Optical Fiber Theories

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    Optical fiber

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    A bundle of optical fibers. Theoretically, using advanced techniques such as DWDM, the

    modest number of fibers seen here could have sufficientbandwidth to easily carry the sum of

    all types of current data transmission needs for the entire planet. (~100 terabits per second per

    fiber[1])

    An optical fiber orfibre is a thin, transparentfiber, usually made ofglassorplastic, fortransmitting light. Fiber optics is the branch ofapplied science and engineering concerned

    with such optical fibers.

    Optical fibers are commonly used in telecommunication systems, as well as in illumination,

    sensors, and imaging optics.

    Contents

    1 Principle of operation

    o 1.1 Materials 2 Optical fiber communication

    o 2.1 Comparison with electrical transmission

    o 2.2 Governing standards

    3 Fiber optic sensors

    4 Other uses of optical fibers

    5 Manufacture

    6 Optical fiber cables

    7 Termination and splicing

    8 History

    9 Notes

    10 References

    11 See also

    1

    http://en.wikipedia.org/wiki/Optical_fiber#column-one%23column-onehttp://en.wikipedia.org/wiki/Optical_fiber#searchInput%23searchInputhttp://en.wikipedia.org/wiki/Optical_fiber#searchInput%23searchInputhttp://en.wikipedia.org/wiki/DWDMhttp://en.wikipedia.org/wiki/DWDMhttp://en.wikipedia.org/wiki/Bandwidthhttp://en.wikipedia.org/wiki/Terabithttp://www.lucent.com/press/0601/010628.bla.htmlhttp://en.wikipedia.org/wiki/Transparency_(optics)http://en.wikipedia.org/wiki/Fiberhttp://en.wikipedia.org/wiki/Glasshttp://en.wikipedia.org/wiki/Glasshttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Applied_sciencehttp://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Telecommunicationhttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Sensorhttp://en.wikipedia.org/wiki/Image-forming_optical_systemhttp://en.wikipedia.org/wiki/Optical_fiber#Principle_of_operation%23Principle_of_operationhttp://en.wikipedia.org/wiki/Optical_fiber#Materials%23Materialshttp://en.wikipedia.org/wiki/Optical_fiber#Optical_fiber_communication%23Optical_fiber_communicationhttp://en.wikipedia.org/wiki/Optical_fiber#Comparison_with_electrical_transmission%23Comparison_with_electrical_transmissionhttp://en.wikipedia.org/wiki/Optical_fiber#Governing_standards%23Governing_standardshttp://en.wikipedia.org/wiki/Optical_fiber#Fiber_optic_sensors%23Fiber_optic_sensorshttp://en.wikipedia.org/wiki/Optical_fiber#Other_uses_of_optical_fibers%23Other_uses_of_optical_fibershttp://en.wikipedia.org/wiki/Optical_fiber#Manufacture%23Manufacturehttp://en.wikipedia.org/wiki/Optical_fiber#Optical_fiber_cables%23Optical_fiber_cableshttp://en.wikipedia.org/wiki/Optical_fiber#Termination_and_splicing%23Termination_and_splicinghttp://en.wikipedia.org/wiki/Optical_fiber#History%23Historyhttp://en.wikipedia.org/wiki/Optical_fiber#Notes%23Noteshttp://en.wikipedia.org/wiki/Optical_fiber#References%23Referenceshttp://en.wikipedia.org/wiki/Optical_fiber#See_also%23See_alsohttp://en.wikipedia.org/wiki/Image:Fiber_optic_bundle.jpghttp://en.wikipedia.org/wiki/Image:Fiber_optic_bundle.jpghttp://en.wikipedia.org/wiki/Optical_fiber#column-one%23column-onehttp://en.wikipedia.org/wiki/Optical_fiber#searchInput%23searchInputhttp://en.wikipedia.org/wiki/DWDMhttp://en.wikipedia.org/wiki/Bandwidthhttp://en.wikipedia.org/wiki/Terabithttp://www.lucent.com/press/0601/010628.bla.htmlhttp://en.wikipedia.org/wiki/Transparency_(optics)http://en.wikipedia.org/wiki/Fiberhttp://en.wikipedia.org/wiki/Glasshttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Applied_sciencehttp://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Telecommunicationhttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Sensorhttp://en.wikipedia.org/wiki/Image-forming_optical_systemhttp://en.wikipedia.org/wiki/Optical_fiber#Principle_of_operation%23Principle_of_operationhttp://en.wikipedia.org/wiki/Optical_fiber#Materials%23Materialshttp://en.wikipedia.org/wiki/Optical_fiber#Optical_fiber_communication%23Optical_fiber_communicationhttp://en.wikipedia.org/wiki/Optical_fiber#Comparison_with_electrical_transmission%23Comparison_with_electrical_transmissionhttp://en.wikipedia.org/wiki/Optical_fiber#Governing_standards%23Governing_standardshttp://en.wikipedia.org/wiki/Optical_fiber#Fiber_optic_sensors%23Fiber_optic_sensorshttp://en.wikipedia.org/wiki/Optical_fiber#Other_uses_of_optical_fibers%23Other_uses_of_optical_fibershttp://en.wikipedia.org/wiki/Optical_fiber#Manufacture%23Manufacturehttp://en.wikipedia.org/wiki/Optical_fiber#Optical_fiber_cables%23Optical_fiber_cableshttp://en.wikipedia.org/wiki/Optical_fiber#Termination_and_splicing%23Termination_and_splicinghttp://en.wikipedia.org/wiki/Optical_fiber#History%23Historyhttp://en.wikipedia.org/wiki/Optical_fiber#Notes%23Noteshttp://en.wikipedia.org/wiki/Optical_fiber#References%23Referenceshttp://en.wikipedia.org/wiki/Optical_fiber#See_also%23See_also
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    12 External links

    [edit]

    Principle of operation

    An optical fiber (American spelling) or fibre (British spelling) is a cylindrical dielectric

    waveguide that transmits light along its axis, by the process of total internal reflection. The

    fiber consists of a densercore surrounded by a claddinglayer. For total internal reflection to

    confine the optical signal in the core, the refractive index of the core must be greater than that

    of the cladding. The boundary between the core and cladding may either be abrupt, instep-

    index fiber, or gradual, ingraded-index fiber.

    A diagram which illustrates the propagation of light through a multi-mode optical fiber.

    Fiber with large (greater than 10 m) core diameter may be analyzed by geometric optics.

    Such fiber is called multi-mode fiber, from the electromagnetic analysis (see below). In a step-

    index fiber, rays of light are guided along the fiber core by total internal reflection. Rays that

    meet the core-cladding boundary at a high angle (measured relative to a line normalto the

    boundary) are completely reflected. The minimum angle for total internal reflection isdetermined by the difference in index of refraction between the core and cladding materials.

    Rays that meet the boundary at a low angle are refracted from the coreinto the cladding,

    where they are not useful for conveying light along the fiber. In this way, the minimum angle

    for total internal reflection determines the acceptance angle of the fiber, often reported as a

    numerical aperture. A high numerical aperture makes it easier to efficiently couple a

    transmitter or receiver to the fiber. However, by allowing light to propagate down the fiber in

    rays both close to the axis and at various angles, a high numerical aperture also increases the

    amount of multi-path spreading, ordispersion, that affects light pulses in the fiber.

    In graded-index fiber, the index of refraction in the core decreases continuously between the

    axis and the cladding. This causes light rays to bend smoothly as they approach the cladding,rather than reflect abruptly from the core-cladding boundary. The resulting curved paths

    reduce multi-path dispersion because high angle rays pass more through the lower-index

    periphery of the core, rather than the high-index center. The index profile is chosen to

    minimize the difference in axial propagation speeds of the various rays in the fiber. This ideal

    index profile is very close to aparabolic relationship between the index and the distance from

    the axis.

    Fiber with a core diameter narrower than a few wavelengths of the light carried, is analyzed as

    anelectromagnetic structure, by solution ofMaxwell's equations, as reduced to the

    electromagnetic wave equation. The electromagnetic analysis may also be required to

    understand behaviors such as speckle that occur when coherentlight propagates in multi-mode fiber. As an optical waveguide, the fiber supports one or more confinedtransverse

    modes by which light can propagate along its axis. Fiber supporting only one mode is called

    2

    http://en.wikipedia.org/wiki/Optical_fiber#External_links%23External_linkshttp://en.wikipedia.org/w/index.php?title=Optical_fiber&action=edit&section=1http://en.wikipedia.org/wiki/Dielectrichttp://en.wikipedia.org/wiki/Waveguide_(optics)http://en.wikipedia.org/wiki/Total_internal_reflectionhttp://en.wikipedia.org/wiki/Refractive_indexhttp://en.wikipedia.org/wiki/Claddinghttp://en.wikipedia.org/wiki/Graded-index_fiberhttp://en.wikipedia.org/wiki/Geometric_opticshttp://en.wikipedia.org/wiki/Geometric_opticshttp://en.wikipedia.org/wiki/Multi-mode_fiberhttp://en.wikipedia.org/wiki/Surface_normalhttp://en.wikipedia.org/wiki/Surface_normalhttp://en.wikipedia.org/wiki/Corehttp://en.wikipedia.org/wiki/Corehttp://en.wikipedia.org/wiki/Corehttp://en.wikipedia.org/wiki/Numerical_aperturehttp://en.wikipedia.org/wiki/Parabolahttp://en.wikipedia.org/wiki/Electromagnetichttp://en.wikipedia.org/wiki/Electromagnetichttp://en.wikipedia.org/wiki/Maxwell's_equationshttp://en.wikipedia.org/wiki/Electromagnetic_wave_equationhttp://en.wikipedia.org/wiki/Electromagnetic_wave_equationhttp://en.wikipedia.org/wiki/Specklehttp://en.wikipedia.org/wiki/Coherence_(physics)http://en.wikipedia.org/wiki/Coherence_(physics)http://en.wikipedia.org/wiki/Transverse_modehttp://en.wikipedia.org/wiki/Transverse_modehttp://en.wikipedia.org/wiki/Transverse_modehttp://en.wikipedia.org/wiki/Image:Optical-fibre.pnghttp://en.wikipedia.org/wiki/Image:Optical-fibre.pnghttp://en.wikipedia.org/wiki/Optical_fiber#External_