OM3 fiber and OM4 fiber are both laser-optimized multimode fibers with 50/125µm fiber cores, which need to meet the ISO 11801 standard. They have many things in common such as the fiber connectors and application scenarios, making them confusing to users. This post will illustrate the detailed comparison of OM3 vs OM4 in five main aspects such as OM3 vs OM4 bandwidth, speed, transmission distance, etc., and give guidance on how to choose between the two in different situations.
One big difference between OM3 and OM4 multimode cable is that OM4 provides a higher modal bandwidth 4700 MHz·km compared to 2000 MHz·km of OM3. Modal bandwidth characterizes the ability of a fiber to transmit a certain amount of information over a certain amount of distance, which means OM4 fiber can transmit more information within the same distance than OM3 fiber. And the modal bandwidth is determined by the modal dispersion in fiber cables. The higher bandwidth available in OM4 means a smaller modal dispersion and thus allows the cable links to be longer with lower losses or attenuation.
The OM3 fiber spec indicates that OM3 fiber is mainly designed for 10 Gb/s transmission speed, but it also can run under 40 Gb/s and 100 Gb/s. As an advancement of OM3 fiber, OM4 fiber is chiefly used for 10G, 40G and 100G Ethernet. Both OM3 and OM4 fibers support 40 Gb/s and 100 Gb/s speeds when they are terminated with 8/12-fiber MTP/MPO connectors and 24-fiber MTP/MPO connectors respectively. The 40G interfaces are 4x10G channels on four fibers per direction and the 100G interfaces are 10x10G channels on 10 fibers per direction.
The transmission distance of OM3 and OM4 fiber cables varies when they are applied to Gigabit, 10GbE, 40GbE and 100GbE applications. You can check the maximum transmission distances of OM3 and OM4 under different transmission speeds in the below figure.
|850 nm Ethernet Distance|
|OM3||1 km||300 m||100 m|
|OM4||1 km||550 m||150 m|
OM4 fiber distance is longer than OM3 fiber distance based on 10, 40 and 100 Gb/s. But the maximum transmission distance of OM4 under 10G remained controversial. As a rule of thumb, it is recognized as 400 m. But it still can achieve up to 550 m if the OM4 fiber has an ultra high quality.
Laser-optimized OM3 and OM4 multimode fiber are defined as an aqua jacket when used with LC connectors, and thus they share the same color. But it is not an easy way for technicians to identify OM3 and OM4 fiber optic cable, especially when staring at the front of a panel where all the adapters look the same. A new violet color for OM4 was introduced to solve this problem, which is also called Erika Violet. But the violet OM4 color has only been applied in Europe and several American companies so far. In terms of OM3 and OM4 cable ended with MTP/MPO connector, OM3 is an aqua jacket while OM4 is an Erika Violet jacket.
To a large extent, cost depends on the construction type of the cable (loose tube, tight buffered, etc.). Therefore, the cost difference of fiber products such as standard fiber patch panels, MTP cassette modules, and fiber patch cords is very small (as the volume of cable is small). At FS.COM, the price discrepancy between OM3 and OM4 fiber optic cable is slight—the 1m PVC OM3 cable price is about $4.2, while the 1m PVC OM4 fiber price is from $3.9 to $4.6.
The vast majority of enterprise 10 GbE link lengths are less than 300 meters so OM3 fiber cable can meet most requirements. Of course, the OM4 with higher bandwidth could address these as well. For 40 GbE and 100 GbE links, OM3 and OM4 fiber have a subtle difference in transmission distance (OM3 for 100 m, OM4 for 150 m). If you need longer transmission distance, OM4 multimode fiber is an ideal option.
For OM3 and OM4 compatibility, OM4 fiber is completely backwards compatible with OM3 fiber since they have the same core diameter. However, when connecting two products with different performance levels the best performance that can be expected will be that of the lower performing component. For example, if one mixes the OM3 and OM4 fiber cable, the best performance that can be expected is that of OM3.