Singlemode or Multimode Fibre?

Posted by Alan 27/02/2018 0 Comment(s) FAQ,

With the NBN becoming a reality right across Australia even with the recent change of Government. Its now time for hard pressed cabling contractors to reap the benefits and opportunities that will arise to revitalise their service offerings and not get left behind and Fibre Optic Cabling could be the way forward.

10 Gigabit Ethernet is standard technology today but with the increased demands for HDTV, video conferencing and especially data centre managers deploying 40Gigabit servers (and even talking up 100Gigabit). The important decision is to install correct the cabling infrastructure that will cope with this demand. The simple answer is Fibre Optic Cable. 

Most Data contractors run for the hills when they hear fibre optic cabling but that should not be the case. 4LAN have noticed a big shift towards pre-terminated fibre assemblies which negates the requirement for expensive splicing equipment and training, but knowledge gives power and confidence and there are plenty of short courses on offer to educate Contractors with regards to the safety, basic principles and the various termination techniques for fibre optic cabling. Although setup costs can be restrictive this should not be a deterrent as there are plenty of options to hire splicing and testing equipment to get you started.

Which fibre do I use, Multimode or Singlemode ? and which Multimode cable is the best option ?

There are two basic fibre families,

Singlemode (SM, OS1.OS2) and Multimode (MM defines four types OM1, OM2, OM3 and OM4)

Sheath options are generally indoor PVC or LSZH and external Nylon with CST or GRP armouring 

Singlemode is fairly straightforward its the smallest of the traditional fibres and is made of 9 micron glass core. Singlemode transmits light via a single ray of light. It has a yellow outer jacket (pvc or lszh) and can be used for links up to 100km.

Multimode transmits many rays (modes) of light simultaneously and has 4 types and is made with larger cores of 62.5 and 50 micron.

OM1 (optical mode 1) is the original of the species and rarely used today. It has the largest core size of 62.5 micron and although suitable for 100Mb and 1Gb it has serious limitations for todays high speed demands typically orange in colour. Certainly not recommended for new installations as it has no benefits over 50 micron fibres.

OM2 It has a core size of 50 microns and again was introduced in the 1980's with 1Gb technology was future proofing but it is now no longer relevant with the developement of "laser optimised" multimode fibres. Again not recommended for new installations.

OM3 is the most widely used multimode fibre today it also has a 50 micron glass core which is laser optimised. It is designed to cope with 40Gb applications up to 100mtrs and is identified by its distinctive aqua colour.

OM4 is the new kid on the block, and has been available for the last couple of years but has only recently been officially standardised. It has a lower insertion loss and an EMB of 4700. It also has a laser optimised 50 micron glass core it is the preferred technology for the emerging standards that will operate at 40Gb and even 100Gb up to 150mtrs and is widely used in Datacentre applications but with little cost difference over OM3 its set to be the benchmark for the future.


 62.5/125 OM1     
    50/125 OM2     
    50/125 OM3     
   50/125 OM4    
    9/125 OS1
100Mb                   2km        2km       2km       2km     100km
1Gb        275mtr        550mtr       800mtr      1100mtr     100km
10Gb        33mtr        82mtr       300mtr      550mtr      40km
40Gb/100Gb        N/A        N/A       100mtr      150mtr      40km

From examining the above table it gives us some important clues as to deciding the best option. For instance your client wants a link between 2 buildings thats approx 200 mtrs long and he wants to make sure its future proof in this case we would recommend an OM3 fibre wheras if the link was 500mtrs we would elect for an OM4 needless to say anything beyond 550mtrs we would opt for Singlemode. These selections will guarantee 10Gb transmissions speeds and higher to cater for future requirements.


Distance                  Hands down singlemode with up to 100Gb over 40km

Speed                       Again singlemode can offer 40Gb same as OM4

Security                   No difference as fibre is a very secure media

Cable cost               Very little difference although singlemode is cheaper

Termination           Singlemode has a smaller core therfore slower and more time consuming

Active devices        Singlemode can be as much as 4 times the cost of multimode (This is the biggest drawback of Singlemode)

So to summarise, Multimode OM3/OM4 is generally used for LAN, inter and intra building links of up to a distance of 500mtrs wheras singlemode even with its prohibitive equipment costs is the only choice for distance based networks and MAN's but it must be noted there will be a trend for singlemode equipment to come down in price which will see the use of singlemode fibre on short links. Call 4LAN on  02 8556 9044  for the best service and pricing.