Physics

LASER

Pumping Source

As we have discussed in the previously, that principle of laser is stimulated emission and for it to take place, population inversion has to be

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Active medium of laser

When energy is given to laser medium (solid, liquid or gas), then only a small fraction of laser medium shows lasing action. This part of

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Components of a Laser

Three main components of laser device are: a)      Active medium: For example in ruby laser, the active medium is aluminum oxide doped with .05 percent

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Types of laser

The lasers can be classified on the basis of state as explained below: a)      State of laser medium: According to the state of laser medium,

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Metastable State

It is also the excited state but having life time of 10-5 to 10-3 seconds. Population inversion occurs only in between the metastable state and

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Population Inversion in Lasers

Normally the population density of atoms/electrons is more in the ground state than the excited state. But if the process of stimulated emission dominates over

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Spontaneous Emission

If the atom in the excited state automatically decays to the ground state by emitting a photon of energy (E2 – E1 = hυ), then

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Stimulated Absorption in Laser

Stimulated Absorption is the starting point to achieve laser. It happens when a photon of light having energy E2 – E1 = hυ (as shown

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Characteristics of Laser beam

A laser beam has the following important characteristics: 1. Directionality: An ordinary source of light emits light waves in all the directions and is highly

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