Step-index multimode fibers are an essential part of many optical communication systems due to their unique features and affordable costs. Despite having lower bandwidth than their graded-index counterparts, they serve a vital role in short-range, low-speed data transmission systems. The refractive index. Bend-insensitive, Pure Silica, Sensor Grade, Step-index, Multimode Fibers feature core diameters ranging from 100–1000 µm. F-MBB Multimode Fiber, Step Index, 500-1100 nm, 0. Multi-mode fiber has a fairly large core diameter that enables multiple light modes to be. Step-index multimode fibers feature a uniform refractive index within the core and a distinct drop at the core-cladding interface. Step ind x MMF are characterized by significant number of modes propagating through fiber.