I’m new to optics and I’m having difficulty reconciling two concepts which to me seem very different but which I know to be equivalent and fundamentally two ways of describing the same phenomenon. The Wikipedia article on [refractive index](https://en.wikipedia.org/wiki/Refractive_index) states under “Microscopic Explanation” that as the electromagnetic fields oscillate, the charges in the material are “shaken” at the same frequency and radiate their own EM wave. If the electrons emit a light wave which is in phase with the light wave shaking them, it will amplify the light. This corresponds to stimulated emission. However, my confusion lies in the fact that if I then read the article on stimulated emission, there is no discussion of the “shaking charges” or radiating dipole. Instead, it focuses on atomic transitions between the excited and ground states. My question is how I should reconcile in my mind these two approaches to understanding stimulated emission? Thank you for your help.