Guest Blog: Good start to BIMMF debate, but it may be prudent to wait

by Eric Leichter, manager of training and technology, CommScope

I appreciate the balanced view that an industry publication like Cabling Installation & Maintenance offers by providing two sides of the bend-insensitive multimode fiber (BIMMF) story. In its January issue, the magazine published two articles that provide opposing viewpoints on this topic. The first article, Compatibility issues with bend-insensitive and standard multimode, warned that a higher connection loss could be seen when matching legacy and BIMMF. The second article, The facts about BIMMF, did not disagree with this claim, stating, "... differences in designs in BIMMF result in differnces in performance." The article went on to describe the deficiencies in some of these designs. After reading and digesting both, a key takeaway for me was that there is no standard that can make a user of these technologies certain of what performance to expect.

Both TIA and IEC have formed working groups to further investigate this new technology; however, it may take some time for the industry to properly define the performance characteristics of a "standard" BIMMF and to develp the new test procedures that will likely be required. Today's test procedures were developed for a traditional graded-index profile fiber and may not be relevant for fibers with a trench profile. "Testing" can include factory testing by the manufacturer (i.e. core diamter, numerical aperture or bandwidth) or testing in the field by an installer (i.e. source, type of patch cord fiber and mandrel to use). Beyond the unknown timing of BIMMF standards, it is also not possible to say now which, if any, of the available BIMMFs will be compliant to a new standard.

It may be best simply to continue to focus on system performance, as high bandwidth and low bit error rates are the keys to high data throughput. For this, we already have standards-based OM3 and OM4 fibers that provide 100G performance. Today, there's no real need to look any further.

CommScope has authored two white papers that explore the issue in further depth. You can access one white paper here and the other one here.

Eric Leichter, CommScope's manager of training and technology, also blogs on CommScope's website. You can see his CommScope blog here.