Single-mode optical modules are best for long distances and fast speeds. They use a thin fiber. Singlemode and multimode SFP modules are two primary categories of hot-swappable optical modules used in optical networks. Each module type uses LC interfaces, and professionals commonly group them together under the name LC SFP modules. In this post, I'll discuss how both Multimode and Single mode fiber compare in terms of: But first. Single-mode fiber uses a 9/125 µm core/cladding structure that supports only one propagation mode, which minimizes modal dispersion and allows signals to travel tens of kilometers with low attenuation. Multimode fibers have larger cores (typically 50/125 µm or 62.