How is light amplified in a laser?
Photons collide with gas particles, multiply, and reflect back and forth in a tube.
Photons “leak” through a partially reflecting mirror, causing them to travel in step.
Integrated circuits in a laser amplify the sound produced by photon emission.
Electric current is amplified and directed into gas particles, which emit photons.
None of the above options are correct.
In a laser, light is amplified through a process called stimulated emission. This occurs when an excited atom is hit by a photon with the same wavelength and energy as the atom's excited state. The atom then releases two photons that are identical in wavelength and energy to the original photon. This creates a chain reaction where more and more photons are produced in a coherent, parallel stream. This process happens in a gain medium, which can be a gas, crystal, or other material. The gain medium is surrounded by mirrors that reflect the photons back and forth, creating a feedback loop that further amplifies the light. Eventually, a small amount of light is allowed to escape through a partially reflecting mirror, creating the laser beam.