Tag Archives: OM1 Fiber

What are OM1, OM2, OM3 and OM4?


There are different types of fiber optic cable. Some types are single-mode, and some types are multimode. Multimode fibers are described by their core and cladding diameters. Usually the diameter of the multimode fiber is either 50/125 µm or 62.5/125 µm. At present, there are four kinds of multi-mode fibers: OM1, OM2, OM3 and OM4. The letters “OM” stand for optical multimode. Each type of them has different characteristics.


Each “OM” has a minimum Modal Bandwidth (MBW) requirement. OM1, OM2, and OM3 fiber are determined by the ISO 11801 standard, which is based on the modal bandwidth of the multimode fiber. In August of 2009, TIA/EIA approved and released 492AAAD, which defines the performance criteria for OM4. While they developed the original “OM” designations, IEC has not yet released an approved equivalent standard that will eventually be documented as fiber type A1a.3 in IEC 60793-2-10.


  • OM1 cable typically comes with an orange jacket and has a core size of 62.5 micrometers (µm). It can support 10 Gigabit Ethernet at lengths up 33 meters. It is most commonly used for 100 Megabit Ethernet applications.
  • OM2 also has a suggested jacket color of orange. Its core size is 50µm instead of 62.5µm. It supports 10 Gigabit Ethernet at lengths up to 82 meters but is more commonly used for 1 Gigabit Ethernet applications.
  • OM3 fiber has a suggested jacket color of aqua. Like OM2, its core size is 50µm. It supports 10 Gigabit Ethernet at lengths up to 300 meters. Besides OM3 is able to support 40 Gigabit and 100 Gigabit Ethernet up to 100 meters. 10 Gigabit Ethernet is its most common use.
  • OM4 also has a suggested jacket color of aqua. It is a further improvement to OM3. It also uses a 50µm core but it supports 10 Gigabit Ethernet at lengths up 550 meters and it supports 100 Gigabit Ethernet at lengths up to 150 meters.

OM1, OM2, OM3 and OM4 multi-mode fiber


There are several differences between four kinds of multi-mode fiber, and we can see them clearly from the table below:
OM1, OM2, OM3 and OM4 multi-mode fiber

  • Diameter: The core diameter of OM1 is 62.5 µm , however, core diameter of the OM2, OM3 and OM4 is 50 µm.
  • Jacket Color: OM1 and OM2 MMF are generally defined by an orange jacket. OM3 and OM4 are usually defined with an aqua jacket.
  • Optical Source: OM1 and OM2 commonly use LED light source. However, OM3 and OM4 usually use 850 nm VCSELs.
  • Bandwidth: At 850 nm the minimal modal bandwidth of OM1 is 200MHz*km, of OM2 is 500MHz*km, of OM3 is 2000MHz*km, of OM4 is 4700MHz*km.

OM3 & OM4 are Superior to OM1&OM2

10G OM3Both OM1 and OM2 work with LED based equipment that can send hundreds of modes of light down the cable, while OM3 and OM4 are optimized for laser (eg. VCSEL) based equipment that uses fewer modes of light. LEDs can not be turned on/off fast enough to support higher bandwidth applications, while VCSELs are capable of modulation over 10 Gbit/s and are used in many high speed networks. For this reason, OM3 and OM4 are the only multi-mode fibers included in the 40G and 100G Ethernet standard. Now OM1 and OM2 are usually used for 1G which are not suitable for today’s higher-speed networks. OM3 and OM4 are used for 10G mostly at present. But in the future, since OM3 and OM4 can support the 40G and 100G, which may make them the tendency.

Related article: Singl-mode vs. Multimode Fiber Cable

The Progress of Multimode Fiber

In 1976, Corning developed 50/125μm by the graded-index multimode fiber and 1983 by Lucent Bell Labs developed 62.5/125μm graded-index multimode fiber, they are two larger amount of Multimode Fiber. The cladding diameter and mechanical properties of these two fibers are same, but different transmission characteristics. They can provide such as Ethernet, Token Ring and FDDI protocols specified in the standard distance required bandwidth, and it can be upgraded to Gb/s rate.

The new multimode fiber standard grades issued by ISO / IEC 11801, Multimode fiber is divided into four categories, OM1, OM2, OM3, OM4. OM1 and OM2 refer to traditional 62.5/125μm and 50/125μm multimode fiber. OM3 and OM4 refer to the new Gigabit 50/125μm multimode fiber.

62.5/125μm Graded-index Multimode fiber(OM1,OM2)

Common 62.5/125μm graded-index multimode fiber is the IEC-60793-2 fiber optic products specification Alb type. As the core diameter and a numerical aperture of 62.5/125μm fiber is greater, which has a strong anti-concentrating ability and bending characteristics, especially in the 20th century, before the mid-1990s, the lower the rate of the LAN, less demanding on the fiber bandwidth, thus making this fiber to obtain the most widely used, becomes 20 years between the mid-1980s to the mid-1990s mainstream products in most countries data communications fiber market. Belong OM1 and OM2 fiber types of Alb full power injection (OFL) bandwidth respectively 200/500MHz.km (850/1300nm) 500/500MHz.km (850/1300nm).

Now you can see the follow products about 62.5 Multimode Fiber

Duplex OM1 62.5/125 Dia2.5mm Fiber Patch Cable

SMA905- SMA905 Duplex OM1 62.5/125 Dia2.5mm Fiber Patch Cable from Fiberstore

50/125μm graded-index multimode fiber(OM1,OM2)

Common 50/125μm OM2 Fiber graded-index multimode fiber is the IEC-60793-2 fiber optic products specification Ala.1 type. Historically, in order to reduce as much as possible the cost of the LAN system, widely used inexpensive LED as the light source, rather than expensive LD. Since the LED output power is low, the divergence angle is much larger than LD, while the core diameter and a numerical aperture of 50/125μm multimode fiber are relatively small, is not conducive to efficient coupling with the LED, as large core diameter and numerical aperture of 62.5/125μm (Alb class) fiber enables more light power coupled into the fiber link to, therefore, 50/125μm graded-index multimode fiber in the mid-90s as good as 62.5/125μm (Alb class) that is widely used fiber.

Since the 20th century, a local area network developed up to lGb / s rate, it didn’t meet the requirement 62.5/125μm OM1 Fiber bandwidth with LED light source. Compared with 62.5/125μm multimode fiber, 50/125μm multimode fiber core diameter and a numerical aperture smaller, 50/125μm gradient in the number of multi-mode fiber conduction mode refractive index of about 62.5/125μm multimode fiber conduction mode 1/2.5, thus effectively reducing the modal dispersion of a multimode optical fiber, such that the bandwidth is significantly increased production costs .50/125μm multimode optical fiber is reduced to about 1/3. So make it again been widely used. IEEE802.3z Gigabit Ethernet standard provides 50/125μm multimode and 62.5/125μm multimode fiber can be used as a transmission medium using Gigabit Ethernet. But for the new network is generally preferred 50/125μm multimode fiber. Belong OM1 and OM2 fiber types are Ala. 1 full power injection (OFL) bandwidth respectively 200/500MHz.km (850/1300nm) and 500/500MHz.km (850/1300nm)

OM3 Fiber

Traditional OM1 and OM2 multimode fiber from the standard mode and design are based LED, as the operating wavelength of 850 nm, a low price VCSEL (Vertical Cavity Surface Emitting Laser) and the emergence of wide application, 850nm importance window increased. VCSEL can be lower than the price of long-wavelength lasers to improve network speed to the user. 50/125μm multimode fiber has a higher bandwidth 850nm window, low price VCSEL can support longer transmission distances for Gigabit Ethernet protocol, and the high rate support longer distances. With the improvement of network speed and size, modulation rates up to 10Gb/s short-wavelength VCSEL laser light sources become one of the high-speed network. Since the difference between the two light-emitting devices, optical fibers must transform itself to adapt to changes in light. In order to meet the needs of 10 Gb / s transfer rate, the International Organization for Standardization / International Electrotechnical Commission (ISO/IEC) and the Telecommunications Industry Alliance (TIA) joint drafting of a new generation of 50 μm core multimode fiber standard. ISO/IEC in the new multi-mode fiber grade they will develop a new generation of multi-mode fiber is zoned 0M3 category (IEC standard A1a.2)

OM4 Fiber

OM4 fiber is optimized for the 50μm core multimode fiber, currently, the OM4 (IEC standard A1a.3) criteria is actually an upgraded version of an OM3 multimode fiber. Compared with standard OM3 OM4 fiber, fiber bandwidth indicators just do upgrade. That OM4 standards are made to improve the 850nm wavelength effective modal bandwidth (EMB) and the full bandwidth of the injection (OFL) compared to OM3 fiber.