TIA standard for wideband multimode fiber, WBMMF, approved

WBMMF enables wave division multiplexing over multimode fiber. The now-standardized fiber type does not yet have an “OM” designation.

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At its June 2016 meeting, the Telecommunications Industry Association’s (TIA) TR-42.12 Optical Fibers and Cables Subcommittee approved the standard ANSI/TIA-492AAAE, which specifies wideband multimode fiber (WBMMF). The specification completed the entire TIA standard-development process in under two years; TR-42 accepted the project request for the standard in October 2014.

An article authored by Cindy Montstream, director of e-learning and standards at Legrand North America’s data communications division, will appear in the August issue of Cabling Installation & Maintenance magazine. That article will update activities of TR-42, including the approval of the WBMMF standard. In her article, Montstream explains, “The standard specifies 50/125-micron laser-optimized fiber that is optimized for enhanced performance for single-wavelength or multi-wavelength transmission systems with wavelengths in the vicinity of 850nm to 950nm. The actual operational band is from 850nm to 953nm. The effective modal bandwidth (EMB) for this new fiber is specified at the lower and upper wavelengths: 4700 MHz·km at 850 nm and 2470 MHz·km at 953 nm. There is no OMx designation yet; the OMx designation comes from ISO/IEC, which currently is debating several options, including OM4w, OM5, and OM5w.”

As we reported in March 2016, the essential value proposition of WBMMF is that rather than needing four separate fibers to transmit four distinct optical signals, the signals can be sent down a single fiber over four separate operating windows. OM3 and OM4 fiber have been optimized to transmit signals in the 850-nm operating window exclusively, and those fibers’ bandwidth performance at other operating windows is less than its bandwidth performance at 850 nm. As a practical matter, OM3 and OM4 fibers can support high-speed transmission at 850 nm only. WBMMF will support high-speed transmission at four wavelengths. One application of WBMMF could be for each optimized wavelength to provide a 10-Gbit/sec “traffic lane,” enabling a duplex WBMMF connection to accommodate 40-Gbit/sec transmission. Another application could be for each lane to support 25 Gbits/sec, enabling a duplex WBMMF connection to accommodate 100-Gbit/sec transmission. Scaling that 25-Gbit/sec/lane model would allow 400-Gbit/sec transmission over 8 wideband multimode fibers.

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