Basic Components of Laser:
The physical principles of lasers are based on the interactions of electromagnetic waves, photons with certain materials. The basic components of laser are given below:
1. Spontaneous Emission: The release of energy in the form of electromagnetic waves or photons when an atom decays on its own from higher energy level to lower energy level is called Spontaneous Emission.
2. Stimulated Emission: When an external stimulus such as electromagnetic wave or photon from external source causes emission of electromagnetic wave or photon of same frequency. Phase and direction as that of the incident photon, the process is called stimulated emission.
3. Absorption: Absorption is a process in which an atom moves from a lower energy level to a higher energy level by absorbing an incident photon of energy equal to the energy difference between the two levels.
4. Population Inversion: The number of atoms per unit volume at a given energy level is called population of that energy level. In normal state, the population in the ground state is maximum and decreases exponentially as one goes to the excited states.
5. Pumping: The technique or method of archiving population inversion by transferring a large number of atoms front the ground state to an excited state by supplying suitable energy from external source is called pumping. The external source of energy is called pumping source.