wdm among the technologies to shine at ofc 98

Feb. 1, 1998

wdm among the technologies to shine at ofc `98

By GRACE F. MURPHY

Wavelength-division multiplexing (wdm) technology will dominate this year`s Conference on Optical Fiber Communication (ofc `98) in the San Jose Conference Center, San Jose, CA, February 22 to 27, sponsored by the Optical Society of America (osa), the Institute of Electrical and Electronics Engineers/Lasers and Electro-Optics Society, and the ieee Communications Society.

This year`s show, expected to draw 7000 people, features exhibits, demonstrations, product presentations, and technical papers concerning the latest advances and applications in fiber-optic technology. According to technical program coordinator Rajiv Ramaswami, Tellabs, Lisle, IL, the conference will mirror the 1997 conference in its focus on systems and wdm needs.

"There are two things happening to ofc right now," he says. "One is the fact that the conference has been moving more and more toward a customer focus, mainly toward systems and networking issues. Ten years ago, it was a component conference. Also, what has happened in the past two years is that wdm has taken off explosively."

wdm technology attracts communications carriers interested in expanding the capacity of their networks without the expense of adding new fiber. By sending more wavelengths over the same number of fiber strands, carriers are able to transmit more traffic on their existing networks. The resulting increase in bandwidth also gives carriers some reserve capacity for future growth.

Tom Koch, program co-chairman, says that sessions and speakers will offer solutions to some problems caused by the fast advancement of wdm technology.

"Applications are driving capacity so hard that tremendous pressure has come back on the performance and functionality of the underlying wdm components," Koch says. Ramaswami says carriers are also looking for ways to manage data transmitted at high speeds.

In addition to offerings about wdm technology, attendees can expect scientific and technical information about fiber and passive components, active optoelectronic and integrated optical devices and components, and systems technologies, subsystems, and networks that use the components.

More than 400 presentations are scheduled, including eight tutorials, five workshops, three symposia, two plenary sessions, 58 invited papers, 288 contributed papers, and 41 short courses throughout the conference (see accompanying schedules on pages 23, 25, and 27). More than half of the presentations are by scientists from outside the United States. Short courses scheduled on Sunday and Monday are each three hours long.

Workshops

Registration opens on Sunday, February 22, followed by pre-conference workshops and short courses. The first workshop, organized by Fahri Diner of Siemens and Ken-Ichi Sato of Nippon Telegraph & Telephone Corp. (ntt), will focus on defining the value of optical networking to network operators.

A second workshop, run by Ashish Vengsarkar of Lucent Technologies, Michael Scobey of Optical Corporation of America, and Alan Willner, University of Southern California, will focus on passive components for wdm systems. The workshop is geared toward evaluating the merits of technologies for two applications--adding and dropping channels in a wdm system, and gain equalization of erbium-doped fiber amplifiers. Discussion is expected to focus on such technologies as fiber gratings, thin-film filters, and planar waveguides, but new developments and proposals will also be reviewed.

The third workshop, "High Capacity Undersea Cable Transmission Networks," will include such topics as the best networking techniques for undersea cable systems, and methods available for increasing the total capacity of transoceanic systems beyond 100 Gbits/sec. Neal Bergano of Tyco Submarine Systems International will lead the workshop. Scheduled subjects include long-haul wdm transmission and networking, long-haul transmission experiments, modulation formats, optical regeneration, ultrahigh-capacity time- division multiplexing (tdm), reconfigurable undersea networks, and computer simulation of optical propagation.

A fourth workshop, "Transmission Modeling Simulation Tools," is scheduled for Monday morning, February 23. The organizers, Curtis Menyuk of the University of Maryland, Baltimore County, and Alan Willner, University of California, Los Angeles, have invited people to demonstrate simulation tools during the workshop. Four papers featuring these tools will be presented.

The last workshop, on Friday, February 27, is the Sixth International Workshop on Optical Networking: Optical Networking in Local Area Networks and Wireless Network Applications. Discussion periods are scheduled after invited presentations.

Plenary session

The conference officially kicks off on Tuesday, February 24, with a plenary session featuring two keynote speakers. Fred Briggs, chief engineering officer, mci Corp., will discuss the importance of the next-generation networks` meeting the demands of Internet and intranet growth rates and their new applications. In his "Next Generation Network" keynote address, Briggs is also scheduled to look at the future of emerging technologies in the global communications industry, such as next- generation switching, advanced intelligent networks, fiber-optic networking, and broadband access.

Tatsuo Izawa, senior vice president of research at ntt, Tokyo, is the second keynote speaker. In "Towards a `Peta Media` Network Society," Izawa predicts a future in which the transmission of petabit levels of information will be routine. He is expected to discuss the social, cultural, and psychological implications of transmitting enormous amounts of data.

During the plenary session, the eleventh John Tyndall Award will be given to Kenichi Iga of the Tokyo Institute of Technology, Japan. The award will recognize Iga`s contributions in the development of surface-emitting lasers and planar microlens arrays for parallel optoelectronics.

Technical program

The ofc `98 technical program will have five categories of invited and contributed papers, covering wdm technology, dispersion compensation, optical add/drop technology, broadband amplifiers, and optical switching and crossconnects. Two topics added to the conference this year are optical restoration and plastic optical fiber. The subcommittees are (I) fibers, cables, and fiber-based devices; (II) optoelectronic and integrated-optics devices and components; (III) system technologies; (IV) networks, switching, and access; and (V) applications.

The Category I subcommittee, chaired by Wayne Sorin, Hewlett-Packard Co., recognizes that higher-capacity systems require dispersion compensation and wider-band amplifiers. One group of researchers is scheduled to discuss a new type of fiber with alternating dispersion characteristics. Other topics include fiber-grating dispersion, broadband amplifiers, and plastic optical fiber.

Ramaswami says plastic optical fiber was added as a topic this year to highlight developments that can make fiber-to-the-desk in a local area network (lan) inexpensive.

"Plastic fiber offers a much cheaper alternative for low-cost, low-performance applications. When you look at fiber-to-the-desk or fiber in a [lan], then plastic fiber becomes attractive, basically for short-distance communication, and is very cheap. Glass fiber that we`re using traditionally is good for long distance and very-high-capacity communication, but it costs more," he says.

Among the key papers in this area is one by V.A. Bhagavatula, G. Berkey, D. Chowdhury, A. Evans, and M.J. Li of Corning Inc., Science and Technology Div. The paper examines novel fibers for dispersion-managed high-bit-rate systems. The fibers, with axially varying dispersion, built-in dispersion compensation, and large effective areas, are made for high-power, high-bit-rate applications. The four-wave mixing efficiency and other fiber and system characteristics of the fibers are scheduled for presentation.

Another paper on loss compensation in dispersion-compensating fiber modules by Raman amplification will be presented by P.B. Hansen of Bell Laboratories, Lucent Technologies; G. Jacobovitz-Veselka, Network Systems, Lucent Technologies; L. Gruner-Nielsen, Lucent Technologies Denmark; and A.J. Stentz, Bell Laboratories, Lucent Technologies. The paper will propose and demonstrate how Raman gain offsets the loss of dispersion-compensating fiber modules without system performance penalties. The paper says the Raman efficiency of the dispersion-compensating fiber is high--2.2 ¥ 10-3--because of the small mode-field diameter of the fiber.

The Category II subcommittee, chaired by John Bowers, University of California at Santa Barbara, focuses on three main areas this year: wavelength conversion technology and devices for wdm, plastic packaging of lasers and other modules, and optical switching and crossconnects.

Kristian Stubkjaer, Technical University of Denmark, is scheduled to present a tutorial that addresses how to convert signals coming into the network on standard wdm channels, and how to reuse wavelengths within the network. Stubkjaer will review existing and potential application areas and address future developments. Other papers about filters, wavelength multiplexers and demultiplexers, and wdm switching technology are scheduled.

A paper by Kimio Tatsuno, Hitachi Ltd., addresses plastic packaging of optical modules for access network system applications. Plastic is presented as a less expensive way to package lasers, telecommunications modules, and telephone applications.

The Category III subcommittee, chaired by Ron Esman, U.S. Naval Research Laboratory, focuses on high-speed transmission. Approximately 30% of the papers refer to wdm technology. Ramaswami says discussions will focus on transmitting the highest possible amount of traffic over the longest possible distance. "There are experiments this year that talk about transmitting 40 wdm channels at 2.5 Gbits/sec each over 12,000 km," he says.

A team from kdd r&d Laboratories, made up of Noriyuki Takeda, Hidenori Taga, Kaoru Imai, Yukio Horiuchi, Keiji Tanaka, Noboru Edagawa, Masatoshi Suzuki, and Shu Yamamoto, will present a paper describing that experiment. The trial used widely gain-flattened low-noise 980-nm-pumped erbium-doped fiber amplifiers and low nonlinearity fiber.

Technicians Osamu Kamatani, Yoshitada Katagiri, and Satoki Kawanishi of ntt Optical Network Systems Laboratories are scheduled to present a paper proposing that future high-speed optical transport networks will require optical tdm signal processing nodes that can control optical short pulses of several picoseconds. The report describes an optical tdm add/drop multiplexer experiment that used a 100-Gbit/sec signal. A phase-lock loop timing extraction circuit and demultiplexer based on photonic downconversion were introduced for a stable add/drop operation.

Another paper, by Kazushige Yonenaga, Mikio Yoneyama, Yutaka Miyamoto, Kazuo Hagimoto, and Kazuto Noguchi, ntt Optical Network Systems Laboratories, outlines a 160-Gbit/sec wdm transmission experiment in which 4-channel multiplexed 40-Gbit/sec optical duobinary signals were transmitted over a 100-km dispersion-shifted fiber.

The Category IV subcommittee, chaired by Adel Saleh, at&t Labs--Research, adds optical restoration as a conference topic for the first time this year. Ramaswami says the subject was added to address various restoration options for fiber-optic routes. Backup capabilities are traditionally handled in the Synchronous Optical Network (sonet) layer, but people are also now looking at solutions in the optical layer, he says.

"What`s changing is that as we build these new optical networks, we can also use capabilities provided by the optical network for protection and restoration. Now when you have a fiber cut, the thing that is going to take care of the fiber cut in terms of rerouting traffic may not be sonet; it might be the optical network itself," Ramaswami says. "Now people have to figure out how best to do this form of protection in the network. Should the optical network do it, should the sonet network do it, or should both do it? And therefore it becomes a very important area for research."

A paper by Paul Bonenfant, Lucent Technologies, looks at the need to control interactions between new and existing client layer survivability mechanisms. Another paper, by Ori Gerstel, Tellabs, looks at the pros and cons of optical protection and restoration mechanisms versus other alternatives in a telecommunications network. The paper also surveys potential applications for optical protection/ restoration and how network topology, protection mechanism, and wavelength conversion can affect implementation. A paper about the fundamental limits of optical transparency will also be presented.

Category V, Applications, was introduced at ofc `97 and will be chaired by Shoa-Kai Liu, mci Corp. This year`s theme covers all the components of an integrated global network--the development, deployment, and management of full-service access networks, high-speed transport, and international submarine networks. Network operators from all over the world will present their views of future network development based on sonet/ Synchronous Digital Hierarchy, dense wdm, optical amplifiers, new types of fiber, other optical components, and high-speed electronics.

The subcommittee is also scheduled to address recent network trials, such as the mci 16 ¥ 16 multiple wavelength, optical crossconnect trial, the Energis Synchronous Transfer Mode-64 trial, and the Southeast Asia-Middle East-Western Europe 3 undersea cable system.

Gary Davis, Niall Robinson, Shoa-Kai Liu, John Fee, and David Way, mci Corp., are scheduled to present the results of the 16 ¥ 16-wavelength trial and its role in developing restored optical transport networks.

mci deployed an optical crossconnect system (occs) to see how integrating existing network equipment and fiber plant with new technology would affect network applications. The network consisted of five separate 16 ¥ 16 occs nodes, OC-48 (2.5-Gbit/sec) and OC-192 (10-Gbit/sec) transport equipment, optical amplifiers, wavelength-division multiplexers, and a DS-1 (1.544-Mbit/sec) wide-area-network control network. Both optical ring and mesh configuration routes were tested, and restoration routes from 50 to 350 km were implemented using non-dispersion-shifted and long-span fiber. Findings up for discussion include a network restoration time of less than 150 msec and areas for improvement such as matrix size, insertion loss, and switching speed.

A paper by John Wright, BT Laboratories, looks at future submarine systems. Topics include reaching 100 Gbits/sec of capacity per cable system, soliton transmission solutions to correct non-linearity and polarization mode dispersion at fast rates over long distances, and optical amplifiers.

Information

For more information about the technical sessions, short courses, workshops, and registration, contact osa Conference Services: tel: (202) 223-0920; fax: (202) 416-6100; e-mail: [email protected].

For more information about exhibits, product demonstrations, and product presentations, contact osa Corporate Services at tel: (202) 416-1950; fax: (202) 416-6130; or e-mail [email protected]. q

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