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Sumitomo Electric Industries: Optical Fibers


Social Infrastructure Lifelines: Optical Communications and Optical Fibers

Optical fibers are cables used to transmit digital data that has been transformed into optical signals. The advantages of optical fiber communications include the fact that using light to communicate means a fast transmission speed for information, and large amounts of data can be transmitted simultaneously.

When communications are conducted by passing electric signals through copper wire, the metal cables used experience interference from external electrical sources, resulting in drawbacks such as noise and signal attenuation. Optical fiber cabling, however, shuts out such external factors, preventing almost all signal leakage and attenuation as well as external interference.

A signal input into copper wire and transmitted 1 km will attenuate to less than one hundredth of the original signal. By contrast, a signal sent through optical fibers will only attenuate by around 2% after 1 km. In other words, laid over the same distance, optical fiber cables will require only a tenth of the total number of amplifiers needed for the same length of copper wire.

Optical communications using optical fibers are now used in broadcast networks and communication lines all over the world; they have become a technology that is no less than a lifeline for today’s social infrastructure. To improve the efficiency of optical communications, optical fibers need to prevent—as much as possible—the attenuation (loss) of light between the transmitting and receiving locations. They also need to be able to transmit light quickly and over long distances.

Optical fibers can be manufactured in either glass or plastic, with each type boasting certain advantages. Glass optical fibers have a low attenuation rate, and are suitable for high-speed transmission over long distances. Plastic optical fibers are resistant to bending, and can easily be connected to other optical fibers and equipment. The type of optimal fiber is selected according to purpose; glass fibers are used for undersea cables, for example, while plastic fibers are employed in short-distance communication networks.

Sumitomo Electric Industries manufacture and sell both types, to a world-leading level.

For example, the PureAccess R5, a plastic-type optical fiber with outstanding bending performance at a 5 mm fiber bend radius. It is a product designed to respond to customer demand, boasting improved performance on standard optical fiber cord, as used in the home or in switching centers, and enabling the further miniaturization of a junction box that contains the optical fiber connection. 

The 5 mm fiber bend radius was set as a new standard by the International Telecommunication Union’s Telecommunication Standardization Sector (ITU-T), and Sumitomo Electric Industries was the very first manufacturer to meet that standard. The PureAccess series was conceived as a single-mode optical fiber that would assure low attenuation caused by bending. It was launched in 2002, and so far has chalked up sales totalling more than 6 million kilometers of fiber. Placed from end to end, 6 million kilometers of fiber would wrap around the globe around 120 times. 

Glass optical fibers by Sumitomo Electric Industries are similarly outstanding: in 2002, its glass fibers broke the record for lowest attenuation, and further succeeded in extending the transmission distance by 30% compared to conventional fibers. The company also achieved a super low attenuation rate of 0.151 dB/km in its developmental research. Today, the lowest attenuation rate of all commercially available Sumitomo Electric glass optical fibers is 0.18 dB/km, indicating how research success has been translated into commercial products.

Optical Fibers: Future Progress

In March 2011, a joint research project by Sumitomo Electric Industries, the National Institute of Information and Communications Technology, and Optoquest Co., Ltd. succeeded in transmitting 109 terabits of data per second using a single optical fiber, smashing the previous world record of 69.1 terabits/second. The result also showed that the 100 terabits/second limit—previously thought to be the maximum transmission volume physically possible for a single fiber—could, in fact, be broken.

Sumitomo Electric Industries has also worked to develop a 7-core fiber capable of resolving the ‘multi-core fiber’ problem, which has long represented a considerable technical challenge.

The findings of Sumitomo Electric’s pioneering experiments are overturning conventional understanding of the capabilities of optical fibers, and are likely to help shape the future of optical fiber–based communications technology. As more countries develop, demand for optical fibers of an ever greater technological standard is certain to increase across the globe, as countries develop their social infrastructures and communications technologies. 

Sumitomo Electric Industries currently command the leading share in optical fiber manufacturing in Japan, as well as one of the top shares for the international market. This is a company that promises to continue to contribute to development and innovation in optical fiber communications.

Jun 28, 2012

About the author
Hiromi Jitsukata is a reporter for Japanest NIPPON
(Sumitomo Electric Industries, Ltd.)