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What are the main differences between 400G and 800G optical transceivers?
May 19 , 2025In the field of data center high-speed interconnection, the core differences between 400G optical transceivers and 800G optical transceivers lie in the divergence of technical paths and application scenarios.
Transmission rate and modulation technology are the core distinctions: 400G uses NRZ modulation, transmitting in parallel through four 100Gbps channels; 800G upgrades to PAM4 technology, with each channel supporting 200Gbps, achieving 800Gbps via four channels. This improves spectral efficiency but imposes stricter requirements on signal processing.
In packaging and wavelength configuration, 400G mainly adopts QSFP-DD/OSFP packages with multimode 850nm or single-mode 1310nm/1550nm wavelengths; 800G integrates four 200G PAM4 channels in the same package via wavelength multiplexing and introduces silicon photonics to enhance integration. While doubling density, this raises demands for thermal management and chips.
For application scenarios, 400G suits medium-scale scenarios like data center leaf-spine interconnection and 5G backhaul (multimode 200m to single-mode 10km); 800G targets high-end scenarios such as core-layer interconnection in hyperscale data centers and AI computing clusters, requiring single-port 800G rate aggregation and long-haul transmission over 40km.
In the industrial ecosystem, 400G continues optimizing niche packaging, while 800G drives the industry toward high integration via innovations like miniaturized coherent modules and co-packaged optics, forming a "high-speed to ultra-high-speed" technical complementarity.
As an innovative enterprise in optical communications, FiberWDM offers a full range of 400G/800G optical transceivers:
For customized fiber optic solutions, contact the FiberWDM technical team at: sales@fiberwdm.com