engines
- the typical component supply chain necessary to create 40G modules invites margin stacking and instability
- the fact that these first two factors have made cost reduction difficult.
Schoenfelder said JDSU intends to address these concerns by developing its own line of DP-QPSK/coherent detection modules using in-house optical components. This modulation approach has already received the blessing of the Optical Internetworking Forum for 100-Gbps DWDM applications, which promotes some degree of volume demand and commonality of modulation scheme. The use of coherent detection in particular lessens and in some cases obviates the need for chromatic and polarization-mode dispersion compensation. And the use of in-house technology means a cheaper, more integrated approach.
The company has or will soon have all the optical components necessary for both the transmit and receive ends of the DP-QPSK/coherent detection equation, Schoenfelder says. He admits that the necessary electronics -- coherent detection requires very advanced analog-to-digital converters and digital signal processing components -- will have to come from outside. However, JDSU has lined up a supplier for this technology for the 40-Gbps application, whose identity Schoenfelder declined to reveal. (The company is still exploring options for 100 Gbps, he said.)
JDSU should have prototypes of such a device available in the latter stages of next year, Schoenfelder predicts. He added that JDSU plans to make the individual components available to the market as well.
The company currently partners with Mintera Corp. to co-market 40-Gbps modules based on Mintera’s version of differential phase-shift keying (DPSK). Schoenfelder says the two companies don’t have a comparable agreement for the DP-QPSK/coherent detection devices. As if to cement what looks to be a parting of the ways down the road, Schoenfelder says JDSU also has a mid-level module on the drawing board that would leverage RZ DQPSK that would provide performance somewhere between present DPSK-based approaches and the future coherent-detection based offerings.