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Definition: optical phenomena involving a nonlinear response to a driving light field

German: Nichtlinearitäten

Categories: fiber optics and waveguides, nonlinear optics

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Lasers can be used for the generation of light with very high optical intensities. These can give rise to a number of nonlinear optical effects (→ nonlinear optics), the most important of which are:

There are also various other effects which are not directly based on optical nonlinearities, but are nevertheless affecting optical phenomena:

In optical fiber technology, optical nonlinearities are of high interest. In fibers there is a particularly long interaction length combined with the high intensity resulting from a small mode area. Therefore, nonlinearities can have strong effects in fibers. Particularly the effects related to the χ(3) nonlinearity – Kerr effect, Raman scattering, Brillouin scattering – are often important, despite the relatively weak intrinsic nonlinear coefficient of silica: either they act as essential nonlinearities for achieving certain functions (e.g. pulse compression), or they constitute limiting effects in high-power fiber lasers and amplifiers.

Usually, the strength of nonlinear effects is determined by the peak power. However, there are cases where stronger effects occur for lower peak powers, as explained in a Spotlight article.

Strong nonlinearities also occur at intensities which are high enough to cause ionization in the medium. This can lead to optical breakdown, possibly even associated with laser-induced damage of the material. In gases, extremely high optical intensities can be applied, which can lead e.g. to high harmonic generation.


[1]G. P. Agrawal, Nonlinear Fiber Optics, 4th edn., Academic Press, New York (2007)
[2]R. Paschotta, tutorial on "Passive Fiber Optics", Part 11: Nonlinearities of Fibers

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See also: nonlinear optics, effective nonlinear coefficient, laser-induced breakdown, nonlinear crystal materials, nonlinear frequency conversion, nonlinear polarization, nonlinear index, saturable absorbers, fibers, The Photonics Spotlight 2007-09-01
and other articles in the categories fiber optics and waveguides, nonlinear optics


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