Long-distance variants, typically referred to as LX, EX, ZX, or ER/LR SFPs, are engineered with higher optical power budgets and longer wavelength lasers (e., 1310nm, 1550nm), enabling transmission distances from 10 km up to 80 km or more over single-mode fiber (SMF). The Cisco 400G QSFP-DD Ultra Long-Haul Coherent Optics Module enables 400G traffic anywhere over dense wavelength division multiplexing amplified networks, and is available in both C-band and L-band. Cisco has expanded the range of 400G digital coherent QSFP-DD transceivers with the 400G QSFP-DD. Some are responsible for connections of a few meters between server racks, while others bear the heavy responsibility of spanning tens of kilometers across a city. This difference is the most fundamental dividing line in the field of optical communication. It provides an ideal solution for large-scale data centers for high-demand. In an era where enterprises are rapidly expanding their network infrastructure, SFP optical transceiver modules designed for long-distance transmission have become essential. LPO (Linear-drive Pluggable Optics), NPO (Near Package Optics), and CPO (Co-Packaged Optics) architectures are becoming core areas of industry focus.
