SEPTEMBER 27, 2007 By Stephen Hardy -- Not surprisingly, exhibitors had a lot to say about high-speed transmission technology at last week's European Conference on Optical Communications (ECOC).
Technologies for both 40- and 100-Gbit/sec were touted. Opnext (search for Opnext), for example, showed off a 43-Gbit/sec module, which paired binary encoding with tunable dispersion compensation. Opnext Director of Product Marketing Ed Cornejo said the company is examining its options for the next generation of modulation format for 40-Gbit/sec modules, with DPSK and DQPSK the leading contenders. Cornejo said that the attributes of the installed fiber in Japan makes DQPSK the leading option for that market, but he said other areas of the world don't have the same constraints.
Meanwhile Alex Schoenfelder, vice president and general manager of integrated photonics at JDSU (search for JDSU), revealed that his company has QPSK and DQPSK products under development that are nearly ready for release. He added that JDSU also is looking at supplying components, such as tunable phase and dispersion compensators, to support duobinary and DPSK applications.
Bookham (search for Bookham) has focused its efforts on DQPSK, says Adrian Meldrum, vice president of sales and marketing at the company. Like Opnext, Bookham hopes to provide a module-level product.
CoreOptics (search for CoreOptics) continues to push coherent receiver technology for transmission at 40 Gbits/sec and above. Saeid Aramideh, senior vice president - global sales, marketing, and business development, predicted that 40-Gbits/sec will find more application in long-haul and ultra-long-haul (LH/ULH) applications, with the metro welcoming short-reach 100-Gbit/sec technology when it becomes available.
On the systems side, Gabriel Yavor, optical product line manager, marketing, within the Optical Networks Division of ECI Telecom (search for ECI Telecom), predicted his company will unveil its 40-Gbit/sec strategy at next year's OFC. He hinted that the company's product will use a "proprietary" modulation format compatible with 50-GHz wavelength spacing. The platform will support transmission lengths perhaps as long as 1,500 km, he added.
Companies also were ready to talk 100G. A demonstration of 107-Gbit/sec transmission using OTDM at the u2t Photonics (search for u2t) booth was the salient event in a Berlin-themed pavilion supported by Berlin Adlershof, a local science and technology park and company incubator.
Alcatel-Lucent (search for Alcatel-Lucent) presented several papers on the topic, including an invited presentation on 8x107 Gbits/sec using serial binary NRZ and vestigial sideband filtering at 100-GHz spacing and another with the Fraunhofer Heinrich-Hertz Institute covering 160-Gbits/sec transmission via RZ-DPSK.
CoreOptics co-presented papers building on its work with Nokia Siemens Networks, and Eindhoven University of Technology discussed previously at OFC. The parties demonstrated 111-Gbit/sec transmission using polarization-multiplexed RZ-DQPSK, a coherent receiver, and a T-spaced equalizer. (The group also presented papers on the use of this technology combination at 43 Gbits/sec, with and without electronic dispersion compensation.)
While much of the publicity around coherent transmission has focused on the receiver, Eblana Photonics (search for Eblana) Chief Executive James O'Gorman says his company's narrow-linewidth lasers are drawing attention for the transmit side of the equation. The company hasn't done much work with coherent transmission at speeds greater than 10 Gbits/sec, but O'Gorman says his firm has had discussions with others doing R&D in this area.
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