Nonlinear optics

Article By:

Reintjes, John F. Sotera Defense Solutions-Optics and U.S. Naval Research Laboratory, Washington, DC.

Anderson, Dana Z. Joint Institute for Laboratory Astrophysics, University of Colorado, Boulder, Colorado.

Kippelen, Bernard School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.455600

A field of study concerned with the interaction of electromagnetic radiation and matter in which the matter responds in a nonlinear manner to the incident radiation fields. The nonlinear response can result in intensity-dependent variation of the propagation characteristics of the radiation fields or in the creation of radiation fields that propagate at new frequencies or in new directions. The nonlinear response can also result in changes to the optical properties of the material, such as absorption or the index of refraction. Nonlinear effects can take place in the traditional phases of materials, that is, solids, liquids, gases, and plasmas, as well as more modern materials including engineered materials such as quantum wells, periodically poled crystals, and Bose-Einstein condensates (a form of matter in which a group of atoms are cooled so close to absolute zero that they coalesce into a single quantum state). They may involve one or more electromagnetic fields as well as internal excitations of the medium. Much of the work done in the field has made use of the high powers available from pulsed lasers, although interactions in resonant materials, quantum wells, or optical fibers can take place with the lower power of diode lasers or continuous-wave lasers. The wavelength range of interest generally extends from the far-infrared to the vacuum ultraviolet, but some nonlinear interactions have been observed at wavelengths extending from the microwave to the x-ray ranges. See also: Laser

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