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Fiber Optic Cables

Comprehensive Understanding of Multimode Fiber Optic Cables

Date: 2015-1-16 17:02:05

Fiber optics technology has become the fastest and most effective high-capacity data communication medium and low attenuation. Cables are at the core of the transmission system, and the cable was used to optical signal in the data transmission paths. The data is modulated within the light waves. According to the demand of the transfer, there are two main modes of cable available - the single mode and the multimode. In this article, we will focus on understanding of multimode fiber optic cable.


First of all, let us understand what an optical fiber is. It is a fiber constructed of glass or plastic of a specific nature. Please note that it does not contain any metal material, because it avoids electromagnetic interference and distortion of information, along with the distance. This results in high accuracy of data along the transmission cable. The objective of these cables is to carry light waves along its length.

The core technology for optical transmission is total internal reflection. Total internal reflection to ensures that the light is always along the body inner reflection material, so always keep a fiber in the body. As a result, the loss of signal is minimized, and hence the distance that the message can be carried without losing the signal is maximized.

The light waves carrying the information along the channel have a path of propagation. A fiber optic cable is called multimode if the cable can support the transmission of multiple paths of propagation. Therefore, multimode fiber cable, the optical fiber network can easily support a higher number of continued to teach at the same time. On the other hand, a single mode optical fiber cable can only support a propagation path, and hence can support a smaller bandwith.

Because multimode cable carry higher amount of information at the same time, they have a higher diameter of the core used to carry the message compared to the single mode ones. Also, the higher diameter can make these cable with power higher amount of transmission power. Usually these are those used for short distance communication cable, usually a distance less than 500 meters. The single-mode cable popular long distance communication. Multimode fiber optic cable and graded index fiber is better in accuracy and performance.
Multimode fiber optic cable has a large diametral core that allows multiple modes of light to propagate. Because of this, the number of light reflections created as the light passes through the core increases, creating the ability for more data to pass through at a given time. Because of the high dispersion and attenuation rate with this type of fiber, the quality of the signal is reduced over long distances. This application is typically used for short distance, data and audio/video applications in LANs. RF broadband signals, such as what cable companies commonly use, cannot be transmitted over multimode fiber.


Multimode fiber is usually 50/125 and 62.5/125 in construction. This means that the core to cladding diameter ratio is 50 microns to 125 microns and 62.5 microns to 125 microns. Shown as the Figure. The transition between the core and cladding can be sharp, which is called a step-index profile, or a gradual transition, which is called a graded-index profile. The two types have different dispersion characteristics and thus different effective propagation distance. Multi-mode fibers may be constructed with either graded or step-index profile.

The numbers 50μm and 62.5μm refer to the diameters of the glass or plastic core, the part of the fiber that carries the light which encodes your data. The dimensions are sometimes specified as 50/125μm and 62.5/125μm, to include the diameter of the cladding. (The cladding confines the light to the core because it has a lower index of refraction.) Cable construction is shown in the following diagram, indicating the cable core, cladding, and outer jacket diameters.

FiberStore multimode fiber cable.jpg

OM1/OM2/OM3/OM4 Fiber Optic Cables

Multimode fibers(MMF) are described using a system of classification determined by the ISO 11801 standard — OM1, OM2, and OM3 — which is based on the modal bandwidth of the multimode fiber. OM4, defined in TIA-492-AAAD by the TIA, was finalized in 2009. The letters "OM" stand for optical multimode. OM1/OM2/OM3/OM4 fiber, technically, these categories did not define a specific fiber size, but rather their optical channel performance.

Transmission Standards 100Mb Ethernet 1Gb Ethernet 10Gb Ethernet 40Gb Ethernet 100Gb Ethernet
OM1 (62.5/125) 2000m(FX) 275m(SX) 33m(SR) Not specified Not specified
OM2(50/125) 2000m(FX) 550m(SX) 82m(SR) Not specified Not specified
OM3(50/125) 2000m(FX) 550m(SX) 300m(SR) 100m(SR4) 100m(SR10)
OM4(50/125) 2000m(FX) 1000m(SX) 550m(SR) 150m(SR4) 150m(SR10)

OM1 specifies 62.5-micron cable and OM2 specifies 50-micron cable. They are commonly used in premises applications supporting Ethernet rates of 10 Mbps to 1 Gbps, which are not suitable though for today's higher-speed networks. Because of their relatively large core size, were ideal for use with LED transmitters.

OM3 and OM4 are both laser-optimized multimode fiber (LOMMF) and were developed to accommodate faster networks such as 10, 40, and 100 Gbps. OM3 and OM4 specifies an 850-nm laser-optimized 50-micron cable.


MMF Over-filled launch(OFL) bandwidth Effect laser launch(EMB) bandwidth
Fiber Type 850nm 1300nm 850nm
OM1 200 500 Not specified
OM2 500 500 Not specified
OM3 1500 500 2000
OM4 3500 500

OM1/OM2/OM3/OM4 can sometimes be distinguished by jacket color: orange jackets for 62.5/125 µm (OM1) and 50/125 µm (OM2),  while Aqua is recommended for 50/125 µm "laser optimized" OM3 and OM4 fiber.

Comparison Between OM3 and OM4

Both OM3 and OM4 are laser optimized, high bandwidth 50µm multimode fiber. The requirements of the OM4 standard are identical to OM3 with the sole exception of the bandwidth values. Both the 850nm EMB and the 850nm over-filled launch (OFL) bandwidth have been increased from the OM3 requirements as below table shows.

OM3 Requirements OM4 Requirements
850nm High Performance EMB(MHz-km) 2000 4700
850nm Legacy Performance OFL(MHz-km) 1500 3500
1300nm Legacy Performance OFL(MHz-km) 500 500

OM3 with a effective modal bandwidth of 2000 MHz/km and OM4 with an effective modal bandwidth of 4700 MHz/km. Why is it increased? There is a belief among some members of the standards community that the 850nm OFL bandwidth needs to be scaled along with the 850nm EMB bandwidth in order to ensure maximum performance reliability.

OM3 and OM4 Are Best Options Of MMF Today

Laser optimized 50µm multimode fiber is the recommended fiber type in today's local area network (LAN) and Data Center (DC) environments in conjunction with 850 nm vertical-cavity surface-emitting lasers (VCSELs). For prevailing 10 Gigabit transmission speeds, OM3 is generally suitable for distances up to 300 m, and OM4 is suitable for distances up to 550 m. The vast majority of commercial buildings and data centers fall within these ranges, and because of LOMMF's lower installation and operation costs, make them the optimal choice even when considering single-mode fiber.

With the spread of 40 Gigabit and 100 Gigabit Ethernet (GbE), OM3 and OM4 also are only well positioned to support these burgeoning data rates over distances of 100m and 150m, respectively. OM4 supports the majority of data center links that utilize 40 and 100 GbE in high-speed/high-performance computing applications driven by server virtualization, cloud computing, streaming video, and everincreasing IP traffic and convergence. 10GbE network core devices are slowly supplanted by 40 and 100 GbE and 40/100 GbE standards don't support previous generation OM1 and OM2 MMF types.

OM1/OM2/OM3/OM4 Fiber Optic Cable Assemblies Available From Efoncable

Fiberstore OM1 Fiber>>OM1 Fiber

Efoncable OM1 fiber exceeds industry standards for fiber optic network protocols including Fast Ethernet, Token Ring, Fiber Distributed Data Interface (FDDI), Asynchronous Transfer Mode (ATM), and Fiber Channel. These fibers are capable of transmitting distances of up to 200m in Gigabit Ethernet (IEEE 802.3z) compliant systems at 850nm and up to 550m at 1300nm. These fibers are also capable of operating at greater distances (greater than 2000m) with slower protocols such as Fast Ethernet, FDDI, and ATM.

Low insertion loss and high return lossSimplex and duplex availableFC, SC, LC, ST, MTRJ, MU and other connector optionsRiser, Plenum, and LSZH cable jacket types availableCompatible with all major brands like Cisco, HP, Foundry, Juniper, etcAny type, any length, any color, custom service available

>>OM2 Fiber
Fiberstore OM2 Fiber

Efoncable OM2 50/125 multimode fiber cables are ideal for Gigabit Ethernet (GbE) laser-rated backbones & LANs, used in fiber optic telecommunications and high speed transmission systems that require simultaneous, bi-directional data transfer. They are specifically designed for use with today's narrower aperture components. 50 µm fiber offers as much as ten times the bandwidth of 62.5 µm fiber. Each cable is 100% optically inspected and tested for insertion loss before you receive it.

Support longer distances and less lower lossSimplex and duplex availableFC, SC, LC, ST, MTRJ, MU and other connector optionsRiser, Plenum, and LSZH cable jacket types availableCompatible with all major brands like Cisco, HP, Foundry, Juniper, etcAny type, any length, any color, custom service available

>>OM3 Fiber
Fiberstore OM3 Fiber

By using OM3 as the fiber standard throughout the data center, the system gains the design flexibility to deploy large numbers of connections in each channel. OM3 systems also can support both very long-reach channels and existing OM2 fiber applications throughout the network. The transmission distance can be greatly increased under the 850nm wavelength with the use of OM3 fiber cables and VCSEL and the OM3 fiber solution becomes the best cost effective cabling solution.

Simplex and duplex availableLC-LC, LC-SC, SC-SC, FC, MTRJ, MU, MPO/MTP and other connector optionsRiser, Plenum, and LSZH cable jacket types availableAny type, any length, any color, custom service available

>>OM4 Fiber
FiberStore OM4 Fiber

OM4 fiber is designed as enhancing the system cost benefits enabled by 850nm VCSELs for existing 1 Gb/s and 10 Gb/s applications as well as 40 Gb/s and 100 Gb/s systems. OM4 fiber is the best option for users needing to run 10Gb/s over links between 300 and 550 meters or running 40 or 100Gb/s between 100 and 150 meters. OM4 is a "universal medium" and supports all existing multimode applications, which is just one of the many reasons it was imperative that OM4 receive standardization in the telecommunications industry.

Simplex and duplex availableLC-LC, LC-SC, SC-SC, FC, MTRJ, MU, MPO/MTP and other connector optionsRiser, Plenum, and LSZH cable jacket types available100% optically tested for maximum performanceAny type, any length, any color, custom service available

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