OM1OM4

OM1 and OM4 are categories within the multimode optical fiber family used in telecommunications and data networks. They are defined in international cabling standards, and are commonly referred to alongside other multimode classes such as OM2 and OM3.

OM1 fiber generally uses a larger core, typically around 62.5 micrometers, and is optimized for light sources based on LEDs. It offers lower bandwidth compared with newer laser-optimized fibers and is primarily associated with legacy networks and shorter-distance applications.

OM4 fiber uses a smaller 50 micrometer core and is designed as a laser-optimized multimode fiber for higher-speed transmissions. It provides a higher bandwidth-distance product and is capable of supporting longer reach at higher data rates, such as 10 gigabits per second and above, which makes it well suited for data centers and high-speed campus networks.

Both OM1 and OM4 share compatibility with the same general multimode fiber infrastructure and connectors, but their performance characteristics depend on matching the correct transceivers and cabling specifications. In practice, achieving the intended performance requires selecting transceivers and components that are designed for the specific OM category and its bandwidth capabilities.

Key differences between OM1 and OM4 include core size, source compatibility (LED for OM1 versus laser-optimized VCSEL for OM4), and the overall bandwidth-distance performance. These distinctions influence suitable applications, with OM1 often found in older installations and OM4 favored for modern high-speed networks and data-center links.

See also: Multimode fiber, ISO/IEC 11801, IEC 60793-2-50.