Title: non-linear optical techniques
Long Title: IUPAC Gold Book - non-linear optical techniques
DOI: 10.1351/goldbook.NT07426
Status: current

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

Notes
1) Some of these spectroscopies are four-wave mixing, hole burning, photon echoes, time-resolved coherent anti-stokes Raman (CARS), transient grating and stimulated pumping. These techniques differ in the nature of the pulse sequence, the geometry and the choice of a spatial direction (phase matching), as well as the mode of detection.
2) Low order non-linear techniques, such as three-wave mixing, are related to the second-order polarization. For a random isotropic medium with inversion symmetry, the second-order polarization 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 polarization and the corresponding 'hyper-susceptibility'.

Related Terms
- anti: https://goldbook.iupac.org//terms/view/A00381
- hole burning: https://goldbook.iupac.org//terms/view/H02834
- inversion: https://goldbook.iupac.org//terms/view/I03146
- isotropic: https://goldbook.iupac.org//terms/view/I03353
- mode: https://goldbook.iupac.org//terms/view/M03958
- polarization: https://goldbook.iupac.org//terms/view/P04712
- sequence: https://goldbook.iupac.org//terms/view/ST06775
- stokes: https://goldbook.iupac.org//terms/view/S06027

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)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/NT07426/html
- json: https://goldbook.iupac.org/terms/view/NT07426/json
- xml: https://goldbook.iupac.org/terms/view/NT07426/xml

Citation: 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. 10.1351/goldbook.NT07426
License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.
Collection: If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .
Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-05-18T07:42:25+00:00