The process by which two photons with frequencies
combine in a non-linear medium to produce a higher energy photon with frequency
- Also known as a parametric upconversion or sum frequency generation.
Upconversion is the reverse process of downconversion.
- The efficiency of the conversion process depends on the parametric gain
in the non-linear material. This in turn depends on the power of the incident
radiation, the photon frequencies, their indices of refraction in the material,
and the non-linear 'hyper-susceptibility' of the material.
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 437
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. doi:10.1351/goldbook