Multimode fiber mode length

Multimode fiber supports short- to medium-range transmission, with maximum distances ranging from 33 meters for OM1 at 10G to 550 meters for OM4 at 10G.

Maximum Transmission Distances by Fiber Type

• OM1 (62.5 µm core, LED source): Supports 100 Mbps Ethernet up to 2 km, 1G Ethernet up to 275 meters, and 10G Ethernet up to 33 meters .
• OM2 (50 µm core, LED source): Suitable for 1G Ethernet and limited 10G applications; 10G Ethernet can reach up to 82 meters .
• OM3 (50 µm core, laser-optimized, VCSEL source): Supports 10G Ethernet up to 300 meters, 40G/100G Ethernet up to 100 meters .
• OM4 (50 µm core, laser-optimized, VCSEL source): Extends 10G Ethernet up to 550 meters and 40G/100G Ethernet up to 150 meters .
• OM5 (50 µm core, wideband multimode, SWDM capable): Backwards compatible with OM4, optimized for multiple wavelengths, suitable for 100G and 400G networks over short distances .

Factors Affecting Multimode Fiber Length

1. Core Size: Larger cores (OM1) allow easier light coupling but suffer from modal dispersion, limiting distance at high speeds. Smaller cores (OM2–OM5) reduce dispersion and support longer distances with laser sources.
2. Light Source: LEDs are used in OM1/OM2, limiting distance and bandwidth. VCSELs in OM3–OM5 enable higher speeds and longer reach.
3. Data Rate: Higher data rates reduce maximum distance due to increased modal dispersion. For example, OM3 can carry 10G up to 300 meters but only 40G/100G up to 100 meters.
4. Modal Dispersion: Multiple light modes in multimode fiber travel at different speeds, which limits the effective transmission distance compared to single-mode fiber .

Practical Considerations

• Short-range networks: OM1 and OM2 are suitable for legacy or intra-building connections.
• Data centers and high-speed LANs: OM3, OM4, and OM5 are preferred for 10G, 25G, 40G, 100G, and beyond, providing longer reach and future-proofing.
• Cost efficiency: Multimode fiber is generally cheaper than single-mode fiber for short distances due to lower-cost transceivers and easier installation . In summary, multimode fiber is ideal for distances up to several hundred meters, with OM3–OM5 fibers offering the longest reach for high-speed applications, while OM1 and OM2 are limited to shorter distances and lower data rates.