QSFP28 Optical Module Low-Loss Technology Support

QSFP28 optical modules are high-speed 100G transceivers designed for low-loss, high-performance Ethernet links, supporting both short- and long-reach applications over multimode and single-mode fiber.

Overview of QSFP28

QSFP28 (Quad Small Form-Factor Pluggable 28) modules provide four lanes of 25 Gbps, aggregating to 100 Gbps Ethernet throughput. They are widely used in data centers, enterprise networks, and telecom infrastructure due to their high port density, low power consumption, and standardized CAUI-4 electrical interface . The modules can support multiple optical technologies, including VCSELs for multimode fiber, DFB lasers for single-mode fiber, PAM4, and coherent optics, depending on the deployment requirements .

Low-Loss and Long-Reach Options

Low-loss QSFP28 modules are designed to minimize optical attenuation, enabling longer link distances without signal degradation. Key types include:

• QSFP-SR4-100G: Supports up to 70m on OM3 and 100m on OM4 multimode fiber using 12-fiber MTP/MPO connectors, ideal for short-reach, low-loss intra-rack connections .
• QSFP-PSM4-100G: Single-mode parallel fiber module supporting up to 500m, suitable for low-loss, medium-range links in data centers .
• QSFP-DR-100G: Uses single-wavelength PAM4 modulation over standard single-mode fiber for up to 500m, providing low-loss performance with duplex LC connectors .
• QSFP28-100G-ZR4: Designed for long-reach 80km links over single-mode fiber at 1310nm, leveraging low-loss coherent optics and FEC for metro and regional networks .
• QSFP-ESR4-100G: Extended short-reach module supporting 200m on OM3 and 300m on OM4, optimized for low-loss, high-bandwidth intra-data center links .

Coherent vs PAM4 Low-Loss Modules

• Coherent QSFP28: Provides extended reach and wavelength tunability, ideal for metro, regional, and long-haul networks. Coherent modules maintain low-loss performance over hundreds of kilometers by compensating for fiber impairments .
• PAM4 QSFP28: Optimized for shorter-range, low-power, cost-effective deployments in data centers. PAM4 modulation allows higher data density per wavelength while maintaining low insertion loss over short distances .

Key Considerations for Low-Loss Deployment

1. Fiber Type: Single-mode fiber (SMF) is preferred for long-reach low-loss links, while multimode fiber (MMF) is suitable for short-reach low-loss connections.
2. Connector Type: MTP/MPO for parallel fiber modules (SR4, PSM4) and LC duplex for single-lambda or coherent modules.
3. FEC and Modulation: Forward Error Correction (FEC) and PAM4 or coherent modulation help maintain low-loss performance over longer distances.
4. Compatibility: QSFP28 modules are generally compatible with major switch vendors (Cisco, Arista, Juniper, Brocade) when certified .

Summary

QSFP28 optical modules provide flexible, low-loss 100G connectivity across a range of distances and fiber types. For short-reach intra-rack links, SR4 or ESR4 modules are ideal. For medium-range low-loss links, PSM4 or DR modules are suitable. For long-reach metro or regional networks, ZR4 coherent modules deliver low-loss performance over tens of kilometers. Choosing the right module depends on distance, fiber type, modulation, and network architecture .