What type of fiber optic cable is used for a 100G optical module

100G optical modules can use either multimode fiber (OM3, OM4, OM5) or single-mode fiber (SMF), depending on the transceiver type and required reach.Multimode Fiber (MMF)

For short-reach 100G connections, multimode fibers are commonly used:

• OM3: Supports up to 70–100 meters for SR4 or BiDi 100G modules using QSFP28 form factor with MPO or duplex LC connectors .
• OM4: Extends reach up to 100 meters for SR4 or BiDi modules, also compatible with QSFP28 and SFP56-DD modules .
• OM5: Designed for wavelength-division multiplexing (WDM) over multimode fiber, supporting similar distances as OM4 but with multiple wavelengths for future-proofing . Connector types for MMF include MPO/MTP for parallel optics (SR4) and duplex LC for BiDi modules .

Single-Mode Fiber (SMF)

For longer distances, single-mode fiber is used:

• 100G-DR1 (500 m), 100G-FR1 (2 km), 100G-LR1 (10 km): These modules operate over SMF using a single wavelength per lane, typically with duplex LC connectors .
• SMF is preferred for inter-data center links or long-haul connections due to lower attenuation and higher reach.

Active Optical Cables (AOCs)

For intra-rack or short inter-rack connections, 100G QSFP28 AOCs combine electrical and optical components in a single cable, converting electrical signals to optical signals for high-speed transmission over short distances (typically within racks) with duplex LC connectors .

Summary

• Short-reach (up to 100 m): Multimode fiber (OM3, OM4, OM5) with MPO or duplex LC connectors.
• Medium to long reach (500 m to 10 km): Single-mode fiber (SMF) with duplex LC connectors.
• Intra-rack or short interconnects: Active Optical Cables (AOCs) with embedded transceivers. Choosing the correct fiber type depends on the transceiver module, distance, and network architecture. For example, SR4 modules use 8-fiber parallel MMF, while BiDi modules use 2-fiber duplex MMF, and DR/FR/LR modules use SMF for longer distances .