OM5 WideBand multimode fibre

OM5 - what brings the new fiber class for optical LANs?

OM5 WideBand multimode fibre

WideBand multimode fibers for SWDM

Today, multimode fibers (MMFs) of the OM3 and OM4 classes are the preferred media for Ethernet and Fiber Channel applications operating at 850 nm with NRZ modulation. If the data rate is to be increased, the effective bandwidth is limited by the modal dispersion of the MMF and the low VCSEL bandwidth.

To overcome this limitation, parallel fiber links operating at 10 and 25 Gbps line speed are used to multiply the capacitance. However, this approach requires an infrastructure based on multi-fiber connection technology (MPO). To continue the proven 2-fiber structures is a 100 Gbps solution and moreover, using a single MMF would be preferable. In this context, WDM techniques can be used. For comparison, an OM4-MMF provides a high modal bandwidth, but only a narrow wavelength range centered at 850 nm, limiting 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 100nm. For backward compatibility, the 850nm wavelength was maintained, resulting in the operating window of 850 to 950nm (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


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.


OM5 - what brings the
new fiber class for
optical LANs?

Those who are monitoring the developments at IEEE802.3 will not suffer from a lack of ideas about the transfer methods at the moment, as a large number of partly overlapping solutions are currently under development or already standard.

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