Laser amplification (mechanism): After the first photons are produced in the gain medium, which process amplifies the light to produce a laser beam? Name the fundamental emission process responsible for optical gain. Choose the correct process.

Concept
A laser amplifies light via stimulated emission, in which an incoming photon induces an excited atom/ion to drop to a lower energy level, emitting a coherent photon in phase and direction with the incident one. With cavity feedback, this yields exponential gain.

Common pitfalls
Confusing the initial spontaneous emission (seed photons) with the stimulated process that drives amplification.

Final Answer
Stimulated emission