optical fibre abbr., OF (rus. волокно, оптическое otherwise световод, волоконный abbr., ОВ) — optical waveguide in the form of thin filament made of optically transparent material in which light is guided along the core.

Description

The most widespread optical fibre (OF) is a thin quartz filament, the core of which has a refractive index greater than the refractive index of the shell. Single-mode quartz fibres are characterised by their uniquely low loss value of ~0.16 dB/km at the wavelength of 1.55 microns.

Optical access networks and local communication networks also use multimode polymer optical fibres that are easier to operate. The guiding properties of the optical fibres are due to the total internal reflection of light at the boundary between the core and the shell. Depending on the diameter of the core and the refractive index difference between the core and the shell, the fibres are divided into the two main types: multimode and single mode fibres.

The optical fibres are primarily used in telecommunications. The parameters of telecommunication fibres are governed by international standards – G.652, G.653, G.655, etc.

The quartz shell of all types of telecommunication fibres has the standard diameter of 125 microns (see Fig.). The core of gradient multimode fibres (GI) can have one of two diameter values: 50 or 62.5 microns. In standard single-mode fibres the regulated parameter is the mode spot size. Other important characteristics of optical fibres are optical losses, chromatic and polarisation mode dispersion, optical nonlinearity and mechanical strength.

Optical fibres are also used for high-power laser transmission in process and medical applications, in fibre-optic sensors, in optical signal processing devices, etc. Specialised fibres are used in those applications along with standard telecommunication fibres. Their core diameter can vary from several microns to hundreds of microns.

A lot of research is being carried out regarding a new class of optical fibres, photonic crystal fibres, which extend the ability to manage the dispersion characteristics and nonlinear properties of fibres.

Illustrations

Standard telecommunication fiber structure [1].
Standard telecommunication fiber structure [1].

Authors

  • Nanii Oleg E.
  • Listvin Vladimir N.

Sources

  1. Listvin A. V., Listvin V.N., Shvyrkov D. V. Optical fibers for communication lines (in Russian). — Moscow: LESARart, 2003. — 288 pp.
  2. Fiber Optic Sensors Ed. by Eh. Udda (in Russian). — Moscow: Tekhnosfera, 2008. — 520 p.

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