Relationship between the refractive index and absorption

  1. 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 :)
     
  2. jcsd
  3. adjacent

    adjacent 1,536
    Gold Member

    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. Ok, thank you.
     
  5. adjacent

    adjacent 1,536
    Gold Member

    Please give thanks by using the "thanks" button. :biggrin:
     
  6. DrDu

    DrDu 4,421
    Science Advisor

    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.
     
  7. Andy Resnick

    Andy Resnick 5,968
    Science Advisor
    Education Advisor

    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. Claude Bile

    Claude Bile 1,479
    Science Advisor

    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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