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What is Multimode Fibre Optic Cabling?

For all fiber optic installation projects the cables will be of a very similar but slightly different construction. Fibre optical cabling is a data cable constructed of glass or plastic cores. These use pulses of light to transfer data singles along the cable. The strands of glass are no larger than a strand of human hair and are clad in a thicker outer coating of glass or plastic. In addition they are surrounded in a plastic insulated sheath or sleeve

The fibre optic cabling cores carry pulses of light which are created and sent by a LED or Laser light source. Hundreds of light pulses can be sent along the cable at the same time

Fibre Optic cables come in multimode and singlemode fibre types and also separated into different classes of performance cables within those categories

What is fibre Optic Cable used for?

For fiber optic installation projects, fibre cables are generally used to link cabinets together. This can be between separate floors or buildings. This is due to their ability to carry a large amount of data traffic over their cable length. Fibre cables generally have a large headroom for bandwidth. Furthermore they can have multiple cores within a smaller cable diameter. Thus allowing many cable links within the same cable. A 24 core fibre optic cable can carry 12 separate transmission links. Furthermore all in the size of a cat5e/Cat6/Cat6a cable. The same transmission links in copper data cabling would require 12 individual cables

Fibre optic cabling is also able to transmit cabling speed over a larger distance. Copper data cabling standards are all based on a maximum distance of 100m. Fibre Optic standard standards are into the 1000m + range in some transmissions. A Cat6a cable will support 10gig upto 100m and in comparison an OM5 cable will support the same speed but up to 550m

What are the two types of fibre optic cable?

Fibre Optic cables are categorised as either MultiMode Fibre Optic Cable or Single mode Fibre Optic Cable

  • Multimode cables are further categorised into OM1, Om2, Om3, Om4 and Om5
  • Singlemode cables are further categorised into OS1 and OS2

What is the difference between single mode and multimode fibre optic cable?

Single mode fibre optic cable has a higher transmission rate and a greater distance ability but the hardware for its transmission are more costly.

The cable itself is made of a single glass fibre strand and is general 9 microns in diameter. The cable required a light source with narrow spectral width which travels directly down the centre of the fibre core

By comparison the multimode fibre cable is 50 microns (62.5 for OM1) in diameter and is constructed of multiple glass fibre strands. The light source is a wide beam of light with different light waves which travel through the cable on different paths or “Modes”. These light modes can become distorted over longer distances

Selection of Optical Multi-Mode Fibre Cabling for Fiber Optic Installation

The volume of data passing over corporate networks has increased at a staggering rate over recent years. Technology has become a vital part of everyday business life and investment in these systems has therefore also grown at a similar pace.

Developments in technology such as desktop virtualization and unified communication tools have placed further strain on the network, and increased the importance of data cabling as part of the wider ecosystem that impacts the end user.

IT cabling, be it copper or fibre, tends to evolve with the new hardware being produced, and it is important that sufficient focus is placed on the choice of cabling as part of a well-rounded IT solution.

Recognise the significance of your cabling choices

Choosing the correct fibre optic cabling will ensure that you get the best possible performance from your IT infrastructure, providing users with fast access to the large amounts of data they need. This in turn maximizes the productivity and effectiveness of the workforce.

Failure to give proportionate attention to network cabling will hamper performance and ultimately undermine investments that have been made elsewhere.

The international standard ISO 11801 specifies five main classes of multi-mode optical fibre interconnect based on the modal bandwidth, which has helped to simplify the process for choosing the appropriate cabling.

  • OM1 – 62.5µm core; 200 MHz-km @ 850nm
  • OM2 – 50µm; 500 MHz-km @ 850nm
  • OM3 – 50µm; 1500 MHz-km @ 850nm
  • OM4 – 50µm; 3500 MHz-km @ 850nm
  • OM5 – 50µm; 3500 MHz-km @ 850nm

The differing bandwidths of these cables allow high network speeds to be maintained over longer transmission distances.

How many cores in fiber optic ethernet cable?

Fibre optic cables work on a transmit and receive transmission basis. The hardware will transmit down core 1 and receive on core 2. Therefore each two way connection requires 2 cores of fibre optic fibre

A single fibre optic cable however can maintain many fibre optic cores within the same cable sheath.

The number of cores within a single cable sheath carries with manufacturer but common core sizes range from 2 cores to 96 cores

Fiber Optic Installation – Fiber Optic Ethernet Cable Distance Chart

Fiber Optic Installation London

What is the maximum length of a Fibre Optic cable? / What length can fibre optic transmit for a fiber optic installation?

For instance, the industry standard minimum reach for a OM3 fiber optic ethernet cable at 10 Gbit/s speed is 300m. While OM1 is capable of supporting similar speeds, this only holds true over short distances. OM4 however can maintain it over an even longer distance (550m).

In the past, people were content with the 1 Gbit/s speeds that were possible with OM1, but in more and more cases this is no longer sufficient.

In our experience working with a range of clients, we are finding more people wanting to upgrade from OM1 to the laser-optimized OM3, OM4 and OM5 to facilitate faster network speeds and greater bandwidth.

Fibre Optic Performance vs. Distance vs. Cost

The decision as to which optical multi-mode cable to choose ultimately comes down to a question of performance requirements, distance and cost.

The ISO 11801 classifications have greatly simplified this decision making process, defining an industry minimum standard reach for varying levels of performance.

OM3 and Om4 are becoming the norm to achieve a 10 Gbit/s network, suitable if you require consistently high speeds to support a range of IP based technologies across your site while OM5 is more prevalent in data centres and slowly working into the main data cabling industry

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