Tag Archives: OM3

Which One Will You Choose for Your 40/100G Network, OM3 or OM4?

40G has been widely used in data centres. 100G will also come soon. To meet these high bandwidths, related fibre cables are needed. OM3 and OM4 can be used to transmit parallel optical signal. But what is their difference? Which one will you choose for your network?

Both OM3 and OM4 are laser optimized fibre. Their cores size is 50/125. Connectors are the same and both operate 850nm VCSELS (Vertical-Cavity Surface-Emitting Lasers) transceivers. So the difference lies in the construction of the fibre cable, which means OM4 cable has better attenuation and can operate at higher bandwidth than OM3.


Attenuation is the reduction in power of the light signal as it is transmitted (dB). Attenuation is caused by losses in light through the passive components, such as cables, cable splices, and connectors. As the connectors are the same, so the difference in OM3 and OM4 performance is in the loss (dB) in the cable. The maximum attenuation of OM3 allowed at 850 nm by the standards is less than 3.5 dB/km, and less than3.0 dB/km for OM4.

Another factor influencing the cable function is dispersion. Dispersion is the spreading of the signal in time due to the different paths the light can take down the fibre. It has two types: chromatic and modal. In multimode fibre transmission, chromatic dispersion is negligible and the modal dispersion is the limiting factor.

The modal dispersion determines the modal bandwidth that the fibre can operate at and this is the difference between OM3 and OM4. Modal bandwidth represents the capacity of a fibre to transmit a certain amount of information over a certain distance and is expressed in MHz*km. The higher the modal bandwidth the more information can be transmitted. The modal bandwidth of OM3 is 2700 megahertz*km while the mod0al bandwidth of OM4 is 4700 megahertz*km. Thus, OM4 allows the cable links to be longer.

Compared with OM3, OM4 has a lower attenuation and operates at a higher modal bandwidth. That means over OM4 less power is lost during the signal transmission and the signal can be transmitted further or through more connectors (which add to the losses). The following table shows the Ethernet distances at 850 nm supported by OM3 and OM4 respectively.

1Gb 10Gb 40Gb 100Gb
OM3 1000m 300m 100m 100m
OM4 1000m 500m 150m 150m

So why is the standard for 40G only 100m on OM3 and 150m on OM4 compared to 300m and 500m for 10G? There are two reasons. First, when the IEEE 802 standard was created they decided to create a standard based on “relaxed” transceiver specifications so that smaller and lower cost transceivers could be used. Two functions of 10G transceivers (clock recovery and attendant re-timing) are absent in both QSFP+ (40G) and CFP (100G) devices. Second, the standard allows for transceivers with wider spectral width lasers which increase chromatic dispersion (pulse spreading). The quality of transceivers is also a factor.

Which will you choose for your 40/100G network, OM3 or OM4? Except the transmission distance and the cable costs, there are additional factors to consider such as the number of cross connects required and the mix of 40G port to 40G port and 40G port to 10G port. Because 40G signal is transmitted across eight pairs of fibre each with 10G. Similarly, it is important to take into account the likely location of future 100G equipment and the possible 100G to 100G, 100G to 40G and 100G to 10G connectivity requirement.

Multimode Fibre Patch Leads from Fiberstore

Fiberstore has been providing quality fibre optical cabling and connectivity solutions to datacomm and telecommunication industries to worldwide customers for over ten years. As a specialized fibre optic cables and patch cables manufacturer, we have conducted rigorous quality controls on each manufacture steps, to make sure that all of our fibre optic cables are completely ROHS and REACH compliant. Our fibre optic patch cables are classified to common multimode fibre cables (OM1, OM2, OM3, OM4 patch cables), armoured fibre patch leads, related fibre cables, MTP/MPO trunk cables, multi-core fibre patch leads as well as many other fibre patch leads. This article is set up to mainly introduce the multi-core fibre patch cords.

Multi-core fibre patch lead get its name as it is consist of multi core fibre, which also called multimode fibre patch lead. Multi fibre patch lead is most commonly used for trunk cable plant and can be as the distribution or breakout patch cable. We offer the fibre trunk patch cables with SC, LC, FC, ST, MTRJ, MU, E2000 connectors, 2-288 cores/fibres are optional to be customised and the sub-branch can be 0.9 mm and 2.0 mm.


For each connector type, like LC, there are LC to FC, LC to SC, LC to ST, LC to MTRJ, LC to MU, LC to E2000, LC to SMA and LC to LC fibre cable, all of which are optically and electrically inspected and tested using accepted industry test procedures as recommended by the most current version of ANSI/TIA-455B standard test procedure for standard fibre optic lead, cables, transducers, sensors, connecting & terminating devices, and other components.

The multi fibre patch leads features include:

  • Multi-fibre channel options
  • Various option of fibre and connector types
  • Standard or custom configurations
  • Easy to use, easy to install and maintain
  • Low insertion loss and back reflection
  • Custom defined specifications
  • Environmentally stable
  • Complete with orange OFNR rated riser/jacket
  • 100% optically tested to ensure high performance
  • According to different requirements, 4 to 966 cores are available


  • FTTH, LAN, Test equipment, Military industry
  • CATV
  • Outside plant
  • Premise networks
  • Aerial distribution
  • Measuring equipment
  • Fibre optic communication system
  • Optical active component and equipment

We offer custom service for customers with options of any fibre type, any connectors, and lengths and even customer logo and label on fibrepatch leads. Fibre types is selectable from 10G OM3, OM4 optical fibre, single mode 9/125 optical fibre, OM1, OM2 multimode 50/125 fibres.