LASER & its Characteristics

LASER which you had been hearing about from many years is an abbreviation for

Light Amplification by Stimulated Emission of Radiation

The following are the characteristics of the laser that differentiate it with the rest of the light sources.

Characteristics of Laser

• Coherence
• Directionality
• Monochromatic
• High intensity

Coherence

We know that visible light is emitted when excited electrons (electrons in higher energy levels) jumped into the lower energy level (ground state). The process of electrons moving from higher energy level to lower energy level or lower energy level to higher energy level is called electron transition.

In ordinary light sources, the electron transition occurs naturally. In other words, electron transition in ordinary light sources is random in time. The photons emitted from ordinary light sources have different energies, frequencies, wavelengths, or colors. Hence, the light waves of ordinary light sources have many wavelengths. Therefore, photons emitted by an ordinary light source are out of phase.

In laser, the electron transition occurs artificially. In other words, in laser, electron transition occurs at a specific time. All the photons emitted in laser have the same energy, frequency, or wavelength. Hence, the light waves of laser light have a single wavelength or color. Therefore, the wavelengths of the laser light are in phase in space and time. In laser, a technique called stimulated emission is used to produce light.

Thus, light generated by the laser is highly coherent. Because of this coherence, a large amount of power can be concentrated in a narrow space.

Directionality

In conventional light sources (lamp, sodium lamp and torchlight), photons will travel in a random direction. Therefore, these light sources emit light in all directions.

On the other hand, in laser, all photons will travel in the same direction. Therefore, the laser emits light only in one direction. This is called the directionality of laser light. The width of a laser beam is extremely narrow. Hence, a laser beam can travel to long distances without spreading.

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Monochromatic

Monochromatic light means a light containing a single color or wavelength. The photons emitted from ordinary light sources have different energies, frequencies, wavelengths, or colors. Hence, the light waves of ordinary light sources have many wavelengths or colors. Therefore, ordinary light is a mixture of waves having different frequencies or wavelengths.

On the other hand, in laser, all the emitted photons have the same energy, frequency, or wavelength. Hence, the light waves of laser have a single wavelength or color. Therefore, laser light covers a very narrow range of frequencies or wavelengths.

High Intensity

You know that the intensity of a wave is the energy per unit time flowing through a unit normal area. In an ordinary light source, the light spreads out uniformly in all directions.

#Credits- https://www.quora.com/What-are-the-characteristics-of-a-laser