Difference of Multi-mode OM1, OM2, OM3 and OM4

July 22, 2021
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"OM" stand for optical multi-mode, that is, optical mode, is the standard of multi-mode fiber to indicate the fiber grade. The bandwidth and maximum distance of different levels of transmission are different. This particle will mainly explain the differences between OM1, OM2, OM3 and OM4 fibers.


Technical parameters

1. OM1 refers to 50 um or 62.5 um core diameter multimode fiber with 850 / 1300 nm full injection bandwidth over 200 / 500 MHz. Km;

2. OM2 refers to 50 um or 62.5 um core diameter multimode fiber with 850 / 1300nm full injection bandwidth over 500 / 500MHz. Km;

3. OM3 is a 50um core diameter multimode fiber optimized by 850nm laser. In 10Gb / s Ethernet with 850nm VCSEL, the fiber transmission distance can reach 300m;

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

Mode Fiber core (um) Fiber type 1Gigabit Ethernet 1000BASE-SX 1Gigabit Ethernet 1000BASE-LX 10Gbps Ethernet 10GbAS 40Gbps Ethernet 40GbASE SR4 100Gbps Ethernet 100GbASE SR4
OM1 62.5/125 Multi-mode 275m 550m 33m Not support Not support
OM2 50/125 Multi-mode 550m 550m 82m Not support Not support
OM3(Laser optimization) 50/125 Multi-mode 550m 550m 300m 100m(SR4) 100m(SR4)
OM4 (Laser optimization) 50/125 Multi-mode 550m 550m 400m 150m(SR4) 150m(SR4)
Single mode 9/125 Single mode 5km (1310nm) 5km(1310nm) 10km(1310nm) N/A N/A

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Design basis


1. The traditional OM1 and OM2 multimode optical fibers use LED (light emitting diode) as the basic light source in standard and design, while OM3 and OM4 are optimized on the basis of OM2 to make them suitable for the transmission of LD (laser diode) too;

2. Compared with OM1 and OM2, OM3 has higher transmission rate and bandwidth, so it is called optimized multimode fiber or 10 Gigabit multimode fiber;

3. OM4 is further optimized on the basis of OM3 and has bsetter performance.




1. OM1: larger core diameter and numerical aperture, stronger light collecting ability and bending resistance;

2. OM2: the core diameter and numerical aperture are relatively small, which effectively reduces the mode dispersion of multimode fiber, significantly increases the bandwidth and reduces the manufacturing cost by 1 / 3;

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

4. OM4: developed for VSCEL laser transmission. The effective bandwidth of OM4 is more than twice that of OM3.




1. OM1 and OM2 have been widely deployed in building applications for many years, supporting up to 1GB Ethernet transmission;

2. OM3 and OM4 optical cables are usually used in the cabling environment of data center, supporting 10G or even 40 / 100G high-speed Ethernet transmission.


When to use OM3 fiber optic patch cord?


OM3 fiber is designed to work with VCSEL which meets the OM-3 optical fiber specification of ISO /IEC11801-2 and meets the requirements of 10 Gigabit Ethernet, including indoor type, indoor / outdoor versatility, etc. The number of fiber cores ranges from 4 to 48. It also supports all applications based on the old multi-mode 50 / 125 fiber, including LED light source and laser light source.


1. if use OM3 fiber, Gigabit Ethernet can extend the transmission distance to 900 meters, which means that when the distance between buildings exceeds 550 meters, users do not have to use expensive laser devices.

2. The standard 62.5/125um can be used in all situations within the oc-12 (622Mb / s) speed range within 2000 meters. In other situation, single mode fiber will be used. However, the emergence of OM3 multi-mode fiber has changed this situation. Because OM3 fiber can improve the transmission distance of Gigabit and 10 Gigabit systems, using 850nm wavelength optical module with VCSEL will be the most cost-effective routing scheme.

3. When the link length exceeds 1000 meters, single-mode fiber is still the only choice at present. Single mode fiber can achieve a transmission distance of 5 km at 1310 nm in Gigabit system and 10 km in 10 Gigabit system.

4. When the link length is less than or equal to 1000m, OM3 50um fiber can be used in Gigabit system, single-mode fiber should be used in the 10 Gigabit system.

5. When the link length is less than 300 meters, OM3 multi-mode fiber can be used in any Gigabit and 10 Gigabit system.


When to use OM4 fiber jumper?


For a typical link, the cost of optical module is very expensive. Although the cost of single-mode fiber is cheaper than that of multimode fiber, the use of single-mode fiber requires a very expensive 1300nm optical module, which costs 2-3times of 850nm modules. Generally speaking, the cost of a multimode fiber system is much lower than that of a single-mode fiber system.


When investing in optical fiber routing scheme, if we can consider increasing the initial investment of wiring and adopting better multimode optical fiber, such as OM4 optical fiber, we can make full use of the current multimode optical fiber technology and reduce the overall cost of the current system; When the system needs to be upgraded to a higher speed system, such as 40g and 100g, OM4 can still be used and will save more cost.


In a word, when the transmission rate is higher than 1GB / s, using multimode fiber is a good system choice. When the system needs higher transmission rate, the following are our guidelines for selecting OM4 fiber:


1. For Ethernet Users, in 10Gb / s system transmission, the transmission distance can reach 300m to 600m; In 40Gb / s and 100GB / s systems, the transmission distance is from 100m to 125m.


2. For campus network users, OM4 fiber will support 4GB / s fiber link length of 400m, The length of 8GB / s optical fiber link is 200m or 16GB / s optical fiber link is 130m.




Multimode fiber technology has been developed from OM1 to OM5, which supports 40 / 100Gbps. This will enable users to get the most effective return on their investment and become the best choice for backbone cabling or fiber to desktop.