As data centers evolve toward higher speeds and denser architectures, optical transceivers remain central to connectivity. Among them, VCSEL-based 850nm multimode optical modules play a pivotal role in short-reach MMF interconnects, offering an optimal balance of cost, efficiency, and scalability for intra–data center links.
850nm Modules in Multimode Fiber Data Centers
For short-reach distances (typically up to 100–150 meters depending on OM3/OM4/OM5 fiber type), 850nm optical modules remain the dominant solution. Standards such as 10GBASE-SR, 40GBASE-SR4, and 100GBASE-SR10 have long relied on MMF infrastructure. Today, high-speed SR8 and SR16 modules extend this advantage, enabling bandwidth scaling while keeping costs competitive compared to single-mode deployments.
Key advantages include:
Lower cost per port compared to single-mode transceivers.
Optimized for short-reach optical links within racks or between rows.
Lower power consumption, making them attractive for high-density environments.
Mature ecosystem with broad vendor interoperability.
Parallel Optics and High-Speed SR Modules
The adoption of parallel optics has driven demand for SR8 and SR16 modules. These leverage multiple 850nm VCSEL channels in parallel, supporting 200G to 400G data rates today, and paving the way toward 800G multimode transceivers.
Challenges from Single-Mode Adoption
While multimode fiber remains strong in short distances, the increasing availability of increasingly cost-competitive single-mode optics challenges its dominance. With PAM4-based 400G and 800G single-mode modules becoming mainstream, operators face a decision: continue with MMF and VCSEL 850nm modules or migrate toward longer-reach single-mode solutions.
Future Outlook
In the coming years, 850nm optical modules will remain vital for cost-sensitive, high-density deployments. Their future lies in:
Integration with next-generation SR standards (SR4.2, SR8, SR16).
Adoption in parallel optics for 400G and beyond.
Hybrid deployments, where multimode handles short-reach while single-mode supports long-haul connections.
As hyperscale operators optimize data center optical interconnects, the balance between multimode and single-mode adoption in data centers will continue to shift. Yet for short-reach, high-volume connections, 850nm optical modules will likely remain the most efficient and scalable solution.
