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    What is the difference between OM1, OM2, OM3, and OM4 fibers?


    "OM" stand for multi optical-mode, is optical mode, is the standard for multimode fiber to represent fiber grade. Different levels of transmission bandwidth and maximum distance, this article will mainly explain the difference between OM1, OM2, OM3 and OM4 fiber.


    1,OM1 refers to 850/1300nm full injection bandwidth of 200/ above 50um or 62.5um core diameter multimode fiber;

    2,OM2 refers to 850/1300nm full injection bandwidth above 500/ 50um or 62.5um core diameter multimode fiber;

    3,OM3 is 850nm laser-optimized 50um core diameter multimode fiber, in the use of 850nm VCSEL 10Gb/s Ethernet, fiber transmission distance can reach 300m;

    4,OM4 is an upgraded version of OM3 multimode fiber, fiber transmission distance can reach 550m.

    typeFiber diameter (sm)The type of fiber1 Gigabit Ethernet 1000BASE-SX1 Gigabit Ethernet 1000BASE-LX10Gbps Ethernet 10GbAS40Gbps Ethernet 40GbASE SR4100Gbps Ethernet 100GbASE SR4
    OM162.5/125Multimode275m550m33mNot supportedNot supported
    OM250/125Multimode550m550m82mNot supportedNot supported
    OM3 (Laser Optimization)50/125Multimode550m550m300m100m(SR4)100m(SR4)
    OM4 (Laser Optimization)50/125Multimode550m550m400m150m(SR4)150m(SR4)


    1, the traditional OM1 and OM2 multimode fiber from the standard and design are LED (Light Emitting Diode) based on the light source, while OM3 and OM4 on the basis of OM2 optimization, so that it is also suitable for the light source LD (Laser Diode laser diode) transmission;

    2, compared with OM1, OM2, OM3 has a higher transmission rate and bandwidth, so called optimized multi-mode fiber or multi-mode fiber;

    3, OM4 on the basis of OM3 re-optimization, with better performance.


    1, OM1: core diameter and numerical aperture is larger, with strong light collection capacity and anti-bending characteristics;

    2, OM2: core diameter and numerical aperture are relatively small, effectively reduce the multi-mode fiber die dispersion, so that the bandwidth significantly increased, production costs are also reduced by 1/3;

    3, OM3: the use of flame retardant skin, can prevent the spread of flame, prevent the emission of smoke, acid gas and toxic gas, and meet the needs of 10Gb/s transmission rate;

    4, OM4: Developed for VSCEL laser transmission, the effective bandwidth is more than double that of OM3.


    1, OM1 and OM2 have been widely deployed in buildings for many years, supporting Ethernet transmission up to 1Gb;

    2, OM3, and OM4 fiber optic cables are typically used in data center cabling environments to support 10G or even 40/100G high-speed Ethernet transmission.


    OM3 fiber is a fiber designed to work with VCSEL, in line with isO/IEC11801-2nd OM-3 fiber specifications, to meet the needs of 10G Ethernet applications. There are many types of OM3 fibers, including indoor, indoor/outdoor versatility, and the number of cores of fibers ranges from 4 to 48 cores. All applications based on old multimode 50/125 fibers are also supported, including LED and laser light sources.

    1, the use of OM3 fiber optic system transmission Gigabit Ethernet transmission distance can be extended to 900 meters, which means that when the distance between buildings more than 550 meters users do not have to use expensive laser devices.

    2, in the distance of 2000 meters, OC-12 (622Mb/s) rate range of various conditions can use the standard 62.5/125 m multimode fiber, in addition to the use of single-mode fiber. However, the emergence of OM3 multimode fiber has changed this situation, because OM3 fiber can improve the transmission distance of Gigabit and 10 gigabit systems, the use of 850nm wavelength light module with VCSEL, will be the most cost-effective cabling solution.

    3, when the link length of more than 1000 meters, single-mode fiber is still the only choice, single-mode fiber in the gigabit system can achieve 5 kilometers of transmission distance at 1310nm wavelength, in the 10-megabit system to achieve a transmission distance of 10 km.

    4, when the link length is less than or equal to 1000 meters, in the gigabit system can be used OM3 50 m multimode fiber, and in the 10 megabit system should be used single-mode fiber.

    5, when the link length is less than 300 meters, OM3 multimode fiber can be applied to any gigabit and 100 megabit system.


    For a typical link, the optical module is about as expensive. Although single-mode fiber is cheaper than multi-mode fiber, the use of single-mode fiber requires very expensive 1300nm optical modules, which cost about 850nm multimode modules 2-3 times, in summary, a multi-mode fiber system costs far less than single-mode optical fiber systems.

    When investing in fiber optic cabling, if you can consider increasing some initial investment in cabling, using better multimode fiber, such as OM4 fiber, you can guarantee to make full use of the current multimode fiber optic technology to reduce the overall cost of the current system, and when the system needs to upgrade to a higher rate system, such as 40G and 100G, OM4 can be used and will be more cost-effective.

    In short, when the transmission rate is greater than 1Gb/s, multimode fiber is a good system choice. When the system needs a higher transmission rate, here are our guidelines for selecting OM4 fibers:

    1. For Ethernet users, the transmission distance can be 300m to 600m in 10Gb/s system transmissions and 100m to 125m in 40Gb/s and 100Gb/s systems.

    2. For campus network users, OM4 fiber will support 4Gb/s fiber link length 400m, 8Gb/s fiber link length 200m or 16Gb/s fiber link length 130m.


    Multimode fiber technology has evolved from OM1 multimode to OM5, which now supports 40/100Gbps, which will give users the most efficient return on their investment and make them the best choice for backbone cabling or fiber-to-desktop.