TOKYO - A newly developed high-speed data link system opens the door to wide application of plastic optical fiber. The fiber would be used in high-speed Ethernet applications.
Ethernet is a communications protocol that allows rapid transmission of data between computer users on a local network. The system, developed by Japan's NEC Corp., combines a high-speed optical-fiber transceiver with low-cost plastic optical fiber, molded lenses and a light-emitting diode light source.
Conventional Ethernet applications using twisted-pair copper wire interconnections have a number of problems. For one thing, complex coding and filtering circuits are needed to suppress electromagnetic interference. This interference is generated by the electrical currents carried by the copper wire.
Plastic optical fibers eliminate EMI - and the cost of suppressing it - because the signals they carry are optical, not electrical. In addition, the total cost of implementing a high-speed network is far less expensive with plastic fiber than it is with copper wire.
In Japan, plastic optical fiber suitable for data communications is manufactured by Mitsu-bishi Rayon Co. Ltd., Toray Industries Inc., and Asahi Chemical Industry Co. Ltd., all of Tokyo.
Other manufacturers include Hoechst AG of Frankfurt, Germany, and Boston Optical Fiber of Marlborough, Mass.
The polystyrene fibers produced by a number of U.S. companies are not suitable for data communications.
For demanding data transmission applications, the fibers are made using acrylic for the core material that actually transmits optical signals and an opaque fluoropolymer as cladding material.
Plastic fiber is not suitable for long distance transmission of optical data because signal loss is too high, but for short dis-tances, plastic has major advantages over glass.
Glass fibers are brittle, difficult to handle, and cost far more than plastic.
Ironically, although the United States is probably the most advanced country in the world in terms of local computer networks, producers of plastic optical fiber see far more potential in Japan and other Asian countries. Because they are not as advanced, they are able to start from scratch using the latest and best technology. In contrast, the United States is already wired up using older twisted-pair technology.