Choosing Between OM3 and OM4 Fiber Optics Cables

The OM3 and OM4 fibers are laser-optimized with a 50/125 core, which is made to comply with the ISO 11801 Standard. The OM3 fiber specs indicate that the OM3 is particularly made for 10 Gb/s transmission speed, but it is also compatible with, and can function under 40 Gb/s and 100 Gb/s. The OM4 fiber is the improved version of the OM3 fiber. The OM4 fiber is mainly used for an Ethernet of 10G, 40G, and 100G. The OM3 and OM4 fiber optics have a minimum of 2000 MHz*km EMB (Effective Modal Bandwidth or laser bandwidth) and 4700 MHz*km EMB respectively. This means that the OM3 can move 2000 Megahertz of data up to 1 km, and OM4 can move 4700 Megahertz of data up to 1 km. For both OM3 and OM4 cables, the EMB is the most effective when the distance remains at 1 km or under; a distance of over 1 km would slow down transmission speed. Regarding compatibility, the OM4 is entirely backwards compatible with the OM3 fiber optics. The chart below provides detailed information on the minimum modal bandwidths of the OM3 and OM4 fibers.

The OM3 and OM4 multimode fibers are compatible with 1GbE, 10GbE, 40GbE, and 100GbE applications, but their transmission distance depends on the application. The chart below displays the maximum transmission distances of the OM3 and OM4 fibers under different transmission speeds. Referring to a speed of 10 Gb/s as an example, with a distance of 550m, the OM4 fiber projects over a longer distance than the OM3 fiber, which only projects a distance of 330m.

However, through the usage of parallel-optics transmission technology, 40G and 100G Ethernet can transmit and receive data simultaneously over multiple fiber optics. The 40G interfaces are 4x10G channels on four fibers per direction, then the OM3/OM4 cable terminated with an 8/12 fiber MTP/MPO connector can be used for 40 Gb/s transmission. 100G interfaces are 10x10G channels on 10 fibers per direction, then the OM3/OM4 cable terminated with the 24 fiber MTP/MPO connector is supposed to support 100 Gb/s.

The OM4 fiber cable costs a third more than the OM3 cable. To a large extent, cost also depends on the construction type of the cable (loose tube, tight buffered, etc.). The cost differences for the fiber accessories such as fiber patch panels, MTP cassette modules, and fiber patch cords, however, are minimal.

To decide whether to choose the OM3 or OM4 fiber, you have two considerations to make. One being the distance limitations of your existing multimode network application. If it exceeds the distance of the OM3 fiber, then the OM4 fiber would be the natural choice. Secondly, you would also have to consider whether you would be upgrading to a higher network speed during the lifespan of the fiber optic cable plant. If you will be, the OM4 fiber would be able to provide you with higher data rates transmission at a longer distance.