# Refractive index(n(ω)) calculation: Kramers-Kronig relations

1. Feb 19, 2011

### ddhirhe

I try to calculate refractive index of experimental spectral data using Kramers-Kronig relations but didn’t succeed. I need your expert advice and help to solve this problem.
Data and expression for KK relation is give in worksheet, where alpha(omwga) is in cm-1. Solution through Matlab or Origin is more helpful for me since I am familiar with this two software.

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• ###### refrective index.xls
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Last edited: Feb 19, 2011
2. Jun 8, 2011

### singhvi

You need to look at the fourier transform method to evaluate hilbert transforms, as the Kronig Kramers transform is nothing but the Hilbert transform. Look it up. There's also a matlab function 'hilbert' for hilbert transform of discrete data.

I have used it myself and it works pretty well

3. Jun 9, 2011

### ddhirhe

Yes, KK relation is the Hilbert transform and no need to write complected program for KK relation in Matlab.

Cheers

Devnath

4. Jan 12, 2012

### Ravian

can you please give details of the steps you have taken to solve your problem. I am facing similar problem, I have n, k values and by using KK want to extrapolate to higher and especially lower energies.
thank

5. Jan 31, 2012

### aminm0a

I want to evaluate refractive index from experimental data using KKR relation. As the data is limited to a finite spectrum, it is difficult to reduce errors related to infinite spectrum integration in KKR.

The calculated hilbert transform directly on 'absorption coefficient' data but it did not make any sense. Can you please elaborate on Hilbert transform in matlab to solve KKR relations.

Thanks,
Amin

6. Jan 31, 2012

### singhvi

That is the kind of stuff I get paid for. :) Can't just give out all the details of the program for free.

7. Jul 6, 2012

### selpira

I have Absortion data vs wavelength. I want to evaluate the refractive index using matlab or origin but I did not success..I use hilbert transform but after that I dont know how to manage the refractive index from these data. Please help!!!