400G QSFP-DD optical transceivers including SR8, DR4, FR4, LR4 and ER4 for data center and cloud networking!

High-performance 400G QSFP-DD optical modules including SR8, DR4, FR4, LR4 and ER4 for data centers, cloud and AI networks. Learn how to choose the right 400G transceiver.

Why 400G Matters

As cloud computing, AI training clusters, and hyperscale data centers continue to grow, 400G optical modules have become a critical building block for high-bandwidth, low-latency network architectures. 

The QSFP-DD (Quad Small Form Factor Pluggable Double Density) form factor enables higher port density while maintaining backward compatibility, making it one of the most widely deployed 400G solutions today.

400G QSFP-DD Module Types Explained

🔹 400G SR8 (Short Reach)
Designed for short-distance connections inside data centers, 400G SR8 supports up to 100 meters over OM4 multimode fiber (MMF).
Typical use cases include switch-to-switch and switch-to-server connections in high-density environments.

🔹 400G DR4 (Direct Reach)
400G DR4 supports up to 500 meters over single-mode fiber (SMF) using parallel optics.
It is widely used in spine–leaf architectures and offers a cost-effective alternative to longer-reach solutions.

🔹 400G FR4 (Fiber Reach)
With a reach of 2 kilometers over SMF, 400G FR4 uses wavelength-division multiplexing (WDM) and is ideal for larger data halls or campus-style data centers.

🔹 400G LR4 (Long Reach)
400G LR4 supports transmission distances up to 10 kilometers, making it suitable for data center interconnect (DCI) and cross-campus deployments.

🔹 400G ER4 (Extended Reach)
For metro and long-distance applications, 400G ER4 can reach up to 40 kilometers over SMF, enabling high-capacity links between geographically separated sites.

Why Choose Compatible 400G Optical Modules

Compatible 400G QSFP-DD transceivers deliver:

• OEM-level performance and reliability

• Verified compatibility with mainstream switches

• Faster delivery and flexible supply

• Lower total cost of ownership (TCO)

For cloud operators and enterprise networks, compatible optics provide a smart balance between performance and cost efficiency.

Conclusion

Choosing the right 400G QSFP-DD optical module depends on distance, fiber type, and network architecture.
From SR8 and DR4 for intra–data center links to LR4 and ER4 for DCI and metro networks, a well-planned 400G deployment ensures scalability and long-term performance.