As data centers, AI computing, and high-performance networking evolve, the demand for scalable, high-bandwidth optical transceivers has surged. The QDD-8X100G-FR and QDD-2X400G-FR4 modules are two key solutions designed to address different network expansion needs, supporting high-speed aggregation, AI cluster connectivity, and hyperscale data center deployments.
This article explores the technical specifications, applications, and benefits of these high-density QSFP-DD transceivers, helping organizations choose the right module for scalable 100G and 400G networking.
1. Overview of QDD-8X100G-FR & QDD-2X400G-FR4
| Transceiver Model | Total Bandwidth | Lane Configuration | Distance | Fiber Type | Form Factor |
| QDD-8X100G-FR | 800G | 8x100G FR (4WDM-2) | 2km | Single-mode fiber (SMF) | QSFP-DD |
| QDD-2X400G-FR4 | 800G | 2x400G FR4 (4x100G per channel) | 2km | Single-mode fiber (SMF) | QSFP-DD |
Both modules utilize the QSFP-DD (Quad Small Form-Factor Pluggable – Double Density) form factor, supporting 800G total bandwidth but catering to different network deployment scenarios.
2. QDD-8X100G-FR: 8x100G for High-Density Aggregation
🔹 Key Features
- 800G aggregate bandwidth (8 lanes of 100G)
- Supports 2km transmission over SMF
- 4WDM-2 modulation for efficient 100G transmission
- Ideal for spine-leaf connectivity & AI interconnects
🔹 Use Cases
✔ 100G AI Server Interconnects – Directly connects 100G AI servers, GPUs, and accelerators to a 400G or 800G fabric.
✔ Spine-Leaf Aggregation – Provides multi-lane 100G breakout options for high-density 100G access networks.
✔ Hyperscale Data Centers – Supports multi-tenant, cloud AI computing environments.
🔹 Deployment Example: AI Data Center
- AI Servers (100G NICs) → QDD-8X100G-FR → 400G/800G AI Leaf Switch
- Ensures low-latency, high-throughput interconnects for machine learning workloads
🔹 Best for AI-driven, high-density 100G connectivity in modern network fabrics.
3. QDD-2X400G-FR4: High-Speed 2x400G Networking
🔹 Key Features
- 800G aggregate bandwidth (2 lanes of 400G)
- Supports 2km transmission over SMF
- 400G FR4 (4x100G per 400G lane)
- Designed for high-speed core network links
🔹 Use Cases
✔ 400G Data Center Interconnects (DCI) – Connects spine switches at 400G per channel.
✔ AI Cluster Backbone – Provides ultra-high-speed AI GPU-to-GPU communication.
✔ Cloud & Edge Computing – Reduces congestion in distributed AI inferencing environments.
🔹 Deployment Example: 800G AI Fabric
- AI Compute Cluster (400G GPUs) → QDD-2X400G-FR4 → 800G Spine Switch
- Ensures fast, lossless AI training and model processing
🔹 Best for high-speed 400G networking, AI training fabrics, and large-scale data center expansion.
4. QDD-8X100G-FR vs. QDD-2X400G-FR4: Key Differences
| Feature | QDD-8X100G-FR | QDD-2X400G-FR4 |
| Total Bandwidth | 800G | 800G |
| Lane Configuration | 8x100G | 2x400G (4x100G per lane) |
| Distance | 2km | 2km |
| Best for | AI Compute & Spine-Leaf Aggregation | High-Speed AI Fabric & 400G Data Center Links |
| Ideal Deployment | Multi-100G AI server interconnects | Ultra-fast 400G networking |
🔹 QDD-8X100G-FR is ideal for connecting multiple 100G devices, while QDD-2X400G-FR4 is optimized for high-speed 400G backbones.
5. Choosing the Right Module for AI & Data Center Networks
✔ Choose QDD-8X100G-FR If:
- You need high-density 100G connectivity (e.g., AI servers, GPUs, 100G NICs)
- Your network architecture requires 8x100G breakout links
- You are deploying spine-leaf switching in hyperscale environments
✔ Choose QDD-2X400G-FR4 If:
- You require high-speed 400G interconnects for AI or cloud computing
- Your infrastructure uses 800G core networking
- You need ultra-low latency for AI model training
Conclusion: Scalable 800G Solutions for Next-Gen Networking
Both QDD-8X100G-FR and QDD-2X400G-FR4 provide 800G networking capabilities, tailored for different use cases:
✅ QDD-8X100G-FR is best for multi-lane 100G deployments in AI computing & data centers.
✅ QDD-2X400G-FR4 is optimized for ultra-fast 400G interconnects in AI, cloud, and hyperscale environments.
🚀 Upgrade your AI and high-speed data center networks with cutting-edge 800G solutions!
About Optech Technology Co. Ltd
Optech Technology Co. Ltd was founded in 2001 in Taipei, Taiwan. The company was created with a sole purpose, to provide a wide and high quality portfolio of optical products to a very demanding and fast evolving market.
To respond to the permanent increase of IP traffic, Optech portfolio is constantly growing. Since the beginning, the company has always been up to date with the latest innovations on the market. Today, we are proud to deliver a large selection of 25G SFP28, 40G QSFP+, 100G QSFP28, 200G QSFP56, 400G QSFP-DD, 800G QSFP-DD and OSFP optical transceivers and cables.
Optech has a large portfolio of products which include optical transceivers, direct attach cables, active optical cables, loopback transceivers, media converters and fiber patch cords.
Through its large selection of optical products, that have a range of data speed from 155 Mbps to 800 Gbps and reach distances up to 120km, Optech products are suitable for various industries such as telecom, data centers as well as public and private networks.
| Part Number | Optech Part Number | Features |
| QDD-2X400G-FR4 | OPDM-S02-13-CBL | 800Gb/s QSFP-DD 2xFR4 single mode mode, Dual LC, 1310nm, up to 2km |
| QDD-2X400G-FR4 | OPDM-S02-13-CBC | 800Gb/s QSFP-DD 2xFR4 single mode mode, Dual CS, 1310nm, up to 2km |
For additional information about the QDD-2X400G-FR4, or price inquiry, please contact us at sales@optech.com.tw
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