AUGUST 14, 2008 By Stephen Hardy -- On the heels of establishing dual-polarization - quadrature phase-shift keying (DP-QPSK) as its preferred modulation format for 100-Gbit/sec DWDM networks, the Optical Internetworking Forum (OIF) has now decided to help define how that format will be implemented.
In the OIF's Q3 meeting in Montreal, the 100G Long Distance DWDM Transmission Project decided that it will develop Implementation Agreements (IAs) for both the transmit- and receive-side optics for DP-QPSK paired with coherent detection. As the OIF's Joe Berthold and David Stauffer explained in an interview yesterday, a single wavelength transmitted via this technique currently would require two receivers (one each for the two polarizations), each of which would in turn demand four demodulators (for the quadrature demodulation). Throw in polarization splitters and transimpedance amplifiers, and equipment designers are looking at a complex and potentially extremely bulky transponder package. The implementation agreements will be designed to help spur multi-source agreements among transponder vendors for efficient, common footprints and designs.
Berthold and Stauffer say the OIF envisions two IAs, one for the transmit function and one for the receive function. In particularly, the IAs will seek to define partitioning of photonic subcomponents for each function. Berthold offers that the agreements will not include dispersion compensation functions.
The OIF sources declined to speculate when the IAs would be completed, noting only that carriers appear to want 100-Gbit/sec transmission capabilities as soon as possible. The group will meet next on the IAs (among other topics) on October 14 in San Diego.
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