Laser

Definition

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term laser stands for Light Amplification by Stimulated Emission of Radiation.

5 Must Know Facts For Your Next Test

1. Lasers operate on the principle of stimulated emission, where an incoming photon causes an excited electron to drop to a lower energy level, releasing a photon.
2. The emitted light from a laser is coherent, meaning the light waves are in phase and have a fixed relationship with each other.
3. Laser light is typically monochromatic, consisting of one wavelength or color, depending on the material and construction of the laser.
4. Population inversion, where more electrons are in an excited state than in the ground state, is necessary for laser operation.
5. Lasers can be classified into different types such as gas lasers (e.g., helium-neon), solid-state lasers (e.g., ruby lasers), and semiconductor lasers (e.g., diode lasers).

Review Questions

• What fundamental principle allows a laser to emit light?
• Why is population inversion crucial for the operation of a laser?
• How does the coherence property of laser light differ from ordinary light?

Related terms

Stimulated Emission: A process by which an incoming photon induces an excited electron to fall to a lower energy level, emitting another photon.

Coherent Light:

Light in which waves maintain a constant phase relationship with each other over time and space.

Monochromatic Light:

Light that consists of one single wavelength or color.