The International Electrotechnical Commission (IEC) optical fiber document structure comprises a hierarchy of a product specification that contains general requirements applicable to multimode and singlemode fibers and sectional specifications that contain requirements specific to each multimode and singlemode fiber category. There are a total of five sectional specifications-four for multimode fiber (categories A1, A2, A3, and A4), and one for singlemode fiber (category B). IEC 60793-2-40, “Sectional Specification for Category A4 Multimode Fibres” covers plastic optical fibers (POFs); it has recently been revised to include four new high-performance fibers and, for the first time, environmental requirements.
Fibers A4a through A4d in the previous version of 60793-2-40 were specified to have a maximum attenuation of 40 dB and a minimum bandwidth of either 10 MHz or 100 MHz over 100 m. Because of recent improvements in polymers and by using new structures such as graded-index profiles, higher-performance plastic fibers are now possible and commercially available (see Standards Watch, Lightwave, August 2003, page 16). To accommodate these advances, four new fibers (A4e through A4h) have been added to the specification. These are specified to have a maximum attenuation as low as 3.3 dB and a minimum bandwidth as high as 5000 MHz over 100 m-a considerable improvement. This improved performance, together with the simplicity of connecting and installing plastic fibers, makes the new A4 fibers attractive competitors to category A1 silica fibers for certain data transmission applications. Category A4a through A4e fibers are specified for operation at only 650 nm. A4f and A4g are also specified for use at 850 and 1300 nm, and A4h fibers are specified exclusively at 850 and 1300 nm.
James J. Refi represents Chromis Fiberoptics in the standards arena and is secretary of IEC SC86A/WG1. He can be reached at firstname.lastname@example.org.