The Emergence of OM3 Fiber

by Mike Connaughton, RCDD, Fiber Optic Product Business Manager

 Adventum OM3

There are two broad categories of optical fiber – single-mode and multimode. Each of these categories contains many variations to suit specific applications. In the data communications segment, the multimode fibers have come to be classified into four categories – OM1, OM2, OM3 and OM4. Technically, these categories did not define a specific fiber size, but rather their optical channel performance. However, in practice, a size is assigned to each one.
OM1 fiber is a 62.5/125 micron fiber. Over the past few years, it has replaced the FDDI-grade fiber that had been widely specified since the mid-1980’s. The performance of the fiber was optimized for use at the 1300 nm wavelength where economical LED’s could be used for FDDI networks. By the early 1990’s, this fiber type made up more than 95% of the multimode fiber quantity shipped in North America. This was thought of as “the” multimode fiber. Many people thought that they could “future-proof” their installation by incorporating this fiber into their cable plant since its superior bandwidth, compared to twisted-pair copper, would surely not be needed.
But along came Gigabit Ethernet.
In the mid-1990’s, Gigabit Ethernet was released. It took advantage of a newer light source called a VCSEL (vertical cavity surface emitting laser). The economical versions of this light source operated at the 850 nm wavelength. In order to exploit this, 50/125 micron fiber was brought back (it never actually went away, but most people forgot that it ever existed). Today, this fiber is classified as OM2. While it has good optical performance at 850 nm, it also maintained good performance at 1300 nm so that it could still be used with the long wavelength LED’s specified for FDDI.
 There was a significant amount of controversy in the structured cabling industry regarding the introduction of OM2 fiber. Both OM1 and OM2 could be used for Gigabit Ethernet, but OM2 supported longer link lengths. Many thought that the customers would be confused by having a choice of multimode fibers. Others (including Berk-Tek) thought that customers would be able to use the option to make more informed choices regarding their own infrastructure.
Eventually, Gigabit Ethernet led the way for 10 Gigabit Ethernet (10 GbE). The increased system bandwidth requireda higher performing fiber which led to the standardization of OM3 in 2002. This was commonly referred to as “laser optimized multimode fiber”, or LOMMF. As storage area networks (SAN’s) began to be integrated into the structure cabling methodology, the application space for these fibers began to grow quickly. OM1 fiber could be used in theory, but really the choice was between OM2 and OM3. Also, improved versions of these fibers (OM2+ and OM3+) gained in popularity.
During this time, the traditional network backbones continued to use OM1 fiber for existing network expansion and moves-adds-changes (MAC) work. While the relative popularity of OM1 declined due to the availability of the other higher performing fibers, it still was responsible for about 2/3 of the of the multimode fiber shipments at the beginning of 2005. The remaining volume was split between OM2 and OM3 fibers.
Several things happened after 2005 that changed the ratio of the fiber types. For example, it had been common for each version of Ethernet to be developed for UTP cabling shortly after the fiber standard was completed.   
The “normal” evolution was that the increased data rate was developed as a backbone speed, where fiber dominates, and then it migrated into the horizontal, where twisted pair dominates. This has yet to happen with 10 GbE as 10GBASE-T equipment has only recently become commercially available. Also, the limited link lengths available from OM1 and OM2 made them unattractive. OM3 fiber became a much more popular choice. Also around this time, the popularity of data centers grew tremendously. Data centers are bandwidth intensive and they create significant demand for 10 GbE products.
Fiber Shipments

As can be seen in the table above, by the beginning of 2008, OM1 dropped below 50%. However, it was still twice as popular as the next most common fiber type. But by the middle of that same year, the shipments of OM3 began to accelerate. This trend led to a momentous occurrence by the end of 2009 – OM1 was no longer the most popular fiber type. What was once considered to be a potential distraction had turned into the most popular fiber type within 10 years!

More recently, as  40/100 Gigabit Ethernet was being developed (it is now standardized), a standard for OM4 fiber was developed. As with the prior fiber types, OM4 fiber has actually been shipping as a de facto standard for several years. It is expected to increase in popularity as bandwidth demands increase, especially in the data center.
The success of the OM3 fiber has enabled the cost effective implementation of many of today’s highest speed networks. Today, OM3 is the minimum performance required in data center standards even though it was unheard of 10 years ago. But, keep an eye on OM4. The lesson learned here is that it is important to think ahead when planning your cabling infrastructure, especially if you plan to be in your facility long term. Take into account the needs that you have today, but also think about what the requirements will be in the years to come. With proper cable infrastructure planning, the equipment upgrades become easier. 

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Carol Oliver Berk-Tek Marketing Analyst