An optical fiber or optical fiber is a flexible and transparent fiber made of a glass (silica) or plastic with a diameter slightly thicker than that of a human hair. Optical fibers are most often used as a means of transmitting light between the two ends of the fiber and are widely used in fiber optic communications, where they allow transmission over longer distances and greater bandwidths than electrical cables.

Fiber optic – What is it

Fiber optics, or fiber optics, refers to the medium and technology associated with the transmission of information as pulses of light along a glass or plastic filament or fiber. A fiber optic cable can contain a variable number of these glass fibers, from a few to a couple of hundred. Around the fiberglass core is another layer of glass called the cladding. A layer known as a buffer tube protects the liner, and a wrap layer acts as the final protective layer for the individual filament.

Optical fiber – Characteristics

Fibers are used in place of metal cables because signals travel along them with less loss; Furthermore, the fibers are immune to electromagnetic interference, a problem that metal cables suffer excessively.

Fibers are also used for lighting and imaging, and are often wrapped in bundles so that they can be used to transport light into or images of confined spaces, as in the case of a fiberscope. Specially designed fibers are also used for a variety of other applications, some of them being fiber optic sensors and fiber lasers.

Optical fibers typically include a core surrounded by a transparent coating material with a lower refractive index. The light is held in the core by the phenomenon of total internal reflection that makes the fiber act as a waveguide.

Fibers that support many propagation paths or transverse modes are called multimode fibers, while those that support only one mode are called single-mode fibers (SMF). Multimode fibers generally have a wider core diameter and are used for short distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links over 1,000 meters (3,300 feet)

Being able to join optical fibers with low losses is important in fiber optic communication. This is more complex than joining an electrical cable or cable and involves careful cutting of the fibers, precise alignment of the fiber cores, and the coupling of these aligned cores. For applications that require a permanent connection, a fusion splice is common. In this technique, an electric arc is used to fuse the ends of the fibers together. Another common technique is mechanical splicing, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made using specialized fiber optic connectors.

The field of applied science and engineering related to the design and application of optical fibers is known as fiber optics. The term was coined by the Indian physicist Narinder Singh Kapany, who is widely recognized as the father of fiber optics.

Fiber optics – History

Daniel Colladon first described this “light source” or “light tube” in an 1842 article entitled “On Reflections of a Ray of Light within a Stream of Parabolic Liquid.” This particular illustration comes from a later Colladon article, in 1884.

Guiding light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures at London, 12 years later.

In the late 19th and early 20th centuries, light was guided through bent rods of glass to illuminate body cavities. Practical applications such as closed internal lighting during dentistry appeared in the early 20th century. The transmission of images through the tubes was independently demonstrated by radio experimenter Clarence Hansell and television pioneer John Logie Baird in the 1920s. In the 1930s, Heinrich Lamm demonstrated that images could be transmitted through a bundle of uninsulated optical fibers and was used for internal medical examinations, but his work was largely forgotten.

Optical fiber – Use

Communication

Fiber optics is used as a medium for telecommunications and computer networks because it is flexible and can be bundled together like cables. It is especially advantageous for long-distance communications, since light propagates through the fiber with little attenuation compared to electrical cables.

Per channel light signals propagating on fiber have been modulated at rates as high as 111 gigabits per second (Gbit / s) by NTT, although 10 or 40 Gbit / s is typical in deployed systems.

Sensors

Fibers have many uses in remote sensing. In some applications, the sensor is itself an optical fiber. In other cases, fiber is used to connect a non-fiber optic sensor to a measurement system. Depending on the application, fiber can be used due to its small size, or the fact that no electrical power is needed at the remote location.

Power transmission

Fiber optics can be used to transmit energy by using a photovoltaic cell to convert light into electricity. While this method of power transmission is not as efficient as conventional ones, it is especially useful in situations where it is desirable not to have a metallic conductor such as in the case of use near MRI machines, which produce strong magnetic fields.

Optical fiber – Advantages

The advantages of fiber optic communication over copper cable systems are:

  • Wide bandwidth – A single fiber optic can carry more than 3,000,000 full-duplex voice calls or 90,000 television channels.
  • Immunity to electromagnetic interference: the transmission of light through optical fibers is not affected by other nearby electromagnetic radiation. The information that travels inside the optical fiber is immune to electromagnetic interference, even electromagnetic pulses generated by nuclear devices.
  • Low loss of attenuation over long distances: loss of attenuation can be as low as 0.2 dB / km in fiber optic cables, allowing transmission over long distances without the need for repeaters.
  • Electrical Isolator – Optical fibers do not conduct electricity, preventing problems with ground loops and lightning conduction. Optical fibers can be threaded onto poles together with high-tension cables.
  • Material costs and theft prevention: Conventional cable systems use large amounts of copper.
  • Security of the information transmitted by the cable: copper can be exploited with very few possibilities of detection.
Samantha Robson
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Dr. Samantha Robson ( CRN: 0510146-5) is a nutritionist and website content reviewer related to her area of ​​expertise. With a postgraduate degree in Nutrition from The University of Arizona, she is a specialist in Sports Nutrition from Oxford University and is also a member of the International Society of Sports Nutrition.

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