 Single-mode versus multi-mode fibre. Fibre optic cabling is a very common aspect of most structured cabling installations. Therefore crossing the correct type of fibre cable is imperative to the successful operation of your technology. In addition within those types, you need to choose the correct category within that cable type bracket. Therefore we compare single-mode versus multi-mode fibre and the differences between them. All fibre cables are constructed of individual cores, with which within the light is transported from transmitter to receiver. These cores are mode of either glass or plastic. Furthermore that consist of the actual inner core and the cladding surrounding and protecting that tube. In addition fibre cables can contain numerous cores within a single cable. Thus bundles of 4, 8, 12, 16, 24, 48 are commonly founds in a single fibre optic cable. Single-mode fibre. The terminology of a single-mode fibre comes from the situation that is transmits a single mode of light down its cores. The transmission is via a laser from the transmitting device. A single mode of light is transported directly the core with minimal reflection within. The inner core is smaller than its counterpart for this reason and is referred to as 9 by 125. This is the 9 micron diameter core coated in a 125 micron cladding. Due to the transmission properties there is less dispersion of light as it travels along the core and therefore there is less loss of the original signal. Thus single-mode fibre is more suited to higher bandwidth requirements. Furthermore it is more suited to longer transmission distance applications. The cable is categorized into two sub-sections OS1 and OS2. OS1 and OS2 differ mainly in their cable construction. Thus OS1 is commonly a tight buffered construction and for internal applications. Likewise OS2 is usually a blown fibre or loose tube construction and for external purposes. They have similar transmission characteristics. However due to less attenuation, transmission loss on OS2 cables it can transmit similar speeds over longer distances. For example some manufacturers will state OS1 transmitting 10 gigabit ethernet up to 2 kilometers and OS2 transmitting 10 gigabit ethernet up to 10 kilometers. This is due to the attenuation loss on OS1 being 1 decibel per kilometer and OS2 being 0.4 decibels per kilometer. Less attenuation equals greater transmission range. Due to the specialist equipment for transmission, the overall cost of a single mode system is higher than that of multi-mode. However the cable can be cheaper to purchase and is the same cost to install. Multi-mode fibre. Multi-mode receives its name in an opposite way to its counterpart. Multiple or many modes of light are transmitted down its core, all of which travel at different wavelengths are in a different path. The light source is usually an LED source. Thus the light is similar to that of shining a torch into the core. Subsequently there is greater modal dispersion, loss, of the light as it travels. For this reason multi-mode doesn't have the same transmission distance capability as single mode. The cores in a multi-mode fibre are considerably larger than single mode. Four of the main categories are 50 by 125 and the legacy OM1 is 62.5 by 125. Notice that the cladding for all fibre cables remains the same and only the internal core size changes. The five categories of multi-mode fibre are OM1, OM2, OM3, OM4 and OM5. Each category is an improvement on its predecessor. Therefore this results in a greater ability to transmit greater bandwidth. Further higher grades are able to transmit the same speeds as the previous grade but over longer distances. Single mode vs multi-mode fibre summary. Core sizes. Single mode are 9 by 125 microns. Multi-mode are 50 by 125 microns and in the OM1 category 62.5 by 125. Transmission. Single mode uses a single mode of light transmitted via a laser light source. Multi-mode used many modes of light via a LED light source. Distance limitations. Single mode are commonly used up to 2 km and often beyond to 10 km. Multi-mode are limited to 550 m performance and therefore mainly used internally or on small campus plots. For a free quotation, please visit our website nmcabling.co.uk or call at 019 23 888 588.