There are five main types of multimode fiber, standardized by ISO/IEC 11801: OM1, OM2, OM3, OM4 and OM5. What is Multimode Fiber? To recap Optical Fiber can be divided into Multimode Fiber (MMF) and Single-Mode optical fiber (SMF). Multimode Fiber (MMF) has a core diameter, typically 50–100 micrometers, has ability to transfer multiple modes of light through the fiber core, uses lower-cost electronics. Identified by ISO 11801 standard, multimode fiber optic cables can be classified into OM1 fiber, OM2 fiber, OM3 fiber, OM4 fiber and newly released OM5 fiber. OM1. This guide explains the five generations of multimode fiber - OM1, OM2, OM3, OM4, and OM5 - covering their physical characteristics, color coding, bandwidth, maximum distances at different data rates, optical sources (LED, VCSEL, SWDM), and real-world applications in enterprise networks and data. This Applications Engineering Note (AE Note) discusses the criteria for properly selecting the optimal multimode fiber (MMF) for enterprise applications. All multimode fibers utilizing the above nomenclature should. Although EN 50173 and ISO/IEC 11801 define fiber categories and performance values for cabled fibers, the specific parameters of the fibers themselves are described in other standards.