Three Basic Components of a Fiber Optic Cable

There are lots of choices when it comes to fiber optic cables like LC multimode fiber patch cord, or LC multimode duplex fiber optic path cable. Standardly, a fiber optic cable has three basic components which are the core, the light signals and the coating. We shall be discussing them in detail.


The core carries the light. It is the smallest and most important part of the optical fiber. The core of the optical fiber is usually made of glass although some are of plastic. Used in the core, is a highly pure silicon dioxide (Si02), a very clear material. Refractive index is raised under controlled conditions through dopants such as Germania, phosphorous pentoxide, or alumina during manufacturing.

There’s no specific diameters for optical fiber cores as different sizes depend on the application. The range of usual glass cores is from as small as 3.7um up to 200um. For telecommunication, core sizes usually used is 9um, 50um and 62.5um. there is majorly two types of optical fiber which include the single-mode fiber and the multimode fiber based on the core sizes.

Single-mode fiber is one with 8 to 10 microns which lets light travels towards the center of the core in a single wavelength.

Multimode fiber is characterized with 50 or 62.5 microns.

On the other hand, optical fiber cores made of plastic are larger.


The cladding covers the core. Its refractive index is lower to ensure the optical fiber works. The cladding and the core are manufactured together from the same silicon dioxide-based material in a permanently fused state whenever the glass cladding is used. A difference in refractive indexes of about 1% is maintained due to different amounts of dopants being added to the core and the cladding during the manufacturing process. Although the numbers are dependent upon the wavelength, the usual core is likely to have a refractive index of 1,49 at 1300nm while that of the cladding is 1.47.

The cladding is manufactured, using standard diameters. Two mostly used diameters are 125um and 140um. Core sizes such as 9um, 50um, and 62.5um, are typically supported by the 125um cladding while 140um cladding has 100um.


This is more like the protective layer of the optical fiber. It protects the cladding from damage by way of engrossing the shocks, nicks, scrapes, and even moisture that could damage the cladding. Without the coating, an optical fiber is very fragile. Glasss fibers are not sold without the coating because they are essential for protection. The diameter of the coating is usually of 250um or 500um. Naturally the coating is colourless; although some applications prefers to colour it easily.


There are lots of combinations of core and cladding sizes. Some standards are needed to ensure equipment and connectors are accorded accurately. While it is very important to have some standards is because when dealing with small components of fiber optics, a little misalignment can endager the entire system. TIA and ITU made available several standards on optical fiber. Key standards that you should be conversant with are ANSI/TIA-568-C.3, ITU-TG.653, ITU-TG.655 and ITU-T G.657. The ANSI/TIA-568-C.3 standard is applicable to premises optical fiber cabling components. The ITU standards are applicable to single mode optical fiber and cable.


Fiber optics now has several classifications in order to suit various conditions, cost and performance. To make the right decision during fiber optic deployments, a professional assistance is needed. This is where we remain your reliable telecom partner at Vesselnet, reading to serve you with our team of experts.


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