Focus on OM5


Welcome to wide-band multimode fibres for SWDM – a new class of fibre to support future data increases and provide a solution to bandwidth limitations.

Today, OM3 and OM4 multimode fibres (MMFs) are the most popular for ethernet and fibre channel applications operating at 850 nm with NRZ modulation. But, if we are to see an increased data rate, the current bandwidth will be limited by the modal dispersion of the MMF and a low VCSEL bandwidth. To overcome this limitation, parallel fibre links, operating at a line speed of 10 and 25 Gbps, can be used to multiply the capacitance. Yet, this approach requires an infrastructure based on multi-fibre connection technology (MPO).

A solution that continues the proven two-fibre structure is one at a 100 Gbps, preferably using a single MMF. This enables the use of WDM techniques. We can take OM4-MMF as an example of a high modal bandwidth, but one with a narrow wavelength range, centered at 850 nm, that limits its WDM capabilities. The cost-effective operation of at least four WDM channels, each with 25 Gbps, requires high-bandwidth broadband MMFs over an extended wavelength range of 100 nm. For backward compatibility, the 850 nm wavelength was maintained, resulting in the operating window of 850 to 950 nm (see Fig. 1). The performance of MMF in a system is related to the effective bandwidth, which is a function of the effective modal bandwidth (EMB) and chromatic dispersion.
Fig. 1
Fig. 1


There are already users whose planning horizon reaches up to 40GbE and beyond. The vast majority of applications are backbone switch-to-switch installations. OM3 with two fibers per line was already present in many cases and a system upgrade often took place step by step. It’s a strong advantage of the described WideBand MMF being fully backwards compatible with all previous MMFs from OM2 to OM3 up to OM4 and not imposing any other requirements to its connecting hardware than the conventional ones.

This allows the WideBand MMF to efficiently migrate existing 10G networks to cost efficient 40G and 100G implementations and further up to 200G. At the same time, WideBand-MMF is recognized by IEEE802.3 as Next-Generation MMF and thus supported in case of upcoming network standards.

Looking to the future

The horizon for some users already extends up to 40 GbE and beyond. The vast majority of current applications are backbone switch-to-switch installations. In many cases an OM3 with two fibres per line is already present with a step-by-step system upgrade. A new, fully backwards compatible wide-band MMF would be a strong advantage. Enabling compatibility with all previous MMFs, from OM2 through to OM4 would also allow an easy migration from existing 10G networks to more cost-efficient 40G and 100G implementations – and potentially all the way up to a future 200G. Wide-band MMF is recognised by IEEE802.3 as a next-generation MMF and is fully supported in case of upcoming network standards. Download the full report below to learn about Prysmian’s OM5 developments.


Ideas, developments and solutions are in abundance, driving new and overlapping innovations at IEEE802.3. Discover cutting-edge insights and a new fibre class to carry heavy data. Download and read the full article.