Which of the following allows for the amplification of light in a laser?

The amplification of light in a laser is fundamentally achieved through a feedback mechanism, which comprises the arrangement of mirrors in the laser cavity. This feedback is crucial as it allows the emitted photons to bounce between the mirrors, stimulating the emission of more photons and thereby amplifying the light.

The feedback mechanism creates conditions that enable the population inversion necessary for laser action, where there are more excited atoms ready to emit photons as compared to atoms in their ground state. As photons collide with excited atoms, they stimulate these atoms to release their energy in the form of more photons, all coherent and in phase with each other. This process leads to the amplification effect that results in the intense beam of light characteristic of lasers.

While mirrors are critical components of the laser system, the broader concept of the feedback mechanism encompasses the role of both the mirrors and the arrangement within the cavity that facilitates the continuous amplification of light. Thus, understanding the entire feedback mechanism is essential for grasping how lasers produce their high-intensity, coherent beams.