What is fiber optic and how does it works? Types & Uses

fiber optic

A fiber optic cable is nothing more than a set of very thin transparent strands of fiberglass or plastic polymers, of the approximate size of a human hair, held together by a protective rubber sheath. The characteristics that distinguish this type of cable from normal copper cables are called "twisted pair" cables, which are those of being able to carry much more data/information per unit of time and at the same time.

They are lighter and more manageable, more flexible, substantially immune to electrical disturbances, and more resistant to external weather conditions (for example, they are less affected by temperature variations). All these features make the fiber cables more performing in terms of transmission capacity and less prone to failures and inconveniences, thus breaking down, and by far.

How does it work? And how does the signal pass through the optical fibers 

A single fiber optic filament consists substantially of two concentric sections: a very transparent internal section and an outer section, placed in a ring concerning the first, opaque and reflective. To better understand it, it would be like taking a mirror and then bending it over itself until it becomes a tube. By doing so, we would obtain an object capable of reflecting the light that passes through it, keeping it "trapped" while avoiding light from the outside can penetrate it. This means that every light pulse that is introduced into the internal section spreads over long distances, continuously bouncing between the mirrored walls, without external interference, and without dispersing to the outside.

On the other hand, a copper pair is more approximate to a busy highway in which the electrons, much larger and heavier than the photons (which, incidentally, have no mass but consist only of an electromagnetic wave of pure energy). They flow along the various lanes in a somewhat chaotic manner, dispersing and hitting each other and sometimes even ending up astray.

Thanks to these particular characteristics, the fiber, or even fibers, optics can obtain performance, in terms of digital data transmission capacity, far superior to its copper counterpart. An Internet connection in Fiber Optic not only does not suffer considerable degradation of the signal over distances usually affected by this type of connection (a few km). But it can exploit a much higher frequency band compared to DSL solutions, thus allowing them to reach potentially very high transmission speeds (even 1024 Mbps, or 1 Gbps).


Types of Fiber Optic Cables

A fiber optic cable is composed of a core (core), which is, in turn, covered with a protective sheath with a low reflectance index (ability to reflect part of the light that goes to affect a material or surface). 

Let's start with the first major subdivision of optical fibers:

- Multi-mode fibers, used for short-distance data transport (up to 600m).

- Single-mode fibers, used for long-distance data transport (even hundreds of km).

Multi-Mode Fibers:

The multi-mode fibers have a core diameter that is greater than the single-mode, roughly on 50/100 uM (micrometers). Why have wider diameters than the wavelength of light they carry? Thanks to this larger core size, they can carry more light than single-mode fibers. Moreover, in multi-mode, unlike single-mode, it is possible to use cheaper devices at the ends of the cable to transmit data, such as LEDs or VCSEL lasers.

It is, therefore, necessary to operate at a wavelength between 850nm and 1300nm. Unlike single-mode, they support multiple propagation modes and are consequently limited by modal dispersion, of which single-mode models are not affected. Another limit of multi-mode is the chromatic dispersion that is created due to the use of an LED as a means of transmitting information. So there is a range of different wavelengths, and each of these travels at one different speed.

Single-Mode Fibers:

The single-mode fibers have a core diameter of between 8 and 10.5 uM. They operate at a wavelength between 1310nm and 1550nm. They use high performance and precision lasers to communicate. They are built to be able to carry the signal even for hundreds of km at speeds up to 40Gbps. Unlike multi-mode, not only does the cable cost more, but the equipment used at the end of the cable is considerably more expensive than those used for multi-mode.

If two optical fibers are to be joined together, the process is more complex than joining two copper cables together. It is necessary to resort to a particular machine (called fusion splicer), which, with the use of an electric arc, and join the fibers with high precision.

Different Uses of Optical Fibers

Use in telecommunications

Since the discovery of the optical fiber and its first use, it has spread exponentially, especially for the larger connections in telecommunications. It has a large transmission capacity, which means that the band supported it is extensive. It is immune to electrical interference due to its constitution and its coating. The disturbance in communications is lacking, unlike its predecessor; it has a high electrical resistance that allows it to be used safely near equipment with high potential or different potential. Its weight is minimal, and it is very resistant to adverse weather conditions.

The use of optical fiber is an innovation in the telecommunications field; in fact, most telephone companies use it for internet connection or simple telephone use.

Use in medicine

The optical fiber, being versatile in all fields, is used in medicine to transport images from inside the body (for example, for endoscopies). It is used during surgery to transport lighting in remote areas, which would, therefore, be difficult to illuminate and for radiation transport, i.e., it is used as a laser during interventions to make exact cuts or dissolve the plaques in the arteries.


What are the advantages of fiber optics?


The higher speed and stability of a connection with the Optical Fiber offers considerable advantages. For example:

- A high download speed, which allows you to download hefty files in no time;

- a high upload speed, beneficial for example if you have to send large email attachments;

- stability and speed in video streaming, especially if you watch high-quality videos;

- stability during online video games, which means a very low ping (i.e., the time it takes the server to respond to your requests) and total lack of lag ;

- Excellent quality of video callsfiber optic, with a fluid and clear image and no audio problem.


1039 Words


Nov 29, 2019


3 Pages

Looking for a professional

Order Now