OM3 (Optical Multimode 3) and OM4 (Optical Multimode 4) are both types of multimode optical fiber that are commonly used in data center and short-reach telecommunications applications. The primary difference between OM3 and OM4 lies in their bandwidth and maximum transmission distance characteristics. Here are the key distinctions:

1. Bandwidth:

• OM3: OM3 fiber has a minimum modal bandwidth of 2000 MHz·km at 850nm.

• OM4: OM4 fiber has a higher minimum modal bandwidth of 4700 MHz·km at 850nm.

2. Maximum Transmission Distance:

• OM3: OM3 fiber is typically designed for shorter-distance applications. It can support 10 Gigabit Ethernet (10GbE) at lengths up to 300 meters and 40/100 Gigabit Ethernet at lengths up to 100 meters.

• OM4: OM4 fiber provides enhanced performance and is designed to support longer distances at higher data rates. It can support 10GbE at lengths up to 550 meters and 40/100GbE at lengths up to 150 meters.

3. Color Identification:

• Both OM3 and OM4 fibers are typically identified by their aqua (light blue) color, which helps distinguish them from other types of fibers.

4. Applications:

• Both OM3 and OM4 fibers are commonly used for high-speed data transmission within data centers and short-distance telecommunications links, especially for applications utilizing multimode transceivers.

In summary, OM4 fiber offers higher bandwidth and longer transmission distances compared to OM3 fiber, making it suitable for applications that require higher data rates over longer distances. The choice between OM3 and OM4 depends on the specific requirements of the network and the desired performance characteristics for a given application.