What is a Laser?
Laser (noun) is a device that creates and amplifies narrow beams of light. Laser stands for light amplification by stimulated emission, and as the meaning implies it emits light through a process of stimulated emission. The trick to generate a light going into one precise direction with the correct arrangement of atoms at the right time and in the right direction.
Three Parts of a Laser: (Slide 2)
A laser consists of three parts:
- An energy source or a pump is used to provide the energy from an external source into the gain medium of a laser. This energy is usually provided in the form of light or electric current, but more exotic sources have been used, such as chemical or nuclear reactions.
- A laser also consists of a gain medium or a laser medium, this is the major determining factor of the wavelength of operation, and other properties, of the laser and it is in the gain medium that the emission of photons take place.
- Optical resonator or optical cavity is the last part of the laser. A simplest example of optical resonator are two parallel mirrors that have different coatings that give them different properties to reflect light, usually one that is a high reflector and the other is a low reflector, which results in some of the light to leave the cavity to produce the laser’s output beam.
(Slide 4) Absorption of Light
This is a quantum mechanical phenomena, where light source or energy from the pump or the energy source provides photons in typical lasers that causes the ground atoms to become excited that causes a transition of atoms or molecules from a lower energy state to a higher energy state. This process results in the atoms absorbing one or more photons resulting in a higher energy atoms or molecules.
(Slide 5) Stimulated...