Multimode fiber optic cable is designed for high-speed data transmission in local area networks (LANs), data centers, and enterprise environments. Multi-mode fiber has a fairly large core diameter that enables multiple light modes to be. Multimode fiber (MMF) is an optical fiber designed to carry multiple light propagation paths—or modes—simultaneously. 5 microns, compared to the ~9-micron core in single-mode fiber. In this blog post, we will discuss the key features and. 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. 5/125 µm) and support multiple.