As increased bandwidth requirements are called out in new installations, particularly 40 and 100 Gb/s standards, transmission distances over fiber optic cables contained in existing infrastructure may become increasingly limited. 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.
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. 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.
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, both Juniper JNP-QSFP-40G-LX4 compatible transceiver and QFX-QSFP-40G-SR4 compatible transceiver from Fiberstore can reach 100m and 150m, respectively over OM3 and OM4 cables.
Since OM3 and OM4 use different fibers inside, the primary cost differs from this. The cost for OM4 is greater due to the manufacture process and also due to economies of scale that the production of OM3 benefits from due to the volumes currently produced. Costs vary depending on the construction type of the cable (loose tube, tight buffered, dry loose tube micro core cable).
In addtion, the additional bandwidth and lower attenuation of OM4 provide additional insertion loss margin. As a result, users of OM4 gain additional safety margin to help compensate for less-than-ideal cabling installations as well as provide margin for degradation due to moves, adds, and changes over the life of the installation.
Although OM4 cable is about twice as expensive as OM3 cable, for the products like standard fiber patch panels, MTP cassette modules, fiber patch cords, the cost difference is very small (as the volume of cable is small). The cost difference starts to build up as the backbones/trunks get longer and the core counts get higher. In Fiberstore, 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. They are assembled and 100% optically tested in the factory prior to shipment.