What Is Negative Absorption Coefficient in Lasers?

In summary, a negative absorption coefficient is a measure of how much a material amplifies radiation passing through it instead of absorbing it. It is caused by stimulated emission and is commonly used in lasers, telecommunications, and medical imaging. A material can only have a negative absorption coefficient for a specific type of radiation, and it is typically measured using a spectrophotometer or calculated using refractive index and extinction coefficient.
  • #1
Rahul Manavalan
10
0
The fact that energy in a laser can propagate without much loss over long distances is quite shocking !
It's a renowned fact that energy is dissipated when propagation takes place through any medium...
(I'm fully aware that laser is an exception)
But I have quite a difficult time understanding the concept of negative absorption.
Is laser the only device that works on the principle or are there more?.??
 
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FAQ: What Is Negative Absorption Coefficient in Lasers?

What is a negative absorption coefficient?

A negative absorption coefficient is a measure of how much a material absorbs radiation per unit length. It indicates how quickly the intensity of radiation passing through the material decreases. A negative absorption coefficient means that the material actually amplifies the radiation passing through it, rather than absorbing it.

What causes a negative absorption coefficient?

A negative absorption coefficient is caused by a process called stimulated emission, where atoms in the material release energy in the form of radiation that is in phase with and adds to the incident radiation. This results in an increase in the intensity of the radiation passing through the material.

What are some applications of materials with a negative absorption coefficient?

Materials with a negative absorption coefficient are commonly used in lasers, where they act as gain media to amplify the laser beam. They also have applications in telecommunications, optical amplifiers, and medical imaging.

Can a material have a negative absorption coefficient for all types of radiation?

No, a material can only have a negative absorption coefficient for a specific type of radiation. For example, a material may have a negative absorption coefficient for infrared radiation, but a positive absorption coefficient for visible light.

How is a negative absorption coefficient measured?

A negative absorption coefficient is typically measured using a spectrophotometer, which measures the intensity of radiation before and after it passes through a material. The difference in intensity is used to calculate the absorption coefficient. Alternatively, it can also be calculated using the material's refractive index and extinction coefficient.

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