Guest editorial 40 Gb/s lightwave systems - IEEE Xplore

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JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 20, NO. 12, DECEMBER 2002

Guest Editorial 40 Gb/s Lightwave Systems

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N THE MIDDLE of what appears to be one of the worst downturns in the telecommunications industry, we bring you a JOURNAL OF LIGHTWAVE TECHNOLOGY Special Issue on “40 Gb/s Lightwave Systems.” To some, it may seem that a special journal issue dedicated to exploring the state-of-the-art of 40-Gb/s transmission is not timely—not because it is late, but because it is early. However, we believe that the seeds of the telecommunications recovery may be found in 40-Gb/s transmission systems. Historically, it has been the cost reductions associated with higher line rate systems that have driven carriers and service providers to install the “next generation” platforms. Traditionally, the cost reductions have been measured in equipment capital expenditures alone, as those reductions were significant enough to justify the move to a new platform. Today, we hear more and more about operational expenditures and the need to reduce these costs as well. In general, operational expenditures are difficult to quantify, making it a challenge to measure the overall cost savings associated with various new system features and performance enhancers. In the case of higher data rate systems, however, it is clearly less expensive in terms of effort and materials to manage, maintain, and spare a system that has fewer manageable entities or “moving parts,” if you will. Some in our industry will argue that, while it is difficult to quantify operational expenditures, it is necessary to do so because costs must be reduced in every aspect of the telecommunications business in order to make service providers profitable again. For example, service providers are being asked to provide more and newer services at cost points that cannot be supported by capital expenditure reductions alone. Still, it is capital expenditure reductions that are the primary metric by which optical transport gear is evaluated. We see this initiative to lower cost structures driving all aspects of the optical communication market, from equipment design to component development to research topic areas. Reflecting that point, we see the drive to lower the cost of 40-Gb/s transmission systems dominating the motivation for the work described in this special issue. While this special issue was not meant to focus on commercial applications of 40-Gb/s data transmission, per se, in the current economic situation, most authors could not help but highlight the cost advantages they believe will be enabled by their technology developments. For example, many papers submitted to this special issue study modulation formats and the ability to propogate 40-Gb/s data signals over longer transparent distances. Since capital expenditures are often characterized in $/Gb/s/km, increasing the transparent distance of systems can

reduce the cost, provided the additional equipment needed to attain the longer transparent distances exhibits the appropriate performance/cost tradeoff. In addition to modulation format, we find in this journal a number of papers addressing Raman amplification for improving optical signal-to-noise ratios and compensation schemes for reducing the deleterious effects of chromatic dispersion and polarization-mode dispersion. Still other papers address the overall component and subsystem market and discuss how reducing the costs and improving the performance of various components can make more robust, cost-effective systems. Overall, the breadth of topics covered in this journal represents a good snapshot of the 40-Gb/s transmission research area as it stands today. There are even a few papers that look forward at even higher data transmission rates. We hope that the readers of this journal will find it to be a useful resource and will use it to expand their knowledge of the field. Most of the work that goes into the production of a special issue such as this one falls on the extremely talented, hardworking, and dedicated Institute of Electrical and Electronics Engineers (IEEE) publications staff. They are always working behind the scenes to maintain the quality of all of the IEEE publications. We are grateful to Douglas Hargis for assisting us in the preparation of this issue, as well as to Linda Matarazzo and Paul Shumate for their determination and inspiration. We also thank Editor-in-Chief Alan E. Willner for giving us the opportunity to serve as Guest Editors. We also wish to thank all of the authors who submitted their work to this special issue and the reviewers who provided thoughtful reviews in record time. The interest in the general subject area was confirmed by a number of submissions and the quality of the work in those submissions. We hope you will enjoy reading this special issue and will keep it close at hand for future reading.

Digital Object Identifier 10.1109/JLT.2002.807865

0733-8724/02/$17.00 © 2002 IEEE

KATIE HALL, Guest Editor Photonex 200 Metro West Technology Drive Maynard, MA 01754 USA FRANKO KUEPPERS, Guest Editor T-Systems Nova Am Kavalleriesand3 Darmstadt, D-64295 Germany KOHICHI TAMURA, Guest Editor Corlux Corporation 47915 Westinghouse Drive Freemont, CA 94539 USA ROBERT MARSLAND, Guest Editor New Focus, Incorporated 8551 Research Way Middleton, WI 53562 USA