Tag Archives: laser

How does a laser work

One must have seen and if not seen then must have heard the term laser. But if you have seen the laser light emitting from a source, then there should be natural question how does a laser work? Therefore let … Continue reading

Posted in LASER | Tagged , , , , , | 4 Comments

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 achieved and maintained. For this, there must be a source of external energy, which can … Continue reading

Posted in LASER | Tagged , , | 3 Comments

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 laser medium is called active medium or active centre. Thus, due to this reason, the … Continue reading

Posted in LASER | Tagged , , | 2 Comments

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, we have solid state lasers like ruby laser,gas lasers like He-Ne laser and carbon dioxide … Continue reading

Posted in LASER | Tagged , , , | Leave a comment

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 lower state. The two states in between the population inversion occurs and laser is achieved, … Continue reading

Posted in LASER | Tagged , , | 1 Comment

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 the process of spontaneous emission, then it may be possible that N2 > N1. Where … Continue reading

Posted in LASER | Tagged , | 3 Comments

Stimulated Emission or Induced Emission

If the atom is in the excited state E2 and a photon of energy exactly equal to E2 – E1 = hυ is incident on it, then the incident photon interacts with the atom in the excited state and then … Continue reading

Posted in LASER | Tagged , , | 3 Comments

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 this process is called spontaneous emission. Generally an atom/electron in excited state can stay for … Continue reading

Posted in LASER | Tagged , | 4 Comments

Stimulated Absorption

When a photon of light having energy E2 – E1 = hυ is incident on an atom in the ground state, the atom in the ground state E1 may absorb the photon and jump to higher energy state E2. This … Continue reading

Posted in LASER | Tagged , , , | 2 Comments

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 divergent. But the divergence or angular spread of a laser is very small. 2. Monochromaticity: … Continue reading

Posted in LASER | Tagged , , | Leave a comment