Relationship between the refractive index and absorption

AI Thread Summary
The discussion centers on the relationship between the refractive index of materials and their light absorption properties. It clarifies that while the refractive index does not directly correlate with light intensity, there is a connection between absorption and refractive index through the Kramers-Kronig relation. The refractive index can be expressed as a complex value, where the real part represents refraction and the imaginary part indicates absorption. Additionally, intensity-dependent effects such as Kerr nonlinearity and saturable absorption are mentioned. Understanding these relationships can aid in geological thin section observations.
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Hello,

I was wondering is there a relation between the refractive index of the material and the amount of light the material absorbs (e.g. the higher n means higher absorption)? If so what is then a relation between the intensity of the light and the refractive index?

p.s. I am trying to apply this to some geological thin section observations, thus a simple explanation would be appreciated.

Thank you :)
 
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asdfghhjkl said:
Hello,

I was wondering is there a relation between the refractive index of the material and the amount of light the material absorbs (e.g. the higher n means higher absorption)? If so what is then a relation between the intensity of the light and the refractive index?

p.s. I am trying to apply this to some geological thin section observations, thus a simple explanation would be appreciated.

Thank you :)
There is no relation between the intensity of light and the refractive index.Refractive index depends on the speed of light through the medium.It varies with wavelength too.
 
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Ok, thank you.
 
asdfghhjkl said:
Ok, thank you.
Please give thanks by using the "thanks" button. :biggrin:
 
There is a relation between absorption and refractive index which is known as Kramers Kronig relation:
http://www.rp-photonics.com/kramers_kronig_relations.html
However, to deduce the one from the other, you need to know the absorption or refractive index ideally for all frequencies.
 
asdfghhjkl said:
Hello,

I was wondering is there a relation between the refractive index of the material and the amount of light the material absorbs (e.g. the higher n means higher absorption)? If so what is then a relation between the intensity of the light and the refractive index?

Echoing DrDu, absorption is often modeled by allowing the refractive index to be complex-valued (say n = η + iκ) the real part η is the 'refractive' component and the imaginary part κ the 'absorption' component. The components are not independent but related through the Kramers-Kronig relation.
 
The intensity-dependent component of the refractive index is known as the Kerr nonlinearity (real part) and saturable absorption (imaginary part).

Claude.
 
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