Fiber Optic -

Fiber Optic is a transmission medium, commonly used in data and telecommunications networks, consisting of a very fine thread of transparent material, glass or plastic materials, by which pulses of light are sent that represent the data to be transmitted. The beam of light is completely confined and propagates inside the fiber with a reflection angle above the limit angle of total reflection, according to Snell's law. The light source can be a laser or a led diode.

In addition, it is in a continuous process of expansion, without knowing exactly limits on it.

Starting from the fact that fiber optic transmits light, all the applications that are based on luminosity (whether due to lack of light, difficult access, decorative purposes or precision search) have a place in this field.

If to all this we add the great capacity of information transmission of this medium, (due to its great bandwidth, low attenuation, to which this information travels at the speed of light, etc.) said applications multiply.

Fields such as telecommunications, medicine, archeology, military practices, mechanics and surveillance benefit from the qualities of this optical tool.

This revolution in the field of telecommunications will turn the world around, as it will make a big step and improve our lives by increasing the capacity to transmit data at high speed and long distances in a safe and feasible manner.

The normal copper conductor is replaced by fine strands of glass that carry data by pulses of light.

Basic Transmission of Fiber Optic

We know that the fiber optic transmits information along the length of the conductor that contains the fiber by means of light and this through transparent fibers being of glass or plastic. A light emitting diode modulated thanks to a light source being this the one that alternated the on and off being this the reference of the electrical input signal which will be the one who carries the information.

The light transmission techniques are divided into three groups, the following being:

Digital modulation, analog modulation and digital modulation with conversion.

Applications of Fiber Optic

Fiber Optic is commonly used as a means of communication for michas different areas.

It is still in studies to be able to carry out a fiber route to provide communications between its central offices in all cities, throughout countries or on long ocean routes.

Many internet or television companies work with it to be able to satisfy the customer and offer a better quality for video phone transmissions or better high quality signals.

Being this ideal for data communications thanks to the fine fiber optic cable, very high speeds can be achieved for transmission.

The signals emitted by it are not affected by distortion due to interference or interruption.

The dielectric properties of optical fibers provide a secure interface between computers, terminals and workstations.

The interest for new optical fibers based on silica with fluorescent capacity in the near infrared (NIR) range, namely between 1 and 2 μm, and as broadband.

This is caused by the fact that, within this spectral range, the fundamental loss in silica is minimal, which is potentially attractive for telecommunications-oriented devices. However, until now, none of "active" fiber, well controllable.

In the reproducibility of its basic properties, it is known as a real candidate for amplification and lasing in NIR, especially for the range of 1150 ... 1530 nm between the well-developed Ytterbium operating ranges (1000 ... 1150 nm) and Erbium (1530 ... 1610 nm) fiber laser systems.

It can be used as a waveguide in medical or industrial applications where it is necessary to guide a beam of light to a target that is not in the line of sight.

The optical fiber can be used as a sensor to measure voltages, temperature, pressure as well as other parameters.

It is possible to use fiber patch cords along with lenses to make long, thin viewing instruments called endoscopes. Endoscopes are used in medicine to visualize objects through a small hole. Industrial endoscopes are used for similar purposes, such as for inspecting the interior of turbines.

Optical fibers have also been used for decorative uses including lighting, Christmas trees.

Optical Fibers are widely used in the field of lighting. For buildings where light can be collected on the roof and be carried by fiber optics to any part of the building.

It is also used to trick the sensory system of taxis, causing the taximeter (some call it a tab account) not to mark the actual cost of the trip.

It is used as a component in the manufacture of translucent concrete, an invention created by the Hungarian architect Ron Losonczi, which consists of a mixture of concrete and fiber optic forming a new material that offers the strength of concrete but additionally, has the peculiarity of letting pass the light wide.

A projection to use Fiber Optic is very profitable since even the companies use it in metropolitan areas and have all the requirements of current communications and allow an expansion of future systems and give way to large expansions according to the needs.

Advantages and Disadvantages of Optical Fiber

The optical fiber being in a popular medium will have to fulfill some communication requirements, it applies to many advantages that it presents over other conventional electric transmission methods, however there are some impediments to be examined before proceeding with the installation, presenting below some considerations:


  • Great capacity
  • Size and weight
  • Electrical interference
  • Isolation
  • Security
  • Reliability and maintenance
  • Versatility
  • Expansion
  • Regeneration of the signal


  • Electro-optical conversion
  • Homogeneous roads
  • Special installation
  • Repairs

Composition of an Optical Fiber

the optical fiber is composed of three different layers: the central core which carries the light, the covering that covers the core and that confines the light inside the nucleus, and the coating that gives protection to the coating.

Core: In silica, molten plastic in which optical waves propagate.

the layers of the silica core and coating differ slightly in their composition, due to small amounts of materials, such as boron or germanium, which are added during the manufacturing time.

Usual Fiber Diameters

These groups are 5 being the main, being the diameters of the core and the coating as we present below:Coating: generally of the same materials as the core, but with additives that confine the optical waves in the nucleus.

Protective coating: It is usually made of plastic and ensures mechanical protection of the fiber

In terms of fiber interferometers, Fabry-Perot and Mach- 'Zehnder's architectures have been extensively exploited for the detection of RI, since their fabrication can be done in a relatively simple, sharp and micro-mechanized manner.

Interestingly, although interferometry approaches are typically associated with high sensitivity this is not the case with PCF interferometers, regardless of whether they are operated in transmission (190.9 nm / RIU), or reflection (6.67 nm / RIU). ). The sensitivity reported for RI sensors based on conical SMF is generally low as well (30 nm / RIU), even if multiple debris cascades (380 nm / RIU). However, it has been shown that a high sensitivity can be achieved if the long millimeter waist is reduced to only a few microns (> 18,600 nm / RIU).

Regarding the use of structures with multiple cores, RI detection based on a double-core fiber has been reported. This architectural sensation has a central nucleus and a lateral nucleus, which are not coupled, with the lateral nucleus exposed to the external medium via chemical etching. By appropriate coupling of this dual core fiber to a smf a michelson interferometer is performed with a sensitivity of 826.8 nm / riu. Sensors of a similar nature, that is, of two cores, where the external core is also selectively exposed to the environment, have been demonstrated with sensitivity> 3,000 nm / riu when the two single-mode cores are coupled, ie in fiber direction coupler.

alternatively, metal coatings can be deposited as in the case of fiber plasmonic devices. the use of appropriately designed coatings around the engraved scf to fine tune the operation and optimize the sensor performance in the range of interest of ri.

Optical Fiber is widely used in telecommunications, since it allows sending large amounts of data over a large distance, with speeds similar to those of radio and higher than those of conventional cable. They are the transmission medium par excellence, being immune to electromagnetic interference, they are also used for local networks, where the advantages of optical fiber over other transmission media need to be exploited.


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