## harmonic frequency generation

https://doi.org/10.1351/goldbook.H02744
Production of @[email protected] of frequency $$k\ \nu$$($$k=2,3,...$$) from @[email protected] of frequency. In general, this effect is obtained through the interaction of @[email protected] light with a suitable optical medium with non-linear @[email protected] The case $$k=2$$ is referred to as @[email protected], $$k=3$$ is frequency tripling and $$k=4$$ is frequency quadrupling. Even higher integer values of $$k$$ are possible.
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2245 [Terms] [Paper]