Testing Installed Fiber Cabling Terminated with MPO Connectors

Several published standards describe how to perform attenuation measurements on installed fiber optic cabling. However, no standard exists that provides guidance for testing installed fiber optic cabling terminated with MPO connectors. Currently, a technical report (TR) is being drafted that provides such testing guidance.

Led by FNet, IEC subcommittee 86C has taken up the challenge with TR/IEC 61282-15. The TR will describe measurement methods for attenuation, polarity, and length. It also will include descriptions of test cords and other elements relevant to multi-fiber testing for both multimode and single-mode fiber. The TR will provide guidance for testing optical fiber cabling that may be installed in residential, commercial, industrial, data centers, and outside plant environments.

The test methods described in the TR requires the use of specialized equipment. The equipment must easily interface to multi-fiber cabling that use MPO connectors; the testers have an MPO interface. To complete a test, a light source and power meter are used. The fibers that can be tested are 50/125 µm and 9/125 µm. The power meter should, for the purpose of polarity measurements, have multiple ports (fiber positions). The power meter should not introduce insertion loss at its port and should interface to an APC or UPC MPO connector.

Testing installed fiber optic cabling terminated with MPO connectors can be challenging. The connector keying and fiber positions can vary. The connector styles, pinned or unpinned, can vary. Fiber positions can vary by row and fiber count. Fiber positions in MPO connectors continue to change and are sometimes not backward compatible. Testers are needed that are adaptable and expandable. However, adding more ports or light sources to a tester can add complexity. Therefore, adapters and test cords allow testers to adapt to cabling under test. For most test methods, the 1-jumper reference method is used. In some cases, where the 1-jumper method cannot be used, a hybrid reference method is used.

Multimode sources need to be encircled flux compliant to IEC 61280-4-1, for 50/125 µm fiber at the source’s optical connector (i.e. bulkhead) or at the test cord output. For multimode fiber testing, only 850 nm testing is needed. There are few if any applications running 1300 nm on 50/125 µm fiber today. Single-mode testing needs 1310 nm and 1550 nm. The TR draft is also drawing interest in TIA and ISO/IEC. The first draft is expected to be reviewed in October, at the IEC meeting. Several meeting cycles will be needed to complete the project. A technical report provides guidance as an informative document but can, in the future, become a standard with normative text.