Stimulated Emission and Amplification

Quick Recap on Stimulated Emission

an excited atom can relax to a stable state by releasing a photon: this is called spontaneous emission.

this photon can interact with another excited atom and cause it to relax back to the normal state.

this atom will release a photon which is identical in energy, direction, and phase with the incident photon.

these two photons can in turn interact with other excited atoms.

We started with one photon, now we have two: we have achieved amplification.