What Is OM3 Fiber?_
OM3 fiber is a laser-optimized multimode fiber (MMF) designed to support 10 Gb/s up to 300 meters and 40/100 Gb/s up to 100 meters using parallel optics. It has an effective modal bandwidth (EMB) of 2000 MHz·km at 850 nm, enabling higher data rates over longer distances than older OM1/OM2 fibers. OM3 is typically terminated with MPO connectors for multi-fiber trunk cables or LC duplex for transceiver connections.
Technical Details
OM3 fiber uses a 50 µm core with a graded-index profile to minimize modal dispersion, and it is specified per ISO/IEC 11801 and TIA-568.3-D. For 400 Gb/s SR8 (8-lane parallel) links, OM3 supports reaches up to 70 meters depending on the transceiver class, while 100 Gb/s SR4 reaches about 100 meters. The fiber is color-coded aqua (light blue) to distinguish it from OM4 (violet) and single-mode (yellow). Connector end-face geometry and cleanliness are critical for low insertion loss and return loss, especially in high-density MPO arrays.
How Leviathan Systems Works with OM3 Fiber
In our field deployments, OM3 is the standard multimode fiber for intra-rack and adjacent-rack GPU-to-switch links in the scale-out network (InfiniBand/Ethernet), typically run as pre-terminated MPO trunk cables between patch panels and NICs. We often pair OM3 with 400 Gb/s SR8 transceivers for GPU nodes, ensuring cable lengths stay within the supported distance to avoid link errors.
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