The Impact of Effective Modal Bandwidth on 100G SWDM Transmission Over 250 m OM5 and Left-Tilt OM4 Multimode Fibers

We demonstrate 100G SWDM4 transmission over 250 m OM5 and left-tilt OM4 multimode fibers. The OM5 fibers are compliant to TIA-492AAAE and the left-tilt OM4 fibers are compliant only to TIA-492AAAD and have a bandwidth peak at a wavelength longer than 850 nm. The “left-tilt” descriptor refers to the leftward leaning slope of the differential mode delay peaks. This is an indication that the peak bandwidth is at a wavelength longer than the measurement wavelength. To measure the margin to the forward error correction limit, 24 250 m channels were constructed from two links of 100 m and 150 m using either left-tilt OM4 or OM5 fiber. Error-free performance was achieved with each of the 24 OM5 channels. None of the 24 left-tilt OM4 channels achieved error-free performance. To further characterize performance, the effective modal bandwidth was measured for 6 left-tilt OM4 fibers and 12 OM5 fibers from the same spools as the fibers used in the margin measurements. The OM4 fibers all have a left tilt at 850 nm and the OM5 fibers have either a left or right tilt. Bit error ratio (BER) versus received power was then measured over 250 m of these fibers. With the OM4 fibers, the long wavelength channels limited the system performance due to low modal bandwidth at longer wavelengths despite the left tilt at 850 nm. We demonstrate the relationship between effective modal bandwidth at 953 nm and BER performance at 910 and 940 nm.