What is meant by stimulated emission?
Stimulated emission of radiation: When an electron is in a different energy level of the fundamental level and returns to the ground state through an incident photon, a new photon is generated with exactly the same frequency, direction and phase to the incident photon.
What conditions do stimulated emission dominates?
As long as there are more atoms in the upper energy level than in the lower, stimulated emission can dominate, and a cascade of photons results.
Why is stimulated emission coherent?
In laser action the stimulating emission triggers a chain reaction in which the radiation from one atom stimulates another in succession until all the excited atoms in the system have returned to normalcy. In doing so, coherent monochromatic light (light of a single wavelength) is emitted.
What is amplification by stimulated emission of radiation?
Light Amplification by Stimulated Emission of Radiation (laser) is a coherent, convergent, and monochromatic beam of electromagnetic radiation. Various laser sources have been applied in LAM to preheat the workpiece including CO2 lasers, solid state lasers, and excimer lasers.
What is difference between spontaneous and stimulated emission?
Spontaneous emission takes place without interaction with other photons, and the direction and phase are random. Stimulated emission takes place when the excited electron interacts with another photon.
Why laser is called stimulated emission?
The word laser is an acronym standing for “Light Amplification by Stimulated Emission of Radiation.” A laser beam is created from a substance known as an active medium, which when stimulated by light or electricity produces photons of a specific wavelength.
What is the difference between stimulated emission and population inversion?
Stimulated emission takes place only when the gain medium is pumped strongly enough and population inversion is created, while spontaneous emission takes place no matter population inversion exists or not.
Why are two photons emitted in stimulated emissions?
A single photon interacting with an excited atom can therefore result in two photons being emitted. If the emitted photons are viewed as a wave, the stimulated emission will oscillate at the incoming light’s frequency and be in phase (coherent), resulting in amplification of the original light wave’s intensity.
What stimulated absorption?
Stimulated absorption occurs when a photon strikes an atom with just exactly the proper energy to induce an electronic transition between two energy states.
What is meant by light amplification?
Light amplification is the process of intensifying the amplitude of an electromagnetic light wave. This process is generally classified into three major categories: laser, parametric and scattering.
Which scientist first came up with the idea of stimulated emission?
Albert Einstein
This process is called “stimulated emission.” Albert Einstein first broached the possibility of stimulated emission in a 1917 paper, having turned his attention the year before from general relativity to the interplay of matter and radiation, and how the two could achieve thermal equilibrium.