Which laser component is primarily responsible for amplifying light through stimulated emission?

Which laser component is primarily responsible for amplifying light through stimulated emission?

• A. Pump source
• B. Cavity
• C. Active Medium
• D. Output Coupler

Answer: (C)

Amplification through stimulated emission happens in the gain, or active, medium of the laser. This material is prepared so that more atoms are in an excited state than in the ground state (population inversion). When a photon that matches the transition passes through, it stimulates those excited atoms to emit a second photon that has the same frequency, phase, and direction. The result is a cascade of photons, increasing the beam’s intensity—this is the amplification. The pump source is what supplies the energy to achieve that population inversion, but it isn’t where the amplification action occurs. The optical cavity provides the necessary feedback, reflecting light back through the medium to encourage multiple passes and build up the coherent beam. The output coupler simply lets part of that light escape as the laser output; it doesn’t amplify the light itself. So, the component that primarily amplifies light via stimulated emission is the active (gain) medium.

Amplification through stimulated emission happens in the gain, or active, medium of the laser. This material is prepared so that more atoms are in an excited state than in the ground state (population inversion). When a photon that matches the transition passes through, it stimulates those excited atoms to emit a second photon that has the same frequency, phase, and direction. The result is a cascade of photons, increasing the beam’s intensity—this is the amplification.

The pump source is what supplies the energy to achieve that population inversion, but it isn’t where the amplification action occurs. The optical cavity provides the necessary feedback, reflecting light back through the medium to encourage multiple passes and build up the coherent beam. The output coupler simply lets part of that light escape as the laser output; it doesn’t amplify the light itself.

So, the component that primarily amplifies light via stimulated emission is the active (gain) medium.