Shannon capacity calculation on multimode fibres

As the ultimate transmission performance of installed multimode fibres is uncertain, there is a need to understand the practical maximum capacity limit that a multimode fibre can support. The authors therefore present a new model to determine the worst-case Shannon capacity limit for multimode fibres. Detailed calculations are reported for fibre-distributed-data-interface (FDDI)-grade and OM1 fibres for operation using serial transmission with a single wavelength near 1310 nm. The method is also applicable to FDDI-grade, OM1, OM2 and OM3 fibres at all wavelengths of operation. The Shannon capacity limit of a multimode fibre is calculated for 220 m link lengths, assuming a link power budget consistent with the IEEE 10GBASE-LRM Gigabit Ethernet standard. It is shown that the Shannon capacity for non-optimised and optimised transmission spectra are at least 42 and 52 Gb/s, respectively.