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Relationship between the refractive index and absorption

  1. Nov 14, 2013 #1

    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 :)
  2. jcsd
  3. Nov 14, 2013 #2


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    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.
    Last edited: Nov 14, 2013
  4. Nov 14, 2013 #3
    Ok, thank you.
  5. Nov 14, 2013 #4


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    Please give thanks by using the "thanks" button. :biggrin:
  6. Nov 14, 2013 #5


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    There is a relation between absorption and refractive index which is known as Kramers Kronig relation:
    However, to deduce the one from the other, you need to know the absorption or refractive index ideally for all frequencies.
  7. Nov 14, 2013 #6

    Andy Resnick

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    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.
  8. Nov 15, 2013 #7

    Claude Bile

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    The intensity-dependent component of the refractive index is known as the Kerr nonlinearity (real part) and saturable absorption (imaginary part).

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