What do lasers utilize to produce electromagnetic radiation?

Lasers, which stand for Light Amplification by Stimulated Emission of Radiation, primarily utilize stimulated emission to generate electromagnetic radiation. In this process, an incoming photon interacts with an excited atom or molecule, prompting it to release another photon. This released photon has the same energy, phase, frequency, and direction as the incoming photon, resulting in a coherent light beam.

This mechanism is the key differentiator for lasers compared to other light sources, which may rely on spontaneous emission, where photons are emitted randomly and independently rather than in a coordinated manner. Stimulated emission amplifies light because it leads to a cascade effect, where multiple photons can be generated from a single one, thus producing a highly concentrated beam of light.

Other processes such as continuous absorption or random decay do not contribute to the coherent and amplified nature of laser light. Continuous absorption involves material absorbing energy consistently over time, while random decay refers to the unpredictability associated with the return of excited electrons to their ground state, which does not create the coherent properties necessary for lasers.