Optical fiber, a technology used since the 1970s, has greatly contributed to the explosion of telecommunications at the global level, allowing communications at long distance and at speeds previously not possible. In the field of telephony and Internet, the "spider web" world woven wire glass.

An optical fiber is a wire glass or thin plastic that allows light to drive over very large distances (several hundreds or thousands of kilometers).

This technology is used in oceanic and terrestrial transmissions of data, because the light signal transits it is capable of transmitting large amounts of information.

Fiber optics, which offer a flow of information significantly higher than that of coaxial cables and support a "broadband", have multiple applications.
They can transmit both television and telephone as video or computer data.

First optical fiber can be used in telecommunications networks were built in 1970 in the laboratories of the U.S. Company Corning Glass Works by Robert Maurer, Peter Schultz and Donald Keck.

Description

In a schematic way, an optical fiber is composed of the following:

• A thread of very fine glass (a few microns in diameter) and in one piece, called "the heart"

• A sheath that surrounds and traps the light in the heart, reflecting multiple times, almost without loss

• A protective sheath that covers several tens to several hundreds of optical fibers

• A very specific connection (which does not prevent the transmission of light).

In the field of optical telecommunications, material is generally very pure silica (which produces very low optical losses) even if they are also plastic fibers.

Principle of operation

The optical fiber is a waveguide that uses REFRACTIVE properties of light.

The electrical signal to be transmitted is first converted into a light signal through a transceiver that uses an LED (light emitting diode) or a laser to produce light.

When a light beam enters one end of the fiber according to a proper angle, it undergoes multiple reflections and spreads to the other end following a zigzag course.

The light signal is then converted into an electrical signal through a detector, usually a photodiode.

When fiber is not yet fed, it is called dark fiber.

Applications

Endoscopy, to look inside the human body, or welds in aircraft engines, was the first application of fiber optics in the early 1950s with the invention of flexible fiberscopes by van Heel and Hopkins.

The invention of the laser in 1960, then allowed to transmit a light signal with enough power over a great distance.
Early attempts telecommunications optical fiber followed by 1966.

Today, more than 80% of long distance communications in the world are transported through a network of optical fiber cables of more than 25 million kilometers.

This technology is also used in the field of sensors (temperature, pressure, etc.) and imaging.

The next application of fiber optics will be the FTTH (Fiber To The Home), a system of very high-speed communication through an optical fiber network at up to the customer.
This technology should soon compete with xDSL technologies and gradually replace ADSL in our homes.

Benefits

The advantages of data transmission by fiber optics are numerous:

• Loss of signal over a large distance is much lower compared to electric transmission in a metallic conductor

• This technology offers transmission speeds high

• Optical fibers are not sensitive to external interference (near a high voltage cable, for example)

• They do not produce heat (unlike copper).