Feature Articles

Advanced coherent communication systems

Two new technologies—coherent optical fiber communication and optical fiber amplifiers—are now combined to bring forth a new era in optical communication. As a result, the resemblance between the evolution of optical communication and radio communication is increasing.

by Takanori Okoshi
Multichannel transmission by subcarrier multiplexing

Over the past few years, there has been a growing recognition that the use of RF and microwave sub-carriers1-3 is very effective for transmission of broad band signals over optical fibers. This is particularly true of video distribution networks, for which digital technology is presently too expensive to be competitive. This paper reviews recent progress in multichannel subcarrier multiplexed (SCM) lightwave systems as applied to both video distribution and other broadband applications.

by Robert Olshansky
Fiber optic distribution systems

In recent years, enormous progress has been made toward the introduction of fiber-based customer access networks, which allow for easy access to a large variety of services. In many countries, pilot projects are in operation or in an advanced planning stage. All these projects offer a multitude of existing or new services to the customer, often at a better quality than the existing telephone or cable television networks. The standardization by CCITT of the Synchronous Digital Hierarchy,1 originally proposed by Bellcore under the name SONET (Synchronous Optical Network), opens the way to standard digital access equipment, operating at 155 Mb/s or 622 Mb/s. There is little doubt that in the near future broadband digital access based on fiber optic transmission will be installed on a large scale worldwide for business customers. This paper discusses the hurdles that have to be overcome to make "fiber to the residential customer" a viable option.

by T.J.B. Swanenburg
Encouraging kids in science: A personal perspective

Getting young people, in general, and girls, in particular, interested in science is a subject of national debate and intense interest. I was lucky enough to be encouraged in science as a child, and was one of the few girls of my age who became physics majors. I've also been lucky enough to work with lots of youth groups, while working full time in engineering. In the hope that some of the perspective I've gained may be helpful to others, I'd like to offer some personal comments on encouraging children in science.

by Janet Shields
Optical communication technology

Since optical fiber transmission is part of the infrastructure of society, its significance may not be apparent to users. However, if you place an international call over the Pacific of the Alantic Ocean, you may experience surprisingly clear communication due to optical Pulse Code Modulation (PCM). That is due to optical fiber transmission.

by Tetsuhiko Ikegami
Undersea lightwave systems

Undersea lightwave communications systems have made rapid advances toward meeting the ever increasing service needs for transoceanic communications. The first generation of undersea systems was installed in 1988 and provided service between North America and Europe across the Atlantic Ocean and between North America and Japan across the Pacific. The second generation system, operating at twice the capacity of the first, is scheduled for service in 1991. Further rapid growth is predicted on both markets, and future technological options are discussed that are capable of meeting these needs.

by P.K. Runge