Can Intense Radiation Enhance Inverse Raman Effect and Multi Photon Absorption?

[tyogav]

Why do we need the presence of an intense radiation in Inverse Raman Effect and Multi Photon Absorption?

 

[Zarqon]

Well, to put it simply, it's because they are higher order processes in the sense that there are multiple photons being involved in the interaction simultaneously. If you have few photons (low intensity) the probability for multiple photons to interact simultaneously is low, but if you increase the photon number (higher intensity) multiple-photon interactions become statistically more likely.