Describe working principle of LASER.

Describe working principle of LASER.
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1 Answer

Answer :

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There are three main processes in semiconductors that are associated with light:

1. Light absorption

2. Spontaneous emission

3. Stimulated emission

Stimulated emission is different. A light photon entering the semiconductor lattice will strike an electron and release energy in the form of another light photon.

The way in which this occurs releases this new photon of identical wavelength and phase. In this way the light that is generated is said to be coherent.

This type of process is the basic principle on which LASER Diode operates.

Photon, with energy equal to E2 – E1 interacts with an atom in upper energy state, causing it to return to lower energy state with the emission of a second photon.

Second photon has the same phase, frequency and polarization as the first.

It is stimulated emission which gives LASER special properties such as narrow spectral width and coherent output radiation

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