100G optical modules, typically QSFP28 transceivers, use MPO or LC optical ports to deliver 100Gbps connectivity, often via four parallel 25Gbps lanes that can be split into lower-speed channels using breakout cables.

Overview of 100G Optical Modules

100G optical modules are hot-pluggable transceivers designed to provide high-speed Ethernet connectivity in data centers, enterprise networks, and telecom environments . The most common form factor is QSFP28 (Quad Small Form-factor Pluggable 28), which aggregates four 25Gbps lanes to achieve a total throughput of 100Gbps . These modules are compatible with IEEE 802.3bm standards and support various link distances depending on the module type and fiber used .

Optical Ports and Connectors

• MPO (Multi-fiber Push-On) connectors: Typically used for parallel fiber connections, carrying 12 or 24 fibers. MPO ports are common in SR4, LR4, and CWDM4 modules for short- and long-reach applications .
• LC connectors: Used in duplex fiber connections, often for breakout or single-lane applications, allowing one 100G port to connect to multiple 25G or 10G devices via breakout cables .

Breakout Functionality

Breakout-capable 100G modules allow a single 100G port to split into multiple lower-speed channels, such as four 25Gbps or 10Gbps links . This is implemented using:

• Breakout DACs (Direct Attach Cables)
• Breakout AOCs (Active Optical Cables)
• Breakout transceivers connecting to SFP+/SFP28 modules This functionality improves port utilization and network flexibility without requiring additional 100G ports .

Module Types and Applications

• SR4: Short-reach multimode fiber, typically up to 100m over OM4 fiber .
• LR4: Long-reach single-mode fiber, up to 10km.
• CWDM4: Coarse Wavelength Division Multiplexing for 2km–10km links.
• ZR4 / ZR: Coherent optics for metro or long-haul links, up to 80km over dark fiber or 300km over DWDM networks . These modules are widely used in data center interconnects, enterprise core networks, and metro networks, providing high-density, low-power, and scalable 100G connectivity .

Summary

A 100G optical module connects to a 100G optical port using MPO or LC connectors, supporting either a single 100Gbps link or multiple lower-speed links via breakout. QSFP28 modules are the industry standard, offering flexibility for short- and long-reach applications, high port density, and compatibility with IEEE standards . Proper selection depends on fiber type, distance, breakout requirements, and network architecture.