OM3/OM4 Fiber

OM3/OM4 Fiber

| 10/28/2015 5:18:00 PM

Fiber optics is a common interface on switches, media converters and other network devices. It is widely adopted, in order to support the extension of a LAN or WAN over [fiber run] distances greater than the 100m that copper is limited to. Its security and wide bandwidth are attributes that provide scalability and reliability.

As fiber continues to be installed globally, its ability to support the variety of speeds that have evolved since 2000 is admirable: 10Mbps, 100Mbps and gigabit; even 10G.  The [glass] fiber for Ethernet networks, transporting  data over the typical protocol used [in LAN/WAN], allows the different kinds of lasers for Single Mode and Multi Mode fiber, ie, FP [Fabrey Perot], DFB [Distributed Feedback Laser] and VCSEL [Vertical Cavity Surface Emitting Laser].  The lasers dictate the kind of distance the laser can support. To be specific, I am only referring to Class 1, Eye Safe lasers used for network equipment. Other laser classifications are relevant to other industries.

But there is a “new” fiber available, OM4. Optical Mode 4 supersedes OM3, which was introduced back in 2005. OM3, OM3+ emerged but a standard had not been ratified, and as a result, OM4 standardized the nomenclature across all manufactures so that the customer now  has a clear idea of the product they are buying. It was ratified by the TIA/EIA as a standard in August of 2009.

So what is OM4?  Aside from having an aqua cable coat, a differentiation from the orange cable coat for Multi Mode fiber and yellow cable coat for Single Mode fiber, OM4 is designed to support 40G and 100G installations, for 850nm Multi Mode fiber.  OM4 uses a VCSEL laser,  and supports up to 550m (whereas OM3 is limited to 300m).  OM4 is backwards compatible with OM3; OM4 is optimized laser fiber for 50 µm  Multi mode (not to be confused with the 50 µm introduced in the late 1980’s for Multi Mode fiber for 10Mbps Ethernet).

As you may remember, fiber is shaped by the speed it has to support. The greater the speed, the less the distance is covered.  So while OM4 can support up to 550m at 10G, it is reduced to 150m for 40G and 100G. The typical protocols, FibreChannel and Ethernet, are shown below for speed to distance values.


400m 4Gbp/s
200m 8 Gbp/s
130m 16 Gbp/s


  1Gbp/s 10Gbp/s 40Gbp/s 100Gbp/s
OM3 1000 300 100 100
OM4 1100 550 150 150

Now that you have an idea of what OM4 fiber is, what is its value?  Where would it be deployed? The Data Center!  While we don’t think about it, the data center impacts everyday life. When was the last time you opened an app on your smartphone, shopped on the Internet or streamed a movie?   The data center is the backbone of those events, and must provide not only secure data, but store and process large amounts of information.  Picture long rows of computer servers and hard drives, and that is the data center.

Large companies such as Apple, Amazon, Google, Microsoft and Yahoo often run their own data centers. Others function like landlords, renting space on their computer racks to financial institutions, healthcare companies and other businesses.  In addition, OM4 is designed to support FibreChannel for 4Gbps, 8Gbps and 16Gbps.

In summary, OM4 allows the future-proofing of the network, is backwards compatible to legacy network speeds, and supports not only data, but voice, video and FibreChannel.  Just as gigabit speed slowly evolved to a common requirement today, 10G and 40G are already more commonly considered. Granted that 40G and 100G are speeds probably discussed more at the integrator or the service provider level, inquiries will still disperse to network device manufacturers.  And the more education we can provide, the better we can serve the customer.

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