IEC updates test methods and product specifications

Th 10stdwatch

Working Group 1 of the International Electrotechnical Commission (IEC) Subcommittee SC86A is currently involved in a major project to modernize optical-fiber standard-test methods and product specifications. The new test methods are organized by fiber "attributes." Typically, a fiber attribute is a specified parameter that can be measured by more than one measurement method.

For example, chromatic dispersion is a fiber attribute that can be measured by three different measurement methods. If conflicts arise due to differences between the measurement methods, they are resolved by a reference test method that is identified for each attribute.

Tom Hanson of Corning Inc., heads a task group in WG1 that is in the process of reformatting and updating the standard test methods. At the last meeting of WG1 in Arezzo, Italy, in April, it was agreed that the environmental, mechanical, and optical tests should be balloted for national committee approval.

The document numbers are 60793-1-xx, where xx is as follows: fiber geometry (20), coating geometry (21), length (22), fiber proof test (30), tensile strength (31), strippability (32), stress-corrosion susceptibility (33), fiber curl (34), attenuation (40), bandwidth (41), chromatic dispersion (42), numerical aperture (43), cable and fiber cut-off wavelength (44), mode-field diameter (45), monitoring (46), macrobending sensitivity (47), temperature cycling (50), and nuclear radiation (51).

These test methods are similar but not identical to those published in the International Telecommunication Union's Recommendations G.650 and G.651. The IEC and ITU strive through active liaison to eliminate any inconsistencies that might arise between their documents.

Fiber-product specifications, applicable to uncabled fiber, are also being updated by WG1. A task group lead by Gerard Kuyt of Plasma Optical Fibres (the Netherlands) is spearheading the effort.

At the Arezzo meeting, proposals from the national committees were harmonized, and a preliminary draft of a new specification for singlemode fibers was produced. An example of a new item is the attenuation at 1625 nm, covering applications in the L-band.

The task group recommended the elimination of the current specification in IEC 60793-2 for the B3 (dispersion-flattened) fiber, since it is not used commercially. Also recommended was an increase in the minimum dispersion for the B4 (nonzero-dispersion) fiber. The new B4 fiber specification accommodates a wider variety of fibers with both positive and negative dispersion.

A discussion of the specification of a low-water-peak fiber was started at the Arezzo meeting and will be continued at the next meeting of SC86A WG1 in Kyoto, Japan, this month. Modifications of transmission parameters (attenuation and bandwidth) for type A1a (50/125-micron) and type A1b (62.5/125-micron) multimode fibers have been recommended by the experts of WG1 and are currently being voted upon by the national committees.Th 10stdwatch

Allen H. Cherin chairs IEC SC86A WG1, and represents Lucent Technologies on several TIA committees. He can be reached at (770) 798-2619; fax: (770) 798-4654; e-mail:

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