SR4 and LR4 optical modules

SR4 modules are optimized for short-range multimode fiber connections, while LR4 modules are designed for long-range single-mode fiber links. Key Differences1. Transmission Distance and Fiber TypeSR4 (Short Range 4-channel): Uses multimode fiber (MMF) and supports short distances—typically up to 100 meters on OM3 and 150 meters on OM4/OM5 fibers for 40G, and up to 100 meters for 100G and 400G SR4 modules.

LR4 (Long Range 4-channel): Uses single-mode fiber (SMF) and supports long distances—up to 10 km for 40G, 100G, and 400G LR4 modules. 2. Wavelength and Transmission TechnologySR4: Employs parallel optics with four channels at 850 nm for 40G and 100G, or four parallel lanes for 400G, transmitting data simultaneously through multiple fibers.

LR4: Uses Wavelength Division Multiplexing (WDM), combining four distinct wavelengths (e.g., 1271 nm, 1291 nm, 1311 nm, 1331 nm for 40G) over a single fiber pair, enabling long-distance transmission. 3. ConnectorsSR4: Typically uses MPO/MTP connectors for multimode fiber.

LR4: Uses duplex LC connectors for single-mode fiber. 4. Power ConsumptionSR4: More power-efficient, generally under 1.

5W for 40G modules. LR4: Slightly higher power consumption due to complex laser technology, usually under 2. 5W for 40G modules.

5. ApplicationsSR4: Ideal for intra-data center connections, short-reach links, and cost-sensitive deployments where multiple fibers are acceptable. LR4: Suitable for inter-campus or long-distance connections, wide-area networks, and scenarios requiring fewer fibers with extended reach.

6. Cost ConsiderationsSR4: Lower cost due to simpler optics and shorter reach. LR4: Higher cost because of WDM technology and long-distance capability.

SummarySR4 and LR4 optical modules serve the same fundamental purpose of high-speed data transmission but are optimized for different network scenarios. SR4 is best for short-range, high-density data center links using multimode fiber, while LR4 is designed for long-range connections over single-mode fiber, supporting distances up to 10 km. Choosing between them depends on distance requirements, fiber type, connector availability, and budget.

For 400G networks, SR4 uses parallel optics, whereas LR4 employs long-wavelength division multiplexing to achieve extended reach.