Multimode fiber is a kind of optical cables which is designed to carry multimode light rays or modes concurrently. Those light rays or modes are reflected at slightly different angles within the optical core which is in the standard 125-μm cladding. And due to its modes tend to disperse over long distance, multimode fiber is applied for communications over short distances. Now there are four types of mulimode fibers: OM1, OM2, OM3 and OM4 types which are of different properties. This article will introduce the four types in details.
OM1 fiber has a core size of 62.5µm with an orange jacket which is at the wavelength of 850 nm /1300 nm. It supports 10 Gigabit Ethernet at lengths up 33 meters but is most commonly used for 100 Megabit Ethernet applications. In the 80’s, 90’s and early 2000’s, the 62.5/125µm OM1 fiber was thought to be the most popular multimode fiber choice for it has the lowest data carrying capacity and shortest distance limitations in comparison with other multimode fiber types.
OM2 fiber commonly comes with an orange jacket but has a core size of 50µm instead of 62.5µm. It also typically operates at 850 nm/1300 nm. It supports 10 Gigabit Ethernet at lengths up to 82 meters but is more commonly used for 1 Gigabit Ethernet applications. The 50/125µm OM2 multimode fiber was first invented by Corning in the 1970s and gradually became popular and even the first choice for newly established networks for it supports longer transmission distance and higher bandwidth.
Note: OM1and OM2 fiber are both orange jacket fiber and work well with LED based equipment.
OM3 fiber is 50µm core diameter with aqua jacket. Optimized for lased based equipment which needs fewer mode of light, it is capable of being applied in 10 Gigabit Ethernet at strengths up to 300 meters. The 50/125 µm OM3 fiber is considered to be the best choice for 10 Gigabit Ethernet unless you need the extra distance provided by OM4. Enhancements on its inception and production technologies enable OM3 to be used in 40 Gigabit and 100 Gigabit Ethernet at lengths up to 100 meters.
OM4 fiber has the same core size and jacket color as OM3 fiber. It is also optimized for laser based equipment. As a further development of OM3 fiber, it can support 10 Gigabit Ethernet at lengths up 550 meters and 100G Gigabit Ethernet at lengths up 150 meters. Now as the rapid development of 40G and 100G Gigabit Ethernet, OM4 fiber is widely applied especially in data centers. It provides the most cost effective solutions for data centers by avoiding the higher costs associated with single-mode laser source.
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