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Nonlinear Optics

Definition: the part of optics dealing with optical nonlinearities and their applications

More general term: optics

Opposite term: linear optics

German: nichtlineare Optik

Category: nonlinear optics


How to cite the article; suggest additional literature

URL: https://www.rp-photonics.com/nonlinear_optics.html

Nonlinear optics is a part of optics, dealing with various kinds of optical nonlinearities and their applications. Such nonlinearities occur e.g. in nonlinear crystal materials (including both dielectrics and semiconductors) or in optical fibers and other waveguide devices. Nonlinear effects with light are those where e.g. applying twice the optical input intensities does not simply result in twice the output intensities. In most cases, one exploits either the <$\chi^{(2)}$> nonlinearity or the <$\chi^{(3)}$> nonlinearity of the medium, and sometimes the delayed nonlinear response based on those. See the article on nonlinearities for more details and examples.

For low optical intensities, nonlinear effects become very weak. Therefore, nonlinear optical effects were very difficult to observe (and basically irrelevant technologically) before the advent of lasers, with which very high intensities can be easily generated.

For applications, a field of particular importance is nonlinear frequency conversion, dealing with the generation of new optical frequencies in nonlinear processes. Another wide area is concerned with the effects of optical nonlinearities in various situations, e.g. for the propagation of intense ultrashort pulses in optical fibers, in supercontinuum generation, or for optical signal processing. In other cases, optical nonlinearities are utilized for measurement processes – for example, in autocorrelators and in devices for frequency-resolved optical gating in the context of ultrashort pulse characterization.

Nonlinear fiber optics partly deals with nonlinear frequency conversion (e.g., with supercontinuum generation and fiber-optical parametric oscillators), but also with other uses of fiber nonlinearities – for example, with nonlinear amplification and signal processing.

Nonlinear interactions are also very important for many experiments in quantum optics.


[1]R. H. Stolen, “The early years of fiber nonlinear optics”, J. Lightwave Technol. 26, 1021 (2008)
[2]G. P. Agrawal, “Nonlinear fiber optics: its history and recent progress”, J. Opt. Soc. Am. B 28 (12), A1 (2011), DOI:10.1364/JOSAB.28.0000A1
[3]E. Garmire, “Nonlinear optics in daily life”, Opt. Express 21 (25), 30532 (2013), DOI:10.1364/OE.21.030532
[4]L. G. Wright et al., “Nonlinear multimode photonics: nonlinear optics with many degrees of freedom”, Optica 9 (7), 824 (2022), DOI:10.1364/OPTICA.461981
[5]N. Bloembergen, Nonlinear Optics, World Scientific Publishing (1964)
[6]R. L. Sutherland, Handbook of Nonlinear Optics, 2nd edn., Marcel Dekker, New York (2003)
[7]R. W. Boyd, Nonlinear Optics, Academic Press, 2nd edn., CRC Press, Boca Raton, FL (2003)
[8]G. P. Agrawal, Nonlinear Fiber Optics, 4th edn., Academic Press, New York (2007)
[9]A. V. Smith, SNLO software for simulating nonlinear frequency conversion in crystals, free download, http://www.as-photonics.com/snlo, from AS-Photonics
[10]A. V. Smith, Crystal nonlinear optics with SNLO examples, ISBN 978-0-692-40044-9, https://as-photonics.com/products/crystal-nlo-book/

See also: optics, nonlinearities, nonlinear polarization, nonlinear crystal materials, nonlinear frequency conversion, supercontinuum generation, quantum optics, fiber optics

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