Comparison of OM4 and OM3 fiber optic cables

OM4 fiber offers higher bandwidth and longer transmission distances than OM3, making it better suited for high-speed and future-proof network deployments.

Core Specifications

Both OM3 and OM4 are laser-optimized multimode fibers (MMF) with a 50/125 µm core/cladding structure, designed for use with VCSEL-based optical transceivers. They share similar physical characteristics, including jacket color (typically aqua) and connector types, and are fully compatible with each other. OM3: Effective Modal Bandwidth (EMB) of 2,000 MHz·km at 850 nm OM4: EMB of 4,700 MHz·km at 850 nm, more than double that of OM3 Higher EMB allows OM4 to transmit data over longer distances without signal degradation due to modal dispersion.

Maximum Transmission Distances

The main practical difference between OM3 and OM4 is the distance they can support at various Ethernet speeds: Ethernet SpeedOM3 Max DistanceOM4 Max Distance1G1,000 m1,000 m10G300 m400 m25G70 m100 m40G100 m150 m100G100 m150 mAt 1G speeds, both fibers perform identically. OM4 provides a longer reach at 10G and above, which is particularly important in large data centers or campus networks where longer cable runs are required.

Practical Considerations

Compatibility: OM4 is fully backward-compatible with OM3, so it can be used in existing OM3 networks without issues. Cost vs. Performance: OM4 is slightly more expensive than OM3, but the extra cost is justified if you anticipate future upgrades to 40G or 100G Ethernet or need longer 10G runs.

Use Cases: OM3 is sufficient for shorter 10G links under 300 meters. OM4 is preferred for high-speed, long-distance, or future-proof deployments, especially in modern data centers.

Summary

While OM3 and OM4 fibers look similar and support the same core speeds, OM4's higher modal bandwidth and extended reach make it the better choice for high-speed networks and future scalability. For networks with shorter runs and 10G or lower speeds, OM3 remains a cost-effective option. The decision should consider link length, current and future data rates, and budget.