Today I’m gonna talk about OM3 and OM4 fiber.

The demand for higher speeds in the enterprise network is rapidly increasing. This is due to the massive amount of storage that’s needed for things such as videos.  OM3 and OM4 are two common types multimode fiber used in local area networks both of these fiber types are considered laser-optimized 50/125 multimode fiber, meaning they both have a 50μm micron diameter core and a 125μm diameter cladding, which is a special coating that prevents light from escaping the core. The OM stands for optical multi-mode.  OM3 and OM4 have been around for years but OM4 was just recently ratified in 2009. The difference between OM3 and OM4 fiber is bandwidth –  2,500 megahertz versus 4,700 megahert. The decision to use OM3 or OM4 is similar to the decision making process with standard 10G network. There are additional factors to consider to take into account such as the reduced transmission distances, the number of cross connects required and the mix of 40G port to 40G port and 40G port to 10G port. Similarly, it is important to take into account the likely location of future 100G equipment and the possible 100G to 100G, 100G to 40G and 100G to 10G connectivity requirement.

OM3 Fiber

OM3 fiber comes with an aqua color jacket. Like the OM2, its core size is 50 µm, but the cable is optimized for laser based equipment. OM3 supports 10 Gigabit Ethernet at lengths up to 300 meters. Besides, OM3 is able to support 40 Gigabit and 100 Gigabit Ethernet up to 100 meters, however, 10 Gigabit Ethernet is most commonly used.

OM4 Fiber

However, it was only called OM4 once the standard had been ratified in 2009. Before 2009 is was known by various names such as OM3+ or Optimised OM3. OM4 fibre is completely backwards compatible with OM3 fiber and shares the same distinctive aqua jacket. OM4 was developed specifically for VSCEL laser transmission and allows 10 Gig/s link distances of up to 550m compared to 300M with OM3. And it’s able to run 40/100GB up to 150 meters utilizing a MPO connector.

 

What’s the Difference: OM3 vs OM4

With so many options, it can be tough to select the most suitable multimode fiber. The first thing to note isOM4 cable has better attenuation and can operate at higher bandwidth than OM3. Since the attenuation of OM4 is lower than OM3 fiber and the modal bandwidth of OM4 is higher than OM3, the transmission distance of OM4 is longer than OM3. Details are shown in the table below. According to your network scale, to choose a more suitable cable type.

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So the difference is just in the construction of the fiber cable. OM4 cable has a different internal construction within the 50/125 core that allows it to operate at much higher bandwidth when measured at the standard modal window of 850nm. OM3 operates at a bandwidth of 2500 megahertz. OM4 has a bandwidth of 4700 megahertz.

 

Fiber Type 100BASE-FX 1000BASE-SX 10GBASE-SR 40GBASE-SR4 100GBASE-SR4
OM3 2000 Meters 550 Meters 300 Meters 100 Meters 100 Meters
OM4 2000 Meters 550 Meters 400 Meters 150 Meters
Advantages 

multimode fiber and components are less expensive and are easier to work with other optical components like fiber connector and fiber adapter, and multimode patch cords are less expensive to operate, install and maintain than single mode fiber cables.

 

NOTE:

1.   OM4 performs better than OM3 cables

2. Attenuation is caused by losses in light through the passive       components, such as cables, cable splices, and connectors. As mentioned above the connectors are the same so the performance difference in OM3 vs OM4  is in the loss (dB) in the cable.

3.  that the connectors are the same, the termination of the connectors is the same, the transceivers are the same (both operate at 850nm VCSELS (Vertical-Cavity Surface-Emitting Lasers), the fiber core size 50/125 is the same and both are Laser Optimised Multimode Fiber (LOMMF).

5. OM3 is fully compatible with OM4.