The selected wavelength determines fiber compatibility. 850 nm SFP modules are designed for multimode fiber (MMF), where modal dispersion limits transmission distance but enables cost-effective short-reach links. Referring to ITU-T, the attenuation of 1310nm is recommended to be ≤0. 3dB/km, while the. OS1 single mode fiber optic cables are made with a single mode fiber core, which means that they have a very small core diameter of 9 microns. Single-mode. For example, the FOA notes that for glass fibers, “we use light in the infrared region. typically around 850, 1300 and 1550 nm” because attenuation is low in those regions.