As we all know, multimode fiber is usually divided into OM1, OM2, OM3, OM4 and OM5 fiber types. When it comes to single mode fiber types, it can be categorized into OS1 and OS2 fiber, which are SMF fiber specifications. Single mode fibers are. 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. There are two main types of fiber optic cables: single mode and multimode. Although they can do the same job in some instances, the different construction methods make each of them better suited to certain tasks and budgets.