Explore LINK-PP's full range of high-quality, compliant 1. 25G SFP, 10G SFP+, 25G SFP28, 40G QSFP+, 100G QSFP28 and 400G optical transceivers today! What is the main difference between single mode and multimode fiber? Single mode fiber has a small core and sends light in one path. Single-mode (SMF) and multi-mode fiber (MMF) use different core sizes, sources and wavelengths. These differences determine which transceivers work with which fiber and how far signals can travel. Understanding the compatibility constraints prevents costly downtime and troubleshooting. Single-mode. In fiber-optic communication, a single-mode optical fiber, also known as fundamental- or mono-mode, is an optical fiber designed to carry only a single mode of light - the transverse mode. An optical fiber is a cylindrical. 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. OS2 cable offers low signal attenuation and high bandwidth.