March 11, 2014
Knowing the Difference Between Single-mode and Multi-mode Fiber Cabling
By Jonathan Keane
The need for fiber optic cabling in data centers will only grow with the increase in data rates, according to Design World.
With the growing need for more and more data, the machinations of fiber optic cabling needs to be explained to a wider audience by breaking down certain differences, like those between single-mode fiber and multi-mode fiber.
Fiber cables consist of a core and cladding layer where data is transmitted through fiber optic cables via pulses of light. This data signal is further transmitted by high-quality glass within the cable. The core is a cylinder of material (generally glass or plastic) that runs through the cable while the cladding is a layer that keeps the light confined to the core.
Single-mode fibers have a smaller core and greater bandwidth and multi-mode fibers has a larger core diameter, meaning more data can pass through.
Fibers are measured in microns, comparing the diameter of the core to that of cladding. For example, a single-mode fiber is usually 9/125. This means the ratio between the core diameter and the cladding is nine microns to 125.
Multi-mode fibers have a noticeably larger core diameters and this is reflected in some of the typical sizes: 50/125 and 62.5/125.
So while single-mode fibers have a higher bandwidth, they are quite expensive and many data centers opt for multi-mode fibers instead.
It’s vital to know the differences between single-mode fibers and multi-mode fibers as the two cannot be mixed and are incompatible with one another. Should you plug in a 9/125 cable into a 62.5/125 cable for example, a considerable amount of data will be lost in transmission.
Fiber cabling is set to grow and grow, replacing copper cabling as it can simply transmit much more data at greater speeds and for longer distances. This is vital too as the longer the distance that data has to travel, it loses more and more of its strength.
Of course, the technology isn’t without its flaws and data will travel much faster through a straight cable so bending of cables is to be avoided. However the development of “bend insensitive fiber” or BIF is already beginning to address this.
Edited by Cassandra Tucker
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