Fiber optic network

Fiber optic networks are used in telecommunication and communication networks or computer networks.

In fiber optic (FO) communications networks, laser emission systems are used. Light waves have a high frequency, and the ability of a signal to carry information increases with frequency.

In the early days of FO, LED emitters were also used, although since 2007 they have practically fallen into disuse.

Applications

FO local area networks (commonly abbreviated LAN) are widely used for long-distance communication, providing transcontinental and transoceanic connections, since an advantage of fiber optic systems is the great distance that a signal can travel before needing a repeater or regenerator to recover its intensity. Currently, the repeaters of the FO transmission systems are separated from each other by about 100 km, compared to approximately 1.5 km in electrical systems. Recently developed optical amplifiers can further increase this distance.

An increasingly widespread application of FO is LANs. LANs are made up of a collection of computers that can share data, applications, and resources, such as printers. Computers on a LAN are separated by distances of up to a few kilometers, and are often used in offices or college campuses. A LAN allows the fast and efficient transfer of information between a group of users and reduces operating costs. This system increases the performance of the equipment and easily allows the incorporation of new users to the network. The development of new electro-optical and integrated optics components will further increase the capacity of fiber systems.

Other connected computing resources include wide area networks (WANs) and private branch exchanges (PBXs). WANs are similar to LANs, but they connect computers separated by greater distances together, located in different short-lived data locations used by most computing applications. When connecting the WANs, it is done through their serial interfaces, to connect router with pc through ethernet interfaces.

Fiber Optic Cable Types

ADSS Self Supported Cable

It is a cable designed to be used in aerial structures, commonly electrical networks or energy distribution (poles or towers), it has technical characteristics that allow it to withstand extreme environmental conditions and the way of installation is through special supports and clamps.

Underwater Cable

It is a cable designed to remain submerged in water. These cables manage to reach great distances, which is why they are widely used to connect continents. Inside, in its composition, they have power cables to feed the optical amplifiers that are normally part of the communications system and, as they are located at great depths, their maintenance is difficult, having to resort to underwater robots (ROVs) and ships / crews specially dedicated to these tasks such as the C/V Île-de-Bréhat or the C/V León Thevenin.

There were some shark attacks on undersea cables that required more protection from them.

OPGW Cable

The OPGW cable (Optical Ground Wire) is a cable that has optical fibers inserted inside a tube, in the central core of the ground wire of electrical circuits. Its optical fibers are fully protected and surrounded by heavy ground cables. It is used by power companies to provide communications along the routes of high voltage lines (generally mounted on the guard wire) and have high availability in the information transmission service.

New technical and economic requirements

FO networks are a network model that allows meeting the new and growing transmission capacity and security needs demanded by telecommunication operating companies, all of this with the greatest possible economy.

Through new technologies, with purely optical network elements, the objectives of increasing transmission capacity and security are achieved.

Increased transmission capacity

When the companies in charge of supplying the communication needs through FO needed greater capacity between two points, but did not have the necessary technologies or FO that could carry more data, the only option left was install more FO between these points. But to carry out this solution, it was necessary to invest a lot of time and money, or else add a greater number of time division multiplexed signals in the same FO, which also has a limit.

It is at this point that wavelength division multiplexing (WDM) provided the obtaining, from a single fiber, of many virtual fibers, transmitting each signal on an optical carrier with a different wavelength. In this way many signals could be sent over the same FO as if each of these signals traveled on its own fiber. There are basically two types of WDM,

• DWDM or Dense Wavelenght Division Modulation= divides the total fiber spectrum into "channels" up to 0.4 nm. It has a high cost of controlling and stabilizing the complex. High precision and high stability lasers are very expensive, as well as associated cooling systems. In telecommunications it is assumed that cost as it is important to have a number of channels.
• CWDM or Coarse Wavelenght Division Modulation= divides the total fiber spectrum into "channels" of 20nm, which involves many less channels than in DWDM although at a lower cost because it does not require such accuracy and stability. Current CWDMs have their limit on 10 Gbps. They are very used in broadcasting.

Increased security

Network designers use many network elements to increase the capacity of the fibers since a break in the FO can have serious consequences.

In the electrical architectures used so far, each element performs its own signal restoration. For a traditional otic fiber system with many channels on one fiber, a fiber break could lead to the failure of many independent systems. However, optical networks can perform protection in a faster and cheaper way, performing signal restoration in the optical layer, rather than in the electrical layer. In addition, the optical layer can provide signal restoration capability in networks that currently do not have a protection scheme. Thus, by implementing optical networks, restoration capacity can be added to embedded asynchronous systems without the need to improve electrical protection schemes.

Cost reduction

In systems that use only electrical multiplexing, each point that demultiplexes signals will need an electrical network element for each of the channels, even if they are not passing data on that channel. On the other hand, if what we are using is an optical network, only those wavelengths that upload or download data to a site will need the corresponding electrical node. The other channels can simply be passed through optically, thus providing great savings in equipment and network administration costs.

Another of the great economic aspects of optical networks is the ability to take advantage of bandwidth, something that did not happen with simple fibers. To maximize the possible capacity in a FO, service companies can improve their income by selling wavelengths, regardless of the data rate (bit rate) that is needed. For customers, this service provides the same bandwidth as dedicated fiber, among others.