Components and types of fiber optics

Fiber Optic Components

• Core: in silica, fused quartz or plastic. Optical waves propagate in it. Diameter: 50 or 62.5  µm for multimode fiber and 9 µm for single-mode fiber.
• Optical sheath: Generally of the same materials as the core but with additives that confine the optical waves in the core.
• The protective coating: it is generally made of plastic and ensures mechanical protection of the  fiber optics careers.

Optical fiber types

Single-mode fiber: Potentially, this is the fiber that offers the greatest capacity for information transport. It has a bandwidth on the order of 100  GHz / km . The highest flows are achieved with this fiber, but it is also the most complex to implant.

The drawing shows that only rays that have a path that follows the axis of the fiber can be transmitted, which is why it has earned the name of "single mode" (mode of propagation, or path of the single light beam). They are fibers that have the diameter of the nucleus in the same order of magnitude as the wavelength of the optical signals they transmit, that is, from about 5 to 8  mm .

If the core is made of a material whose refractive index is very different from that of the shell, then we are talking about single-mode fibers with a stepped index. The high fluxes that can be achieved are the main advantage of single-mode fibers, since their small dimensions imply delicate handling and entail connection difficulties that are still poorly mastered.

• Gradient Gradient Index Multimode Fiber - Gradient Gradient Index multimode fibers have a passband that goes up to 500  MHz / km . Its principle is based on the fact that the refractive index inside the core is not unique and decreases when it moves from the core to the shell.

The light rays are focused towards the axis of the fiber, as can be seen in the drawing. These fibers allow the dispersion between the different modes of propagation through the fiber core to be reduced. Multimode fiber with gradual gradient index size 62.5 / 125  m (core diameter / shell diameter) is standardized, but other types of fibers can be found:

• Stepwise index multimode 100/140  mm .
• Multimode with gradual gradient index 50/125  mm .

Multimode stepped index fiber: Multimode stepped index fibers are made of glass, with an attenuation of 30  dB / km , or plastic, with an attenuation of 100  dB / km . They have a passband that goes up to 40   MHz / km

In these fibers, the core is made up of a uniform material whose refractive index is clearly higher than that of the surrounding shell. The passage from the core to the roof therefore entails a brutal variation of the index, hence its name staggered index.

Fiber optic communications

Internet

The fiber optic Internet connection service breaks down the biggest limitation of cyberspace: its exasperating slowness. The purpose of the following article is to describe the mechanism of action, the advantages and disadvantages.

To navigate the global network of networks, the Internet , not only do you need a computer, a modem, and some programs, but you also need a great deal of patience. The cyberspace is a slow world to despair. A user can spend several minutes waiting for a page to load or several hours trying to download a program from the Net to their PC .

This is because telephone lines, the means that most of the 50 million users use to connect to the Internet, were not created to transport videos, graphics, texts and all the other elements that travel from one place to another in the Net.

But phone lines are not the only route to cyberspace. Recently a service allows connecting to the Internet through fiber optics. Fiber optics makes it possible to surf the Internet at a speed of two million bps, unthinkable in the conventional system, in which the majority of users connect at 28,000 or 33,600 bps.

Networks

Fiber optics is increasingly used in communication, because light waves have a high frequency and the ability of a signal to carry information increases with frequency.

Fiber optic laser systems are used in communications networks. Many fiber networks for long-distance communication operate today, providing transcontinental and transoceanic connections. An advantage of fiber optic systems is the great distance that a signal can travel before needing a repeater to recover its intensity.

Fiber optic repeaters are currently approximately 100 km apart from each other, compared to approximately 1.5 km in electrical systems. Newly developed fiber optic amplifiers can further increase this distance. Another increasingly widespread application of fiber optics is local area networks. Unlike long-distance communications, these systems connect a series of local subscribers with centralized equipment such as computers or printers. This system increases equipment performance and allows new users to join the network easily.

The development of new electro-optical and integrated optics components will further increase the capacity of fiber systems.

Local area network or LAN, set of computers that can share data, applications and resources (for example printers).

Computers on a local area network (LAN) are separated by distances of up to a few kilometers, and are often used in offices or university campuses. A LAN enables the fast and efficient transfer of information within a group of users and reduces operating costs. Other connected computing resources are Wide Area Networks (WANs) or Private PBXs.

WANs are similar to LANs, but connect computers separated by greater distances, located in different parts of a country or in different countries; They employ specialized and expensive physical equipment and lease communications services. PBXs provide continuous computer connections for specialized data transfer such as telephone transmissions, but are not suitable for emitting and receiving the short-lived spikes of data used by most computer applications.

Public communication networks are divided into different levels; according to the operation, the transmission capacity, as well as the scope they define. For example, if you are approaching from the outside towards the interior of a large city, you have first the interurban network and the provisional network, then the prolonged lines of traffic with the lowest capacity from remote areas (rural network), towards the center the urban network and finally the subscriber lines.

The parameters dictated by practice are the transmission section that can be covered and the specific bit rate as well as the appropriate type of optical fiber, that is, cables with single-mode or multimode fibers fiber optics technician job description.

Telephony

Due to the standardization of existing interfaces, fiber optic transmission systems are available for public telecommunication network levels in a wide application, contrary to systems of the subscriber network (subscriber line), there are first of all a number of considerations.

For the connection of a telephone it is completely sufficient with the existing copper conductors. Precisely with the introduction of broadband services such as videoconferencing, videotelephony, etc., fiber optics will become essential for the subscriber.

With the BIGFON (integrated urban fiber optic broadband telecommunications network), extensive experiences have been gathered in this regard. According to the strategy developed, broadband services will later be expanded with radio and television distribution services in an integrated broadband telecommunications network ( IBFN ).