Although there is a difference in size, it's not easily visible to the naked eye as they are smaller than a human hair's width. With a protective cladding, both single mode and multimode fibers have a. Multi-mode optical fiber is a type of optical fiber mostly used for communication over short distances, such as within a building or on a campus. Multi-mode links can be used for data rates up to 800 Gbit/s. Multi-mode fiber has a fairly large core diameter that enables multiple light modes to be. Multimode fibers are fibers having multiple guided modes at the operating wavelength — sometimes only a few (→ few-mode fibers), but often many. This larger core allows multiple modes of light to propagate simultaneously. What you can see when you put a connector on an optical.