Collective name applied to techniques related to non-linear optical effects.
- 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
pulse sequence, the geometry and the choice of a spatial direction (phase matching),
as well as the mode of detection.
- 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'.
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 374
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook