What Is Fiber Optic And What Are Its Types?


We all have a simple idea of ​​fiber optics for Internet connection and how fast it has been, creating a revolution in telecommunications. For this reason, we want to talk in more detail about what types of fiber optics there are, their advantages and disadvantages, to decide which one suits your needs.

Fiber Optics And Its Origins

The transmission media used to communicate signals from one point to another are copper cables, coaxial cables, waveguides, and radio links. All these means have their advantages and disadvantages.

Since the 1980s, an alternative medium to all of them called fiber optics has been developed, constituting the new frontier in telecommunications transmission. The ability to take advantage of all the capacity that light possesses to transmit information over long distances has been possible thanks to the improvement of the laser and the manufacture of very thin glass threads (less than the thickness of a human hair). Called “optic fiber.” Inside these fiber-optic threads, a modulated light beam is used to transport information based on the principle of total internal reflection and Snell’s law.

Parts That Make Up The Optical Fiber

The optical fiber is composed of the following parts:

  • The core or central part, made of fused silica glass (SiO2) and optically transparent, is where the light beam is guided. Its maximum diameter is 62.5 µm (according to the ANSI standard)
  • The cladding covers the core and prevents light from leaving the body. It is also made of glass but with a lower refractive index. Its diameter is 125 µm for all types of fiber.
  • Primary coating (primary buffer). It consists of plastic with a width of 250 µm that surrounds the previous fiber components to protect them since they are too fragile to be handled directly and increase their mechanical resistance.
  • Other common additional elements include secondary cladding, structural and reinforcing elements, outer sheath, and protection against water.

Once this brief introduction has been made, we can understand the different types of an optical fiber according to a certain characteristic.

What Types of Fiber Optics Are There?

Depending on the characteristic we focus on, we can have different types of Fiber Optic, which makes them more suitable for use.

Types of Fiber Optic According To The Cable Termination

  • FTTH. It comes from the acronym for Fiber-to-the-home. The fiber optic par excellence connects the operator’s switchboard with our home or office. It is the most direct, fastest (sometimes above the contracted speed), reliable and secure way to connect to the Internet. They can reach speeds between 300 Mbps and 1 Gbps. This fiber is also known as shared fiber and is the most common and most used.
  • FTTN. Fiber-to-the-node, the fiber optic cable connection runs from the carrier’s main hub to an intermediate node. It is linked to the point where the service has been contracted employing copper or coaxial cable from that intermediate node.
  • FTTA. Fiber-to-the-antenna takes the fiber optic connection to the telephone antennas to provide high speed. It covers the need for higher mobile bandwidth for smartphones and tablets.
  • FTTB. Fiber to the Building, the fiber optic connection reaches the Building. From there, it is distributed through copper or coaxial cable to each house or room, depending on the type of Building (hospital, offices, urbanizations, etc.).

In short, there is a clear difference between FTTH and the rest since it takes the network to the final point within our home. In contrast, the rest use coaxial cable terminations ( HFC ) from an issue (more or less far from the Building) to the connection point, therefore using electrical signals and thus being more susceptible to interference.

This is the best known and used classification, although there are other classifications:

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Types of Fiber Optic According To Cable Mode

  • SMF. Single-mode fiber or Single-Mode-Fiber has a diameter between 8 µm and 10 µm. It only allows one mode of transmission (parallel to the axis of the thread), so it can transport signals over a very long distance, at high speed, and without suffering just attenuation. They are yellow (OS1 and OS2).
  • MMF. Multimode fiber or Multimode-Fiber has a diameter between 50 µm and 62.5 µm, and it can transmit multiple rays of light simultaneously since, having a larger diameter, the light can bounce at different angles. It is generally used for short distances from fiber cable or patch panel connection to equipment. They are orange (OM1, OM2) and blue (OM3, OM4).

They are not used to connecting long distances, about 2 km.

Types of Fiber Optic Depending on The Transmission Mode

  • Simplex. Composed of fiber and a connector at each end
  • Duplex. They are composed of 2 fibers and two connectors at each end. Each thread is marked “A” or “B” or uses different colored protective covers to differentiate itself.

As we can see, there are many classifications and types of an optical fiber according to the cable, transmission, material, etc. Still, the most used sort is according to the termination of the wiring, and in this sense, we have shared fiber and dedicated fiber.

Shared Fiber

Shared fiber is the one that offers the highest speed and is, therefore, the one most used by most Internet Providers. 

As we have already pointed out before, we refer to FTTH (Fiber To The Home). We find different structures since various infrastructures or Internet Links are based on Fiber Optic in the shared fiber optic models.

Links Based On Shared Fiber

The most common links in Shared Fiber are FTTH and HFC, as we have already mentioned before.


This type of link allows the most direct, fast, reliable, and secure way to connect to the Internet since it connects each of the points or nodes between the central office of the Internet Provider or distributor with the home or office. This link allows a direct connection to the client or user.

With this type of connection, we can ensure a good download speed download velocity but not upload speed.


As we have already pointed out before, in this type of link, the connection is not direct but rather connects through an intermediate node that reaches its destination (home or office) through a coaxial cable.

They connect the zone nodes with the central, but a coaxial cable starts from the zone node, combining two connection sections: optical and coaxial. These connections that use two lines are usually more affordable, but they are more susceptible to electromagnetic interference.


Symmetric Fiber has been an advance for Internet browsing. This kind of connection is now a trend and is increasingly used.

Symmetrical optical fiber allows the user to have the same upload speed as the download speed in the Internet connection.

It was given greater importance when contracting the Internet at the download speed (download). With the standardization and use of different applications, social networks, etc., the same matter is beginning to be given to the rate of uploading files, photographs, videos, etc.

Dedicated Fiber

Dedicated fiber is a type of fiber optic for an Internet connection so that it arrives directly from the Provider to the client without divisions or intermediate cables. This allows the client or user to be assured that the relationship will not be interfered with by third parties, nor will it be reduced.

This type of fiber allows interconnection solutions with high demand that require higher bandwidth.


The dedicated fiber will be simple or not its implementation depending on the geographical situation. For this reason, it is especially recommended for special privacy needs.

It is a type of fiber optic indicated above all for Companies, Offices, and administrations. Above all, they wish to interconnect their different delegations and equipment with a fluid connection and high transfer capacity, privacy, and storage.

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