Term: non-linear optical techniques
https://doi.org/10.1351/goldbook.NT07426

Definition:
Collective name applied to techniques related to non-linear optical effects.

Notes:
0) Some of these spectroscopies are four-wave mixing, @H02834@, photon echoes, time-resolved coherent @A00381@-@S06027@ Raman (CARS), transient grating and stimulated pumping. These techniques differ in the nature of the pulse @ST06775@, the geometry and the choice of a spatial direction (phase matching), as well as the @M03958@ of detection.
1) Low order non-linear techniques, such as three-wave mixing, are related to the second-order @P04712@. For a random @I03353@ medium with @I03146@ symmetry, the second-order @P04712@ vanishes and then the lowest order optical non-linear techniques, as well as the higher order non-linear techniques are related to the third-order @P04712@ and the corresponding 'hyper-susceptibility'.

Related Terms:
1) hole burning (http://doi.org/10.1351/goldbook.H02834).
2) anti (http://doi.org/10.1351/goldbook.A00381).
3) stokes (http://doi.org/10.1351/goldbook.S06027).
4) sequence (http://doi.org/10.1351/goldbook.ST06775).
5) mode (http://doi.org/10.1351/goldbook.M03958).
6) polarization (http://doi.org/10.1351/goldbook.P04712).
7) isotropic (http://doi.org/10.1351/goldbook.I03353).
8) inversion (http://doi.org/10.1351/goldbook.I03146).

Source: PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 374 (https://doi.org/10.1351/pac200779030293)

Citation: 'non-linear optical techniques' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.NT07426

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