FAQ About OM4 Fiber

The explosion in demand for bandwidth in enterprise networks is driving an urgent need for higher Ethernet network speeds. Increasingly, these higher bandwidth system requirements have dictated a need to transition from cost-effective multi-mode systems to more costly single-mode systems. Until OM4 was formally specified, many 40G and 100G applications would have had to make the leap to single-mode system solutions. OM4 effectively provides an additional layer of performance that supports these applications at longer distances.

What is “OM4” fiber?

OM4 is a laser-optimized, high bandwidth 50 micrometer multimode fiber. In August of 2009, TIA/EIA approved and released 492AAAD, which defines the performance criteria for this grade of optical fiber. It can be used to enhance the system cost benefits enabled by 850 nm VCSELs for the earlier 1 G and 10 Gb/s applications as well as the 40 and 100 Gb/s systems. For example, Fibestore's Push-Pull MPO patch cable is manufactured using laser-optimized, 50/125, OM4 multimode cable, and supports speeds up to 100GbE. OM4 fiber can support Ethernet, Fibre Channel, and OIF applications, allowing extended reach upwards of 550 meters at 10 Gb/s for ultra long building backbones and medium length campus backbones. OM4 fiber is also especially well suited for shorter reach data center and high performance computing applications.

What are the standards that define the use of OM4 fiber?

There are a number of standards under development that will define the use of OM4 fiber for high-speed transmission. Within the TIA, work is progressing on TIA-492AAAD, which will contain the OM4 fiber performance specifications. Similarly, IEC is working in parallel to adopt equivalent specs that is documented in the international fiber standard IEC 60793-2-10.

What bandwidth does the standard specify for OM4 fiber?

As of this writing, there is general agreement among the standards committees that OM4 has a significantly higher bandwidth (EMB of 4700 MHz-km with VCSEL launch at 850 nm) than OM3. It is also backward compatible with applications calling for OFL bandwidth of at least 500 MHz-km at 1300 nm (e.g. FDDI, IEEE 100BASE-FX, 1000BASE-LX, 10GBASE-LX4, and 10GBASE-LRM). There was some discussion and debate within the standards groups about a minimum OFL bandwidth requirement at 850 nm. It has been shown that fibers with higher OFL bandwidth can perform better with VCSELs that launch more power into outer modes. That is why the existing OM3 fiber standards require a minimum 1500 MHz-km OFL bandwidth at 850 nm.

What’s the difference between OM3 and OM4?

It is important to note that OM4 glass is not necessarily designed to be a replacement for OM3. Despite the relatively long-standing availability of OM4, there are no plans to obsolete OM3 fiber optic cabling. For most systems, OM3 glass is sufficient to cover the bandwidth needs at the distances of the current installation base. Most system requirements can still be reliably and cost effectively achieved with OM3, and this glass type will remain available for the foreseeable future. Despite the availability of OM4 glass, OM3 is quite capable of 40 and 100 Gb/s applications albeit at significantly shorter distances than OM4. For instance, Cisco QSFP-40G-CSR4 compatible transceiver from Fiberstore can reach 300m and 400m, respectively over OM3 and OM4 cables.

A variety of cable configurations are available utilizing the OM4 fiber for in-building and inter-building applications including the following types: distribution, breakout, interconnect, loose tube and industrial armored. All of Fiberstore’s OM4 cable assemblies are with high quality and competitive prices. They are assembled and 100% optically tested in the factory prior to shipment.