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11 décembre 2013 3 11 /12 /décembre /2013 15:25


Now you know what the difference is between multimode and singlemode fiber (if you don't, go to our march 2009 blog), it's time to look at another more complete classification : OS1, OS2, OM1, OM2, OM3 and the most recent OM4.


Regular visitors to our blog or of the small word of fiber will recodnize the S of Singlemode and the M of Multimode within this classification.

Singlemode fibers (OS) are classified by their maximum attenuation :

1.0 dB/km for OS1 (1310 et 1550nm)

0.4 dB/km for OS2 (1310 et 1550nm)


Multimode fibers (OM) have a bandwidth OFL from 200 MHz/km for OM1 fibers to 3500 MHz/km for OM4 fibers depending on fiber bandwith



Note : if you want full information, you can lookat the ISO/IEC 11801 norm which gives detailed definitions of the complete technical caracteristics of the different types of singlemode and multimode fibers.



Transporting Gigabit signals (1000 Base ..) is very limited on a multimode fiber (250 meters with OM1 and 500 meters with OM2 fibers). The manufacturers have therefore tried to improve the multimode fiber characteristics in order to increase the feasible transportation distances for Gigabit and 10G.


As a result, new multimode fibers with higher performances have been created. These fibers have been normalised : OM3 and OM4.


So when transporting Gigabit, don't forget to ask about the type and the caracteristics of the fiber in question !


To summarise take a look at this convenient tab : :


  OS1 OM1 OM2 OM3 OM4
Fiber core diameter 62.5µ 50µ 50µ 50µ
Main application

Very long


(videosurveillance and

IP networks)

Long distance


(less than 4 km)

and IP networks

Long distance


(less tha 4 km)

and IP networks

medium distance IP Gigabit networks and

data center


Most common IP signal

10/100/1000Mbps/10Gb/s 100Mb/s 100mb/s and 1Gb/s 10 Gb/s 10Gb/s
Bandwidth ****









Your input is always welcome, so do not hesitate to add your comments.


see you soon, take care




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